Important Yield Component Research Articles

Natural variation of RGN1a regulates grain number per panicle in japonica rice.

The grain number per panicle (GNP) is an important yield component. Identifying naturally favorable variations in GNP will benefit high-yield rice breeding. Here, we performed a genome-wide association study using a mini-core collection of 266 cultivated rice accessions with deep sequencing data and investigated the phenotype for three years. Three genes, i.e., TOTOU1 (TUT1), Grain height date 7 (Ghd7), and Days to heading 7/Grain height date 7.1/Pseudo-Response Regulator37 (DTH7/Ghd7.1/OsPRR37), which regulate GNP, were found in the quantitative trait loci (QTL) identified in this study. A stable QTL, qGNP1.3, which showed a strong correlation with variations in GNP, was repeatedly detected. After functional and transgenic phenotype analysis, we identified a novel gene, regulator of grain number 1a (RGN1a), which codes for protein kinase, controlling GNP in rice. The RGN1a mutation caused 37.2%, 27.8%, 51.2%, and 25.5% decreases in grain number, primary branch number per panicle, secondary branch number per panicle, and panicle length, respectively. Furthermore, breeding utilization analysis revealed that the additive effects of the dominant allelic variants of RGN1a and DTH7 played a significant role in increasing the grain number per panicle in japonica rice. Our findings enrich the gene pool and provide an effective strategy for the genetic improvement of grain numbers.

Transcriptomic analysis reveals the regulation of early ear-length development in maize

Ear length is an important component of maize grain yield. However, the ear length is a complex quantitative trait, and the underlying molecular mechanisms remain poorly understood. Here, the chromosome segment substitution line (CSSL) 1283 displayed a longer ear length compared with the recipient parent Xu178. An RNA sequencing analysis of Xu178 and CSSL1283 ears during three undifferentiated ear developmental stages identified 1,991 differentially expressed genes (DEGs). A gene ontology analysis of the DEGs showed that genes related to transcription factors and response to abiotic stimulus were significantly enriched. Furthermore, the expression of DEGs associated with AP2/EREBP and WRKY transcription factors and heat shock proteins was upregulated in CSSL1283. In addition, several genes encoding protein kinase were differentially expressed between Xu178 and CSSL1283. Our study provided a genetic resource for the dissection of the molecular mechanisms of ear-length development and for uncovering candidate genes to increase maize ear length.

Genotype × Environment Interaction in the Coffee Outturn Index of Amazonian Robusta Cultivars

The coffee outturn index, understood as the relation between the cherry coffee fruit harvested from the field and its respective processed grains, is an important component of the Coffea canephora bean yield. The aim of this study was to quantify the coffee outturn index of the Amazon Robusta cultivars grown in irrigated and dryland Western Amazon environments. According to the maturation cycle of each clone, washed samples of cherry coffee were collected considering a completely randomized factorial design for characterization of the effects of genotypes, environments, and the genotype × environment (G×E) interaction. The contrasting environments of Porto Velho, RO, and Ouro Preto do Oeste, RO, Brazil, represent most of the coffee growing sites located in Am and Aw climate types, cultivated in Red and Yellow Oxisols, typical of the Western Amazon. The weight reductions through drying exhibited a G×E interaction of the complex type, which is characterized by a change in the ordering of genotypes from one environment to another, whereas the weight reductions through hulling exhibited a G×E interaction predominantly of the simple type. The reduction in weight due to drying was more affected by the environment than reduction in weight after pulping. The clones BRS1216, BRS 3220, and BRS3137 had the highest outturn index estimates and the clones BRS2314, BRS3213, and BRS2336 had the lowest outturn index estimates. The clones BRS2299, BRS3210, BRS3193, and BRS2357 had performance near the mean value of this group of genotypes. Considered together, the genotypes had a mean outturn of 24.41%, with an amplitude from 22.5% to 27.2%.

Inheritance of seed weight and growth habit in 10 intercross chickpea (Cicer arietinum) nested association mapping populations

AbstractObjective of investigationChickpea is a major global food legume for which seed weight and plant growth habit are important yield and harvestability components for plant breeding. This study tested seed weight and plant growth habit inheritance and identified quantitative trait loci (QTL).Experimental materialA 10 nested association mapping (NAM) populations of chickpea were created from crosses between ‘Gokce’, a cultivar and wild crop relative accessions of Cicer reticulatum and Cicer echinospermum. Families were then developed to the F2:4 generation.Method of investigationA 10 families were grown at the Field Experiment Station, Harran University near Şanlıurfa, Turkey during 2019.Data collectionA 100‐seed weight and prostrate or erect growth habit was scored in the field. Two families were genotyped for 60 single‐nucleotide polymorphisms (SNP).Result and conclusionsA 100‐seed weight showed polygenic control, and three QTLs were found. Growth habit was controlled by one or two QTLs. The two traits were significantly correlated for five populations. The crop wild relatives of chickpea contain variations at novel loci affecting seed weight compared to the literature.

Identification and validation of stable quantitative trait loci for yield component traits in wheat

Grain weight and grain number are important yield component traits in wheat and identification of underlying genetic loci is helpful for improving yield. Here, we identified eight stable quantitative trait loci (QTL) for yield component traits, including five loci for thousand grain weight (TGW) and three for grain number per spike (GNS) in a recombinant inbred line population derived from cross Yangxiaomai/Zhongyou 9507 across four environments. Since grain size is a major determinant of grain weight, we also mapped QTL for grain length (GL) and grain width (GW). QTGW.caas-2D, QTGW.caas-3B, QTGW.caas-5A and QTGW.caas-7A.2 for TGW co-located with those for grain size. QTGW.caas-2D also had a consistent genetic position with QGNS.caas-2D, suggesting that the pleiotropic locus is a modulator of trade-off effect between TGW and GNS. Sequencing and linkage mapping showed that TaGL3-5A and WAPO-A1 were candidate genes of QTGW.caas-5A and QTGW.caas-7A.2, respectively. We developed Kompetitive allele specific PCR (KASP) markers linked with the stable QTL for yield component traits and validated their genetic effects in a diverse panel of wheat cultivars from the Huang-Huai River Valley region. KASP-based genotyping analysis further revealed that the superior alleles of all stable QTL for TGW but not GNS were subject to positive selection, indicating that yield improvement in the region largely depends on increased TGW. Comparative analyses with previous studies showed that most of the QTL could be detected in different genetic backgrounds, and QTGW.caas-7A.1 is likely a new QTL. These findings provide not only valuable genetic information for yield improvement but also useful tools for marker-assisted selection.

Transcriptional signatures of wheat inflorescence development

In order to maintain global food security, it will be necessary to increase yields of the cereal crops that provide most of the calories and protein for the world’s population, which includes common wheat (Triticum aestivum L.). An important wheat yield component is the number of grain-holding spikelets which form on the spike during inflorescence development. Characterizing the gene regulatory networks controlling the timing and rate of inflorescence development will facilitate the selection of natural and induced gene variants that contribute to increased spikelet number and yield. In the current study, co-expression and gene regulatory networks were assembled from a temporal wheat spike transcriptome dataset, revealing the dynamic expression profiles associated with the progression from vegetative meristem to terminal spikelet formation. Consensus co-expression networks revealed enrichment of several transcription factor families at specific developmental stages including the sequential activation of different classes of MIKC-MADS box genes. This gene regulatory network highlighted interactions among a small number of regulatory hub genes active during terminal spikelet formation. Finally, the CLAVATA and WUSCHEL gene families were investigated, revealing potential roles for TtCLE13, TtWOX2, and TtWOX7 in wheat meristem development. The hypotheses generated from these datasets and networks further our understanding of wheat inflorescence development.

Genome-Wide Association Study of Agronomic Traits in European Spring Barley from Polish Gene Bank

The barley old cultivars can be used as a source of genetic diversity to breed new varieties well adapted to different environmental conditions. In this study, 431 European barley accessions were evaluated phenotypically across 2 years under field conditions and genotypically using DArTseq to gain insight into the genetic architecture of phenology, biomass, yield components, and seed yield traits. Accessions were grouped into sub-collections by cultivation period (group A—cultivated prior to 1985, B—cultivated after 1985, and C—Polish landraces), and by European country of origin or European region, to compare their phenological and agronomic value for 16 traits such as: days to heading (DH), days to milk-waxy stage (DMW), days to maturity (DM), days to harvest (DPH), plant height (PH), lodging (LT), row number (RN), spike density (SD), spike length (SL), grain per spike (NGS), glume colour (GC1), grain awn type (GAT), grain covering (GT), grain pericarp colour (GPC), and 1000—grain weight (TGW), and to indicate marker-trait associations (MTAs) with these traits. Based on the results, phenotypic plants per se under field conditions and spikes, or seeds under laboratory conditions it was possible to cluster the collection. DH negatively correlated with PH and important yield components, such TGW. Overall, the genome-wide association study (GWAS) analysis identified 143 MTAs associated with these traits. Twenty-three MTAs were associated with plant phenological stages: 5 MTAs with DH, 6 MTAs with DMW, 5 MTAs with DM, and 9 MTAs with DPH. Eighty-nine SMTAs for plant phenotypic traits were identified: 1 for LT and 88 MTAs for PH. Thirty-one markers were identified for agronomic yield traits: 16 MTAs for SD, 11 MTAs for NGS, and 4 for TGW. One association result, 7241263-17 on chromosome 2H, corresponded to the genomic region mapped for DM, DPH, and SD. Marker 3258999-37-C/T on chromosome 2H, significant for NGS, was closely located to results 3263044-31-G/T for SD and 3263989-64-A/C for DMW. On chromosome 6H, closely located were markers significant for SD (3255466-35-C/G) and for NGS (3259102-57-C/A). Moreover, on chromosome 6H, closely located were markers significant for SD (3918801-14-G/A), for NGS (3666407-49-T/G), and for DMW (3663162-62-A/C). The well-characterized barley collection and identified MTAs markers will be used to create a Polish Genebank platform and will serve as a valuable resource for precise breeding programs.

A Study under Sodic Soil Condition for Estimation of Correlation and Path Coefficient Analysis of Rice (Oryza sativa L.) Yield and Its Component Traits

Effective selection necessitates knowledge of the nature and extent of population variation, character correlation with yield among individuals, and effect of environment on the assertion of these traits. Under timely seeded and irrigated conditions in sodic soil, this study used Augmented Block Design (ABD) to investigate correlations and path coefficients between yield and yield components in 85 germplasms, including four checks (Pusa sungandha-4, NDR-2065, sarjoo-52, Narendra usar-3). The correlation coefficient expresses the relationship between two variables, but it contains no information regarding cause and effect, such as which variable is dependent and which is independent. As a result, path-coefficient analysis must be utilized to examine the direct and indirect impact of numerous independent characters on a dependent character. The GYPP exhibited highly significant and positive correlations with BYPP and HI. When the genotypic correlation was assigned, it was discovered that characters like BYPP and HI had a positive direct impact on GYPP whereas characters DFF and DM were exhibited negative direct impact on GYPP. The most important indirect yield component was BYPP. As a result, these traits should be emphasized and further evaluated as a selection criterion for future rice improvement programmes in sodic soil.

Fine mapping and characterization of a major QTL for grain weight on wheat chromosome arm 5DL.

We fine mapped QTL QTKW.caas-5DL for thousand kernel weight in wheat, predicted candidate genes and developed a breeding-applicable marker. Thousand kernel weight (TKW) is an important yield component trait in wheat, and identification of the underlying genetic loci is helpful for yield improvement. We previously identified a stable quantitative trait locus (QTL) QTKW.caas-5DL for TKW in a Doumai/Shi4185 recombinant inbred line (RIL) population. Here we performed fine mapping of QTKW.caas-5DL using secondary populations derived from 15 heterozygous recombinants and delimited the QTL to an approximate 3.9Mb physical interval from 409.9 to 413.8Mb according to the Chinese Spring (CS) reference genome. Analysis of genomic synteny showed that annotated genes in the physical interval had high collinearity among CS and eight other wheat genomes. Seven genes with sequence variation and/or differential expression between parents were predicted as candidates for QTKW.caas-5DL based on whole-genome resequencing and transcriptome assays. A kompetitive allele-specific PCR (KASP) marker for QTKW.caas-5DL was developed, and genotyping confirmed a significant association with TKW but not with other yield component traits in a panel of elite wheat cultivars. The superior allele of QTKW.caas-5DL was frequent in a panel of cultivars, suggesting that it had undergone positive selection. These findings not only lay a foundation for map-based cloning of QTKW.caas-5DL but also provide an efficient tool for marker-assisted selection.

Association studies in linseed (Linum usitatissimum L.) under different production systems over locations

The present experiment was conducted to determine the important yield components and their association with one another and with yield. The experiment was laid out under two production systems over four different locations in the mid-hills of the North-western Himalayas. Correlation studies indicated a strong positive correlation for seed yield with harvest index (EI   0.668**; EII  0.472**) and biological yield (EI   0.362; EII  0.532) in both the production systems. Whereas, a non-significant positive correlation was observed for the number of primary branches (EI  0.103; EII   0.122) and the number of secondary branches (EI  0.033; EII   0.160) in both production systems. Whereas, among other traits highly significant correlation was observed for days to 50% flowering with days to 75% maturity in both production systems (EI 0.837**; EII 0.781**) followed by plant height (EI- 0.626**; EII- 0.562**) and technical plant height (EI  0.617**; EII  0.598**). Path coefficient analysis indicated that only biological yield (EI 0.70348; EII 0.60597) and harvest index (EI 0.90210; EII 0.53283) showed a highly significant direct effect with seed yield in both production systems. This showed that selection for biological yield and harvest index would have a direct positive effect in the improvement of grain yield and are the most important determinants of yield in linseed. However, traits such as number of primary branches, number of secondary branches and 1000 seed weight should also be given significant importance since these traits also showed a positive correlation with seed yield but with indirect effects via biological yield and harvest index in EI and EII, respectively. Keywords: Linseed, correlation, path analysis, seed yield

Boundary domain genes were recruited to suppress bract growth and promote branching in maize.

Grass inflorescence development is diverse and complex and involves sophisticated but poorly understood interactions of genes regulating branch determinacy and leaf growth. Here, we use a combination of transcript profiling and genetic and phylogenetic analyses to investigate tasselsheath1 (tsh1) and tsh4, two maize genes that simultaneously suppress inflorescence leaf growth and promote branching. We identify a regulatory network of inflorescence leaf suppression that involves the phase change gene tsh4 upstream of tsh1 and the ligule identity gene liguleless2 (lg2). We also find that a series of duplications in the tsh1 gene lineage facilitated its shift from boundary domain in nongrasses to suppressed inflorescence leaves of grasses. Collectively, these results suggest that the boundary domain genes tsh1 and lg2 were recruited to inflorescence leaves where they suppress growth and regulate a nonautonomous signaling center that promotes inflorescence branching, an important component of yield in cereal grasses.

Determination of Yield, Yield Component Technological and Physiological Characteristics in Different Cotton (Gossypium hirsutum L.) Varieties - I

This study was carried out with the aim of evaluating the performance of the varieties in terms of yield, agronomic, morphological, physiological parameters and fiber quality criteria by using 10 cotton varieties that are widely planted in the Southeastern Anatolia Region. The study was conducted in 2017 in Bismil district of Diyarbakır with 4 replications according to randomized block design. In the study there were statistically significant differences between varieties in terms of seed cotton yield, fiber yield, first picking percentage, ginning percentage, canopy temperature, NDVI value, number of sympodial branches, number of first fruiting branches, number of bolls, boll weight, boll seed weight and all observed fiber technological characteristic, while there were non-significant association for plant height, number of monopodial branches and chlorophyll content (SPAD value). According to the results of analysis it was determined that PG 2018 for seed cotton yield , fiber yield, first node of fruiting branches and canopy temperature, Stoneville 468 and Carla for first picking percentage, Lima for number of sympodial branches, boll weight and ginning outturn, PG 2018 and Lima for number of bolls, DP 499 for boll seed weight, Stoneville 468 and DP 499 for NDVI values and Gloria variety had highest values for technological characteristic. In the study, the variety with higher canopy temperature, which is one of the physiological parameters, had higher seed cotton yield, fiber yield and some important yield components. However, it has been determined that the quality of fiber technological properties does not show parallelism with physiological parameters, quality properties are closely related to genetic structure and are relatively less affected by environmental conditions.

Response of common bean to plant growth promoting rhizobacteria under different levels of phosphorus

The usage of biofertilizer as alternative or support to mineral fertilizer encourage continuously due to fertilizer cost and environmental pollution. The effect of three phosphorus doses (0, 30, and 60 kg ha-1 P2O5) with a control and different commercial biofertilizers, Bontera (Bacillus amyloliquefociens, Bacillus pumilus, Bacillus subtilis, Bacillus licheniformis, Bacillus megaterium, Trichoderma harzianum, Trichoderma kanigi), Bactoboost (Bacillus subtilis, Bacillus magaterium, Loctococcus spp.), Koklendirici (Bacillus subtilis, Bacillus magaterium, Loctococcus spp.), Lifebac NP (Bacillus subtilis, Bacillus magaterium), natural organic matter and humic substances (NSAH) (15% organic matter, 6% organic carbon, 13% humic + fulvic acid), and Rhizobia (Rhizobium leguminosorum)) were investigated. Increasing phosphorus doses positively affected all the investigated characters. Koklendirici biofertilizer positively affected the important yield components, but highest grain yield was determined in the NSAH plots. Increasing phosphorus (P) doses did not affect nitrogen (N), potassium (K), magnesium (Mg), and copper (Cu) contents of the grain while phosphorus, calcium (Ca), iron (Fe), manganese (Mn), and zinc (Zn) contents showed an increase. Difference in climate might have influenced these results. These results indicated that understanding of bio and mineral fertilizer would enable us to use biofertilizer as an alternative to mineral fertilizer to common bean production.

Genome-wide association study reveals novel quantitative trait loci and candidate genes of lint percentage in upland cotton based on the CottonSNP80K array.

Thirty-four SNPs corresponding with 22 QTLs for lint percentage, including 13 novel QTLs, was detected via GWAS. Two candidate genes underlying this trait were also identified. Cotton (Gossypium spp.) is an important natural textile fiber and oilseed crop cultivated worldwide. Lint percentage (LP, %) is one of the important yield components, and increasing LP is a core goal of cotton breeding improvement. However, the genetic and molecular mechanisms underlying LP in upland cotton remain unclear. Here, we performed a genome-wide association study (GWAS) for LP based on 254 upland cotton accessions in four environments as well as the best linear unbiased predictors using the high-density CottonSNP80K array. In total, 41,413 high-quality single-nucleotide polymorphisms (SNPs) were screened, and 34 SNPs within 22 quantitative trait loci (QTLs) were significantly associated with LP. In total, 175 candidate genes were identified from two major genomic loci (GR1 and GR2), and 50 hub genes were identified through GO enrichment and weighted gene co-expression network analysis. Two candidate genes (Gh_D01G0162 and Gh_D07G0463), which may participate in early fiber development to affect the number of fiber protrusions and LP, were also identified. Their genetic variation and expression were verified by linkage disequilibrium blocks, haplotypes, and quantitative real-time polymerase chain reaction, respectively. The weighted gene interaction network analysis showed that the expression of Gh_D07G0463 was significantly correlated with that of Gh_D01G0162. These identified SNPs, QTLs and candidate genes provide important insights into the genetic and molecular mechanisms underlying variations in LP and serve as a foundation for LP improvement via marker-assisted breeding.

Genetic Variability and Trait Association in Indian Mustard [Brassica juncea (L.) Czern and Coss

Background: Twenty-four released varieties of Indian Mustard were evaluated during rabi 2015-16 and 2016-17 under irrigated environment to study character association for seed yield and its component traits. Methods: Analysis of variance on thirteen quantitative characters was carried out and pooled over the years. Path analysis was carried out using correlation coefficients to know the yield contributing traits. Result: Significant differences were noticed for all the traits among the genotypes. The genotypic and phenotypic variation is higher for seed yield/plant, 1000 seed weight, secondary branches/plant and total siliquae/plant. Heritability estimate were very high for 1000 seed weight, siliqua length, plant height, seeds/siliqua, total siliquae/plant and days to maturity. Genetic advance as percent of mean were high for seed yield/plant, 1000 seed weight, secondary branches/plant and total siliquae/plant. The correlation of seed yield/plant shows significant positive association with days to maturity, primary branches/plant, secondary branches/plant, total siliquae/plant, siliqua length, seeds/siliqua, 1000 seed weight and length of main shoot. From correlation coefficients and path analysis it appeared that length of main shoot, 1000 seed weight, number of secondary branches/plant and days to maturity were most important yield components having highly positive direct and indirect effects.

Genome-wide association studies dissect the genetic architecture of seed shape and size in common bean.

Seed weight and size are important yield components. Thus, selecting for large seeds has been a key objective in crop domestication and breeding. In common bean, seed shape is also important since it influences industrial processing and plays a vital role in determining the choices of consumers and farmers. In this study, we performed genome-wide association studies on a core collection of common bean accessions to dissect the genetic architecture and identify genomic regions associated with seed morphological traits related to weight, size, and shape. Phenotypic data were collected by high-throughput image-based approaches, and utilized to test associations with 10,362 single-nucleotide polymorphism markers using multilocus mixed models. We searched within genome-associated regions for candidate genes putatively involved in seed phenotypic variation. The collection exhibited high variability for the entire set of seed traits, and the Andean gene pool was found to produce larger, heavier seeds than the Mesoamerican gene pool. Strong pairwise correlations were verified for most seed traits. Genome-wide association studies identified marker–trait associations accounting for a considerable amount of phenotypic variation in length, width, projected area, perimeter, and circularity in 4 distinct genomic regions. Promising candidate genes were identified, e.g. those encoding an AT-hook motif nuclear-localized protein 8, type 2C protein phosphatases, and a protein Mei2-like 4 isoform, known to be associated with seed size and weight regulation. Moreover, the genes that were pinpointed are also good candidates for functional analysis to validate their influence on seed shape and size in common bean and other related crops.

Gene mining of 100‐grain weight and the number of four‐seed pods in soybean (Glycine max)

AbstractThe number of four‐seed pods and 100‐grain weight are important yield components in soybean. Typically, they are negatively correlated traits. Generally, soybean varieties with a high 100‐grain weight and a higher number of three‐ or four‐seed pods are more likely to obtain a high yield. It is difficult to select for double‐excellent traits that meet the needs of farmers and the market using conventional breeding methods. The purpose of this study was to mine genes associated with the number of four‐seed pods and 100‐grain weight in soybean. Whole‐transcriptome sequencing was performed on four specific chromosome segment substitution lines (HWMN, HWFN, LWMN and LWFN) combined with the distribution of blocks imported from wild soybean DNA fragments and gene annotation. The material was sampled in each of the eight development stages. Among them, globular embryo formation, heart embryo formation, and cotyledon primordium formation were used to mine differentially expressed genes (DEGs). A total of 3792 DEGs were identified, and 25 expression patterns were obtained by the K‐means rapid clustering method. GO enrichment analysis of DEGs was performed by Agrigo, and a total of 43 GO terms were enriched. Through annotation analysis, 126 DEGs associated with seed size and number were obtained. Combined with analysis of the introduced DNA fragments of wild soybean ZYD00006, 19 genes that eventually aligned on those blocks were obtained. Six representative genes were selected as candidate genes, namely, Glyma.07G218200, Glyma.05G162100, Glyma.19G240800, Glyma.04G180300, Glyma.05G214400 and Glyma.12G146700. They may regulate the formation of 100‐grain weight and the number of four‐seed pods, which will provide reference information for the genetic improvement of agronomic traits, such as seed number per pod and 100‐grain weight of soybean, in the future and will enrich the theoretical basis of high yield in soybean.

Identification of Genetic Loci on Chromosome 4B for Improving the Grain Number per Spike in Pre-Breeding Lines of Wheat

The grain number per spike (GNPS) is an important yield component, and much attention is given to the increase in GNPS for current yield improvement of common wheat. Here, a panel of 259 pre-breeding lines and elite commercial varieties were collected for the investigation of 12 agronomic traits, especially for spike-related traits, with 2-year replicates. The high correlation between GNPS and kernel number per spikelet (KNS) suggested that the high GNPS trait in our pre-breeding lines was mainly controlled by grain set number per spikelet. Genome-wide association studies (GWAS) using the 660K SNP genotyping assay suggested that a major locus on chromosomes 4BS contributed to the high GNPS trait, which contributed to 33% and 48% of the variation in KNS and GNPS, respectively. A good diagnostic KASP marker AX-109286577 flanking the 4BS locus was developed for easy selection of the large spike trait. Taken together, the results suggested that untapped rare allele variation in our pre-breeding lines can be used for improvement of the yield component of set grain number per spike.

Genetic variation in YIGE1 contributes to ear length and grain yield in maize.

Ear length (EL), which is controlled by quantitative trait loci (QTLs), is an important component of grain yield and as such is a key target trait in maize breeding. However, very few EL QTLs have been cloned, and their molecular mechanisms are largely unknown. Here, using a genome wide association study (GWAS), we identified a QTL, YIGE1, which encodes an unknown protein that regulates EL by affecting pistillate floret number. Overexpression of YIGE1 increased female inflorescence meristem (IM) size, increased EL and kernel number per row (KNPR), and thus enhanced grain yield. By contrast, CRISPR/Cas9 knockout and Mutator insertion mutant lines of YIGE1 displayed decreased IM size and EL. A single-nucleotide polymorphism (SNP) located in the regulatory region of YIGE1 had a large effect on its promoter strength, which positively affected EL by increasing gene expression. Further analysis shows that YIGE1 may be involved in sugar and auxin signal pathways to regulate maize ear development, thus affecting IM activity and floret production in maize inflorescence morphogenesis. These findings provide new insights into ear development and will ultimately facilitate maize molecular breeding.

Genetic and Environmental Effects on Grain Size Uniformity in Winter Wheat

Grain size is an important yield component and also influences flour yield, seed vigor and early plantlet development. It is usually described by the weight (or mass) of thousand grains or average of dimensions of a sample, without paying attention to the variability of individual grains. However, variation in individual grain size is economically important for milling industry, because many small grains are lost during the cleaning process prior to milling and a high proportion of small grains is indicative of a poor flour yield. Also, when grains are sown for a new crop, grain mass variability increases the heterogeneity of germination and leads to non-uniform seedling emergence and crop establishment, often leading to decreased yield. We analyzed using the software ImageJ (http://imagej.nih.gov/ij/) individual grain size distributions of samples 80 to 120 individual grains each, harvested from yield trials at NARDI Fundulea Romania with 13 cultivars grown on four management variants, during two years. Individual grain projected area, as a proxy of grain size, ranged from 8.18 to 29.06 mm2, and for most cultivars minimum values of individual grain projected area were less than half of maximum values. On average over all management variants and years, coefficients of variation (s%) varied from less than 14% in cultivars Bezostaya 1, Glosa and Pajura to more than 15.5% in cultivars Adelina and Litera. ANOVA for the coefficients of variation of grain projection areas showed that the main source of variation was the effect of cultivars, which was significant when tested both against the Error and the interaction Cultivars*Years. The effect of the four studied managements was significant when tested against the Error, but not when tested against the interaction with Years, suggesting that the managements did not have the same effect in the two years of study. The large differences between cultivars found in our study provide opportunities in breeding for higher grain uniformity.