Search

The elemental concentrations of both plants and soils are sensitive to variations in precipitation due to the limiting roles of water on soil processes and plant growth in karst ecosystems of Southwestern China; however, precipitation is predicted to increase in this region. Nevertheless, it is unclear how the elemental composition of soils and plants might respond to such increases in moisture. Particularly, how potassium (K) may behave as a key mediator in the regulation of the water potential of plants. For this study, the responses of the elemental composition of both soils and plants to the variable addition of water were investigated. Two grasses (Cymbopogon distans and Arundinella setosa) and two shrubs (Carissa spinarum and Bauhinia brachycarpa) were investigated under four levels of watering treatments 0%, +20%, +40%, and +60%, relative to the annual rainfall, respectively. Compared to the control (CK), the soil water content (SWC) increased to 3.75, 3.86, and 4.34 mg g -1 in T1, T2, and T3 groups, respectively (p < 0.05). Non-metal elements (C, H, N, S, and P, except for Si) in the soil were relatively stable with water addition; however, metal elements (Al, Na, Mg, Fe, and K, along with Si) increased significantly, whereas Zn and Ca decreased (p < 0.05). With water addition, leaf N and P remained unchanged in all four species, while K, Mg, and S decreased in both shrubs (higher C:K, N:K, and P:K). Increases in Fe, Si, and K were observed in both grasses (lower C:K, N:K, and P:K), which suggested that K played distinct roles for water regulation in shrubs and grasses. These findings implied that the elemental compositions of both soils and plants might be altered with increasing precipitation in the future, where different plant types may adopt distinct K-regulation strategies to cope with variable soil moisture., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Arbuscular mycorrhizal fungi (AMFs) are important plant symbionts, but we know little about the effects of plant taxonomic identity or functional group on the AMF community composition. To examine the effects of the surrounding plant community, of the host, and of the AMF pool on the AMF community in plant roots, we manipulated plant community composition in a long-term field experiment. Within four types of manipulated grassland plots, seedlings of eight grassland plant species were planted for 12 wk, and AMFs in their roots were quantified. Additionally, we characterized the AMF community of individual plots (as their AMF pool) and quantified plot abiotic conditions. The largest determinant of AMF community composition was the pool of available AMFs, varying at metre scale due to changing soil conditions. The second strongest predictor was the host functional group. The differences between grasses and dicotyledonous forbs in AMF community variation and diversity were much larger than the differences among species within those groups. High cover of forbs in the surrounding plant community had a strong positive effect on AMF colonization intensity in grass hosts. Using a manipulative field experiment enabled us to demonstrate direct causal effects of plant host and surrounding vegetation., (© 2019 The Authors. New Phytologist © 2019 New Phytologist Trust.)

Like other eukaryotes, the nuclear genome of plants consists of DNA with a small proportion of low-copy DNA (genes and regulatory sequences) and very abundant DNA sequence motifs that are repeated thousands up to millions of times in the genomes including transposable elements (TEs) and satellite DNA. Retrotransposons, one class of TEs, are sequences that amplify via an RNA intermediate and reinsert into the genome, are often the major fraction of a genome. Here, we put research on retrotransposons into the larger context of plant repetitive DNA and genome behaviour, showing features of genome evolution in a grass genus, Brachiaria, in relation to other plant species. We show the contrasting amplification of different retroelement fractions across the genome with characteristics for various families and domains. The genus Brachiaria includes both diploid and polyploid species, with similar chromosome types and chromosome basic numbers x = 6, 7, 8 and 9. The polyploids reproduce asexually and are apomictic, but there are also sexual species. Cytogenetic studies and flow cytometry indicate a large variation in DNA content (C-value), chromosome sizes and genome organization. In order to evaluate the role of transposable elements in the genome and karyotype organization of species of Brachiaria, we searched for sequences similar to conserved regions of TEs in RNAseq reads library produced in Brachiaria decumbens. Of the 9649 TE-like contigs, 4454 corresponded to LTR-retrotransposons, and of these, 79.5 % were similar to members of the gypsy superfamily. Sequences of conserved protein domains of gypsy were used to design primers for producing the probes. The probes were used in FISH against chromosomes of accesses of B. decumbens, Brachiaria brizantha, Brachiaria ruziziensis and Brachiaria humidicola. Probes showed hybridization signals predominantly in proximal regions, especially those for retrotransposons of the clades CRM and Athila, while elements of Del and Tat exhibited dispersed signals, in addition to those proximal signals. These results show that the proximal region of Brachiaria chromosomes is a hotspot for retrotransposon insertion, particularly for the gypsy family. The combination of high-throughput sequencing and a chromosome-centric cytogenetic approach allows the abundance, organization and nature of transposable elements to be characterized in unprecedented detail. By their amplification and dispersal, retrotransposons can affect gene expression; they can lead to rapid diversification of chromosomes between species and, hence, are useful for studies of genome evolution and speciation in the Brachiaria genus. Centromeric regions can be identified and mapped, and retrotransposon markers can also assisting breeders in the developing and exploiting interspecific hybrids.

The GC content in the third codon position (GC(3)) exhibits a unimodal distribution in many plant and animal genomes. Interestingly, grasses and homeotherm vertebrates exhibit a unique bimodal distribution. High GC(3) was previously found to be associated with variable expression, higher frequency of upstream TATA boxes, and an increase of GC(3) from 5' to 3'. Moreover, GC(3)-rich genes are predominant in certain gene classes and are enriched in CpG dinucleotides that are potential targets for methylation. Based on the GC(3) bimodal distribution we hypothesize that GC(3) has a regulatory role involving methylation and gene expression. To test that hypothesis, we selected diverse taxa (rice, thale cress, bee, and human) that varied in the modality of their GC(3) distribution and tested the association between GC(3), DNA methylation, and gene expression. We examine the relationship between cytosine methylation levels and GC(3), gene expression, genome signature, gene length, and other gene compositional features. We find a strong negative correlation (Pearson's correlation coefficient r = -0.67, P value < 0.0001) between GC(3) and genic CpG methylation. The comparison between 5'-3' gradients of CG(3)-skew and genic methylation for the taxa in the study suggests interplay between gene-body methylation and transcription-coupled cytosine deamination effect. Compositional features are correlated with methylation levels of genes in rice, thale cress, human, bee, and fruit fly (which acts as an unmethylated control). These patterns allow us to generate evolutionary hypotheses about the relationships between GC(3) and methylation and how these affect expression patterns. Specifically, we propose that the opposite effects of methylation and compositional gradients along coding regions of GC(3)-poor and GC(3)-rich genes are the products of several competing processes.

makkah - Saudi Arabia, is one of the most important cities, which faced a reduction in natural vegetative cover, due to the hot aridity, with a maximum temperature around 40-49°C, and scarcity of rainfall, the rate of rainfall is between 50-80 mm/year. A plant is supposed to be native if it has occurred naturally in a particular region, ecosystem, or habitat without human intervention. The aim of this study was to study the flora around Makkah city by choosing eight stands from different localities. The field work included relevé, the plots were about 10 × 10 meters in size. The study revealed that the eight stands were represented by 20 species belong to 8 families, Fabaceae and Apocynaceae were dominant by (34%), (25%) followed by Amaranthaceae (13%), Poaceae (12%) and Cucurbitaceae (5%); then (Apiaceae & Asteraceae) were represented by (4%), while Solanaceae was represented by only (3%) of the vegetation. Phanerophytes (40%) were the dominant while Hemicryptophytes (He) were the lowest value of life form (10%). The Floristic categories Saharo-Arabian (SA) and Sudano-Zambezian (AZ) were the dominant (38%), while Mediterranean (ME), Saharo-Sindian (SSI), Tropical (TR), Irano-Turanian (IT) were lowest value (6%). Rhazya stricta has a high number of species that were observed in native plants in study area (17%), while Cenchrus biflorus, Leptadenia pyrotechnica, Lycium shawii, Panicum turgidum, Senegalia asak, Senna italica, Stipellula capensis, Vachellia flava and Vachellia tortilis were the lowest with 3% over the stands. Finally, the diversity in species deficiency in Makkah. [ABSTRACT FROM AUTHOR]

The evolutionary speed hypothesis (ESH) states that the molecular evolutionary rates of plants in the warm areas are higher than that in the cool areas. Nevertheless, largely due to the scarcity of molecular data from lower taxonomic lineages, ESH remains elusive in plants. In this study, we comprehensively conducted genome-wide comparative analyses of a total of 76 chloroplast (cp) genomes of the bamboos (Poaceae: Bambusoideae), with 10 of them newly generated, to test the ESH via investigating the potential association between their cp genome evolutionary rate and geographical distribution pattern. The results showed extreme heterogeneity of the evolutionary rate within the bamboos, with the lowest value found in temperate bamboos (tribe Arundinarieae) being approximately 1/4 of that in the tropical ones (tribe Olyreae). All the 91 non-coding loci and 75 coding loci evolve consistently faster in tribe Olyreae than that in tribe Arundinarieae. Most of the non-coding (82 out of 91) and coding (73 out of 75) loci in the tropical woody bamboos (tribe Bambuseae) also evolve faster than those in the temperate woody bamboos (tribe Arundinarieae). Moreover, the split of tropical and temperate bamboos was apparently accompanied with the change of cp genome evolutionary rate. This is by far the first case using cp genome data to support the ESH via showing the tropical plants evolve faster than their closely related temperate ones, and will shed new light on our understanding of ESH and the adaptation of plants. [ABSTRACT FROM AUTHOR]

Question: The impact of ants on the vegetation and soil seed bank of alpine meadows on the Qinghai‐Tibetan Plateau is largely unknown. We questioned how the mound‐building ant, Camponotus herculeanus, affects the above‐ground vegetation, the soil seed bank and physico‐chemical properties of the soil. Location: An alpine meadow in the northeast margin of the Qinghai‐Tibetan Plateau (37°40′ N, 102°32′ E), China. Methods: We used field and greenhouse studies to determine the above‐ground vegetation parameters and soil physico‐chemical properties, and the soil seed bank composition under the mound (UM), the herbage circle at about 10 cm width around the outside of the mound (mound edge, ME) and the area 1 m from the center of the mound (control). Results: (a) The mound edge had higher vegetation height, greater above‐ground biomass, lower vegetation coverage and lower plant richness than controls; (b) Gramineae had a higher total importance value, which was based on the height, coverage and biomass of each plant species, and composed a higher biomass proportion in the mound edge than in controls (68% vs. 38%), while most of the perennial dicotyledons were restricted to the controls; (c) dicotyledons were the main seed group in the 0–8 cm layer of soilUM (43%), soilME (51%) and soilcontrol (60%), while Gramineae had a significantly higher seed density and percentage of total seeds in the soilUM (16,507 ± 2,882.7 seeds/m3, 28.1%) than in the soilcontrol (4,200 ± 799.5 seeds/m3, 10.2%); and (d) soil in the 0–8 cm layer under the mound had lower water content and lower bulk density than soil on the mound edge and in controls. Conclusions: Mound‐building activity of Camponotus herculeanus increased the proportion of Gramineae and decreased the proportion of dicotyledons at the site of the study indicating, that mound building could enhance the transformation of a grass and sedges community to mainly a grass community in the alpine meadow. [ABSTRACT FROM AUTHOR]

The significance of the systematic position for the traits of a leaf, mesophyll, chloroplasts, and pigment complex in steppe plants has been examined for three families (Asteraceae, Poaceae, and Rosaceae) from different geographical regions of Russia and Mongolia. The species belonging to a particular family affects, first of all, the parameters of the whole leaf–its thickness and density–as well as the size and number of mesophyll cells. In contrast, mesophyll parameters and pigment content independent of the taxon, and both reflect the convergent response of plants belonging to different taxa to climate. [ABSTRACT FROM AUTHOR]

Early plant use is seldom described in the archaeological record because of poor preservation. We report the discovery of grass bedding used to create comfortable areas for sleeping and working by people who lived in Border Cave at least 200,000 years ago. Sheaves of grass belonging to the broad-leafed Panicoideae subfamily were placed near the back of the cave on ash layers that were often remnants of bedding burned for site maintenance. This strategy is one forerunner of more-complex behavior that is archaeologically discernible from ~100,000 years ago. [ABSTRACT FROM AUTHOR]

Competitive interactions between plants can affect patterns of allocation to reproductive structures through modulation of resource availability. As floral traits involved in plant attractiveness to pollinators can be sensitive to these resources, competition with any neighbouring species may influence the attractiveness of insect-pollinated plants. While pollination research has primarily focused on above-ground interactions, this study aims at investigating if the presence of a competitor plant can modulate neighbouring insect-pollinated plant attractiveness to pollinators and resulting fecundity, especially through below-ground competitive interactions for soil resources. We set up a plot experiment in which we grew an insect-pollinated plant, Sinapis alba (Brassicaceae), in a mixture dominated by a wind-pollinated plant, Holcus lanatus (Poaceae). Individuals of S. alba were either subjected to or isolated from (with buried tubes in the soil) below-ground competition. Across the flowering season, floral traits involved in attractiveness of S. alba and pollinator visitation were followed at the plot and plant level to investigate different scales of attractiveness. At the end of the experiment, seeds were harvested to assess plant fecundity. Competition had a significant negative effect on plot and plant floral display size as well as flower size while nectar traits were not affected. When plants of S. alba were in competition, the time to first visit was altered: the proportion of plots that received a visit was smaller for a given time; in other words, it took more time for a given proportion of plots to be visited and some plots were even never visited. Moreover, pollinators made fewer visits per plots. The proportion of viable seeds produced by S. alba in competition was lower and probably linked to the competition itself rather than changes in pollinator visitation. This study suggests that competitive interactions between plants can modulate pollination interactions even when competing plant species are not insect-pollinated. [ABSTRACT FROM AUTHOR]

Weed control between plastic covered, raised beds in Florida vegetable crops relies predominantly on herbicides. Broadcast applications of post-emergence herbicides are unnecessary due to the general patchy distribution of weed populations. Development of precision herbicide sprayers to apply herbicides where weeds occur would result in input reductions. The objective of the study was to test a state-of-the-art object detection convolutional neural network, You Only Look Once 3 (YOLOV3), to detect vegetation both indiscriminately (1-class network) and to detect and discriminate three classes of vegetation commonly found within Florida vegetable plasticulture row-middles (3-class network). Vegetation was discriminated into three categories: broadleaves, sedges and grasses. The 3-class network (Fscore = 0.95) outperformed the 1-class network (Fscore = 0.93) in overall vegetation detection. The increase in target variability when combining classes increased and potentially negated benefits from pooling classes into a single target (and increasing the available data per class). The 3-class network Fscores for grasses, sedges and broadleaves were 0.96, 0.96 and 0.93 respectively. Recall was the limiting factor for all classes. With consideration to how much of the plant was identified (broadleaves and grasses), the 3-class network (Fscore = 0.93) outperformed the 1-class network (Fscore = 0.79). The 1-class network struggled to detect grassy weed species (recall = 0.59). Use of YOLOV3 as an object detector for discrimination of vegetation classes is a feasible option for incorporation into precision applicators. [ABSTRACT FROM AUTHOR]

This article addresses the phytocoenotic diversity of psammophytic grass communities in the southern part of the nonchernozem zone of Russia, where the restoration of Scots pine (Pinus sylvestris) is either ongoing or potentially possible. Community structure and composition formation trends developing under the influence of key environmental and coenotic factors have been identified. The studies were carried out in Bryansk, Kaluga, and Smolensk oblasts in 2010–2018; over 150 geobotanical releves of psammophytic grass communities have been produced. This vegetation belongs to the class Koelerio-Corynephoretea Klika 1931, which combines dry grasslands on sandy soils and rocky outcrops in the temperate and boreal zones of Europe, on islands of the North Atlantic, and in Greenland. Differences between environmental regimes of various habitats occupied by psammophytic communities have been identified. In most cases, the environmental amplitudes of syntaxonomic units vary significantly by the three key edaphic factors (moisture, soil reaction, and soil richness in mineral nitrogen) and form pretty compact environmental spaces: within each syntaxon, numerical values of the above factors, expressed in score points, normally vary within a narrow range. Regression analysis has established that the species richness of psammophytic communities depends statistically significantly only on the mineral nitrogen supply and soil moisture. Based on the statistical analysis results, the number of Pinus sylvestris plants of any age does not depend on the species richness in the community, total projective cover of the grass stand (excluding the Scots pine), separately calculated moss and lichen projective covers, and average numerical values of environmental factors identified by H. Ellenberg in the community. It is established that numbers of pine trees on study sites depend on only one factor: distance from the diaspora source determining the invasion possibility. The data on the phytocoenotic and floristic diversity of the psammophytic grass vegetation are to be incorporated into the unified database on the southern part of the nonchernozem zone of Russia to identify environmental and botanical–geographical features of this plant community type in the region. [ABSTRACT FROM AUTHOR]

Lorenz von Seidlein and colleagues discuss improving house designs in rural Africa to benefit health. [ABSTRACT FROM AUTHOR]

Production risk has been ignored in most of the analysis of GM technology, which has mostly focused on its effects on mean yield. We use stochastic dominance to quantify the effect of GM traits on the entire distribution of yields in corn in the USA under a wide range of growing conditions. Although no GM hybrid outperforms conventional hybrids under all growing conditions, we present evidence that most GM hybrids can be considered as improvements of the yield distribution. [ABSTRACT FROM AUTHOR]

Introduction: Micronutrient deficiencies are prevalent in Nepal where starchy foods constitute a large proportion of diets and consumption of micronutrient-rich foods is inadequate. We conducted a study to determine whether rice would be an appropriate vehicle for micronutrient fortification in Nepal. Materials and methods: In Bajura in remote rural Nepal, we conducted a household survey to characterize rice intakes in 195 households, and a double-blinded acceptability test with 177 social safety net rice consumers ≥18 years of age. Of these, 168 tasted fortified and unfortified rice to assess whether respondents could differentiate between fortified and non-fortified rice and their sensory properties. Rice was fortified by blending hot extruded kernels containing 6 micronutrients together with non-fortified rice at a 1:99 ratio. We used binomial tests to assess whether participants could correctly differentiate fortified rice, from non-fortified rice and paired t-tests to compare scores for sensory qualities of cooked fortified and non-fortified rice. We used multiple regression to test associations between per capita consumption and age, gender, wealth and food security. Results: Per capita consumption of rice (median 216g/day, IQR 144.0, 288.0) did not vary by wealth but was +52.08g, (95% CI 10.43, 93.72) higher amongst moderately to severely food insecure households compared with food secure / mildly food insecure. Most respondents could not differentiate fortified rice from non-fortified rice: 37.5% identified uncooked fortified rice and 39.3% cooked rice, which was not different from the 33% expected by chance (p = 0.22 and p = 0.09 respectively). The sensory qualities of fortified rice were acceptable (scoring 3.9 out of 5) and did not differ from non-fortified rice (p>0.05). Conclusion: A rice fortification programme implemented through the Nepal Food Corporation’s social safety nets has potential because purchase and consumption of rice is high and fortified rice is acceptable among consumers in remote food insecure areas of Nepal. [ABSTRACT FROM AUTHOR]

Evaluation of soil redistribution rates and influence on crop yield in agricultural catchments is very important information, which can provide a scientific basis for arrangement of soil and water conservation measures and sustainable crop production. In recent decades, the soil erosion has greatly aggravated in the Mollisol region of Northeast China due to unreasonable land management, which in turn has reduced crop yield. The objectives of this study were to investigate the spatial distribution of soil redistribution and the relationship between crop yield and soil redistribute at a catchment of the Chinese Mollisol region. A total of 176 soil samples were collected based on a 200 m by 200 m grid and 4 yr of corn (Zea mays L.) yields were measured. The 137Cs trace technique and Zhang Xinbao’s mass balance model indicated that the soil redistribution rates ranged from −7122.25 to 5471.70 t km−2 yr−1 and averaged −830.10 t km−2 yr−1. Soil erosion dominated in the research area. The corn yields for four years ranged from 43.24 to 136.19 kg km−2 and averaged 90.42 kg km−2. The spatial distribution of soil redistribution rates and corn yield showed a similar ribbon and plaque characteristics at the catchment. An equation between corn yield and soil redistribution rates was fitted and showed that there was a significant negative correlation between corn yield and soil erosion rates, while there was no relationship between the corn yield and soil deposition rates. Therefore, effective soil and water conservation measures are urgently needed to increase crop yield and realize sustainable land-use management. [ABSTRACT FROM AUTHOR]

Xanthomonas oryzae pv. oryzicola (Xoc), the causal agent of bacterial leaf streak, is one of the most severe seed-borne bacterial diseases of rice. However, the molecular mechanisms underlying Xoc in response to oxidative stress are still unknown. In this study, we performed a time-course RNA-seq analysis on the Xoc in response to H2O2, aiming to reveal its oxidative response network. Overall, our RNA sequence analysis of Xoc revealed a significant global gene expression profile when it was exposed to H2O2. There were 7, 177, and 246 genes that were differentially regulated at the early, middle, and late stages after exposure, respectively. Three genes (xoc_1643, xoc_1946, xoc_3249) showing significantly different expression levels had proven relationships with oxidative stress response and pathogenesis. Moreover, a hypothetical protein (XOC_2868) showed significantly differential expression, and the xoc_2868 mutants clearly displayed a greater H2O2 sensitivity and decreased pathogenicity than those of the wild-type. Gene localization and phylogeny analysis strongly suggests that this gene may have been horizontally transferred from a Burkholderiaceae ancestor. Our study not only provides a first glance of Xoc’s global response against oxidative stress, but also reveals the impact of horizontal gene transfer in the evolutionary history of Xoc. [ABSTRACT FROM AUTHOR]

Agricultural activity, urban development and habitat alteration have caused the disappearance of the western spadefoot (Spea hammondii) from 80% of its geographic range in southern California. Despite the western spadefoot’s continuing decline, little research has been conducted on its natural history. The home range of adult spadefoots is unknown, and their use of upland habitat is poorly understood. Both factors are important for the long-term conservation of the species because adult spadefoots spend the majority of their lives away from breeding pools in self-excavated burrows. Between January 2012 and January 2013, we surgically implanted radio transmitters in 15 spadefoots at two locations and recorded their movements and habitat use. The mean distance moved between burrow locations was 18 m (SD ± 24.1 m, range1–204 m). The mean distance of burrows from the breeding pools was 40 m (SD ± 37.42 m, range 1–262 m). Rain was a significant predictor of spadefoot movement, with more rain predicting higher probability of movement and larger distances moved. At remote sensing scale (1 m) spadefoots selected grassland habitat for their burrow locations. At the microsite scale (< 1 m) spadefoots strongly selected duff over grass or shrub cover. Spadefoots burrowed in friable, sandy/loam soil with significantly less clay than random pseudoabsence points. This research enhances our understanding of a little-studied species and will contribute to the development of effective management plans for the western spadefoot. [ABSTRACT FROM AUTHOR]

Aim: Identify key factors driving legume seedlings performance in saline-sodic soils. Methods: Five plots were established in paired sub-humid steppes with saline-sodic soils dominated by Distichlis spicata or Panicum coloratum. In each plot, Lotus tenuis was sown in autumn and individual plants were collected close to nurse plants (dominant species), and in open areas, at the end of the cold and warm seasons. Carbon and nutrient acquisition (through C and O isotopic composition and N and P content measurements) and plant symbiotic functioning (through N fixation by rhizobia and mycorrhizal colonization measurements) were determined. Results: Biomass of legume grown close to a nurse plant was always higher than in open areas. This increase was higher close to P. coloratum and to D. spicata in the cold and warm seasons, respectively. In both cases, L. tenuis improved its nutrient acquisition and symbiosis functioning. N-acquisition and rhizobia efficiency increased in the most facilitated L. tenuis plants in the cold season while P-acquisition was greater in the warm season. Conclusions: Grass-to-legume facilitation in sub-humid steppes with saline-sodic soils was detected in cold and warm seasons, differing between steppes in relationship with the vegetation growing rate and the establishment and functioning of legume-rhizobia-mycorrhiza symbioses. [ABSTRACT FROM AUTHOR]

With the introduction of multi-camera systems in modern plant phenotyping new opportunities for combined multimodal image analysis emerge. Visible light (VIS), fluorescence (FLU) and near-infrared images enable scientists to study different plant traits based on optical appearance, biochemical composition and nutrition status. A straightforward analysis of high-throughput image data is hampered by a number of natural and technical factors including large variability of plant appearance, inhomogeneous illumination, shadows and reflections in the background regions. Consequently, automated segmentation of plant images represents a big challenge and often requires an extensive human-machine interaction. Combined analysis of different image modalities may enable automatisation of plant segmentation in “difficult” image modalities such as VIS images by utilising the results of segmentation of image modalities that exhibit higher contrast between plant and background, i.e. FLU images. For efficient segmentation and detection of diverse plant structures (i.e. leaf tips, flowers), image registration techniques based on feature point (FP) matching are of particular interest. However, finding reliable feature points and point pairs for differently structured plant species in multimodal images can be challenging. To address this task in a general manner, different feature point detectors should be considered. Here, a comparison of seven different feature point detectors for automated registration of VIS and FLU plant images is performed. Our experimental results show that straightforward image registration using FP detectors is prone to errors due to too large structural difference between FLU and VIS modalities. We show that structural image enhancement such as background filtering and edge image transformation significantly improves performance of FP algorithms. To overcome the limitations of single FP detectors, combination of different FP methods is suggested. We demonstrate application of our enhanced FP approach for automated registration of a large amount of FLU/VIS images of developing plant species acquired from high-throughput phenotyping experiments. [ABSTRACT FROM AUTHOR]

Soil salinity is a major threat to crop production worldwide. The global climate change is further accelerating the process of soil salinization, particularly in dry areas of the world. Increasing genetic variability of currently used wheat varieties by introgression of exotic alleles/genes from related progenitors’ species in breeding programs is an efficient approach to overcome limitations due to the absence of valuable genetic diversity in elite cultivars. Synthetic hexaploid wheat (SHW) is widely regarded as donor of favourable exotic alleles to improve tolerance against biotic and abiotic stresses such as salinity stress. In this study, synthetic backcross lines (SBLs) winter wheat population “Z86”, derived from crosses involving synthetic hexaploid wheat Syn86L with German elite winter wheat cultivar Zentos, was evaluated for salinity tolerance at different developmental stages under controlled and field conditions in three growing seasons. High genetic variability was detected across the SBLs and their parents at various growth stages under controlled as well as under salt stress field trials. Greater performance of Zentos over Syn86L was detected at germination stage across all salt treatments and with respect to shoot dry weight (SDW) and root dry weight (RDW) at seedling stage. Whereas for the root length (RL) and the shoot length (SL) Syn86L surpassed the elite cultivar and most of the progenies. Our experiments revealed for almost all traits that some genotypes among the SBLs showed higher performance than their parents. Furthermore, positive transgressive segregations were detected among the SBLs for germination at high salinity levels, as well as for RDW and SDW at seedling stage. Therefore, the studied Z86 population is a suitable population for assessment of salinity stress on morphological and physiological traits at different plant growth stages. The identified SBLs provide a valuable source for genetic gain through recombination of superior alleles that can be directly applied in breeding programs for efficiently breeding cultivars with improved salinity tolerance and desired agronomic traits. [ABSTRACT FROM AUTHOR]

Aphids are major pests of wheat crop in Pakistan inflicting considerable economic losses. A better knowledge of landscape scale spatial distribution of aphids and their natural enemies could be used to improve integrated pest management programs. Therefore, the present study aimed to document spatio-temporal variations in populations of wheat aphids and their natural enemies in Pakistan. The 2-year survey study was carried out at ten experimental farms located in five districts of four contrasted agro-ecological zones of eastern Pakistan (Punjab area) i.e. District Chakwal in arid zone, Gujranwala in rice-cropped zone, Faisalabad in central mixed-cropped zone, and Khanewal and Multan in cotton-cropped zone. The dominant aphid species i.e. Schizaphis graminum, Rhopalosiphum padi, R. maidis and Sitobion avenae varied significantly among the five districts surveyed. The population of S. graminum was observed more abundant in arid, R. padi in rice, S. avenae in aird and rice, and R. maidis in cotton-I zones. Aphids ended their population dynamics on 25th March in central mixed-cropped zone and 12th April in other three zones. Various species of natural enemies, mainly Coccinella septumpunctata, C. undecimpunctata, Menochilus sexmaculata, Chrysoperla carnea, Syrphidae and parasitoid mummies were inconsistently observed in four agro-ecological zones. The population of C. septumpunctata, was observed more abundant in rice zone, C. undecimpunctata and C. carnea in cotton-I and arid zones, M. sexmaculata in cotton-I and II zones, Syrphidae in cotton-I zone and parasitoid mummies in rice and arid zones. There were no clear relationships between aphid and the natural enemy populations. The present study may serve as a baseline regarding distribution of wheat aphids and their natural enemies and the results provided insights for further studies on the potential top-down (natural enemies) versus bottom-up (fertilization and irrigation regimes) forces in management of wheat aphids in eastern Pakistan. [ABSTRACT FROM AUTHOR]

Tremendous amounts of nitrogen (N) fertilizer have been added to arable lands, often resulting in substantial effects on terrestrial ecosystems, including soil acidification, altered enzyme activities and changes in microbial community composition. Soil microbes are the major drivers of soil carbon (C) and N cycling; therefore, understanding the response of microbial communities to elevated N inputs is of significant importance. This study was carried out to investigate the influences of different N fertilization rates (0, 182, and 225 kg ha-1 representing control, low, and high N supply for each crop season for summer maize and winter wheat) on soil biochemical attributes, extracellular enzyme activities, and the microbial community composition in a winter wheat-summer maize rotation cropping system in north-central China. The results showed that N addition significantly decreased the soil pH in both the wheat and maize seasons. Microbial biomass N (MBN) decreased following N fertilization in the wheat season, while the opposite trend in MBN was observed in the maize season. Response ratio analysis showed that the activities of enzymes involved in C, N, and phosphorus cycling were significantly enhanced under N enrichment in both the wheat and maize seasons, and higher enzyme activities were noted in the high N addition treatment than in the low N addition treatment. A linear increase in fungal abundance with the N addition gradient was observed in the wheat season, whereas the fungal abundance increased and then decreased in the maize season. The bacterial abundance showed an increased and then decreased trend in response to the N addition gradient in both the wheat and maize crop seasons. Moreover, the partial least squares path model (PLS-PM) analysis showed that soil pH and soil organic carbon (SOC) were the most important soil variables, causing shifts in the soil bacteria. Furthermore, compared with the N-cycling enzymes, the C-cycling enzymes were significantly affected by the soil pH and SOC. Taken together, these results suggest that the effect of N addition on enzyme activities was consistent in both crop seasons, while the effects on MBN and microbial community composition to N addition were highly variable in the two crop seasons. Moreover, N fertilization-induced changes in the soil chemical properties such as soil acidity and SOC played a substantial role in shaping the microbial community. [ABSTRACT FROM AUTHOR]

Chloroplast plays an important role in the plant life cycle. However, the details of its development remain elusive in rice. In this study, we report the fine-mapping of a novel rice gene wpb1 (white panicle branch 1), which affects chloroplast biogenesis, from a tropical japonica variety that results in an albino panicle branches at and after the heading stage. The wpb1 variety was crossed with Nipponbare to generate the F2 and BC1F2 populations. Green and white panicle branch phenotypes with a 3:1 segregation ratio was observed in the F2 population. Bulked segregant analysis (BSA) based on whole genome resequencing was conducted to determine the wpb1 locus. A candidate interval spanning from 11.35 to 23.79M (physical position) on chromosome 1 was identified. The results of BSA analysis were verified by a 40K rice SNP-array using the BC1F2 population. A large-scale F2 population was used to pinpoint wpb1, and the locus was further narrowed down to a 95-kb interval. Furthermore, our results showed that the expression levels of the majority of the genes involved in Chl biosynthesis, photosynthesis and chloroplast development were remarkably affected in wpb1 variety and in F2 plants with a white panicle branch phenotype. In line with the results mentioned above, anatomical structural examination and chlorophyll (Chl) content measurement suggested that wpb1 might play an important role in the regulation of chloroplast development. Further cloning and functional characterization of the wpb1 gene will shed light on the molecular mechanism underlying chloroplast development in rice. [ABSTRACT FROM AUTHOR]

Globally, gains in sweet corn [Zea mays L.var. rugosa (or saccharata)] are a fraction of the yield advances made in field corn (Zea mays L.) in the last half-century. Grain yield improvement of field corn is associated with increased tolerance to higher plant densities (i.e., crowding stress). Processing sweet corn hybrids that tolerate crowding stress have been identified; however, such hybrids appear to be under-planted in the processing sweet corn. Using crowding stress tolerant (CST) hybrids, the objectives of this study were to: (1) identify optimum plant densities for a range of growing conditions; (2) quantify gaps in production between current and optimum plant densities; and (3) enumerate changes in yield and ear traits when shifting from current to optimum plant densities. Using a CST shrunken-2 (sh2) processing sweet corn hybrid, on-farm plant density trials were conducted in thirty fields across the states of Illinois, Minnesota and Wisconsin, from 2013 to 2017 in order to capture a wide variety of growing conditions. Linear mixed-effects models were used to identify the optimum plant density corresponding to maximum ear mass (Mt ha-1), case production (cases ha-1), and profitability to the processor ($ ha-1). Kernel moisture, indicative of plant development, was unaffected by plant density. Ear traits, such as ear number and ear mass per plant, average ear length, and filled ear length declined linearly with increasing plant density. Nonetheless, there was a large economic benefit to the grower and processor by shifting to higher plant densities in most environments. This research shows that increasing plant densities of CST hybrids from current (58,475 plants ha-1) to optimum (73,075 plants ha-1) could improve processing sweet corn green ear yield and processor profitability on average of 1.13 Mt ha-1 and $525 ha-1, respectively. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of additive and non-additive genes on the efficiency of nitrogen (N) use and N responsiveness in inbred popcorn lines. The parents, hybrids and reciprocal crosses were evaluated in a 10x10 triple lattice design at two sites and two levels of N availability. To establish different N levels in the two experiments, fertilization was carried out at sowing, according to soil analysis reports. However, for the experiments with ideal nitrogen availability, N was sidedressed according to the crop requirement, whereas for the N-poor experiments sidedressing consisted of 30% of that applied in the N-rich environment. Two indices were evaluated, the Harmonic Mean of the Relative Performance (HMRP) and Agronomic Efficiency under Low Nitrogen Availability (AELN), both based on grain yield at both N levels. Both additive and non-additive gene effects were important for selection for N-use efficiency. Moreover, there was allelic complementarity between the lines and a reciprocal effect for N-use efficiency, indicating the importance of the choice of the parents used as male or female. The best hybrids were obtained from inbred popcorn lines with contrasting N-use efficiency and N responsiveness. [ABSTRACT FROM AUTHOR]

Nitrogen (N) is an important element required for plant growth and development, which also affects plant yield and quality. Autophagy, a conserved pathway in eukaryotes, degrades and recycles cellular components, thus playing an important role in N remobilization. However, only a few autophagy genes related to N remobilization in rice (Oryza sativa) have been reported. Here, we identified a core autophagy gene in rice, OsATG8b, with increased expression levels under N starvation conditions. It was investigated the function of OsATG8b by generating three independent homozygous 35S-OsATG8b transgenic Arabidopsis thaliana lines. The overexpression of OsATG8b significantly enhanced autophagic flux in the transgenic Arabidopsis plants. It was also showed that over-expressing OsATG8b promoted growth and development of Arabidopsis, in which the rosette leaves were larger than those of the wild type (WT), and the yield increased significantly by 25.25%. In addition, the transgenic lines accumulated more N in seeds than in the rosette leaves. Further examination revealed that overexpression of OsATG8b could effectively alleviate the growth inhibition of transgenic Arabidopsis under nitrogen (N) stress. N partitioning studies revealed that nitrogen-harvest index (NHI) and nitrogen use efficiency (NUE) were significantly increased in the transgenic Arabidopsis, as well as the 15N-tracer experiments revealing that the remobilization of N to seeds in the OsATG8b-overexpressing transgenic Arabidopsis was high and more than WT. Based on our findings, we consider OsATG8b to be a great candidate gene to increase NUE and yield, especially under suboptimal field conditions. [ABSTRACT FROM AUTHOR]