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[EN]The earliness and adaptation of native corn of Tamaulipas in restrictive environments allows considering it a source of variability for genetic improvement programs, so it is necessary to know the genetic effects that control its variation. The objective was to determine the gene action that controls the variation of the earliness of native corn populations of Tamaulipas and the relationship of earliness with grain yield. In Güémez, Tamaulipas, in the agricultural cycles of autumn-winter 2019-2020 and spring-summer 2020 with application and non-application of insecticide to combat S. frugiperda, the genetic effects of days to male and female flowering of six corn populations, their direct and reciprocal crosses were evaluated, through a diallel analysis with the Griffing method, the correlation between flowering and grain yield was analyzed. For male and female flowering, there were no effects of general combining ability and there were effects of specific combining ability, reciprocal and maternal: the variation between cultivars was explained in 53% for male flowering and 45% for female flowering by effects of specific combining ability, for male flowering 38% of the variation between cultivars and 43% for female flowering was due to reciprocal effects. The variation between cultivars depended on non-additive effects and there was cytoplasmic inheritance involved in their expression. Earliness was positively correlated with grain yield in the spring-summer cycle without insecticide application. With high specific combining ability, TML3S3×VHA and Cam×VHA stood out, to take advantage of the reciprocal effects in Cam×VHA, the order of the parents must be considered., [ES]La precocidad y adaptación del maíz nativo de Tamaulipas en ambientes restrictivos, permite considerarlo fuente de variabilidad para programas de mejoramiento genético, por ello es necesario conocer los efectos genéticos que controlan su variación. El objetivo fue determinar la acción génica que controla la variación de la precocidad de poblaciones de maíz nativo de Tamaulipas y la relación de la precocidad con el rendimiento de grano. En Güémez, Tamaulipas, en otoño invierno 2019-2020 y primavera-verano 2020 con aplicación y no aplicación de insecticida para combatir S. frugiperda, se evaluaron los efectos genéticos de días a floración masculina y femenina de seis poblaciones de maíz, sus cruzas directas y reciprocas, mediante un análisis dialélico con el método de Griffing, se analizó la correlación entre la floración y el rendimiento de grano. Para floración masculina y femenina no existieron efectos de aptitud combinatoria general y existieron efectos de aptitud combinatoria especifica, recíprocos y maternos: la variación entre cultivares se explicó en 53% para floración masculina y 45% para femenina por efectos de aptitud combinatoria especifica, para floración masculina 38% de la variación entre cultivares y 43% para femenina fue debida a efectos recíprocos. La variación entre cultivares, dependió de efectos no aditivos y existió herencia citoplasmática involucrada en su expresión. La precocidad se correlacionó positivamente con el rendimiento de grano en el ciclo primavera-verano sin aplicación de insecticida. Con aptitud combinatoria especifica alta sobresalieron TML3S3×VHA y Cam×VHA, para aprovechar los efectos recíprocos en Cam×VHA hay que considerar el orden de los progenitores.

Delayed senescence could contribute to maintain yield under water stress and low nitrogen stress. Landraces from arid areas can provide favorable alleles for stay green under stress. The objectives of this study were to estimate varietal and heterosis effects of Algerian Saharan populations and their crosses for stay-green under water stress and no-nitrogen fertilization and to identify the most promising populations as sources of stay-green under stress. Six Algerian maize populations were evaluated in a diallel under water stress (300 mm irrigation) versus control (600 mm) and no-nitrogen fertilization versus 120 kg/ha N fertilization. Both varietal and specific heterosis were involved in delayed senescence under stress. Breeding programs could capitalize additive components by using the populations IZM or IGS with favorable varietal effects for delayed senescence under nitrogen stress, or dominance effects by using the population AOR with favorable heterotic effects for plant color under water and nitrogen stresses. Based on specific heterosis, under water stress conditions with no-nitrogen supply, the most promising cross was AOR × IZM for delayed senescence, while IZM × BAH (with no-nitrogen supply), and SHH × BAH (with nitrogen fertilizer), will allow a longer maintenance of the plant coloration. We suggest reciprocal recurrent selection with these populations for developing drought-tolerant and low nitrogen hybrids to improve stay-green.

The present dataset belongs to an untargeted metabolomic study proposed to uncover pathways implicated in resistance to Fusarium ear rot (FER) and fumonisin contamination in the maize kernel and to look for possible biomarkers, using maize inbreds genetically related but with contrasting levels of resistance. The dataset are LC-MS and LC-MS/MS experimental data for untargeted metabolomics of maize immature kernels extracts from eight recombinant inbred lines (RILs) with different level of resistance to FER and fumonisin accumulation at two sampling dates (3 and 10 days) after Fusarium verticillioides inoculation (dat). Spectral data were adquired in a LC-ESI-QTOF mass spectrometer (Bruker Daltonics). MS acquisition was performed in both negative and positive ionization modes for full scan and auto MS/MS, in a mass scan range of m/z 100-1200 with Bruker OTOF Control and DataAnalisys software (Bruker Daltonics). Raw data were converted to .mzML format with ProteoWizard MSConvert tool (Version: 3.0.23163-09bc765). FER and fumonisin resistant RILs are labeled as 1758, 1762, 1766, 1768; susceptible RILs are labeled as 1757, 1759, 1761, 1763. For each combination of RIL and sampling date three biological replicates were analized and can be found inside each RIL MS data .zip file. MS/MS data were obtained from a bulk of the 3 replicates for each RIL-sampling date combination and can be found in the MS/MS data .zip files. Discriminant metabolites between resistant and susceptible RILs were rather found at 10 than 3 dat. Differences for membrane lipid homeostasis, methionine metabolism, and indolacetic acid conjugation seemed highly relevant to distinguish between resistant and susceptible inbreds, confirming the polygenic nature of resistance to FER and fumonisin contamination in the maize kernels. Some specific metabolites such as the polyamine spermidine and/or the alkaloid isoquinoline seemed to be promising indirect selection traits to improve resistance to FER and redu, FER and fumonisin resistant RILs are labeled as 1758 (RIL125), 1762 (RIL128), 1766 (RIL114), 1768 (RIL279); susceptible RILs are labeled as 1757 (RIL14), 1759 (RIL348), 1761 (RIL319), 1763 (RIL152).

Cold reduces maize (Zea mays L.) production and delays sowings. Cold tolerance in maize is very limited, and breeding maize for cold tolerance is still a major challenge. Our objective was to detect QTL for cold tolerance at germination and seedling stages. We evaluated, under cold and control conditions, 919 Dent and 1009 Flint inbred lines from two nested association mapping designs consisting in 24 double-haploid populations, genotyped with 56,110 SNPs. We found a large diversity of maize cold tolerance within these NAM populations. We detected one QTL for plant weight and four for fluorescence under cold conditions, as well as one for plant weight and two for chlorophyll content under control conditions in the Dent-NAM. There were fewer significant QTL under control conditions than under cold conditions, and half of the QTL were for quantum efficiency of photosystem II. Our results supported the large genetic discrepancy between optimal and low temperatures, as the quantity and the position of the QTL were very variable between control and cold conditions. Furthermore, as we have not found alleles with significant effects on these NAM designs, further studies are needed with other experimental designs to find favorable alleles with important effects for improving cold tolerance in maize.

Maize (Zea mays L.) is one of the major crops of the world for feed, food, and industrial uses. It was originated in Central America and introduced into Europe and other continents after Columbus trips at the end of the 15th century. Due to the large adaptability of maize, farmers have originated a wide variability of genetic resources with wide diversity of adaptation, characteristics, and uses. Nowadays, in Europe, maize is mainly used for feed, but several food specialties were originated during these five centuries of maize history and became traditional food specialties. This review summarizes the state of the art of traditional foodstuffs made with maize in Southern, South-Western and South-Eastern Europe, from an historic evolution to the last research activities that focus on improving sustainability, quality and safety of food production.

Fusarium verticillioides has been known as a causing agent of maize ear rot for long time, but the discovery of fumonisins, mycotoxins produced by F. verticillioides, increased concerns on kernel infection by F. verticillioides. A bulk-segregant RNA-seq approach has been used to identify differentially expressed genes (DEG) between bulks of four resistant and four susceptible inbreds to Fusarium ear rot (FER) and kernel fumonisin contamination in order to uncover the pathways involved in resistance. All inbreds were originated from the same F2 population. Plants were selfcrossed and 15 days later the main ear of the plant was inoculated. RNA-seq analysis was done with RNA extracted from kernels collected 10 days after inoculation using three biological replicates for each bulk (different plants of each inbred were used in each replicate). Bulk samples were barcoded and prepared for sequencing at Novogene Co., Ltd, where 150 bp paired-end (PE) reads were obtained on an Illumina 1.9.

In temperate world-wide regions, maize kernels are often infected with the fumonisin-producing fungus Fusarium verticillioides which poses food and feed threats to animals and humans. As maize breeding has been revealed as one of the main tools with which to reduce kernel contamination with fumonisins, a pedigree selection program for increased resistance to Fusarium ear rot (FER), a trait highly correlated with kernel fumonisin content, was initiated in 2014 with the aim of obtaining inbred lines (named EPFUM) with resistance to kernel contamination with fumonisins and adapted to our environmental conditions. The new released EPFUM inbreds, their parental inbreds, hybrids involving crosses of one or two EPFUM inbreds, as well as commercial hybrids were evaluated in the current study. The objectives were (i) to assess if inbreds released by that breeding program were significantly more resistant than their parental inbreds and (ii) to examine if hybrids derived from EPFUM inbreds could be competitive based on grain yield and resistance to FER and fumonisin contamination. Second-cycle inbreds obtained through this pedigree selection program did not significantly improve the levels of resistance to fumonisin contamination of their parental inbreds; however, most EPFUM hybrids showed significantly better resistance to FER and fumonisin contamination than commercial hybrids did. Although European flint materials seem to be the most promising reservoirs of alleles with favorable additive and/or dominance effects for resistance to kernel contamination with fumonisins, marketable new Reid × Lancaster hybrids have been detected as they combine high resistance and yields comparable to those exhibited by commercial hybrids. Moreover, the white kernel hybrid EPFUM-4 × EP116 exploits the genetic variability within the European flint germplasm and can be an alternative to dent hybrid cultivation because white flint grain can lead to higher market prices.

Fusarium verticillioides poses a threat to worldwide maize production due to its ability to infect maize kernel and synthesize fumonisins that can be accumulated above safety levels for humans and animals. Maize breeding has been proposed as key tool to decrease kernel contamination with fumonisins, but metabolic studies complementary to genomic approaches are necessary to disclose the complexity of maize resistance. An untargeted metabolomic study was proposed using inbreds genetically related but with contrasting levels of resistance in order to uncover pathways implicated in resistance to Fusarium ear rot (FER) and fumonisin contamination in the maize kernel and to look for possible biomarkers. Metabolite determinations were performed in kernels collected at 3 and 10 days after inoculation with F. verticillioides (dat). Discriminant metabolites between resistant and susceptible RILs were rather found at 10 than 3 dat, although metabolite differences at later stages of colonization could be driven by subtle variations at earlier stages of infection. Within this context, differences for membrane lipid homeostasis, methionine metabolism, and indolacetic acid conjugation seemed highly relevant to distinguish between resistant and susceptible inbreds, confirming the polygenic nature of resistance to FER and fumonisin contamination in the maize kernels. Nevertheless, some specific metabolites such as the polyamine spermidine and/or the alkaloid isoquinoline seemed to be promising should be explored in future studies in order to clarify if its content can be used as an indirect selection traits to improve resistance to FER and reduce fumonisin accumulation. Therefore, in vitro and in vivo experiments will be necessary to validate the inhibitory effects of these compounds on fumonisins biosynthesis Con formato: Inglés (Estados Unidos).

The bean weevil Acanthoscelides obtectus is one of the world’s main pests of stored beans. The heterogeneous inbred family (HIF) population of near-isogenic lines (NILs) could be an exceptional strategy to study the inheritance of the resistance against A. obtectus. We developed a HIF population of 148 NILs of R-bufa-80-12. The objectives of this research were as follows: (1) to study and understand the genetics of the attack resistance to A. obtectus in a HIF population and (2) to identify the best lines to provide weevil resistance. The pure lines of the HIF population showed a great variability for all the analyzed traits. The traits studied in this research have a normal distribution showing continuous variation, so they are considered to be quantitatively inherited. The heritabilities for resistance traits were low and very low, ranging from 0.09 to 0.17. The heritability for 100 seed weight was the highest, with a significant value of 0.90. The best lines of the HIF population for resistance to A. obtectus comprised Line-45, Line-129, Line-124, Line-142 and Line-47. In general, these lines presented lower preference of adults, and lower consumption in grams and in percentages. However, lines 45 and 129 are the most interesting from a commercial point of view because they combine resistance and seed weight.

The study of yield and resistance/tolerance to pest are related traits fundamental for maize breeding programs. Genomic selection (GS), which uses all marker information to calculate genomic breeding values, is presented as an emerging alternative to phenotypic and marker-assisted selections for improving complex traits controlled by many genes with small effects. Therefore, although phenotypic selection (PS) has been effective for increasing resistance and yield under high infestation with maize stem borers, higher genetic gains are expected to be obtained through GS based on the complex architecture of both traits. Our objective was to test whether GS is more effective than PS for improving resistance and/or tolerance to maize stem borers and grain yield.

The improvement of maize double cropping has become increasingly important in recent years. In order to establish breeding programs for sustainable maize production, the goals of the research were (i) to understand the correlations between grain and stover yield and saccharification efficiency, and (ii) to identify QTL and metabolic pathways to design of breeding programs in a double exploitation approach. We carried out a genome-wide association study (GWAS) and a metabolic pathway analysis using a panel of highly diverse maize inbreds. As results, we have obtained that the regulation of energetic and developmental pathways have been pointed out as key pathways related to stover quantity and utilization, while no specific pathways could be identified in relation to grain yield. However, due to the moderate high heritability of yields and their positive correlation a phenotypic selection approach would be adequate for the improvement of both yields, while for saccharification efficiency improvement upcoming genomic selection models are more advisable. Overall, breeding strategies that manage the dual use of maize are viable and will contribute to a more sustainable maize crop in the near future.

The earlinessand adaptation of native corn of Tamaulipas in restrictive environments allows consideringit a source of variability for genetic improvement programs, so it is necessary to know the genetic effects that control its variation. The objective was to determine the gene action that controls the variation of the earlinessof native cornpopulations of Tamaulipas and the relationship of earlinesswith grain yield. In Güémez, Tamaulipas, in the agricultural cycles of autumn-winter 2019-2020 and spring-summer 2020with application and non-application of insecticide to combat S.frugiperda, the genetic effects of days to male and female flowering of six cornpopulations,their direct and reciprocal crosses were evaluated, through a diallelanalysis with the Griffing method, the correlation between flowering and grain yield was analyzed. For male and female flowering,there were no effects of general combining abilityand there were effects of specific combining ability, reciprocal and maternal: the variation between cultivars was explained in 53% for male flowering and 45% for female flowering by effects ofspecific combining ability, for male flowering 38% of the variation between cultivars and 43% for female flowering wasdue to reciprocaleffects.The variation between cultivars depended on non-additive effects and there was cytoplasmic inheritance involved in theirexpression.Earlinesswas positively correlated with grain yield in the spring-summer cyclewithout insecticide application.With high specific combining ability, TML3S3×VHA and Cam×VHAstood out,to take advantage of the reciprocal effects in Cam×VHA, the order of the parents must be considered, La precocidad y adaptación del maíz nativo de Tamaulipas en ambientes restrictivos, permite considerarlo fuente de variabilidad para programas de mejoramiento genético, por ello es necesario conocer los efectos genéticos que controlan su variación. El objetivo fue determinar la acción génica que controla la variación de la precocidad de poblaciones de maíz nativo de Tamaulipas y la relación de la precocidad con el rendimiento de grano. En Güémez, Tamaulipas, en otoño-invierno 2019-2020 y primavera-verano 2020 con aplicación y no aplicación de insecticida para combatir S. frugiperda, se evaluaron los efectos genéticos de días a floración masculina y femenina de seis poblaciones de maíz, sus cruzas directas y reciprocas, mediante un análisis dialélico con el método de Griffing, se analizó la correlación entre la floración y el rendimiento de grano. Para floración masculina y femenina no existieron efectos de aptitud combinatoria general y existieron efectos de aptitud combinatoria especifica, recíprocos y maternos: la variación entre cultivares se explicó en 53% para floración masculina y 45% para femenina por efectos de aptitud combinatoria especifica, para floración masculina 38% de la variación entre cultivares y 43% para femenina fue debida a efectos recíprocos. La variación entre cultivares, dependió de efectos no aditivos y existió herencia citoplasmática involucrada en su expresión. La precocidad se correlacionó positivamente con el rendimiento de grano en el ciclo primavera-verano sin aplicación de insecticida. Con aptitud combinatoria especifica alta sobresalieron TML3S3×VHA y Cam×VHA, para aprovechar los efectos recíprocos en Cam×VHA hay que considerar el orden de los progenitores

Sitophilus zeamais (Motsch.) (Coleoptera: Curculionidae) has a global distribution and is one of the most important post-harvest pests of maize (Zea mays L.). Some Mexican maize races could be a novel source of resistance against S. zeamais to improve commercial maize, generating lines, varieties, and hybrids with resistance to the pest. These are original races from the center of origin of maize and have been exposed to selection pressure from S. zeamais and other pests for thousands of years, which probably resulted in some type of resistance. We studied the resistance of Mexican maize races to S. zeamais focusing on antixenosis, antibiosis, and tolerance. Antibiosis reduces the survival and reproduction of the insect or prolongs the time between generations, whereas antixenosis reduces the rate of initial and successive accumulation of the insect population. Obligate-antibiosis and free-choice bioassays were performed, and in those experiments, resistance traits and the consumption by S. zeamais were measured. The most resistant accession showed high adult mortality and fewer adults in the 1st generation, where the number of emerged adults is an ideal trait to evaluate the level of maize resistance to the pest. Net consumption (in grams) is the most economically important trait because it indicates the gross amount lost in a store, while yield losses (percentage of consumption) allow for studying tolerance. The type of endosperm did have an influence on the resistance/tolerance to S. zeamais. The flint varieties showed significantly higher mortality of adults before entering the seed, a lower quantity of emerged adults of the first generation in the obligate-antibiosis bioassay, and lower net consumption and percentage in both bioassays. In general, the varieties of the races Cristalino de Chihuahua, Apachito, and Azul showed high levels of resistance, with the Cristalino-079 (flint) and Azul (floury) accessions also being tolerant, and low levels of consumption

Forage oats (Avena sativa L.) are globally important for milk and meat production, and, to a lesser extent, for the human diet. In Mexico, oats are a strategic crop, occupying the fourth place in cultivated area, only after maize for grain, bean, and sorghum for grain. Droughts are the main problem for oat production in Mexico. This study evaluated the germination and seedling growth of several oat varieties in response to drought stress simulated by PEG-6000 treatments of different osmotic pressure in order to identify drought-resistant genotypes. The Teporaca genotype was the most outstanding in the three levels of OP compared to its control with 0.0 of Osmotic Potential (OP). The Teporaca genotype showed the largest root length and the lowest diminishment of root length under osmotic stress conditions. This genotype also had the largest shoot length in the three osmotic stress levels. Regarding root fresh weight, Babicora stands out with 98.5% and Teporaca with 43% in the most severe level. Teporaca, Menonita, and Babicora showed the outstanding root dry weights of 346.5%, 327.2%, and 251.2%, respectively. These varieties had higher root dry weight than their own controls in water in the most severe level of OP. In conclusion, the Teporaca, Menonita, and Karma genotypes showed the highest osmotic stress tolerance and could be used as sources of favorable alleles to improve oat drought tolerance.

Landraces of maize (Zea mays L.) have a variability not found in the elite hybrids due to the bottleneck during selection. There is a renewed interest in using that variability, incorporating alleles for specific traits, or widening the general variability of elite germplasm. In Europe, there is also an interest in the direct use of local landraces by farmer’s associations seeking agriculture that preserves crop diversity. Pre-breeding programs are aimed to reduce the yield gap among landraces and improved materials. In the Misión Biológica de Galicia we have carried out three cycles of a S recurrent selection program for yield on four local landraces from Northwestern Spain with the objective of obtaining improved populations that might be cultivated by farmers and that could be used as sources of superior inbred lines. One hundred plants were selfed in each landrace and the S families were evaluated in a 10 × 10 simple lattice. The 20 S families with the highest grain yields were randomly intercrossed to form the selected population of each landrace. After three cycles of selection, each population and its cycles of selection were evaluated in three locations for two years. All the populations had a consistent yield gain in the first cycle of selection. However, the response in later cycles differed among the populations: one population had a continuous increase of 21% per cycle while two populations had a reduced yield in the last cycles. Our results highlight the need to include secondary traits to avoid unintentional indirect effects. We conclude that, in pre-breeding programs, it could be worthy to use large effective numbers to prevent inbreeding depression, particularly when the objective is the direct use of improved landraces. Another conclusion is that recurrent selection does not seem to be as efficient on European germplasm as it is on Corn Belt varieties. Finally, obtaining valuable new germplasm requires a sustained, long-term effort.

Drought is the main constraint to maize production in the Mediterranean area. This is the first report of breeding temperate maize populations from the Algerian desert. The objective of this study was to evaluate response to selection for reduced anthesis-silking interval (ASI) in Algerian maize under drought and control conditions. Three cycles of selection for reduced ASI were carried out in four populations under control and drought conditions, and the breeding program was evaluated under both conditions. Selection under drought was more efficient than under control conditions, particularly for the LOM and TAO populations. Selection for low ASI reduced ASI and days per cycle for BTM and IGS, respectively, under drought conditions. Selection for ASI reduced anthesis in BTM, when selected under drought and evaluated under control conditions. Significant yield increase was observed for BTM under optimal conditions. Significant genetic gain for yield was observed for the population LOM under drought. Therefore, the improved Algerian populations BTM and TAO could be a novel source for reducing ASI and for earlier flowering time as a mechanism for avoiding drought. Furthermore, we propose these populations as sources to develop tolerant inbred lines and to find quantitative trait loci for drought tolerance.

Sitotroga cerealella (Oliv.) (Lepidoptera: Gelechiidae) is one of the most important post-harvest pests of maize Zea mays L. Some Mexican maize races (Z. mays) could be a novel source of resistance against S. cerealella to improve commercial maize varieties, lines and hybrids. We studied the resistance of Mexican maize races, recollected at Chihuahua State to S. cerealella. We focused on antibiosis and tolerance of maize to S. cerealella. Cristalino-079 maize race shows low level of consumption in grams and percentage, increased larvae mortality before to entering the seed. In addition, Cristalino-079 reduced first adult’s generation and show the largest biological cycle. Due to the small number of emerged adults, there was very little grain weight loss in resistant maize race. The compound that causes high mortality of larvae before to entering the grain is in the pericarp of resistant maize races. The compound that causes longest development time is in the endosperm and embryo. Cristalino-079 show the better level of resistance to S. cerealella infestation in almost all traits studied and this can be used as source of resistance for maize breeding.

Higher hydroxycinnamate content makes maize tissues more recalcitrant to damage by insects, less digestible by ruminants, and less suitable for biofuel production. In a Genome Wide Association Analysis (GWAS) study carried out in a maize MAGIC population, we identified 24 SNPs associated with esterified cell wall-bound hydroxycinnamates, that represented 15 Quantitative Traic Loci (QTL). We identified new genomic regions associated to cell wall bound hydroxycinnamates in maize stover that could have an impact on their content across different genetic backgrounds. The high resolution QTL described in this study could be valuable for addressing positional mapping of genes involved in hydroxycinnamate biosynthesis and could uncover genes implicated in the esterification of hydroxycinnamic acids to the arabinoxylan chains that are poorly understood. However, we found that genetic correlation coefficients between hydroxycinnamate content and economical important traits such as saccharification efficiency, animal digestibility andi pest resistance were low to moderate, so modify specific hydroxycinnamates to indirectly improve cultivar performance will be unsuitable.

Increasing drought incidence and infertile soils require the improvement of maize for nitrogen use efficiency (NUE) under drought conditions. The objectives were to assess tolerance and genetic effects of Algerian populations under no‐nitrogen and water stress. We evaluated a diallel among six Algerian maize populations under no‐nitrogen vs. 120 kg/ha N fertilization and drought vs. control. Variability was significant among populations and their crosses for NUE under drought. Additive genetic effects could be capitalized using the populations BAH and MST, with high grain nitrogen utilization efficiency (NUtE). The most promising crosses were SHH × AOR with no‐nitrogen supply under both water regimes for NUtE, AOR × IGS, under water stress for partial factor productivity (PFP), and well‐watered conditions with nitrogen supply for protein content; AOR × IZM for agronomic nitrogen use efficiency (AE) under water stress; and AOR × BAH for grain nutrient utilization efficiency (NUtE) under well‐watered conditions with nitrogen. These parents could be promising for developing drought‐tolerant or/and low nitrogen hybrids to improve these traits. Maximum heterosis could be exploited using those populations and crosses. Reciprocal recurrent selection could be used to take advantage of additive and non‐additive gene effects found based on estimations of genetic parameters.

BACKGROUND: Captures and seasonal abundance of Xylotrechus arvicola (Coleoptera: Cerambycidae) in relation to climatic factors were studied in vineyards between the years 2013 and 2020. Insects captures from vine wood in two Vitis vinifera varieties were evaluated every year by counting the number of insects captured with CROSSTRAP®. The captured insects were grouped (by sex and total) into ranges of 10 days and compared to climatic data (daily average, temperature and rainfall) for each cultivar and year. RESULTS: The capture periods spanned from 1 June and 31 July, with the period from 1 to 30 June having the greatest number of insect captures, as long as weather conditions were favourable, i.e. temperature above 20.00 °C and accumulated rainfall in 10 days lower than 0.40 mm, verified through the analysis of parameter estimates, in which, only the temperature parameter was significantly. CONCLUSIONS: The study provided useful information for the integrated pest management of X. arvicola through mass trapping in vineyards when temperature exceeds 20.00 °C and the accumulated rainfall is less than 0.40 mm in 10 days to obtain peak captures. This is the first quantitative study of X. arvicola control associated with temperature and rainfall in Vitis vinifera. © 2022 Society of Chemical Industry.

Maize stalks support leaves and reproductive structures and functionally support water and nutrient transport; besides, their anatomical and biochemical characteristics have been described as a plant defense against stress, also impacting economically important applications. In this study, we evaluated agronomical and stem description traits in a subset of maize inbred lines that showed variability for cell wall composition in the internodes. Overall, a great proportion of lignin subunit G and a low concentration of p-coumaric acid and lignin subunit S are beneficial for greater rind puncture resistance and taller plants, with a greater biomass yield. Also, the greater the proportions of subunit H, the longer the internode. Finally, the lower the total hemicellulose content, the greater the rind puncture resistance. Our results confirmed the effect of the cell wall on agronomic and stalk traits, which would be useful in applied breeding programs focused on biomass yield improvement.

Fusarium verticillioides is a causal agent of maize ear rot and produces fumonisins, which are mycotoxins that are toxic to animals and humans. In this study, quantitative trait loci (QTLs) and bulk-segregant RNA-seq approaches were used to uncover genomic regions and pathways involved in resistance to Fusarium ear rot (FER) and to fumonisin accumulation in maize kernels. Genomic regions at bins 4.07–4.1, 6–6.01, 6.04–6.05, and 8.05–8.08 were related to FER resistance and/or reduced fumonisin levels in kernels. A comparison of transcriptomes between resistant and susceptible inbred bulks 10 days after inoculation with F. verticillioides revealed 364 differentially expressed genes (DEGs). In the resistant inbred bulks, genes involved in sink metabolic processes such as fatty acid and starch biosynthesis were downregulated, as well as those involved in phytosulfokine signaling and many other genes involved in cell division; while genes involved in secondary metabolism and compounds/processes related to resistance were upregulated, especially those related to cell wall biosynthesis/rearrangement and flavonoid biosynthesis. These trends are indicative of a growth–defense trade-off. Among the DEGs, Zm00001d053603, Zm00001d035562, Zm00001d037810, Zm00001d037921, and Zm00001d010840 were polymorphic between resistant and susceptible bulks, were located in the confidence intervals of detected QTLs, and showed large differences in transcript levels between the resistant and susceptible bulks. Thus, they were identified as candidate genes involved in resistance to FER and/or reduced fumonisin accumulation.

Maize (Zea mays L.) has limited cold tolerance, and breeding for cold tolerance is a noteworthy bottleneck for reaching the high potential of maize production in temperate areas. In this study, we evaluate a large panel of 836 maize inbred lines to detect genetic loci and candidate genes for cold tolerance at the germination and seedling stages. Genetic variation for cold tolerance was larger than in previous reports with moderately high heritability for most traits. We identified 187 significant single-nucleotide polymorphisms (SNPs) that were integrated into 159 quantitative trait loci (QTL) for emergence and traits related to early growth. Most of the QTL have small effects and are specific for each environment, with the majority found under control conditions. Favorable alleles are more frequent in 120 inbreds including all germplasm groups, but mainly from Minnesota and Spain. Therefore, there is a large, potentially novel, genetic variability in the germplasm groups represented by these inbred lines. Most of the candidate genes are involved in metabolic processes and intracellular membrane-bounded organelles. We expect that further evaluations of germplasm with broader genetic diversity could identify additional favorable alleles for cold tolerance. However, it is not likely that further studies will find favorable alleles with large effects for improving cold tolerance in maize.

Cellulosic ethanol derived from fast growing C4 grasses could become an alternative to finite fossil fuels. With the potential to generate a major source of lignocellulosic biomass, maize has gained importance as an outstanding model plant for studying the complex cell wall network and also to optimize crop breeding strategies in bioenergy grasses. A genome-wide association study (GWAS) was conducted using a subset of 408 Recombinant Inbred Lines (RILs) from a Multi-Parent Advanced Generation Intercross (MAGIC) Population in order to identify single nucleotide polymorphisms (SNPs) associated with yield and saccharification efficiency of maize stover. We identified 13 SNPs significantly associated with increased stover yield that corresponded to 13 QTL, and 2 SNPs significantly associated with improved saccharification efficiency, that could be clustered into 2 QTL. We have pointed out the most interesting SNPs to be implemented in breeding programs based on results from analyses of averaged and yearly data. Association mapping in this MAGIC population highlight genomic regions directly linked to traits that influence the final use of maize. Markers linked to these QTL could be used in genomic or marker-assisted selection programs to improve biomass quality for ethanol production. This study opens a possible optimisation path for improving the viability of second-generation biofuels.

Drought and low nitrogen are major stresses for maize (Zea mays L.), and maize populations from the Sahara Desert are potential sources of stress tolerance. The objectives were to assess the tolerance and varietal and heterosis effects of Algerian populations under no-nitrogen fertilization and water stress. A diallel among six Algerian maize population was evaluated under drought (300 mm irrigation) vs. control (600 mm) and no-nitrogen fertilization vs. 120 kh ha N fertilization. Genotypes showed significant differences and genetic effects for water-and nitrogen-stress tolerance. We propose a reciprocal recurrent selection to take advantage of additive and non-additive effects, using AOR and IGS, since they showed good performance in optimum and stress conditions, for improving yield heterosis for AOR × IGS. Negative effects are not expected on plant height, anthesis– silking interval or early vigor. These populations and BAH could be sources of inbred lines tolerant to drought and no-nitrogen fertilization. There was no relationship between origin and genetic group and stress tolerance per se or as parents of tolerant crosses. These populations and crosses could be used as base material among Algerian populations, for breeding programs focusing on tolerance to water or nitrogen stress.

Drought is the main stress for agriculture, and maize (Zea mays L.) germplasm from the Sahara has been identified as potential source of drought tolerance; however, information about adaptation of semitropical maize germplasm from the Sahara to temperate areas has not been reported. Our objective was assessing the adaptation of maize germplasm from Saharan oases as sources of drought tolerance for improving yield and biomass production under drought conditions in temperate environments. A collection of maize populations from Saharan oases was evaluated under drought and control conditions in Spain and Algeria. Algerian populations were significantly different under drought for most traits, and the significant genotype × environment interactions indicated that drought tolerance is genotype-dependent, but tolerance differences among genotypes change across environments. Based on yield, the Algerian maize populations PI527474, PI527478, PI527472, PI527467, PI527470, and PI527473 would be appropriate sources of drought tolerance for temperate environments. Concerning biomass production, the most interesting populations were PI527467, PI542685, PI527478, and PI527472. These Saharan populations could provide favorable alleles for drought tolerance for temperate breeding programs, and could also be used for studying mechanisms and genetic regulation of drought tolerance.

Forage feedstock is the greatest source of energy for livestock. Unfortunately, less than 50% of their fiber content is actually digested and assimilated by the ruminant animals. This recalcitrance is mainly due to the high concentration of plant cell wall material and to the limited digestion of the fiber by the microorganisms. A Genome-Wide Association Study (GWAS) was carried out in order to identify Single Nucleotide Polymorphisms (SNPs) associated with forage digestibility traits in a maize Multi-Parent Advanced Generation Intercross (MAGIC) population. We identified seven SNPs, corresponding to five Quantitative Trait Loci (QTL), associated to digestibility of the organic matter, 11 SNPs, clustered in eight QTLs, associated to Neutral Detergent Fiber (NDF) content and eight SNPs corresponding with four QTL associated with Acid Detergent Fiber (ADF). Candidate genes under the QTL for digestibility of the organic matter could be the ones involved in pectin degradation or phenylpropanoid pathway. Transcription factor genes were also proposed for the fiber QTL identified, in addition to genes induced by oxidative stress, or a gene involved in lignin modifications. Nevertheless, for the improvement of the traits under study, and based on the moderate heritability value and low percentage of the phenotypic variability explained by each QTL, a genomic selection strategy using markers evenly distributed across the whole genome is proposed.

Maize’s (Zea mays L.) nutrient content can be modified through selection. The objective of this study was to assess the nutritive value of 13 maize hybrids from four endosperm types, and the relationship between nutrient concentration, agronomic and rheological value. The hybrids were evaluated in two locations of Northwestern Spain over two years. There was genetic diversity among endosperm types and genotypes for all nutrients, with significant environmental effects, but few genotype × environment interactions. Flint hybrids had the highest protein and lipid content. The mutant wx1 significantly increased protein and reduced lipid, and both wx1 and o2 reduced ash and starch content and increased total fiber. Variability among hybrids within the wx1 endosperm was significant for most nutrients. Correlations between nutrients were rarely significant, implying that protein and lipid can be improved independently. Protein and lipid were negatively correlated with grain yield and plant height. However, improving nutrient content could alter agronomic performance, as nutrients had significant negative effects on rheological factors, particularly protein and lipid, which had negative effects on whole meal and on bread characteristics. Therefore, nutrient content can be improved in maize, but negative effects on agronomic and quality have to be taken into account.

Lodging is one of the causes of maize (Zea mays L.) production losses worldwide and, at least, the resistance to stalk lodging has been positively correlated with stalk strength. In order to elucidate the putative relationship between cell wall, stalk strength and lodging resistance, twelve maize inbreds varying in rind penetration strength and lodging resistance were characterized for cell wall composition and structure. Stepwise multiple regression indicates that H lignin subunits confer a greater rind penetration strength. Besides, the predictive model for lodging showed that a high ferulic acid content increases the resistance to lodging, whereas those of diferulates decrease it. These outcomes highlight that the strength and lodging susceptibility of maize stems may be conditioned by structural features of cell wall rather than by the net amount of cellulose, hemicelluloses and lignin. The results presented here provide biotechnological targets in breeding programs aimed at improving lodging in maize.

Breeding for cold tolerance in maize is an important objective in temperate areas. The objective was to carry out a highly efficient study of quantitative trait loci (QTLs) for cold tolerance in maize. We evaluated 406 recombinant inbred lines from a multi-parent advanced generation intercross (MAGIC) population in a growth chamber under cold and control conditions, and in the field at early and normal sowing. We recorded cold tolerance-related traits, including the number of days from sowing to emergence, chlorophyll content and maximum quantum efficiency of photosystem II (F/F). Association mapping was based on genotyping with near one million single nucleotide polymorphism (SNP) markers. We found 858 SNPs significantly associated with all traits, most of them under cold conditions and early sowing. Most QTLs were associated with chlorophyll and F/F. Many candidate genes coincided between the current research and previous reports. These results suggest that (1) the MAGIC population is an efficient tool for identifying QTLs for cold tolerance; (2) most QTLs for cold tolerance were associated with F/F; (3) most of these QTLs were located in specific genomic regions, particularly bin 10.04; (4) the current study allows genetically improving cold tolerance with genome-wide selection.

The genetic basis of commercial maize (Zea mays L.) is quite narrow. The incorporation of exotic germplasm, i.e. all germplasm that does not have immediate usefulness without selection for adaptation, is a way of enhancing the genetic basis of the material that a breeder can use. The populations of maize ‘Purdue Synthetic A o2’ (Purdue A) and ‘Purdue Synthetic B o2’ (Purdue B) were subjected to 18 cycles of recurrent mas selection for early flowering in Northwestern Spain. To evaluate the efficiency of selection, the original populations, the cycles of selection 6, 12, and 18, and five hybrid checks were evaluated in four environments in Spain. Both populations responded positively to selection for earlier female flowering with linear regression being highly significant. The change in the number of days from planting to silking was similar in both populations (1.01 days to silking/cycle of selection). Plant height, kernel moisture at harvest, and yield decreased significantly in both populations. Selection for early silking was efficient and resulted on similar decreases of kernel moisture in both populations, but yield and biomass decreased strongly. Therefore, although we must pay careful attention to agronomical important traits, these early o2 populations can be incorporated to a breeding program under short season conditions.

[Background]: Corn borers constitute an important pest of maize around the world; in particular Sesamia nonagrioides Lefèbvre, named Mediterranean corn borer (MCB), causes important losses in Southern Europe. Methods of selection can be combined with transgenic approaches to increase the efficiency and durability of the resistance to corn borers. Previous studies of the genetic factors involved in resistance to MCB have been carried out using bi-parental populations that have low resolution or using association inbred panels that have a low power to detect rare alleles. We developed a Multi-parent Advanced Generation InterCrosses (MAGIC) population to map with high resolution the genetic determinants of resistance to MCB., [Results]: We detected multiple single nucleotide polymorphisms (SNPs) of low effect associated with resistance to stalk tunneling by MCB. We dissected a wide region related to stalk tunneling in multiple studies into three smaller regions (at ~ 150, ~ 155, and ~ 165 Mb in chromosome 6) that closely overlap with regions associated with cell wall composition. We also detected regions associated with kernel resistance and agronomic traits, although the co-localization of significant regions between traits was very low. This indicates that it is possible the concurrent improvement of resistance and agronomic traits., [Conclusions]: We developed a mapping population which allowed a finer dissection of the genetics of maize resistance to corn borers and a solid nomination of candidate genes based on functional information. The population, given its large variability, was also adequate to map multiple traits and study the relationship between them.

Maize is used in bakery and gluten free food for celiac patients. The objective of this study was to assess the effects of maize mutants with high-amylopectin (waxy1) or quality protein (opaque2) in dough bread by using near-isogenic maize hybrids for waxy1 (wx1) and opaque2 (o2). Differences between wx1 and its wild type allele (Wx1) were significant more often than for o2. Agronomic performance was low for o2 and fair for wx1 hybrids. Among the meal traits, wx1decreased flotation, onset pasting temperature, maximum and final viscosity, trough, breakdown, total set back, and area under the apparent viscosity curve, and increased water binding capacity. Concerning bread traits, o2 had no significant mean effects, while wx1 increased reddish crumb color, retarded recovery elasticity and cohesiveness, and reduced hardness, chewiness and instant recovery speed. Therefore, we can use waxy maize for improving maize bread quality, and the choice of the maize genotype could significantly affect the final results.

Alternative approaches to linkage and association mapping using inbred panels may allow further insights into loci involved in resistance to Fusarium ear rot and lead to the discovery of suitable markers for breeding programs. Here, the suitability of a maize multiparent advanced generation intercross population for detecting quantitative trait loci (QTLs) associated with Fusarium ear rot resistance was evaluated and found to be valuable in uncovering genomic regions containing resistance-associated loci in temperate materials. In total, 13 putative minor QTLs were located over all of the chromosomes, except chromosome 5, and frequencies of favorable alleles for resistance to Fusarium ear rot were, in general, high. These findings corroborated the quantitative characteristic of resistance to Fusarium ear rot in which many loci have small additive effects. Present and previous results indicate that crucial regions such as 210 to 220 Mb in chromosome 3 and 166 to 173 Mb in chromosome 7 (B73-RefGen-v2) contain QTLs for Fusarium ear rot resistance and fumonisin content.

Two decades of investigations on maize resistance to Mediterranean corn borer (Sesamia nonagrioides Lefebvre; MCB) have shown that breeding for increased resistance to stem tunnelling by MCB often resulted in reduced yield because significant genetic correlation between both traits exists in some backgrounds. Unlike phenotypic selection, marker-assisted selection (MAS) could differentiate markers linked only to one trait from those linked simultaneously to yield potential and susceptibility to the pest. In the current study, the suitability of MAS for improving resistance to stem tunnelling without adverse effects on yield has been tested. The unfavourable genetic relationship between yield potential and susceptibility could be overcome using MAS. Gains obtained using MAS were weak, because genetic variance explained by the quantitative trait loci (QTL) was low but results encourage us to persevere in using marker information for simultaneous improvement of resistance and yield especially if genome-wide approaches are applied. Approaches to detect QTL are widely used, but studies on the suitability of markers linked to QTL for performing MAS have been mostly neglected.

[Background] Plant breeding has been proposed as one of the most effective and environmentally safe methods to control fungal infection and to reduce fumonisin accumulation. However, conventional breeding can be hampered by the complex genetic architecture of resistance to fumonisin accumulation and marker-assisted selection is proposed as an efficient alternative. In the current study, GWAS has been performed for the first time for detecting high-resolution QTL for resistance to fumonisin accumulation in maize kernels complementing published GWAS results for Fusarium ear rot., [Results] Thirty-nine SNPs significantly associated with resistance to fumonisin accumulation in maize kernels were found and clustered into 17 QTL. Novel QTLs for fumonisin content would be at bins 3.02, 5.02, 7.05 and 8.07. Genes with annotated functions probably implicated in resistance to pathogens based on previous studies have been highlighted., [Conclusions] Breeding approaches to fix favorable functional variants for genes implicated in maize immune response signaling may be especially useful to reduce kernel contamination with fumonisins without significantly interfering in mycelia development and growth and, consequently, in the beneficial endophytic behavior of Fusarium verticillioides.

Antioxidant activity (AA) of black maize kernels attributed mainly to polyphenols has potential effects on health and possible defense functions against pests. Our objective was to evaluate the effects of maize polyphenols and AA in survival and growth of larvae of the corn borer Sesamia nonagrioides. We carried out two bioassays with S. nonagrioides larvae grown in artificial diet with white and black maize flour and control. AA was tested spectrophotometrically on each of the diets using four methods. The different measurements of AA were strongly correlated, indicating that these measurements were highly reliable. The control diet, the white-maize-diet and black-maize-diet with vitamin C and without H2O2 had the highest antioxidant activity. The processing of the maize flour altered the AA of the polyphenols. The control treatment had the highest AA, and vitamin C had stronger AA than polyphenols. AA of vitamin C hides that of polyphenols probably due to environmental effects, dilution of polyphenols, or interactions with other substances. Larvae grew more in the control diet and the addition of H2O2 had not significant effects on weight. There was a weak rank correlation between AA and larval weight. Mortality was lowest for the control diet with or without H2O2 followed by white maize with or without H2O2 and black maize without H2O2. Effects of polyphenols depend on other substances that might interact with them. The results indicate that antioxidant activity has insecticide effects on young larvae and, as the larvae grow, antioxidants have positive effects on larvae.

Understanding of the genetic basis of quantitative traits such as resistance to pest and yield are necessary to optimize the breeding programs to simultaneously improve both characters. Genome Wide Association Studies (GWAS) are useful tools to achieve this goal, especially when the mapping population is a Multi-Parent Advanced Generation Intercross (MAGIC) population. A MAGIC population of 672 recombinant inbred lines (RIL) was generated after inter-mating for six generations a synthetic variety composed of eight genetically diverse founder lines. This MAGIC population have been genotyped by genotyping based on the sequence (GBS) and evaluated for resistance to attack by the Mediterranean Corn Borer (MCB, Sesamia nonagrioides) and for yield, plant height and silking. We found seven QTL and six candidate genes for grain resistance, forty-eight QTL and sixty candidate genes for plant height, thirty-four QTL and forty-nine candidate genes for silking time, five QTL and nine genes for tunnel length, and finally fifteen QTL and twenty-four candidate genes for grain yield. We expect that tunnel length produced by MCB larvae attack and plant height also increase when yield is improved due to the genetic correlation between these traits. The intermediate role of plant height on the undesirable genetic relationship between yield and resistance was highlighted suggesting that tradeoff between plant growth and resistance could mediate that undesirable relationship. MAGIC population was useful to discover genomic regions involved in MCB resistance with greater precision than those determined using more structured populations,. The GRMZM2G178190 (Zm00001d048129) gene related to the natural resistance could intervene in the ear resistance and the GRMZM2G057140 (Zm00001d043286) gene that is related to the regeneration of the cell wall could be related to stem resistance to corn borer attacks. A genetic improvement program can be designed with the 5 QTL detected for tunnel length

Cold tolerance is a complex trait that limits adaptation of maize in temperate areas. The available literature shows that cold tolerance is regulated by large number of QTLs with small effects and weak consistence across genotypes. However, previous studies have involved a limited number of genotypes with narrow genetic diversity, and scarce genetic recombination mapping populations. We investigated the genetics underlying cold tolerance in a multi-parent advanced generation inter-cross (MAGIC) population genotyped using genotyping by sequencing (GBS) with near one million SNPs. This MAGIC population consisted on recombinant inbred lines (RILs) released from a synthetic population (EPS21) obtained from Spanish, Italian, and French flints, and two non-Reid Corn Belt inbred lines. A set of 406 RILs was evaluated in a growth chamber under cold and control conditions, as well as in the field at early and late sowing dates. Our results showed no evidence for any single large-effect quantitative trait loci (QTLs); however, a region on chromosome 2 had a dense concentration of significant QTLs for fluorescence (Fv/Fm) that were consistent in growth chamber and early field sowing. Besides, we identified numerous additional small-effect QTLs for cold tolerance-related traits in growth chamber (64 QTLs) and early field sowing (61 QTLs). The large number of markers involved, the small effects explained by each QTL, and the difficulties on collecting phenotypic data, encourage the implementation of genomic selection programs to improve cold tolerance in maize.

In current study, GWAS has been performed for the first time for detecting high-resolution QTL for resistance to fumonisin accumulation in maize kernel. A subset of 270 inbred lines from a maize diversity panel (composed of 302 inbred lines) that represents much of the diversity available in public breeding sector around the world was evaluated under inoculation with Fusarium verticillioides. Significant associations between polymorphisms at SNPs in bins 1.07, 1.09, 2.08, 3.02, 3.04, 3.05, 3.06, 3.08, 3.09, 4.02, 4.05, 5.02, 6.07, 7.05, 8.07, 9.03 and fumonisin accumulation (determined by ELISA tests) in maize kernel were detected. At least, four associations should be behind novel QTL because QTL were not found in that bin or in adjacent bins in previous studies (Robertson-Hoyt et al. 2006; Maschietto et al. 2017). These novel QTLs for fumonisin content would be at bins 3.02, 5.02, 7.05, and 8.03. Genes likely involved in ROS production, ROS-scavenging and ROS-detoxification, in signaling and/or regulation of plant hormone-mediated responses and lipid metabolism were proposed as candidate genes behind significant associations.

La mejora de la resistencia a la plaga de los taladros conlleva indirectamente una reducción del rendimiento. Valoramos la utilidad de la selección asistida por marcadores (SAM) para evitar estos efectos adversos. Las ganancias obtenidas con la SAM fueron pequeñas debido probablemente a que la varianza genética explicada por el QTL fue baja por lo que un programa de selección genómica podría ser interesante para la mejora simultanea de resistencia y rendimiento.

Multi-parent Advanced Generation Intercross (MAGIC) populations offer intermediate characteristics between bi-parental and association mapping populations. MAGIC populations enclose higher polymorphism diversity than bi-parental populations, but keeps detection power at higher levels than in association mapping populations. On the other hand, resolution is greatly improved compared to bi-parental populations due to inter-mating of multiple founders for several generations before self-crossing. A MAGIC population of approximately 700 inbred lines was generated after inter-mating for six generations a synthetic variety composed of eight inbred lines with contrasting susceptibility to Fusarium ear rot (FER). A subset of 339 inbred lines of this MAGIC population have been genotyped by genotyping by sequencing (GBS) and evaluated for resistance to FER; polymorphisms at 9 SNPs were significantly associated with resistance to FER. Significant SNPs are mapped at 53103370 and 55250804 bp in chromosome 2; at 216876071 bp (bin 3.09) in chromosome 3; at 164651229, 164651230, and 164651232 bp (bin 5.04) in chromosome 5; at 156669384bp (bin7.04) in chromosome 7; and at 45294620 and 45294624 bp in chromosome 9 (RefGen_v2). The region 160-175 Mbp in chromosome 5, where three significant SNPs were located in the current study, deserves special attention because it seems to contain allelic variability relevant for differences for resistance to FER in many backgrounds.