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Phenotypic plasticity refers to changes expressed by a genotype across different environments and is one of the major means by which plants cope with environmental variability. Multi-fold differences in phenotypic plasticity have been noted across crops, with wild ancestors and landraces being more plastic than crops when under stress. Plasticity in response to abiotic stress adaptation, plant architecture, physio-reproductive and quality traits are multi-genic (QTL). Plasticity QTL (pQTL) were either collocated with main effect QTL and QEI (QTL × environment interaction) or located independently from the main effect QTL. For example, variations in root plasticity have been successfully introgressed to enhance abiotic stress adaptation in rice. The independence of genetic control of a trait and of its plasticity suggests that breeders may select for high or low plasticity in combination with high or low performance of economically important traits. Trait plasticity in stressful environments may be harnessed through breeding stress-tolerant crops. There exists a genetic cost associated with plasticity, so a better understanding of the trade-offs between plasticity and productivity is warranted prior to undertaking breeding for plasticity traits together with productivity in stress environments. Phenotypic plasticity refers to changes expressed by a genotype across different environments and is one of the major means by which plants cope with environmental variability. Mull-fold differences in phenotypic plasticity have been noted across crops, with wild ancestors and landraces being more plastic than crops when under stress. Plasticity in response to abiotic stress adaptation, plant architecture, physio-reproductive and quality traits are multi-genic (QTL). Plasticity QTL (pQTL) were either collocated with main effect QTL and QEI (QTL x environment interaction) or located independently from the main effect QTL. For example, variations in root plasticity have been successfully introgressed to enhance abiotic stress adaptation in rice. The independence of genetic control of a trait and of its plasticity suggests that breeders may select for high or low plasticity in combination with high or low performance of economically important traits. Trait plasticity in stressful environments may be harnessed through breeding stress-tolerant crops. There exists a genetic cost associated with plasticity, so a better understanding of the trade-offs between plasticity and productivity is warranted prior to undertaking breeding for plasticity traits together with productivity in stress environments.

Crop production in Sub-Saharan Africa (SSA) is constrained by rainfall variability and declining soil fertility. This has over time led to a decrease in crop yield, among them also maize. This decrease is also experienced in the sub-humid and semi-arid locations of Kenya. Among the commonly used soil and water management practices in SSA are Conservation Agriculture (CA) and integrated soil fertility management (ISFM). Crop response to these management practices is influenced by the existence of soil fertility gradients which are common among smallholder farmers. This paper presents results from a study done in the sub-humid and semi-arid location of Kenya, focusing on the effects of CA- and/or ISFM-based practices on maize yield. Trials were set out on farms within the two locations using a one farm one replicate randomized design. In each farm, CA-based treatment, no tillage with residue retention (NTR), ISFM-based treatment, conventional tillage with use of manure (CTM), a combination of CA + ISFM, no tillage with residue retention and use of manure (NTRM) and a control, (C) were laid down on fields representing high and low fertility soils. The trials started in the long rains of 2017 (LR2017) running for four seasons i.e., LR2017, short rains 2017 (SR2017), long rains 2018 (LR2018) and short rains 2018 (SR2018). Soil water content (SWC) and nitrogen use efficiency (NUE) were also monitored and evaluated. In either high or low fertility fields, maize grain yield was significantly different between the control and both NTR, CTM and NTRM with no significant differences between NTR, CTM and NTRM. Maize grain yield increase compared to the control was highest under ISFM in the low fertility fields in both locations and all seasons. For example, during the last season, SR2018, NTR, CTM and NTRM significantly increased maize grain yield by 136 %, 297 %, and 208 %, respectively, compared to the control, in the low fertility fields of sub-humid Kibugu. In the semi-arid Machang’a, the increase by NTR, CTM and NTRM, respectively, in the low fertility fields was 146 %, 379 % and 183 % for SR2018. This was linked to the tendency of ISFM to improve crop yield in the short run. For both locations, SWC and NUE were highest under NTR. In the sub-humid Kibugu, during SR2018, at the grain filling stage, 78 days after sowing, SWC under NTR, CTM and NTRM was higher by 16 %, 9 % and 20 %, respectively, compared to the control. Also at 78 days after sowing, in the semi-arid Machang’a, SWC was 18 %, 7 % and 15 % significantly higher under NTR, CTM and NTRM, respectively, compared to the control. The higher SWC observed under NTR and NTRM was related to no tillage with residue retention while under CTM it was related to improved soil organic matter through manure addition. NUE, on the other hand, was 26 % and 23 % in Kibugu and Machang’a, respectively, and lowest under the combined practice (NTRM), i.e., 19 % and 15 % in Kibugu and Machang’a, respectively. The high NUE under CA was attributed to the placement of urea in the planting holes while maintaining residue on the soil surface. The low NUE under NTRM was linked to fertilizer N immobilization. Lastly, from the biomass yield, our study showed that monocrop maize under NTR requires a kick-starting by an ISFM-based practice in the low fertility fields of the semi-arid region.

Fecal sludge (FS) contains a significant amount of plant nutrients. FS (treated/untreated) has been used as soil ameliorant in several countries. Use of FS-based compost on lettuce may meet reservations due to possible microbiological contamination. The objectives of this research are: (1) To determine the fertilizer value of different formulations of sawdust and fecal sludge compost (SDFS) pellets, and (2) to compare the effect of these SDFS formulations with poultry manure, commercial compost, mineral fertilizer, and non-fertilization on lettuce cultivation. The SDFS products were made by enriching, and pelletized with ammonium sulphate, mineral-NPK, or ammonium sulphate + muriate of potash + triple superphosphate. Lettuce was cultivated in a greenhouse and an open field. The result showed that the saleable fresh weight lettuce yield obtained from all SDFS pellets with/without enrichments were higher than those obtained from commercial compost, poultry manure, mineral fertilizer, or no fertilizer. Cultivation in the open field gave higher yields than those in the greenhouse. No helminth eggs were detected in composts or lettuces. Some fecal coliforms were detected in lettuces fertilized with almost all fertilizers tested, including NPK and non-fertilized control. A properly treated fecal sludge-based fertilizer can be a sustainable solution for lettuce production, which helps urban and peri-urban agriculture.

Carbon exchange over croplands plays an important role in the European carbon cycle over daily to seasonal time scales. A better description of this exchange in terrestrial biosphere models-most of which currently treat crops as unmanaged grasslands-is needed to improve atmospheric CO2 simulations. In the framework we present here, we model gross European cropland CO2 fluxes with a crop growth model constrained by grain yield observations. Our approach follows a two-step procedure. In the first step, we calculate day-to-day crop carbon fluxes and pools with the WOrld FOod STudies (WOFOST) model. A scaling factor of crop growth is optimized regionally by minimizing the final grain carbon pool difference to crop yield observations from the Statistical Office of the European Union. In a second step, we re-run our WOFOST model for the full European 25 x 25 km gridded domain using the optimized scaling factors. We combine our optimized crop CO2 fluxes with a simple soil respiration model to obtain the net cropland CO2 exchange. We assess our model's ability to represent cropland CO2 exchange using 40 years of observations at seven European FluxNet sites and compare it with carbon fluxes produced by a typical terrestrial biosphere model. We conclude that our new model framework provides a more realistic and strongly observation-driven estimate of carbon exchange over European croplands. Its products will be made available to the scientific community through the ICOS Carbon Portal and serve as a new cropland component in the CarbonTracker Europe inverse model.

In modern agriculture, seeking eco-friendly ways to promote plant growth and enhance crop productivity is of priority. Biostimulants are a group of substances from natural origin that contribute to boosting plant yield and nutrient uptake, while reducing the dependency on chemical fertilizers. Developing biostimulants from by-products paves the path to waste recycling and reduction, generating benefits for growers, food industry, registration and distribution companies, as well as consumers. The criteria to select designated by-products for valorizing as biostimulant are: absence of pesticide residue, low cost of collection and storage, sufficient supply and synergy with other valorization paths. Over the years, projects on national and international levels such as NOSHAN, SUNNIVA, and Bio2Bio have been initiated (i) to explore valorization of by-products for food and agriculture industries; (ii) to investigate mode of action of biostimulants from organic waste streams. Several classes of waste-derived biostimulants or raw organic material with biostimulant components were shown to be effective in agriculture and horticulture, including vermicompost, composted urban waste, sewage sludge, protein hydrolysate, and chitin/chitosan derivatives. As the global market for biostimulants continues to rise, it is expected that more research and development will expand the list of biostimulants from by-products. Global nutrient imbalance also requires biostimulant to be developed for targeted market. Here, we review examples of biostimulants derived from agricultural by-products and discuss why agricultural biomass is a particularly valuable source for the development of new agrochemical products.

Research in maize is often performed using inbred lines that can be readily transformed, such as B104. However, because the B104 line flowers late, the kernels do not always mature before the end of the growing season, hampering routine seed yield evaluations of biotech traits introduced in B104 at many geographical locations. Therefore, we generated five hybrids by crossing B104 with the early-flowering inbred lines CML91, F7, H99, Mo17, and W153R and showed in three consecutive years that the hybrid lines proved to be suitable to evaluate seed yield under field conditions in a temperate climate. By assessing the two main processes driving maize leaf growth, being rate of growth (leaf elongation rate or LER) and the duration of growth (leaf elongation duration or LED) in this panel of hybrids, we showed that leaf growth heterosis was mainly the result of increased LER and not or to a lesser extent of LED. Ectopic expression of the transgenes GA20-oxidase (GA20-OX) and PLASTOCHRON1 (PLA1), known to stimulate the LER and LED, respectively, in the hybrids showed that leaf length heterosis can be stimulated by increased LER, but not by LED, indicating that LER rather than LED is the target for enhancing leaf growth heterosis. To enable transgenic maize research, hybrids between the inbred B104 that can be routinely transformed and early flowering inbreds were evaluated for yield components in three consecutive years. In addition, we show that leaf elongation rate is the main contributor to leaf growth heterosis in these hybrids, which can even be stimulated by overexpressing GA20OXIDASE, a known regulator of leaf elongation rate. Although leaf elongation duration has a limited contribution to the growth heterosis, the effect of the ectopic expression of PLASTOCHRON1, known to enhance leaf elongation duration and leaf growth, is still observed in the hybrids. This detailed understanding of the growth processes driving heterosis will be key to further breed for high yielding hybrids.

Summary Increased biomass yield and quality are of great importance for the improvement of feedstock for the biorefinery. For the production of bioethanol, both stem biomass yield and the conversion efficiency of the polysaccharides in the cell wall to fermentable sugars are of relevance. Increasing the endogenous levels of gibberellic acid (GA) by ectopic expression of GA20‐OXIDASE1 (GA20‐OX1), the rate‐limiting step in GA biosynthesis, is known to affect cell division and cell expansion, resulting in larger plants and organs in several plant species. In this study, we examined biomass yield and quality traits of maize plants overexpressing GA20‐OX1 (GA20‐OX1). GA20‐OX1 plants accumulated more vegetative biomass than control plants in greenhouse experiments, but not consistently over two years of field trials. The stems of these plants were longer but also more slender. Investigation of GA20‐OX1 biomass quality using biochemical analyses showed the presence of more cellulose, lignin and cell wall residue. Cell wall analysis as well as expression analysis of lignin biosynthetic genes in developing stems revealed that cellulose and lignin were deposited earlier in development. Pretreatment of GA20‐OX1 biomass with NaOH resulted in a higher saccharification efficiency per unit of dry weight, in agreement with the higher cellulose content. On the other hand, the cellulose‐to‐glucose conversion was slower upon HCl or hot‐water pretreatment, presumably due to the higher lignin content. This study showed that biomass yield and quality traits can be interconnected, which is important for the development of future breeding strategies to improve lignocellulosic feedstock for bioethanol production.

The use of positioned mineral fertilizer phosphorus (P) starters reduces the risk of yield penalties in maize production. However, it also increases the soil P surplus and attendant risk of P losses to the environment, in particular on farms with ample supplies of livestock manures. We examined whether routine applications of starter P can be refrained from if manure is injected in subsurface bands close to the anticipated position of the maize rows as an alternative to the conventional even injection at random lateral positions relative to the rows. Fourteen field experiments were executed on sandy soils in The Netherlands. In these experiments comparisons were made of the nitrogen (N) and P-concentrations in shoots and of dry matter (DM), N and P-yields over time, between evenly injected liquid manure (with and without starter P) and band-injected liquid manure. Silage yields of DM, N and P generally responded positively (P

Food security in Sub-Saharan Africa, particularly in semi-arid tropics (41% of the region; 6 months of dry season) is threatened by droughts, dry spells and infertile soils. In Zimbabwe, 74% of smallholder farming areas are located in semi-arid areas mostly in areas with soils of low fertility and water holding capacity. The dominant crop in these areas, maize (Zea mays L.), is susceptible to drought. Under smallholder farming in Zimbabwe, conventional tillage entails cutting and turning the soil with a mouldboard plough thereby burying weeds and crop residues. Seed is planted by hand into a furrow made by the plough, ensuring that crops germinate in relatively weed free seedbeds. Inter-row weed control is performed using the plough or ox-drawn cultivators and hand hoes. Conventional tillage has been criticised for failure to alleviate negative effects of long dry spells on crops and to combat soil loss caused by water erosion estimated at 50 to 80 t ha-1 yr-1. Therefore, conservation tillage has been explored for improving soil and water conservation and crop yields. Our objective was to determine the maize yield advantage of the introduced technology (conservation tillage) over conventional tillage (farmers’ practice) based on a review of experiments in semi-arid Zimbabwe. We use a broad definition of conservation tillage instead of the common definition of =30% cover after planting. Eight tillage experiments conducted between 1984 and 2008 were evaluated. Conventional tillage included ploughing using the mouldboard plough and digging using a hand hoe. Conservation tillage included tied ridging (furrow diking), mulch ripping, clean ripping and planting pits. Field-edge methods included bench terraces (fanya juus) and infiltration pits. Results showed small yield advantages of conservation tillage methods below 500 mm rainfall. For grain yields =2.5 t ha-1 and rainfall =500 mm, 1.0 m tied ridging produced 144 kg ha-1 and mulch ripping 344 kg ha-1 more than conventional tillage. Above 2.5 t ha-1 and for rainfall >500 mm, conventional tillage had =640 kg ha-1 yield advantage. Planting pits had similar performance to ripping and conventional tillage but faced digging labour constraints. Experiments and modelling are required to test conservation tillage seasonal rainfall thresholds. Constraints to adoption of conservation tillage by smallholder farmers necessitate best agronomic practices under conventional tillage while work on adoption of alternative tillage methods continues.

Aims Dianthus caryophyllus is a commercially important ornamental flower. Plant growth promoting rhizobacteria are increasingly applied as bio-fertilisers and bio-fortifiers. We studied the effect of a rhizospheric isolate Klebsiella SGM 81 strain to promote D. caryophyllus growth under sterile and non-sterile conditions, to colonise its root system endophytically and its impact on the cultivatable microbial community. We identified the auxin indole-3-acetic acid (IAA) production of Klebsiella SGM 81 as major bacterial trait most likely to enhance growth of D. caryophyllus. Methods ipdC dependent IAA production of SGM 81 was quantified using LC-MS/MS and localised proximal to D. caryophyllus roots and correlated to root growth promotion and characteristic morphological changes. SGM 81 cells were localised on and within the plant root using 3D rendering confocal microscopy of gfp expressing SGM 81. Using Salkowski reagent IAA production was quantified and localised proximal to roots in situ. The effect of different bacterial titres on rhizosphere bacterial population was CFU enumerated on nutrient agar. The genome sequence of Klebsiella SGM 81 (accession number PRJEB21197) was determined to validate PGP traits and phylogenic relationships. Results Inoculation of D. caryophyllus roots with Klebsiella SGM 81 drastically promoted plant growth when grown in agar and soil, concomitant with a burst in root hair formation, suggesting an increase in root auxin activity. We sequenced the Klebsiella SGM 81 genome, identified the presence of a canonical ipdC gene in Klebsiella SGM 81, confirmed bacterial production and secretion of IAA in batch culture using LC-MS/MS and localised plant dependent IAA production by SGM 81 proximal to roots. We found Klebsiella SGM 81 to be a rhizoplane and endophytic coloniser of D. caryophyllus roots in a dose dependent manner. We found no adverse effects of SGM 81 on the overall rhizospheric microbial population unless supplied to soil in very high titres. Conclusion Klebsiella SGM 81 effectively improves root traits of D. caryophyllus in a dose dependent manner, likely through tryptophan dependent IAA production in the rhizoplane and potentially within the intercellular spaces of root tissue. Under optimal plant growth promoting conditions in non-sterile soil, the high total microbial titre in the rhizosphere supports a mutualistic relationship between Klebsiella SGM 81 and carnation that potentially extends to the wider rhizosphere microbiota. Electronic supplementary material The online version of this article (10.1007/s11104-017-3440-5) contains supplementary material, which is available to authorized users.

Carbon exchange over croplands plays an important role in the European carbon cycle over daily to seasonal time scales. A better description of this exchange in terrestrial biosphere models-most of which currently treat crops as unmanaged grasslands-is needed to improve atmospheric CO2 simulations. In the framework we present here, we model gross European cropland CO2 fluxes with a crop growth model constrained by grain yield observations. Our approach follows a two-step procedure. In the first step, we calculate day-to-day crop carbon fluxes and pools with the WOrld FOod STudies (WOFOST) model. A scaling factor of crop growth is optimized regionally by minimizing the final grain carbon pool difference to crop yield observations from the Statistical Office of the European Union. In a second step, we re-run our WOFOST model for the full European 25 x 25 km gridded domain using the optimized scaling factors. We combine our optimized crop CO2 fluxes with a simple soil respiration model to obtain the net cropland CO2 exchange. We assess our model's ability to represent cropland CO2 exchange using 40 years of observations at seven European FluxNet sites and compare it with carbon fluxes produced by a typical terrestrial biosphere model. We conclude that our new model framework provides a more realistic and strongly observation-driven estimate of carbon exchange over European croplands. Its products will be made available to the scientific community through the ICOS Carbon Portal and serve as a new cropland component in the CarbonTracker Europe inverse model.

Ribosome-inactivating proteins (RIPs) are a class of cytotoxic enzymes that can depurinate rRNAs thereby inhibiting protein translation. Although these proteins have also been detected in bacteria, fungi, and even some insects, they are especially prevalent in the plant kingdom. This review focuses on the RIPs from cereals. Studies on the taxonomical distribution and evolution of plant RIPs suggest that cereal RIPs have evolved at an enhanced rate giving rise to a large and heterogeneous RIP gene family. Furthermore, several cereal RIP genes are characterized by a unique domain architecture and the lack of a signal peptide. This advanced evolution of cereal RIPs translates into distinct structures, activation mechanisms, and physiological roles. Several cereal RIPs are characterized by activation mechanisms that include the proteolytic removal of internal peptides from the N-glycosidase domain, a feature not documented for non-cereal RIPs. Besides their role in defense against pathogenic fungi or herbivorous insects, cereal RIPs are also involved in endogenous functions such as adaptation to abiotic stress, storage, induction of senescence, and reprogramming of the translational machinery. The unique properties of cereal RIPs are discussed in this review paper.

Mycotoxins including aflatoxins, deoxynivalenol, fumonisins and ochratoxin A are among the main fungal secondary metabolites detected as natural contaminants in South America in different commodities such as peanuts (aflatoxins), cereals (deoxynivalenol and fumonisins) or grapes (ochratoxin A). Different strategies including crop rotation, tillage practices, fungicide application and planting less susceptible cultivars are used in order to reduce the impact of these mycotoxins in both food and feed chains. The development of fungicide resistance in many fungal pathogens as well as rising of public concern on the risks associated with pesticide use led to the search for alternative environmentally friendly methods. Biological control of plant pathogens and toxigenic fungi offers an alternative that can complement chemical control in the frame of an integrated pest management to reduce the impact of mycotoxins in the food and feed chains. The advances made in Argentina on reducing the impact of toxigenic fungi and mycotoxins in peanut, grapes and cereals using the biocontrol strategy are summarised. Native bacteria, yeasts and filamentous fungi have been selected to evaluate them as potential biocontrol agents. Field trials showed that Bacillus subtilis RC 218 and Brevibacillus sp. RC 263 were effective at reducing deoxynivalenol accumulation in wheat. The application of Clonostachys rosea isolates on wheat stubble reduced Fusarium colonisation on the stubble. Bacillus amyloliquefaciens and Microbacterium oleovorans showed good activity to control both Fusarium verticillioides growth and the accumulation of fumonisins at pre-harvest stage in maize. Control of toxigenic Aspergillus flavus and aflatoxin accumulation in peanuts was achieved using a native atoxigenic Aspergillus flavus strain based on competitive exclusion of the toxigenic strains. Kluyveromyces thermotolerans strains were used as biocontrol agents to reduce the impact of Aspergillus section Nigri and ochratoxin A accumulation in grapes. Fil: Chulze, Sofia Noemi. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Microbiología e Inmunología. Cátedra de Micología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina Fil: Palazzini, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Microbiología e Inmunología. Cátedra de Micología; Argentina Fil: Torres, Adriana Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Microbiología e Inmunología. Cátedra de Micología; Argentina Fil: Barros, Germán Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Microbiología e Inmunología. Cátedra de Micología; Argentina Fil: Ponsone, Maria Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Instituto Nacional de Tecnología Agropecuaria; Argentina Fil: Geisen, R.. Max Rubner-Institut; Alemania Fil: Schmidt Heydt, M.. Max Rubner-Institut; Alemania Fil: Köhl, J.. Wageningen UR. Plant Research International, Wageningen; Países Bajos

Mixed cropping is practised widely in developing countries and is gaining increasing interest for sustainable agriculture in developed countries. Plants in intercrops grow differently from plants in single crops, due to interspecific plant interactions, but adaptive plant morphological responses to competition in mixed stands have not been studied in detail. Here the maize (Zea mays) response to mixed cultivation with wheat (Triticum aestivum) is described. Evidence is provided that early responses of maize to the modified light environment in mixed stands propagate throughout maize development, resulting in different phenotypes compared with pure stands. Photosynthetically active radiation (PAR), red:far-red ratio (R:FR), leaf development, and final organ sizes of maize grown in three cultivation systems were compared: pure maize, an intercrop with a small distance (25 cm) between maize and wheat plants, and an intercop with a large distance (44 cm) between the maize and the wheat. Compared with maize in pure stands, maize in the mixed stands had lower leaf and collar appearance rates, increased blade and sheath lengths at low ranks and smaller sizes at high ranks, increased blade elongation duration, and decreased R:FR and PAR at the plant base during early development. Effects were strongest in the treatment with a short distance between wheat and maize strips. The data suggest a feedback between leaf initiation and leaf emergence at the plant level and coordination between blade and sheath growth at the phytomer level. A conceptual model, based on coordination rules, is proposed to explain the development of the maize plant in pure and mixed stands.

Farmers in China have gradually increased plant density in maize to achieve higher yields, but this has increased risk of lodging due to taller and weaker stems at higher plant densities. Plant growth regulators can be used to reduce lodging risk. In this study, for the first time, the performance of a mixture of the plant growth regulators ethephon and diethyl aminoethyl hexanoate (DA-6), called EDAH is tested at different plant densities and in different cultivars. Grain yield, yield components and grain quality as well as plant height and lodging percentage were determined in two years (2012 and 2013), using two maize hybrids, ZD 958 and Pioneer 335 at densities of 4.5, 6.0, 7.5 and 9.0 plants m−2 with and without foliar application of EDAH at 7 expanded leaves stage. EDAH significantly increased grain yield (by 7.8–8.0%), kernel number per ear (by 2.9–4.0%) and 1000-kernel weight (by 3.3–5.1%). Lodging percentage increased with plant density and was decreased by EDAH application in 2013. Optimal density was 7.5 plants m−2. The number of ears per unit ground area increased linearly with plant density, but number of kernels per ear and kernel weight showed an optimum. The two tested cultivars differed in yield and quality. No effects of EDAH on grain quality parameters (protein, oil and starch content) were found. We conclude that EDAH can improve lodging resistance and yield in maize, and that the yield effect of EDAH also occurs if lodging is not reduced.

Reliable quantitative methods are needed to comply with current EU regulations on the mandatory labeling of genetically modified organisms (GMOs) and GMO-derived food and feed products with a minimum GMO content of 0.9 %. The implementation of EU Commission Recommendation 2004/787/EC on technical guidance for sampling and detection which meant as a helpful tool for the practical implementation of EC Regulation 1830/2003, which states that "the results of quantitative analysis should be expressed as the number of target DNA sequences per target taxon specific sequences calculated in terms of haploid genomes". This has led to an intense debate on the type of calibrator best suitable for GMO quantification. The main question addressed in this review is whether reference materials and calibrators should be matrix based or whether pure DNA analytes should be used for relative quantification in GMO analysis. The state of the art, including the advantages and drawbacks, of using DNA plasmid (compared to genomic DNA reference materials) as calibrators, is widely described. In addition, the influence of the genetic structure of seeds on real-time PCR quantitative results obtained for seed lots is discussed. The specific composition of a seed kernel, the mode of inheritance, and the ploidy level ensure that there is discordance between a GMO % expressed as a haploid genome equivalent and a GMO % based on numbers of seeds. This means that a threshold fixed as a percentage of seeds cannot be used as such for RT-PCR. All critical points that affect the expression of the GMO content in seeds are discussed in this paper.

Leaves are vital organs for biomass and seed production because of their role in the generation of metabolic energy and organic compounds. A better understanding of the molecular networks underlying leaf development is crucial to sustain global requirements for food and renewable energy. Here, we combined transcriptome profiling of proliferative leaf tissue with in-depth phenotyping of the fourth leaf at later stages of development in 197 recombinant inbred lines of two different maize (Zea mays) populations. Previously, correlation analysis in a classical biparental mapping population identified 1,740 genes correlated with at least one of 14 traits. Here, we extended these results with data from a multiparent advanced generation intercross population. As expected, the phenotypic variability was found to be larger in the latter population than in the biparental population, although general conclusions on the correlations among the traits are comparable. Data integration from the two diverse populations allowed us to identify a set of 226 genes that are robustly associated with diverse leaf traits. This set of genes is enriched for transcriptional regulators and genes involved in protein synthesis and cell wall metabolism. In order to investigate the molecular network context of the candidate gene set, we integrated our data with publicly available functional genomics data and identified a growth regulatory network of 185 genes. Our results illustrate the power of combining in-depth phenotyping with transcriptomics in mapping populations to dissect the genetic control of complex traits and present a set of candidate genes for use in biomass improvement.

Plant oils have so far been mostly directed toward food and feed production. Nowadays however, these oils are more and more used as competitive alternatives to mineral hydrocarbon-based products. This increasing demand for vegetable oils has led to a renewed interest in elucidating the metabolism of storage lipids and its regulation in various plant systems. Cereal grains store carbon in the form of starch in a large endosperm and as oil in an embryo of limited size. Complementary studies on kernel development and metabolism have paved the way for breeding or engineering new varieties with higher grain oil content. This could be achieved either by increasing the relative proportion of the oil-rich embryo within the grain, or by enhancing oil synthesis and accumulation in embryonic structures. For instance, diacylglycerol acyltransferase (DGAT) that catalyses the ultimate reaction in the biosynthesis of triacylglycerol appears to be a promising target for increasing oil content in maize embryos. Similarly, over-expression of the maize transcriptional regulators ZmLEAFY COTYLEDON1 and ZmWRINKLED1 efficiently stimulates oil accumulation in the kernels of transgenic lines. Redirecting carbon from starch to oil in the endosperm, though not yet realized, is discussed. (C) 2011 Elsevier Ireland Ltd. All rights reserved.

Scales in transport of water to roots are compared with the length and volume scales by using the concepts associated with the representative elementary volume (REV). The possibility of a mismatch between model scale and system scale when using a Darcy-Buckingham-based model to describe soil water transport to a single root is evaluated. In the absence of a mismatch, the replication requirements for evaluating the Darcy-Buckingham-based model near a single root are discussed by using a synthesis of the elementary scales involved, including those for soil, plant and roots, and of the measurement device. By using REV scales from lattice-Boltzmann simulations, the effective half-root mean distance and the available measurement techniques, the evaluation of Darcy-based single root uptake models is possible in roughly 50% of the combinations of soil- and root-system properties. On the basis of an assessment of the scale characterizing natural soil variability, the number of replicates required to assess the average root water uptake profile near a single root is large, and either requires miniaturization of the measurement methods for the hydraulic transport characteristics, or very homogeneous (artificial) growing media with little variability. Variability of water uptake per unit root length will increase the number of samples required.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; An integrated consensus genetic map for apple was constructed on the basis of segregation data from four genetically connected crosses (C1 = Discovery x TN10-8, C2 = Fiesta x Discovery, C3 = Discovery x Prima, C4 = Durello di Forli x Fiesta) with a total of 676 individuals using CarthaGene(R) software. First, integrated female-male maps were built for each population using common female-male simple sequence repeat markers (SSRs). Then, common SSRs over populations were used for the consensus map integration. The integrated consensus map consists of 1,046 markers, of which 159 are SSR markers, distributed over 17 linkage groups reflecting the basic chromosome number of apple. The total length of the integrated consensus map was 1,032 cM with a mean distance between adjacent loci of 1.1 cM. Markers were proportionally distributed over the 17 linkage groups (chi(2) = 16.53, df = 16, p = 0.41). A non-uniform marker distribution was observed within all of the linkage groups (LGs). Clustering of markers at the same position (within a 1-cM window) was observed throughout LGs and consisted predominantly of only two to three linked markers. The four integrated female-male maps showed a very good colinearity in marker order for their common markers, except for only two (CH01h01, CH05g03) and three (CH05a02z, NZ02b01, Lap-1) markers on LG17 and LG15, respectively. This integrated consensus map provides a framework for performing quantitative trait locus (QTL) detection in a multi-population design and evaluating the genetic background effect on QTL expression

Background: To sustain the global requirements for food and renewable resources, unraveling the molecular networks underlying plant growth is becoming pivotal. Although several approaches to identify genes and networks involved in final organ size have been proven successful, our understanding remains fragmentary. Results: Here, we assessed variation in 103 lines of the Zea mays B73xH99 RIL population for a set of final leaf size and whole shoot traits at the seedling stage, complemented with measurements capturing growth dynamics, and cellular measurements. Most traits correlated well with the size of the division zone, implying that the molecular basis of final leaf size is already defined in dividing cells of growing leaves. Therefore, we searched for association between the transcriptional variation in dividing cells of the growing leaf and final leaf size and seedling biomass, allowing us to identify genes and processes correlated with the specific traits. A number of these genes have a known function in leaf development. Additionally, we illustrated that two independent mechanisms contribute to final leaf size, maximal growth rate and the duration of growth. Conclusions: Untangling complex traits such as leaf size by applying in-depth phenotyping allows us to define the relative contributions of the components and their mutual associations, facilitating dissection of the biological processes and regulatory networks underneath.

Cadmium (Cd) is a toxic, biologically non-essential and highly mobile metal that has become an increasingly important environmental hazard to both wildlife and humans. In contrast to conventional remediation technologies, phytoremediation based on legume rhizobia symbiosis has emerged as an inexpensive decontamination alternative which also revitalize contaminated soils due to the role of legumes in nitrogen cycling. In recent years, there is a growing interest in understanding symbiotic legume rhizobia relationship and its interactions with Cd. The aim of the present review is to provide a comprehensive picture of the main effects of Cd in N-2-fixing leguminous plants and the benefits of exploiting this symbiosis together with plant growth promoting rhizobacteria to boost an efficient reclamation of Cd-contaminated soils. The authors thank lose Maria Becerril and Carlos Garbisu fir helpful comments, The research leading to these results has received funding from the Basque Government (IT526-10; IT624-13). MIGS is the recipient of a fellowship for recent doctors until their integration in postdoctoral programs by the Investigation Vice-rector's office of the University of the Basque Country UPV/EHU. We apologize to all colleagues whose work could not be discussed because of space limitations

Monocotyledonous crops including cereals, sugar cane, banana and cassava make an important tribute to agricultural commodities both in production and value worldwide. Diseases caused by nematodes in monocots are well documented and new data are emerging on interactions of these pathogens with some important monocotyledonous crop species. This review focuses on major monocotyledonous plant-nematode systems describing the biology and genetics of some interactions and highlighting efforts to identify and select resistant genetic resources. Molecular and histological data are presented having in the spotlight sedentary nematodes of the suborder Tylenchina. Histological observations are presented during nematode development and host resistance responses, comparing monocot and dicot plant hosts. Subsequently we focus on the recently published transcriptomics of monocotyledonous plant responses looking at specific metabolic changes and their role during plant-nematode interactions. Insights that may be learned from nematode interactions with dicotyledonous hosts are also discussed. As a final point, we look at nematode effectors during monocots-nematode interactions exploiting de novo transcriptome data produced from root-knot nematodes and cyst nematodes.

Background and aims A fast and reliable phenotyping system forms a major bottleneck in root exudation research. Our goal was to develop such a system to quantify genetic and environmental effects on root exudation. Another aim was characterizing non-sterile phenotyping. Methods We developed a system in which plants can be grown with non-sterile shoot environments and sterile rhizospheres. These sterile systems were compared with non-sterile controls. Results In non-sterile rhizospheres exogenous carbon disappeared quickly with a half-life of 2 to 3 h and root exudate concentrations remained below detection limit. In sterile rhizospheres exogenous carbon levels were relatively stable or depleted slower than in non-sterile rhizospheres and organic acid build-up occurred. Tomato (Solanum lycopersicum) could be grown with sterile roots for several months. Conclusions The differences in carbon depletion in sterile and non-sterile rhizospheres was most likely due to the absence of microbial catabolism in sterile rhizospheres. These results prove that using a sterile phenotyping system is essential to study the quantity and composition of root exudates. The sterile system described in this paper eliminates the obscuring effect caused by microbes on exudation levels. It offers a stable, reliable and easy phenotyping method and can be used to investigate genetic and environmental effects on exudation.

The global demand for food is increasing because of the growing world population. At the same time, availability of arable land is shrinking. Traditional plant breeding methods have made and will continue to make important contributions toward meeting the need for more food. In many areas of the world, however, the problem is food quality. There may be enough energy available from food, but the staple foods lack certain essential nutrients. In the developed world, demand for "functional foods" ( that is, foods that provide health benefits beyond basic nutrition) is increasing. Nutritional improvements in foods could help to meet both of these demands for improved food quality. Modern agricultural biotechnology, which involves the application of cellular and molecular techniques to transfer DNA that encodes a desired trait to food and feed crops, is proving to be a powerful complement to traditional methods to meet global food requirements. An important aspect of biotechnology is that it provides access to a broad array of traits that can help meet this need for nutritionally improved cultivars. The new varieties developed through modern biotechnology have been identified by a number of terms, including genetically modified (GM or GMO), genetically engineered (GE or GEO), transgenic, biotech, recombinant, and plants with novel traits (PNTs). For the present discussion, the term "GM" will be used because of its simplicity and broad public recognition.

Crop models need accurate simulation of the interdependent processes of crop development and leaf area production. Crop development proceeds according to genotype characteristics and environmental influences, specifically temperature and photoperiod. It can be partly described by thermal requirements for development intervals and coefficients that describe genotype adaptation. The objectives of this study were to (a) quantify (i) time of tassel initiation, tasselling and silking; (ii) thermal intervals for initiation, appearance and expansion of successive leaves (iii) thermal duration from initiation to tip appearance and from tip appearance to collar appearance, and (iv) leaf area and canopy cover as measured by leaf area index (LAI) in contrasting cultivars of maize grown in the field in a cool environment; and (b) relate these to plant characteristics and environmental variables, particularly temperature. For these purposes, three cultivars of maize were grown in three and four cultivars in two serial plantings from 18 April to 24 June in field experiments at Wageningen, The Netherlands, in 1997, and detailed data on crop development, leaf production and environmental variables were collected. The base temperature (T-b) for maize was confirmed as 8degreesC, but thermal time calculation needs to be re-examined to explore a recovery period after chilling injury. Equations that relate foliar properties to total leaf number and ordinal leaf position were derived. Individual leaf area can be described by the modified bell curve, and differences in temporal increase in LAI were related to parameters of leaf initiation, appearance and expansion. (C) 2002 Elsevier Science B.V. All rights reserved.

Organic anion exudation by roots as a mechanism of aluminium (Al) resistance has been intensively studied lately. In the present study, we evaluated qualitative and quantitative aspects of root exudation of organic anions in maize genotypes of distinct sensitivity to Al in response to Al exposure. Roots of maize seedlings were grown axenically in nutrient solution and root exudates were collected along the whole seminal root axis for a short period ( 4 h) using a divided-root-chamber technique. In root exudates collected from 10-mm long root apices, citrate accounted for 67% of the total organic anions found, followed by malate (29%), trans-aconitate (3%), fumarate (

International audience; Background and Aims Experimental evidence challenges the approximation, central in crop models, that developmental events follow a fixed thermal time schedule, and indicates that leaf emergence events play a role in the timing of development. The objective of this study was to build a structural development model of maize (Zea mays) based on a set of coordination rules at organ level that regulate duration of elongation, and to show how the distribution of leaf sizes emerges from this.Methods A model of maize development was constructed based on three coordination rules between leaf emergence events and the dynamics of organ extension. The model was parameterized with data from maize grown at a low plant population density and tested using data from maize grown at high population density.Key Results The model gave a good account of the timing and duration of organ extension. By using initial conditions associated with high population density, the model reproduced well the increase in blade elongation duration and the delay in sheath extension in high-density populations compared with low-density populations. Predictions of the sizes of sheaths at high density were accurate, whereas predictions of the dynamics of blade length were accurate up to rank 9; moderate overestimation of blade length occurred at higher ranks.Conclusions A set of simple rules for coordinated growth of organs is sufficient to simulate the development of maize plant structure without taking into account any regulation by assimilates. In this model, whole-plant architecture is shaped through initial conditions that feed a cascade of coordination events.

Realising that rainwater harvesting (RWH) improves crop productivity, smallholder farmers in semi-arid Zimbabwe modified contour ridges traditionally used for rainwater management by digging infiltration pits inside contour ridge channels in order to retain more water in crop fields. However, scientific studies on crop yield benefits of infiltration pits have not been conclusive. Combining field-edge RWH methods such as contour ridges with infiltration pits with in-field practices may enhance crop yield benefits. Thus, the objective of the study was to assess soil moisture and maize yield improvement of combining infiltration and planting pits. Field experiments were conducted in Rushinga, Zimbabwe for three seasons at three sites using a split-plot design: main-plot factor, field-edge rainwater management method (RWMM); and split-plot factor, tillage method. Soil moisture content was measured weekly using gravimetric and Time Domain Reflectometry (TDR) methods. A household and field survey to establish farmers’ perceptions, typology and availability of field-edge RWMM was conducted. In order to share experiences and enhance stakeholders’ learning, field days were held. Lateral movement of soil water was measured up to 2 m downslope from infiltration pits, hence infiltration pits did not improve maize yield and soil moisture content in the cropping area. Maize yield (kg ha−1) was 45% higher under conventional tillage (2697) than planting pits (1852) but the yield gap decreased from 90 to 30% in the first and third year respectively. The value of infiltration pits is in reducing soil erosion by water and growing high value horticultural crops inside and close to pits, a view shared by host farmers and other stakeholders. Planting pits are an option for farmers without access to draught power and a fall-back method. Research is required to determine soil moisture, maize yield benefits and waterlogging risk in fields with underlying impermeable layers that enhance lateral flow of water.

The order and orientation (arrangement) of all 91 sequenced scaffolds in the 12 pseudomolecules of the recently published tomato (Solanum lycopersicum, 2n = 2x = 24) genome sequence were positioned based on marker order in a high-density linkage map. Here, we report the arrangement of these scaffolds determined by two independent physical methods, bacterial artificial chromosome–fluorescence in situ hybridization (BAC-FISH) and optical mapping. By localizing BACs at the ends of scaffolds to spreads of tomato synaptonemal complexes (pachytene chromosomes), we showed that 45 scaffolds, representing one-third of the tomato genome, were arranged differently than predicted by the linkage map. These scaffolds occur mostly in pericentric heterochromatin where 77% of the tomato genome is located and where linkage mapping is less accurate due to reduced crossing over. Although useful for only part of the genome, optical mapping results were in complete agreement with scaffold arrangement by FISH but often disagreed with scaffold arrangement based on the linkage map. The scaffold arrangement based on FISH and optical mapping changes the positions of hundreds of markers in the linkage map, especially in heterochromatin. These results suggest that similar errors exist in pseudomolecules from other large genomes that have been assembled using only linkage maps to predict scaffold arrangement, and these errors can be corrected using FISH and/or optical mapping. Of note, BAC-FISH also permits estimates of the sizes of gaps between scaffolds, and unanchored BACs are often visualized by FISH in gaps between scaffolds and thus represent starting points for filling these gaps.

Several QTLs for cell wall degradability and lignin content were previously detected in the F288 × F271 maize RIL progeny, including a set of major QTLs located in bin 6.06. Unexpectedly, allelic sequencing of genes located around the bin 6.06 QTL positions revealed a monomorphous region, suggesting that these QTLs were likely “ghost” QTLs. Refining the positions of all QTLs detected in this population was thus considered, based on a linkage map densification in most important QTL regions, and in several large still unmarked regions. Re-analysis of data with an improved genetic map (173 markers instead of 108) showed that ghost QTLs located in bin 6.06 were then fractionated over two QTL positions located upstream and downstream of the monomorphic region. The area located upstream of bin 6.06 position carried the major QTLs, which explained from 37 to 59 % of the phenotypic variation for per se values and extended on only 6 cM, corresponding to a physical distance of 2.2 Mbp. Among the 92 genes present in the corresponding area of the B73 maize reference genome, nine could putatively be considered as involved in the formation of the secondary cell wall [bHLH, FKBP, laccase, fasciclin, zinc finger C2H2-type and C3HC4-type (two genes), NF-YB, and WRKY]. In addition, based on the currently improved genetic map, eight QTLs were detected in bin 4.09, while only one QTL was highlighted in the initial investigation. Moreover, significant epistatic interaction effects were shown for all traits between these QTLs located in bin 4.09 and the major QTLs located in bin 6.05. Three genes related to secondary cell wall assembly (ZmMYB42, COV1-like, PAL-like) underlay QTL support intervals in this newly identified bin 4.09 region. The current investigations, even if they were based only on one RIL progeny, illustrated the interest of a targeted marker mapping on a genetic map to improve QTL position.

Since the advent of modern plant breeding in the 1930s, North American maize has undergone a dramatic adaptation to high-input agriculture. Despite the importance of genetic contributions to historical yield increases, little is known about the underlying genomic changes. Here we use high-density SNP genotyping to characterize a set of North American maize lines spanning the history of modern breeding. We provide a unique analysis of genome-wide developments in genetic diversity, ancestry, and selection. The genomic history of maize is marked by a steady increase in genetic differentiation and linkage disequilibrium, whereas allele frequencies in the total population have remained relatively constant. These changes are associated with increasing genetic separation of breeding pools and decreased diversity in the ancestry of individual lines. We confirm that modern heterotic groups are the product of ongoing divergence from a relatively homogeneous landrace population, but show that differential landrace ancestry remains evident. Using a recent association approach, we characterize signals of directional selection throughout the genome, identifying a number of candidate genes of potential agronomic relevance. However, overall we find that selection has had limited impact on genome-wide patterns of diversity and ancestry, with little evidence for individual lines contributing disproportionately to the accumulation of favorable alleles in today's elite germplasm. Our data suggest breeding progress has mainly involved selection and recombination of relatively common alleles, contributed by a representative but limited set of ancestral lines.

International audience; Recent progress in genotyping and resequencing techniques have opened new opportunities for deciphering quantitative trait variation by looking for associations between traits of interest and polymorphisms in panels of diverse inbred lines. Association mapping raises specific issues related to the choice of appropriate (i) panels and marker-densities and (ii) statistical methods to capture associations. In this study, we used a panel of 314 maize inbred lines from the dent pool, composed of inbred material from public institutes (113 inbred lines) and a private company (201 inbred lines). We showed that local LD was higher and genetic diversity lower in the material of private origin than in the public material. We compared the results obtained by different software for identifying population structure and computing relatedness among lines, and ran association tests for earliness related traits. Our results confirmed the importance of the mite polymorphism of Vgt1 on flowering time, but also showed that its effect can be captured by zmRap2.7 polymorphisms located 70 kb apart. We also highlighted associations with polymorphisms within genes putatively involved in lignin biosynthesis pathway, which deserve further investigations.

Genetic markers, from morphological to molecular, in function with early Heterosis is a prerequisite for the successful commercial maize production. It does not appear in any cross of two inbred lines, and therefore, the determination of combining abilities of parental lines is essential. The most commonly used method for determining combining abilities is diallel analysis. Besides conventional methods for diallel analysis, a new biplot approach has been sugested. In this paper, we studied the combining ability for grain yield in a set of genotypes obtained by diallel crossing system of six inbred lines. Both, the Griffing's conventional method and the biplot approach have been used for diallel analysis. Comparing the GCA values from biplot analysis and Griffing's method, similar results can be observed, with the exception of NS L 1051 and NS L 1000 whose ranks are interchanged. Biplot analysis enables the SCA estimation of parent inbred, and the highest SCA has inbred B73D. Biplot analysis also allows the estimation of the best crosses. Inbred B73D shows the best results when crossed with testers Mo17Ht, NS L 1051 and N152, inbred N152 combines best with testers NS L 1001 and NS L 1000, whereas the cross of inbred NS L 1051 with tester B73D results with the highest grain yield per plant in comparison with other testers. Određivanje kombinacionih sposobnosti roditeljskih inbred linija, radi iskorištavanja heterozisa, je od suštinske važnosti. Najčešće korišćen metod je dialelna analiza. Pored konvencionalnih metoda dialelne analize za procenu kombinacionih sposobnosti, u poslednje vreme prisutan je i novi pristup analize kombinacionih sposobnosti. U ovom radu smo proučavali kombinacione sposobnosti za prinos zrna u setu genotipova dobijenih dialelnim sistemom ukrštanja šest linija. Pored primene konvencionalne metode analize po Griffingu, korišten je i biplot pristup za sagledavanje podataka. Upoređujući vrednosti OKS dobijenih biplot analizom i primenom Griffing-ovog metoda, dobijeni su slični rezultati, sa izuzetkom NS L 1051 i NS L 1000 čiji su rangovi zamenjeni. Biplot analiza omogućava i procenu PKS samih roditeljskih linija. Najveća vrednost PKS zapažena je kod linije B73D, a zatim slede: NS L 1051, NS L 1001, Mo17Ht, N152 i NS L 1000. Biplot analiza takođe omogućava i procenu najboljih ukrštanja. Inbred linija B73D pokazala je najbolje rezultate u ukrštanju sa linijama Mo17Ht, NS L 1051 i N152, N152 sa NS L 1001 i NS L 1000, dok se linija NS L 1051 najbolje kombinuje sa testerom B73D.

Bundle-sheath conductance (gbs) affects CO2 leakiness, and, therefore, the efficiency of the CO2-concentrating mechanism (CCM) in C4 photosynthesis. Whether and how gbs varies with leaf age and nitrogen status is virtually unknown. We used a C4-photosynthesis model to estimate gbs, based on combined measurements of gas exchange and chlorophyll fluorescence on fully expanded leaves of three different ages of maize (Zea mays L.) plants grown under two contrasting nitrogen levels. Nitrogen was replenished weekly to maintain leaf nitrogen content (LNC) at a similar level across the three leaf ages. The estimated gbs values on leaf-area basis ranged from 1.4 to 10.3 mmol m-2 s-1 and were affected more by LNC than by leaf age, although gbs tended to decrease as leaves became older. When converted to resistance (rbs = 1/gbs), rbs decreased monotonically with LNC. The correlation was presumably associated with nitrogen effects on leaf anatomy such as on wall thickness of bundle-sheath cells. Despite higher gbs, meaning less efficient CCM, the calculated loss due to photorespiration was still low for high-nitrogen leaves. Under the condition of ambient CO2 and saturating irradiance, photorespiratory loss accounted for 3–5% of fixed carbon for the high-nitrogen, versus 1–2% for the low-nitrogen, leaves.

Biochemical properties of fusicoccin receptors are strongly influenced by the phospholipid environment. In this report we have studied the effect of different exogenous phospholipases on fusicoccin binding ability of both plasma membrane and solubilised receptors. Among the phospholipases tested only phospholipase A2; showed an inhibitory effect on fusicoccin binding. In particular, the influence of this enzyme on the time course and reversibility of the fusicoccin binding reaction was studied. The inhibitory effect of phospholipase A2 was the consequence of fatty acid release. The usual fatty acids of plasma membrane phospholipids were active in inhibiting the interaction of fusicoccin with its receptors. It is concluded that a phospholipid associated to the fusicoccin receptor might play a significant role in the modulation of binding.

Background Safety assessment of genetically modified organisms is currently often performed by comparative evaluation. However, natural variation of plant characteristics between commercial varieties is usually not considered explicitly in the statistical computations underlying the assessment. Results Statistical methods are described for the assessment of the difference between a genetically modified (GM) plant variety and a conventional non-GM counterpart, and for the assessment of the equivalence between the GM variety and a group of reference plant varieties which have a history of safe use. It is proposed to present the results of both difference and equivalence testing for all relevant plant characteristics simultaneously in one or a few graphs, as an aid for further interpretation in safety assessment. A procedure is suggested to derive equivalence limits from the observed results for the reference plant varieties using a specific implementation of the linear mixed model. Three different equivalence tests are defined to classify any result in one of four equivalence classes. The performance of the proposed methods is investigated by a simulation study, and the methods are illustrated on compositional data from a field study on maize grain. Conclusions A clear distinction of practical relevance is shown between difference and equivalence testing. The proposed tests are shown to have appropriate performance characteristics by simulation, and the proposed simultaneous graphical representation of results was found to be helpful for the interpretation of results from a practical field trial data set.

Article de revue (Article scientifique dans une revue à comité de lecture); International audience; Plants react to their environment and to management interventions by adjusting physiological functions and structure. Functional-structural plant models (FSPM), combine the representation of three-dimensional (3D) plant structure with selected physiological functions. An FSPM consists of an architectural part (plant structure) and a process part (plant functioning). The first deals with (i) the types of organs that are initiated and the way these are connected (topology), (ii) co-ordination in organ expansion dynamics, and (iii) geometrical variables (e.g. leaf angles, leaf curvature). The process part may include any physiological or physical process that affects plant growth and development (e.g. photosynthesis, carbon allocation). This paper addresses the following questions: (i) how are FSPM constructed, and (ii) for what purposes are they useful? Static, architectural models are distinguished from dynamic models. Static models are useful in order to study the significance of plant structure, such as light distribution in the canopy, gas exchange, remote sensing, pesticide spraying studies, and interactions between plants and biotic agents. Dynamic models serve quantitatively to integrate knowledge on plant functions and morphology as modulated by environment. Applications are in the domain of plant sciences, for example the study of plant plasticity as related to changes in the red:far red ratio of light in the canopy. With increasing availability of genetic information, FSPM will play a role in the assessment of the significance towards plant performance of variation in genetic traits across environments. In many crops, growers actively manipulate plant structure. FSPM is a promising tool to explore divergent management strategies.

The most suitable drying parameters in drying corn in bulk by warm air were determined. 250 kg of corn was employed for each test. Air flow rate was kept constant at 1 m The corn seeds used in the tests were dried at five different temperature values until the moisture of 16.4% was reduced to 10%. The dried corn seeds were examined from the point of view of drying time, germination rate, germination vigour, energy consumption and economic cost.

Potato chromosome 5 harbours numerous genes for important qualitative and quantitative traits, such as resistance to the root cyst nematode Globodera pallida and the late blight fungus, Phytophthora infestans . The genes make up part of a “hot spot” for resistances to various pathogens covering a genetic map length of 3 cM between markers GP21 and GP179. We established the physical size and position of this region on chromosome 5 in potato and tomato using fluorescence in situ hybridization (FISH) on pachytene chromosomes. Five potato bacterial artificial chromosome (BAC) clones with the genetically anchored markers GP21, R1-contig (proximal end), CosA, GP179, and StPto were selected, labeled with different fluorophores, and hybridized in a five-colour FISH experiment. Our results showed the location of the BAC clones in the middle of the long arm of chromosome 5 in both potato and tomato. Based on chromosome measurements, we estimate the physical size of the GP21–GP179 interval at 0.85 Mb and 1.2 Mb in potato and tomato, respectively. The GP21–GP179 interval is part of a genome segment known to have inverted map positions between potato and tomato.

Crops grown from non-genetically modified seed should contain no more than 0.9% GM material. The very diverse nature of EU landscapes implies that coexistence measures must be adapted to regional conditions. Rigid rules, such as the requirement of large isolation distances everywhere, may raise the cost of coexistence measures, particularly in densely planted areas, without necessarily meeting the objectives of the European Commission. One of the objectives of the SIGMEA programme (Sustainable Introduction of GM Crops into European Agriculture is a Specific Targeted Research Project in the EC), within which this work was conducted, was to provide tools for the management of coexistence at the landscape level. We compared four contrasting maize production zones (in Alsace and Aragon) using MAPOD ® , a spatially-explicit model of gene flow, and randomly allocating GM crops to maize plots. We calculated two indicators of potential interest to different stakeholders (not only farmers and regulators, but also collecting firms and industry): (1) the proportion of the non-GM maize area not complying with a given threshold and (2) the mean cross pollination rate obtained if the harvests of all the conventional plots were to be mixed in a silo. Our results suggest that it is possible to classify the regional landscapes in terms of the level of risk (for different thresholds depending on market standards—e.g. 0.1%; 0.4%; 0.9%) with few structural characteristics easily calculated from GIS and agricultural statistics data (Mean field area; proportion of the Agricultural Used Area (AUA) devoted to maize, GM maize proportion, maize flowering dynamics and wind characteristics). The mean cross pollination rate increases with GM maize proportion in all the landscapes but the effect of this factor is modulated by structural variables of the landscapes.

Nearly three decades ago Farquhar, von Caemmerer and Berry published a biochemical model for C 3 photosynthetic rates (the FvCB model). The model predicts net photosynthesis ( A ) as the minimum of the Rubisco-limited rate of CO 2 assimilation ( A c ) and the electron transport-limited rate of CO 2 assimilation ( A j ). Given its simplicity and the growing availability of the required enzyme kinetic constants, the FvCB model has been used for a wide range of studies, from analysing underlying C 3 leaf biochemistry to predicting photosynthetic fluxes of ecosystems in response to global warming. However, surprisingly, this model has seen limited use in existing crop growth models. Here we highlight the elegance, simplicity, and robustness of this model. In the light of some uncertainties with photosynthetic electron transport pathways, a recently extended FvCB model to calculate A j is summarized. Applying the FvCB-type model in crop growth models for predicting leaf photosynthesis requires a stomatal conductance ( g s ) model to be incorporated, so that intercellular CO 2 concentration ( C i ) can be estimated. In recent years great emphasis has been put on the significant drawdown of Rubisco carboxylation-site CO 2 concentration ( C c ) relative to C i . To account for this drawdown, mesophyll conductance ( g m ) for CO 2 transfer can be added. We present an analytical algorithm that incorporates a g s model and uses g m as a temperature-dependent parameter for calculating A under various environmental scenarios. Finally we discuss a C 4 -equivalent version of the FvCB model. In addition to the algorithms already elaborated for C 3 photosynthesis, most important algorithms for C 4 photosynthesis are those that capture the CO 2 concentrating mechanism and the extra ATP requirement by the C 4 cycle. Although the current estimation of the C 4 enzyme kinetic constants is less certain, applying FvCB-type models to both C 3 and C 4 crops is recommended to accurately predict the response of crop photosynthesis to multiple, interactive environmental variables.

International audience; Plants modify nutrient availability by releasing chemicals in the rhizosphere. This change in availability induced by roots (bioavailability) is known to improve nutrient uptake by individual plants releasing such compounds. Can this bioavailability alter plant competition for nutrients and under what conditions? To address these questions, we have developed a model of nutrient competition between plant species based on mechanistic descriptions of nutrient diffusion, plant exudation, and plant uptake. The model was parameterized using data of the effects of root citrate exudation on phosphorus availability. We performed a sensitivity analysis for key parameters to test the generality of these effects. Our simulations suggest the following. ( 1) Nutrient uptake depends on the number of roots when nutrients and exudates diffuse little, because individual roots are nearly independent in terms of nutrient supply. In this case, bioavailability profits only species with exudates. ( 2) Competition for nutrients depends on the spatial arrangement of roots when nutrients diffuse little but exudates diffuse widely. ( 3) Competition for nutrients depends on the nutrient uptake capacity of roots when nutrients and exudates diffuse widely. In this case, bioavailability profits all species. Mechanisms controlling competition for bioavailable nutrients appear to be diverse and strongly depend on soil, nutrient, and plant properties.

In maize, two major quantitative-trait loci (QTLs) on chromosome bins 1.06 and 2.04 have been shown to affect root architecture and a number of agronomic traits, including grain yield. The QTL on bin 2.04 (root-ABA1) also affects root lodging and ABA concentration in the leaf. To evaluate the effects of root-ABA1 better, near-isogenic lines (NILs) have been produced and evaluated per se and in testcross combinations under different water regimes. Additionally, the NILs have been crossed to obtain large mapping populations suitable for the fine-mapping of root-ABA1 and, eventually, its map-based cloning. The identification of the sequence responsible for a target QTL can be facilitated by the candidate-gene approach coupled with a comparative in silico analysis based on sequence information of model species and other crops. Genomics, when appropriately integrated with other relevant disciplines, will positively impact our understanding of root growth and functions

The effects of chemophytostabilization practices on arbuscular mycorrhiza (AM) of Deschampsia cespitosa roots at different depths in soils highly contaminated with heavy metals were studied in field trials. Mycorrhizal parameters, including frequency of mycorrhization, intensity of root cortex colonization and arbuscule abundance were studied. Correlations between concentration of bioavailable Cd, Zn, Pb and Cu in soil and mycorrhizal parameters were estimated. An increase in AM colonization with increasing soil depth was observed in soils with spontaneously growing D. cespitosa. A positive effect of chemophytostabilization amendments (calcium phosphate, lignite) on AM colonization was found in the soil layers to which the amendments were applied. Negative correlation coefficients between mycorrhizal parameters and concentration of bioavailable Cd and Zn in soil were obtained. Our results demonstrated that chemophytostabilization practices enhance AM colonization in D. cespitosa roots, even in soils fertilized with high rates of phosphorus. Addition of phosphorus and lignite in chemophytostabilization increased arbuscular mycorrhizal colonization of Deschampsia cespitosa roots.

We studied the effect of Silicon (Si) on Casparian band (CB) development, chemical composition of the exodermal CB and Si deposition across the root in the Si accumulators rice and maize and the Si non-accumulator onion. Plants were cultivated in nutrient solution with and without Si supply. The CB development was determined in stained root cross-sections. The outer part of the roots containing the exodermis was isolated after enzymatic treatment. The exodermal suberin was transesterified with MeOH/BF3 and the chemical composition was measured using gas chromatography-mass spectroscopy (GC-MS) and flame ionization detector (GC-FID). Laser ablation-inductively coupled plasma-mass spectroscopy (LA-ICP-MS) was used to determine the Si deposition across root cross sections. Si promoted CB formation in the roots of Si-accumulator and Si non-accumulator species. The exodermal suberin was decreased in rice and maize due to decreased amounts of aromatic suberin fractions. Si did not affect the concentration of lignin and lignin-like polymers in the outer part of rice, maize and onion roots. The highest Si depositions were found in the tissues containing CB. These data along with literature were used to suggest a mechanism how Si promotes the CB development by forming complexes with phenols. DFG/SCHR 506/12-1

Biological systems are exceedingly complex. The unraveling of the genome in plants and humans revealed fewer than the anticipated number of genes. Therefore, other processes such as the regulation of gene expression, the action of gene products, and the metabolic networks resulting from catalytic proteins must make fundamental contributions to the remarkable diversity inherent in living systems. Metabolomics is a relatively new approach aimed at improved understanding of these metabolic networks and the subsequent biochemical composition of plants and other biological organisms. Analytical tools within metabolomics including mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy can profile the impact of time, stress, nutritional status, and environmental perturbation on hundreds of metabolites simultaneously resulting in massive, complex data sets. This information, in combination with transcriptomics and proteomics, has the potential to generate a more complete picture of the composition of food and feed products, to optimize crop trait development, and to enhance diet and health. Selected presentations from an American Chemical Society symposium held in March 2005 have been assembled to highlight the emerging application of metabolomics in agriculture.