Multiple Agronomic Traits Research Articles

Field characterization of endemic wild Vigna accessions collected from biodiversity hotspots of India to identify promising genotypes for multiple agronomic and adaptive traits

Wild Vigna species possess a reservoir of useful genes that have potential to be utilized in improvement of cultivated mungbean and urdbean. The level of genetic diversity in representative accessions of cultivated and wild Asiatic Vigna species collected from diversity-rich endemic areas of India was investigated using morphological descriptors. Data were recorded on 27 qualitative and quantitative traits in 44 wild and cultivated accessions belonging to 12 Vigna species grown over 2 years and analyzed to compute mean and variances for each trait. Cluster analysis following unweighted pair group method based on arithmetic mean grouped accessions into five clusters with cluster I accommodating most of the accessions. The different accessions showed variation at species level based on morphological descriptors. 3 accessions viz., IC251424 and IC251425 of V. radiata and IC331436 of V. trilobata were superior for multiple traits viz., number of seeds/pod, seed quality and early maturity. Likewise for seed size, IC 298665 of V. unguiculata and PRR 2008-2 of V. umbellata were identified as promising donors while for earliness, 3 accessions of V. trilobata (IC 331545, IC 349701 and JAP/10-7), 1 of V. radiata (IC 251427) and 1 each of V. mungo (IC 251385) and V. unguiculata (IC 298665) were identified as maturing significantly early and therefore, could be used in hybridization programme for introgression of these traits. This evaluation and characterization study on endemic Vigna species provides useful information for improving mungbean and urdbean cultivars through recombination breeding.

Field characterization of endemic wild Vigna accessions collected from biodiversity hotspots of India to identify promising genotypes for multiple agronomic and adaptive traits

Wild Vigna species possess a reservoir of useful genes that have potential to be utilized in improvement of cultivated mungbean and urdbean. The level of genetic diversity in representative accessions of cultivated and wild Asiatic Vigna species collected from diversity-rich endemic areas of India was investigated using morphological descriptors. Data were recorded on 27 qualitative and quantitative traits in 44 wild and cultivated accessions belonging to 12 Vigna species grown over 2 years and analyzed to compute mean and variances for each trait. Cluster analysis following unweighted pair group method based on arithmetic mean grouped accessions into five clusters with cluster I accommodating most of the accessions. The different accessions showed variation at species level based on morphological descriptors. 3 accessions viz., IC251424 and IC251425 of V. radiata and IC331436 of V. trilobata were superior for multiple traits viz., number of seeds/pod, seed quality and early maturity. Likewise for seed size, IC 298665 of V. unguiculata and PRR 2008-2 of V. umbellata were identified as promising donors while for earliness, 3 accessions of V. trilobata (IC 331545, IC 349701 and JAP/10-7), 1 of V. radiata (IC 251427) and 1 each of V. mungo (IC 251385) and V. unguiculata (IC 298665) were identified as maturing significantly early and therefore, could be used in hybridization programme for introgression of these traits. This evaluation and characterization study on endemic Vigna species provides useful information for improving mungbean and urdbean cultivars through recombination breeding.

Development of elite restoring lines by integrating blast resistance and low amylose content using MAS

Blast resistance and grain quality are major problems in hybrid rice production in China. In this study, two resistance (R) genes, Pi46 and Pita, along with the gene Wxb, which mainly affects rice endosperm amylose content (AC), were introgressed into an elite indica restoring line, R8166, which has little blast resistance and poor grain quality through marker-assisted selection (MAS). Eight improved lines were found to have recurrent genome recovery ratios ranging from 88.68 to 96.23%. Two improved lines, R163 and R167, were selected for subsequent studies. R167, which has the highest recovery ratio (96.23%), showed no significant differences in multiple agronomic traits. In contrast, R163 with the lowest recovery ratio (88.68%) exhibited significant differences in heading date and yield per plant compared with the recurrent parent. At two developmental stages, R163 and R167 had greatly enhanced resistance to blast over the recurrent parent. Similar trends were also observed for agronomic traits and blast resistance in R163- and R167-derived hybrids when compared with the counterparts from R8166. In addition, R163, R167, and their derived hybrids significantly improved the grain quality traits, including amylose content (AC), gel consistency (GC), chalky grain rate (CGR), and degree of endosperm chalkiness (DEC). It confirmed the success of efficiently developing elite restoring lines using MAS in this study.

Breeding Sorghum Using Induced Mutations: Future Prospect for Namibia

In arid and semi-arid regions of the world sorghum stands out as a climate change-ready crop with high potential for the production of food, feed, fodder, fiber and fuel in the face of increasing human population. The present review highlights induced mutation breeding technique as a potential tool for improving sorghum in Namibia. The review discussed the following issues; crop improvement using mutagens, mutant screening, selection and evaluation, impact of induced mutation breeding, factors for declining production and future implication of sorghum mutation breeding. In Namibia, severe drought stress resulting in total crop failure has become frequent. This is partly a consequence of farmers growing crop varieties which cannot withstand impact of drought. As such Namibia has limited drought tolerant varieties available for the diverse agro-ecologies. Farmers keep growing the familiar landraces which performs well in good rainfall years but fails to produce stable yield with irregular and erratic rainfall. Thus, breeding new sorghum varieties of high yield and quality combined with multiple agronomic traits including pest and disease resistance and high efficiency in nutrient and water use is needed. Induced mutation is one of the breeding methods utilized worldwide to supplement conventional breeding for developing superior varieties with desirable traits in different crops. Development of high yielding, drought tolerant, and dwarf sorghums with early maturity enables effective utilization of available soils moisture and in optimizing plant density for achieving higher yield in farmers’ fields. Recombination breeding through exploitation of natural genetic variability and mutation breeding to reduce the plant height without disturbing agronomic superiority of elite lines is recommended for sorghum improvement in Namibia.

Chromosomal localization of genes conferring desirable agronomic traits from Agropyron cristatum chromosome 1P.

Agropyron cristatum (L.) Gaertn. (2n = 4x = 28, PPPP), a wild relative of common wheat, possesses many potentially valuable genes for wheat breeding. To transfer these genes into wheat, a series of wheat-A. cristatum derivatives have been obtained in our laboratory. In this study, a wheat-A. cristatum derivative II-3-1 was obtained, which was proven to contain a 1P (1A) disomic substitution and 2P disomic addition line with 40 wheat chromosomes and two pairs of A. cristatum chromosomes by genomic in situ hybridization (GISH) and molecular markers analysis. By further backcrossing with the wheat parent Fukuhokomugi (Fukuho) and self-fertilization, three different lines were separated from II-3-1, including wheat-A. cristatum 1P disomic addition line II-3-1a, 2P disomic addition line II-3-1b and 1P (1A) disomic substitution line II-3-1c. Because 2P addition line had been reported before, we aimed to investigate 1P disomic addition line II-3-1a and wheat-A. cristatum 1P (1A) disomic substitution line II-3-1c. Analysis of different genetic populations demonstrated that 1P chromosome harbored multiple agronomic traits, such as elevated spike length, increased tillering ability, reduced plant height and spikelet density. Besides, bristles on the glume ridges as an important morphological marker was located on 1P chromosome. Therefore, the novel 1P addition and substitution lines will be used as important genetic materials to widen the genetic resources of wheat.

Improvement of multiple agronomic traits by a disease resistance gene via cell wall reinforcement.

The major disease resistance gene Xa4 confers race-specific durable resistance against Xanthomonas oryzae pv. oryzae, which causes the most damaging bacterial disease in rice worldwide. Although Xa4 has been one of the most widely exploited resistance genes in rice production worldwide, its molecular nature remains unknown. Here we show that Xa4, encoding a cell wall-associated kinase, improves multiple traits of agronomic importance without compromising grain yield by strengthening the cell wall via promoting cellulose synthesis and suppressing cell wall loosening. Strengthening of the cell wall by Xa4 enhances resistance to bacterial infection, and also increases mechanical strength of the culm with slightly reduced plant height, which may improve lodging resistance of the rice plant. The simultaneous improvement of multiple agronomic traits conferred by Xa4 may account for its widespread and lasting utilization in rice breeding programmes globally.

Revisiting the Decoded Genomes to Promptly Reveal their Genomic Perspectives

Post Arabidopsis thaliana , 55 genomes comprising 49 different plant species have been decoded by use of clone-by-clone, whole genome shotgun and next-generation sequencing approaches. The structural outcomes of these sequenced genomes shed light on their genomic constitution, particularly the way genes, transposable elements and genetic markers are orga-nized within the genomes. The functional outcomes provide a brief account of specific phenotypic trait characteristics of crop genomes by digging deep into the genetic make-up of transcription factors, regulato-ry elements and gene families governing multiple ag-ronomic traits in these crop plants. The comparative and evolutionary outcomes deduce the genetic basis of biological diversity and basic process of ge-nome evolution by analysing the syntenic relationships among genes and genomes/chromosomes of the se-quenced crop plants. Therefore, a revisit to published genome sequence landmarks in 30 major cultivated food crops constituting major groups (cereals, leg-umes, vegetables, fruits, oil seeds and fibres) would significantly assist us to gain a detailed insight into their genome organization and dissect the structural, functional, comparative and evolutionary intricacies for identifying species- and lineage-specific genes con-trolling multiple characteristics in crop plants. The es-sential inputs obtained will be helpful in devising efficient strategies to develop high-yielding climate-ready crop varieties through translational genomics.

Pyramiding of Pi46 and Pita to improve blast resistance and to evaluate the resistance effect of the two R genes

Utilization of R (resistance) genes to develop resistant cultivars is an effective strategy to combat against rice blast disease. In this study, R genes Pi46 and Pita in a resistant accession H4 were introgressed into an elite restorer line Hang-Hui-179 (HH179) using the marker-assisted backcross breeding (MABB) procedure. As a result, three improved lines (e.g., R1791 carrying Pi46 alone, R1792 carrying Pita alone and R1793 carrying both Pi46 and Pita) were developed. The three improved lines had significant genetic similarities with the recurrent parent HH179. Thus, they and HH179 could be recognized as near isogenic lines (NILs). The resistance spectrum of the three improved lines, which was tested at seedling stage, reached 91.1, 64.7 and 97.1%, respectively. This was markedly broader than that of HH179 (23.5%). Interestingly, R1793 showed resistance to panicle blast but neither R1791 nor R1792 exhibited resistance at two natural blast nurseries. The results implied that the stacking of Pi46 and Pita resulted in enhanced resistance, which was unachievable by either R gene alone. Further comparison indicated that the three improved lines were similar to HH179 in multiple agronomic traits; including plant height, tillers per plant, panicle length, spikelet fertility, and 1 000-grain weight. Thus, the three improved lines with different R genes can be used as new sources of resistance for developing variety. There is a complementary effect between the two R genes Pi46 and Pita.

Mapping QTLs and association of differentially expressed gene transcripts for multiple agronomic traits under different nitrogen levels in sorghum.

BackgroundSorghum is an important C4 crop which relies on applied Nitrogen fertilizers (N) for optimal yields, of which substantial amounts are lost into the atmosphere. Understanding the genetic variation of sorghum in response to limited nitrogen supply is important for elucidating the underlying genetic mechanisms of nitrogen utilization.ResultsA bi-parental mapping population consisting of 131 recombinant inbred lines (RILs) was used to map quantitative trait loci (QTLs) influencing different agronomic traits evaluated under normal N (100 kg.ha−1 fertilizer) and low N (0 kg.ha−1 fertilizer) conditions. A linkage map spanning 1614 cM was developed using 642 polymorphic single nucleotide polymorphisms (SNPs) detected in the population using Genotyping-By-Sequencing (GBS) technology. Composite interval mapping detected a total of 38 QTLs for 11 agronomic traits tested under different nitrogen levels. The phenotypic variation explained by individual QTL ranged from 6.2 to 50.8 %. Illumina RNA sequencing data generated on seedling root tissues revealed 726 differentially expressed gene (DEG) transcripts between parents, of which 108 were mapped close to the QTL regions.ConclusionsCo-localized regions affecting multiple traits were detected on chromosomes 1, 5, 6, 7 and 9. These potentially pleiotropic regions were coincident with the genomic regions of cloned QTLs, including genes associated with flowering time, Ma3 on chromosome 1 and Ma1 on chromosome 6, gene associated with plant height, Dw2 on chromosome 6. In these regions, RNA sequencing data showed differential expression of transcripts related to nitrogen metabolism (Ferredoxin-nitrate reductase), glycolysis (Phosphofructo-2-kinase), seed storage proteins, plant hormone metabolism and membrane transport. The differentially expressed transcripts underlying the pleiotropic QTL regions could be potential targets for improving sorghum performance under limited N fertilizer through marker assisted selection.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0696-x) contains supplementary material, which is available to authorized users.

Pyramiding and evaluation of both a foreign Bacillus thuringiensis and a Lysine-rich protein gene in the elite indica rice 9311.

Gene pyramiding is an efficient approach for the genetic improvement of multiple agronomic traits simultaneously. In this study, we pyramided two foreign genes, cry1Ac driven by the rice Actin I promoter, and lysine-rich protein (LRP), driven by the endosperm-specific GLUTELIN1 (GT1) promoter, into the elite indica cultivar 9311. These two genes were chosen in an attempt to enhance insect-resistance and Lysine (Lys) content. In the pyramided line, the foreign gene cry1Ac was efficiently expressed in the leaves and stems, and exhibited highly efficient resistance to striped stem borer (SSB, Chilo suppressalis Walker) in the laboratory and rice leaf folder (RLF, Cnaphalocrocis medinalis Guenee) in the field. Furthermore, the LRP gene was highly expressed in the endosperm and produced a remarkable increase of Lys content in the seeds of the pyramided line. The data from field trials demonstrated that most of the agronomic traits including yield were well maintained in the pyramided line compared to the parental control. These results strongly suggest that the foreign cry1Ac and LRP genes have remarkable application potential in rice, and the resultant pyramided line serves as an ideal bridge material for the improvement of insect-resistance and high Lys rice in the future.

Germplasm Release: Three Potato Clones Incorporating Combined Resistances to Early Blight from S. palustre and Late Blight from S. bulbocastanum into a S. tuberosum Background

Three clones in a segregating population derived from a cross between the disease resistant parents +297 and K41 are being released as germplasm with resistance to both early blight, caused by Alternaria solani, and late blight, caused by Phytophthora infestans. The source of resistance to early blight in +297 is the wild species S. palustre and late blight resistance in K41 is conferred by the RB gene from S. bulbocastanum. These clones, named BR3, BR5, and BR85 (BR for Blight Resistant), yield well at a temperate zone latitude. In addition to containing heritable resistance to both early and late blights, these clones possess multiple other desirable agronomic traits, are fertile, and readily cross to cultivars.

Diversity characterization and association analysis of agronomic traits in a Chinese peanut (Arachis hypogaeaL.) mini‐core collection

Association mapping is a powerful approach for exploring the molecular basis of phenotypic variations in plants. A peanut (Arachis hypogaea L.) mini-core collection in China comprising 298 accessions was genotyped using 109 simple sequence repeat (SSR) markers, which identified 554 SSR alleles and phenotyped for 15 agronomic traits in three different environments, exhibiting abundant genetic and phenotypic diversity within the panel. A model-based structure analysis assigned all accessions to three groups. Most of the accessions had the relative kinship of less than 0.05, indicating that there were no or weak relationships between accessions of the mini-core collection. For 15 agronomic traits in the peanut panel, generally the Q + K model exhibited the best performance to eliminate the false associated positives compared to the Q model and the general linear model-simple model. In total, 89 SSR alleles were identified to be associated with 15 agronomic traits of three environments by the Q + K model-based association analysis. Of these, eight alleles were repeatedly detected in two or three environments, and 15 alleles were commonly detected to be associated with multiple agronomic traits. Simple sequence repeat allelic effects confirmed significant differences between different genotypes of these repeatedly detected markers. Our results demonstrate the great potential of integrating the association analysis and marker-assisted breeding by utilizing the peanut mini-core collection.

Genetic characterization of a core collection of flax (Linum usitatissimum L.) suitable for association mapping studies and evidence of divergent selection between fiber and linseed types

BackgroundFlax is valued for its fiber, seed oil and nutraceuticals. Recently, the fiber industry has invested in the development of products made from linseed stems, making it a dual purpose crop. Simultaneous targeting of genomic regions controlling stem fiber and seed quality traits could enable the development of dual purpose cultivars. However, the genetic diversity, population structure and linkage disequilibrium (LD) patterns necessary for association mapping (AM) have not yet been assessed in flax because genomic resources have only recently been developed. We characterized 407 globally distributed flax accessions using 448 microsatellite markers. The data was analyzed to assess the suitability of this core collection for AM. Genomic scans to identify candidate genes selected during the divergent breeding process of fiber flax and linseed were conducted using the whole genome shotgun sequence of flax.ResultsCombined genetic structure analysis assigned all accessions to two major groups with six sub-groups. Population differentiation was weak between the major groups (FST = 0.094) and for most of the pairwise comparisons among sub-groups. The molecular coancestry analysis indicated weak relatedness (mean = 0.287) for most individual pairs. Abundant genetic diversity was observed in the total panel (5.32 alleles per locus), and some sub-groups showed a high proportion of private alleles. The average genome-wide LD (r2) was 0.036, with a relatively fast decay of 1.5 cM. Genomic scans between fiber flax and linseed identified candidate genes involved in cell-wall biogenesis/modification, xylem identity and fatty acid biosynthesis congruent with genes previously identified in flax and other plant species.ConclusionsBased on the abundant genetic diversity, weak population structure and relatedness and relatively fast LD decay, we concluded that this core collection is suitable for AM studies targeting multiple agronomic and quality traits aiming at the improvement of flax as a true dual purpose crop. Our genomic scans provide the first insights into candidate regions affected by divergent selection in flax. In combination with AM, genomic scans have the ability to increase the power to detect loci influencing complex traits.

Quantitative Trait Loci Affecting Oil Content, Oil Composition, and Other Agronomically Important Traits in Oat

Groat oil content and composition are important determinants of oat (Avena sativa L.) quality. We investigated these traits in a population of 146 recombinant inbred lines from a cross between ‘Dal’ (high oil) and ‘Exeter’ (low oil). A linkage map consisting of 475 Diversity Arrays Technology (DArT) markers spanning 1271.8 cM across 40 linkage groups was constructed. Quantitative trait locus (QTL) analysis for groat oil content and composition was conducted using grain samples grown at Aberdeen, ID, in 1997. Quantitative trait locus analysis for multiple agronomic traits was also conducted using data collected from hill plots and field plots in Ottawa, ON, in 2010. Using simple and composite interval mapping methods, QTLs for oil content, palmitic acid (16:0), stearic acid (18:0), oleic acid (18:1), linoleic acid (18:2), and linolenic acid (18:3) were identified. Two of the loci associated with oil content were associated with all of the fatty acids examined in this study, and most oil‐related QTL showed similar patterns of effect on the fatty acid profile. These results suggest the presence of pleiotropic effects on oil‐related traits through influences at specific nodes of the oil synthesis pathway. In addition, 12 QTL‐associated markers (likely representing nine unique regions) were associated with plant height, heading date, lodging, and protein content.

Registration of ‘Saluki 4910’ Soybean [Glycine max (L.) Merr.] with High Yield Potential and Resistance to Multiple Diseases

‘Saluki 4910’ (Reg. No. CV‐507, PI 665035) soybean [Glycine max (L.) Merr.] was developed at Southern Illinois University, Carbondale, IL, and released in May 2010. The objective was the development of a line with high yield and resistance to the important diseases soybean cyst nematode (SCN) and sudden death syndrome (SDS; caused by Fusarium virguliforme O'Donnell & T. Aoiki, sp. nov.). Saluki 4910 is an F5 selection from the cross of ‘Pana’ and TN96‐58 that advanced from the F2 generation by the modified single‐seed descent method. It is a late maturity group IV (relative maturity 4.9) soybean line that was tested for yield and multiple agronomic traits in four locations in southern Illinois and 14 field environments in the Uniform MG IV‐S Tests, Southern States. In combined analyses across 3 yr (2006–2008) in southern Illinois, Saluki 4910 (LS03‐4294) averaged 3977 kg ha−1, which was 5.9% more than ‘5R531’ and 9.6% more than ‘Manokin’. In the Uniform MG IV‐S Tests, Southern States, the yield of Saluki 4910 averaged 3539 kg ha−1, which was 11.4% better than ‘5002T’, 4.8% better than ‘AG 4403’, 1.9% better than ‘AG 4903’, and 3.8% better than ‘DK 4844’. In the Southern Illinois University SDS and frogeye leaf spot (FLS; caused by Cercospora sojina Hara) trials, Saluki 4910 showed high resistance to both diseases. Additionally, in the USDA Southern Preliminary and Uniform tests, the line showed high resistance to SCN HG Type 0 (Race 3) and stem canker [caused by Diaporthe phaseolorum (Cooke & Ellis) Sacc.],. Saluki 4910 was released because of its usefulness for production in the Midwest due to its competitive yield, relatively high protein content, and resistance to SCN HG Type 0 (Race 3), SDS, FLS, and stem canker, and as a parental line in soybean breeding programs.

Expression level of a gibberellin 20-oxidase gene is associated with multiple agronomic and quality traits in barley

The use of dwarfing genes has resulted in the most significant improvements in yield and adaptation in cereal crops. The allelic dwarfing gene sdw1/denso has been used throughout the world to develop commercial barley varieties. The sdw1 gene has never been used successfully for malting barley, but only for a large number of feed varieties. One of the gibberellin 20-oxidase genes (Hv20ox₂) was identified as the candidate gene for sdw1/denso. Semi-quantitative real-time RT-PCR revealed that Hv20ox₂ was expressed at different levels in various organs of barley. Transcriptional levels were reduced in leaf blade, sheath, stem and rachis tissue in the barley variety Baudin with the denso gene. Subsequently, the relative expression levels of Hv20ox₂ were determined by quantitative real-time RT-PCR in a doubled haploid population and mapped as a quantitative trait. A single expression quantitative trait locus (eQTL) was identified and mapped to its structural gene region on chromosome 3H. The eQTL was co-located with QTLs for yield, height, development score, hectolitre weight and grain plumpness. The expression level of Hv20ox₂ was reduced fourfold in the denso mutant, but around 60-fold in the sdw1 mutant, compared to the control variety. The reduced expression level of Hv20ox₂ enhanced grain yield by increasing the number of effective tillers, but had negative effects on grain and malting quality. The sdw1 gene can be used only in feed barley due to its severe reduction of Hv20ox₂ expression. The gene expression marker for Hv20ox₂ can be used to distinguish different alleles of sdw1/denso.

Genetic analysis and characterization of a new maize association mapping panel for quantitative trait loci dissection

Association mapping based on the linkage disequilibrium provides a promising tool to identify genes responsible for quantitative variations underlying complex traits. Presented here is a maize association mapping panel consisting of 155 inbred lines with mainly temperate germplasm, which was phenotyped for 34 traits and genotyped using 82 SSRs and 1,536 SNPs. Abundant phenotypic and genetic diversities were observed within the panel based on the phenotypic and genotypic analysis. A model-based analysis using 82 SSRs assigned all inbred lines to two groups with eight subgroups. The relative kinship matrix was calculated using 884 SNPs with minor allele frequency > or = 20% indicating that no or weak relationships were identified for most individual pairs. Three traits (total tocopherol content in maize kernel, plant height and kernel length) and 1,414 SNPs with missing data < 20% were used to evaluate the performance of four models for association mapping analysis. For all traits, the model controlling relative kinship (K) performed better than the model controlling population structure (Q), and similarly to the model controlling both population structure and relative kinship (Q + K) in this panel. Our results suggest this maize panel can be used for association mapping analysis targeting multiple agronomic and quality traits with optimal association model.

Pleiotropic changes in Arabidopsis f5h and sct mutants revealed by large-scale gene expression and metabolite analysis

Hydrocinnamic acid esters, lignin, flavonoids, glucosinolates, and salicylic acid protect plants against UV exposure, oxidative stress, diseases, and herbivores. Through the phenylpropanoid pathway, certain Brassicaceae family members, including Arabidopsis thaliana and Brassica napus, accumulate large amounts of the anti-nutritive sinapoylcholine (sinapine) in the seed. We successfully down-regulated activities of key enzymes in the pathway including F5H and SCT and achieved reduction of sinapine and lignin in B. napus seeds. Despite this success, it was unclear how multiple agronomic traits were affected in the transgenic plants. Here, we report altered large-scale gene expression of new alleles of f5h and sct mutants of A. thaliana and resultant accumulation of sinapoylglucose, disinapoylglucose, quercetin-3-O-rhamnoside, salicylic acid glucoside, and total indolyl glucosinolates in the two mutants. Expression of several flowering genes was altered in these mutants when grown under drought and NaCl treatments. Furthermore, both mutants were more susceptible to fungal infection than the wild type. Microarray experiments identified distinctive spatial and temporal expression patterns of gene clusters involved in silique/seed developmental processes and metabolite biosynthesis in these mutants. Taken together, these findings suggest that both f5h and sct mutants exhibit major differences in accumulation of diverse metabolites in the seed and profound changes in global large-scale gene expression, resulting in differential pleiotropic responses to environmental cues. Electronic supplementary material The online version of this article (doi:10.1007/s00425-009-1007-2) contains supplementary material, which is available to authorized users.

Quantitative trait locus analysis of multiple agronomic traits in the model legumeLotus japonicus

The first quantitative trait locus (QTL) analysis of multiple agronomic traits in the model legume Lotus japonicus was performed with a population of recombinant inbred lines derived from Miyakojima MG-20 x Gifu B-129. Thirteen agronomic traits were evaluated in 2004 and 2005: traits of vegetative parts (plant height, stem thickness, leaf length, leaf width, plant regrowth, plant shape, and stem color), flowering traits (flowering time and degree), and pod and seed traits (pod length, pod width, seeds per pod, and seed mass). A total of 40 QTLs were detected that explained 5%-69% of total variation. The QTL that explained the most variation was that for stem color, which was detected in the same region of chromosome 2 in both years. Some QTLs were colocated, especially those for pod and seed traits. Seed mass QTLs were located at 5 locations that mapped to the corresponding genomic positions of equivalent QTLs in soybean, pea, chickpea, and mung bean. This study provides fundamental information for breeding of agronomically important legume crops.

Antibiosis to Corn Earworm, Helicoverpa zea Boddie, by Cowpea Genotypes

ABSTRACT Corn earworm (Helicovrpa zea Boddie) is a pest of cow-pea in many regions of the United States. The larvae chew round holes in cowpea pods to feed on the developing grains, and thus, affect the yield and seed quality. Studies were conducted to identify antibiosis to corn earworm (CEW) in diverse cowpea genotypes which had been identified to provide better yields in the Delmarva (Delaware, Maryland and Virginia) peninsula region. A series of bioassays were performed to evaluate the newly formed terminal trifoliolates of field grown cowpea for antibiosis to CEW. Results showed significant differences in larval weights in all bioassays. The genotypes which gave the lowest larval weights were Mississippi Silver and Quick pick Pinkeye, while the genotype, Champion, provided the largest weights of larvae in virtually all tests. Therefore, this genotype could probably be used as a susceptible check for future cowpea antibiosis studies to CEW. Results also indicate that some genotypes of cowpea that provided consistently lower weights of larvae, including Mississippi Silver and Quick pick Pinkeye, have higher levels of antibiosis to corn earworm larvae than genotypes Champion and Dixielee. These superior genotypes need to be evaluated for multiple pest resistance and other desirable agronomic traits. The antibiosis could be integrated with other methods of cowpea pest management to reduce the amount of insecticides for the management of CEW and other insect pests of cowpea.