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

Objective of investigation

Chickpea 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 material

A 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 investigation

A 10 families were grown at the Field Experiment Station, Harran University near Şanlıurfa, Turkey during 2019.

Data collection

A 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 conclusions

A 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.     

Screening for resistance to clover rot (Sclerotinia spp.) among a diverse collection of red clover populations (Trifolium pratense L.)

Red clover (Trifolium pratense) is an important perennial forage crop that is widely cultivated in Europe. Clover rot remains a major disease in red clover, but resistance breeding is hampered by the lack of available sources of resistance. Moreover, little is known about the factors that influence clover rot resistance. In this paper we evaluated the variation in clover rot susceptibility among a diverse collection of 113 red clover accessions, with the aim of identifying more resistant accessions. Clover rot susceptibility was assessed with a high throughput bio-test on young plants. We found significant variation in clover rot susceptibility, within and among accessions. ‘Tedi’, ‘Maro’ and ‘No 292’ were the most resistant accessions. Fifteen diploid accessions were more susceptible than the average accession with the cultivar ‘Nemaro’ being the most susceptible. Clover rot susceptibility was not correlated with isoflavone levels from Mullaney et al. (Agronomy abstract. ASA, Madison, p 195, 2000). Cultivars were more resistant than landraces and wild accessions and tetraploid cultivars were more resistant than diploid cultivars. Besides the in-depth analysis for clover rot susceptibility, possible correlations with plant architecture and other diseases were investigated. Growth habit, branching, plant yield, flowering date and susceptibility to mildew, virus and rust diseases were investigated in a 3-year field trial. Unlike previously suggested, clover rot susceptibility was not correlated with branching or with plant yield over three years. On the other hand, late flowering accessions and accessions with erect growth habit were less susceptible to clover rot. Clover rot susceptibility was not correlated with susceptibility to rust disease (Uromyces trifolii) or viral diseases, but negatively with susceptibility to mildew (Erysiphe polygoni). Because no completely resistant accessions were found, the best way to improve clover rot resistance would be to select recurrently for resistant genotypes among diverse cultivars and landraces with lower susceptibility. Tetraploidisation of diploid populations with a higher resistance level can provide an additional level of protection.     

Agronomic and genetic diversity in intermediate wheatgrass (Thinopyrum intermedium)

Intermediate wheatgrass [Thinopyrum intermedium (Host) Barkworth & D. R. Dewey] plant introductions (PI) have played a critical role in the development of improved intermediate wheatgrass cultivars. The objective of this study was to characterize a large number of intermediate wheatgrass populations over its native range for dry matter yield (DMY), crude protein (CP), in vitro true digestibility (IVTD), neutral detergent fibre (NDF), and rhizome development and genetic diversity and structure to identify superior populations and possible geographical regions in which to collect. Analysis of molecular variance using 643 AFLP bands partitioned 31% of the total genetic variation among these populations with 69% variance detected within populations. Bayesian cluster analysis identified two large groups designated as Asian and European under K = 2. In general, European accessions had greater DMY than did Asian accessions. Observed trends were towards greater CP values in populations with Asian ancestry. Selection index values above zero were observed in populations with European ancestry, and the exception was the late‐maturing (208 days to bloom) populations with Asian ancestry. Plant populations 383 551, 383 561, 401 161, 401 173, 440 021, 578 692 (cv. Tegmar) and 598 740 had rhizome scores greater than 7.0. Despite significant differences detected between populations (Φ_ST = 0.3136; P < 0.001), there was strong indication of admixed co‐ancestry or possible gene flow between K = 2–9 models.     

Relationships among seed quality characteristics in a collection of western wheatgrass germplasms

Although western wheatgrass [Pascopyrum smithii (Rydb.)] is an important perennial grass species for agriculture and conservation management in central and western North America, its lack of adequate seed production and seedling vigor limits its effectiveness. To address the weaknesses a study was conducted to assess rhizome spread, seed production, seed weight, germination percentage, and emergence rate of seed produced from 48 western wheatgrass cultivars and germplasm accessions at a field site near Nephi, UT, USA during 2007 and 2008. The western wheatgrass cultivars had approximately two times higher seed production than the germplasm accessions during both 2007 and 2008 and also had higher seed weight in 2007 and emergence rate in 2008. The germplasm accessions had higher seed weight in 2008. For the remaining traits there were no differences among the different germplasm sources. Based on principle component analysis a subset of cultivars and germplasm accessions with high seed production and emergence rate were identified that could be used to produce improved cultivars and germplasms. There was little evidence of strong relationship between geographic, genetic, and phenotypic distances among the various lines examined. Additionally, based on genetic marker data, a subset of lines was grouped into three populations. Based on these results, selection among lines could occur to maximize agricultural performance regardless of site of origin, or within population selection could be practiced to meet conservation goals of minimizing hybridization among populations.     

Drought tolerance in perennial ryegrass (Lolium perenne L.) as assessed by two contrasting phenotyping systems

The objectives of this research were to establish a practicable phenotyping platform for assessing the drought stress response of perennial ryegrass (Lolium perenne L.; Lp), and to use this platform for evaluating the variation for drought tolerance among a panel of 39 diverse Lp populations. A moderate‐to‐strong correlation was assessed between the performance of plants grown in a hydroponics system, where the stress was generated by the addition of polyethylene glycol (PEG), and those grown in the field in a rainout shelter. Following the application of drought stress, tetraploid Lp populations, along with a small number of reference Festulolium and Festuca sp. accessions, were able to develop more shoot and root dry matter than diploid Lp populations. The onset of drought symptoms was also delayed within these accessions and the plants recovered better once drought had been relieved. Although most of the diploid Lp populations were drought susceptible, there was a considerable accession‐to‐accession variation for performance under drought stress conditions. Measuring biomass production and post‐drought recovery in rainout shelter experiments in combination with the assessment of root biomass accumulation in PEG‐supplemented hydroponics represented a viable means of screening Lp germplasm for drought tolerance.     

Identification of pre‐ and posthaustorial resistance to rust (Uromyces viciae‐fabae) in lentil (Lens culinaris) germplasm

Lentil (Lens culinaris Medik.) is an important cool‐season legume that can be severely damaged by rust (Uromyces viciae‐fabae (Pers.) Schröt.) in many parts of the world. In this work, a collection of L. culinaris germplasm accessions was screened under growth chamber conditions for response to U. viciae‐fabae. Several sources of incomplete resistance have been identified, both of hypersensitive and of non‐hypersensitive nature. Incomplete hypersensitive resistance was due to a late‐acting host cell necrosis that resulted in an intermediate infection type (IT). Incomplete non‐hypersensitive resistance was due to a hampered cell penetration not associated with host cell necrosis, reducing the number of haustoria per colony and therefore hindering the growth of the colony and reducing and retarding disease development in spite of a high IT.     

Inheritance of seed resistance to bruchids in cultivated mungbean (Vigna radiata, L. Wilczek)

Bruchid beetles or seed weevils are the most devastating stored pests of grain legumes causing considerable loss to mungbean (Vigna radiata (L.) Wilczek). Breeding for bruchid resistance is a major goal in mungbean improvement. Few sources of resistance in cultivated genepool were identified and characterized, however, there has been no study on the genetic control of the resistance. In this study, we investigated the inheritance of seed resistance to Callosobruchus chinensis (L.) and C. maculatus (F.) in two landrace mungbean accessions, V2709BG and V2802BG. The F₁, F₂ and BC generations were developed from crosses between the resistant and susceptible accessions and evaluated for resistance to the insects. It was found that resistance to bruchids in seeds is controlled by maternal plant genotype. All F₁ plants derived from both direct and reciprocal crosses exhibited resistance to the bruchids. Segregation pattern of reaction to the beetles in the F₂ and backcross populations showed that the resistance is controlled by a major gene, with resistance is dominant at varying degrees of expressivity. Although the presence of modifiers was also observed. The gene is likely the same locus in both V2709BG and V2802BG. The resistant gene is considered very useful in breeding for seed resistance to bruchids in mungbean.     

Initial screening of chili and sweet pepper germplasm for resistance to chili thrips, Scirtothrips dorsalis Hood

Summary A preliminary evaluation for resistance to chili thrips, Scirtothrips dorsalis Hood of 41 and 194 pepper (Capsicum annuum L.) germplasms during 1987 and 1988, respectively, indicated chili accessions may be a promising source of resistance. In contrast, all sweet pepper accessions tested were highly susceptible. A number of chili accessions produced a moderate yield, in spite of a high thrips infestation indicating tolerance to S. dorsalis. Rating for thrips damage was more reliable and efficient than estimating thrips numbers in screening pepper accessions for resistance to thrips. Highly significant, positive correlation between ratings at the seedling stage and final rating for thrips damage indicated the feasibility of screening pepper accessions at the seedling stage. Comparing the similarities in rating among accessions resulted in 40 distinct groups. The variance-covariance matrix of the data from these 40 groups was subjected to principal component analysis. This accounted for 56 and 18 per cent of the variation across the two principal axes, respectively. Projection of chili and sweet pepper accessions along these two axes revealed three distinct clusters. About 80 per cent of chili accessions formed the first cluster, 58 per cent of the sweet pepper accessions formed the second cluster and a third cluster exhibited intermediate ratings for thrips damage. The significance of these findings in relation to geographical divergence and resistance to thrips among pepper accessions is discussed.     

The effectiveness of evaluating wild species: searching for sources of resistance to bruchid beetles in the genus Vigna subgenus Ceratotropis

A species level germplasm collection representing 76% of known taxa in the genus Vigna subgenus Ceratotropis was evaluated for resistance to two species of bruchid beetles, Callosobruchus chinensis and C. maculatus. Seven taxa consisting of 29 accessions were found to be resistant to C. chinensis and 4 taxa consisting of 24 accessions were found to be resistant to C. maculatus. This compared with no resistant accessions being found in several hundred landrace accessions of mungbean, V. radiata var. radiata, in the same subgenus. Sometimes resistance was found in all accessions of a particular taxon, such as complete resistance to both C. chinensis and C. macualtus in V. umbellata. Other taxa showed intra taxon variation for resistance such as V. reflexo-pilosa andV. minima. The levels and patterns of resistance among taxa were diverse. The results suggest that various factors cause resistance to bruchid in the subgenus Ceratotropis. While the number of eggs laid on seeds generally reflected seed size, one small seeded cultivar of V. mungo var. mungo, black gram, had an unusually high number of eggs laid per seed. No correlation was found between seed size and levels of resistance. The species level germplasm collection, which reflects the core collection concept in trying to maximize genetic diversity in a limited number of accessions, has enabled a large number of potentially useful sources of resistance to bruchid beetles to be found efficiently. This revised version was published online in July 2006 with corrections to the Cover Date.     

Inter and intra-species Inter Simple Sequence Repeat (ISSR) variations in the genus Cicer

Intra and inter-species ISSR variation and use of ISSR markers in determination of genetic relationship were investigated in an accession collection representing twoperennial and six annual Cicerspecies. Screening of Ciceraccessions with SSR primers revealed highly reproducible amplicon profiles with relatively high multiplex ratios. Many of the primers generated amplicon profiles with which not only the differences among species can readily be identified, but also polymorphisms within species could be detected more efficiently. PCR products at 150 gel positions detected using six SSR primers in Cicer accessions were treated as dominant DNA markers and utilized to compute the distances among accessions and species. Cluster analysis of accessions and species revealed groupings that corroborate our previous studies of relationships based on allozyme and AFLP analysis. Consistent with the AFLP analysis carried out in the same accession collection, ISSR-based groupings indicated that perennial C. incisumis genetically close to the annuals of the second crossability group (C. pinnatifidum,C. bijugum, C. judaicum) while C. reticulatum is the closest wild species to the cultivated chickpea. ISSR-based variation estimates were relatively higher when compared to previous estimates computed from RAPD and AFLP data. Technically, ISSR analysis combines the PCR-based targeting of microsatellite-associated polymorphisms with no prior sequence requirement and stringent PCR conditions. Similarly, when compared to AFLP analysis, it is less technically demanding allowing to survey polymorphic loci in the genome. Thus, ISSR-PCR technology is a reliable, fast, and cost-effective marker system that can be used to study genetic variation and genetic relationships in the genusCicer. This revised version was published online in July 2006 with corrections to the Cover Date.     

Chloride tolerance in soybean and perennial Glycine accessions

Diversity for chloride tolerance exists among accessions of perennial Glycine. Accessions whose tolerance thresholds exceed those of Glycine max cultivars may be useful germplasm resources. Soybean cultivars including ‘Jackson’ (sensitive) and ‘Lee’ (tolerant) and 12 accessions of perennial Glycine were evaluated for sodium chloride tolerance after 14 days in hydroponic culture at 0, 5, 10, and 15 g L^-1 NaCl. Sodium chloride had adverse effects on the growth of G. max cultivars and perennial Glycine accessions; however differential responses to salinity were observed among accessions. Considerably greater variation in sodium chloride tolerance existed among the perennial Glycine accessions than among the G. max cultivars. Sodium chloride tolerance thresholds ranged from 3.0 to 17.5 g L^-1 NaCl for the perennial accessions but only ranged from 5.2 to 8.0 g L^-1 for the cultivars, based on a Weibull model of leaf chlorosis. All G. max cultivars were severely injured or killed by NaCl at 10 g L^-1 and above. Five tolerant perennial Glycine accessions, G. argyrea 1626, G. clandestina 1388 and 1389, and G. microphylla 1143 and 1195, were significantly lower in leaf chlorosis score than any of the G. max cultivars at the 10 g L^-1 NaCl treatment. Two accessions, G. argyrea 1626 and G. clandestina 1389 were able to tolerate 15 g L^-1 NaCl with only moderate visual injury while all other accessions were severely injured or killed at this salt level. Variability for chloride tolerance observed among the perennial Glycine accessions has potential utility for developing enhanced salt tolerance in soybean. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetic diversity in a germplasm collection of Brassica rapa subsp rapa L. from northwestern Spain

In Galicia (northwestern Spain), Brassica rapa subsp. rapa L. includes turnips, turnip greens, and turnip tops. The objectives of this study are (i) to determine the genetic diversity and morphological resemblances among the B. rapa landraces of northwestern Spain in order to have information relative to the resources preserved, and (ii) to evaluate their agronomic characteristics, considering the three potential products that can be harvested. A collection of 120 landraces was evaluated for 34 morphological and agronomical traits by an augmented design at two locations. Two landraces were the most promising for turnips production (MBG-BRS0183 and MBG-BRS0256), two showed the best characteristics for turnip greens (MBG-BRS0082 and MBG-BRS0184), and three were the most appropriate landraces for turnip tops production (MBG-BRS0143, MBG-BRS0173 and MBG-BRS0401). Landraces were classified into five clusters (A–E) using the Ward–MLM (Modified Location Model) strategy: (A) included plants with the worst agronomic potential, (B) included most of the turnip populations with rosette growth habit, (C) included turnip populations without rosette growth habit, having more vigorous plants than cluster B, (D) gathered the most vigorous local varieties, with the highest early vigor, fresh matter content per leaf, and number of secondary stems per plant, and (E) landraces characterized by their earliness, large flowering periods, high numbers of secondary stems, and large seed weights. As conclusion, landraces evaluated in this work displayed enough variability to differentiate among appropriate populations for each one of the distinct crops. Their classification, using the Ward–MLM strategy, grouped accessions with similar characteristics into homogeneous categories.     

Intra species variation in Atylosia scarabaeoides (L.) Benth., a wild relative of pigeonpea (Cajanus cajan (L.) Millsp.)

Summary Atylosia scarabaeoides (L.) Benth., a wild relative of pigeonpea, possesses several useful genes which can be utilized for pigeonpea improvement. In the present study, 33 accessions of A. scarabaeoides were evaluated at ICRISAT Center during the 1987 rainy season for variation in some useful traits to identify parents for inter-generic hybridization. A large variation was observed for leaf components, seed size, pod length, seeds/pod, days to flowering, seed protein, sulphur amino acids, resistance to cyst nematode, phytophthora blight, sterility mosaic, fusarium wilt, pod borer, pod fly, and pod wasp. Only four accessions were found to have more than 28% protein content. Methionine and cystine contents were marginally higher than in pigeonpea but the variation was not large enough to utilize them in the breeding program. In A. scarabaeoides. accessions resistant to fusarium wilt, phytophthora blight, sterility mosaic, and cyst nematode were detected. Compared to pigeonpea, the A. scarabaeoides accessions were less susceptible to lepidopteran borer and were immune to pod fly damage. Accessions ICPW 89 and ICPW 111 in short- (100–120 days), and ICPW 94 and ICPW 118 in medium-duration (140–180 days) were identified as potential parents for use in inter-generic hybridization.ICRISAT Journal Article No. 967     

绿豆种质资源农艺性状的因子分析及综合评价

为合理利用绿豆种质资源,本研究以55份绿豆种质资源为材料,通过对其10个农艺性状进行因子分析及聚类分析。结果表明:10个农艺性状的变异系数为8.57%~47.19%,其中单株粒重变异系数最大,生育期变异系数最小。将10个农艺性状简化为结荚数因子、高度因子、粒数因子、粒重因子和生育期因子5个独立的主因子,该5个主因子可以反映原始信息的86.340%。经综合得分排序,评选出10份性状优良的绿豆种质资源。聚类分析将55份种质资源的10个数量性状分为3大类,类群I、类群II、类群III分别包括22份、7份、26份材料。结合综合评价和聚类分析认为,在黑龙江绿豆生产中,‘安绿8号’、‘佳木斯黄绿豆’、‘冀绿1号’可作为品种选育的改良亲本,也可大面积种植利用。     

Field screening ofPisum accessions to evaluate their susceptibility to the pea weevil (Coleoptera: Bruchidae)

Summary Seventeen unreplicated field trials over nine sites and four years were used to classifyPisum germplasm (P. sativum L. &P. fulvum Sibth. & Sm) as potential sources of resistance to the pea weevil,Bruchus pisorum (L.). The emergence of adult weevils from <10% of harvested seed was used as the selection criterion to indicate possible resistance. A total of 1900Pisum accessions were assessed using the field trials and 1754 of theP. sativum accessions were eliminated. However in the 18P. fulvum accessions screened, the level of infestation by pea weevil was always below the arbitrary resistance threshold selected. This suggests thatP. fulvum accessions could be a valuable source of resistance to the pea weevil.     

Screening wild Lycopersicon species for resistance to powdery mildew (Oidium lycoperiscum)

Since the late 1980s powdery mildew, designated Oidium lycopersicum, frequently invaded the tomato crop in Western Europe. All commercial cultivars are susceptible. To screen for resistance in wild species a reliable and efficient disease test was developed. Young plants with two to three true leaves are inoculated at high relative humidity by spraying with a freshly prepared suspension of 2×10⁴ conidia, ml^–1. Symptoms are periodically evaluated according to a scale based on the percentage of leaf area with mycelium.One hundred and twenty seven accessions, representing eight wild Lycopersicon species, were screened for resistance to O. lycopersicum. A large variation in resistance was found between species. L. hirsutum was the most resistant species; L. pennellii was moderately resistant; species of the subgeneric group of L. esculentum and of the peruvianum-complex were all susceptible. L. parviflorum was classified separately due to a large variation between accessions. Except for this species, a low variation was found between accessions within species. High levels of resistance were observed in four accessions of L. hirsutum, in one of L. parviflorum and in one of L. peruvianum. This resistance is characterized by a very low disease incidence and a strongly restricted mycelium growth and lack of sporulation.     

Identification of RAPD markers linked to recessive genes conferring siliqua shatter resistance in Brassica rapa

Shattering of siliquae causes significant seed loss in canola (Brassica napus) production worldwide. There is little genetic variation for resistance to shatter in canola and, hence, the trait has been studied in B. rapa. Previous studies have shown two randomly segregating recessive genes to be responsible for shatter resistance. Three random amplified polymorphic DNA markers were identified as being linked to shatter resistance using bulked segregant analysis in a F₃B. rapa population. The population was derived from a cross between a shatter‐susceptible Canadian cultivar and a shatter‐resistant Indian line. Of the three markers, RAC‐3₉₀₀ and RX‐7₁₀₀₀ were linked to recessive sh1 and sh2 alleles, and SAC‐20₁₃₀₀ was linked to both dominant Sh1 and Sh2 alleles. The common marker for the dominant wild‐type allele for the two loci was explained to have resulted from duplication of an original locus and the associated markers through chromosome duplication and rearrangements in the process of evolution of the modern B. rapa from its progenitor that had a lower number of chromosomes. Segregation data from double heterozygous F₃ families, although limited, indicated the markers were not linked to each other and provided further evidence for the duplication hypothesis.     

Genetic analysis of powdery-mildew (Erysiphe graminis f.sp. hordei) resistance derived from wild barley (Hordeum vulgare ssp. spontaneum)

The inheritance of resistance to powdery mildew was investigated in 20 accessions of Hordeum spontaneum and in 20 F₄ lines derived from crosses between the variety ‘Aramir’ and 13 accessions of H. spontaneum. Two resistance genes were detected in 17 accessions, and three resistance genes in one accession. In two accessions, only one resistance gene was present. The 20 breeding lines showed a large variation in infection type and infection level. The genetic relationship between the resistance genes detected was investigated in the seven most resistant F₄ lines. These F₄ lines were divided into three groups which carried different resistance genes. In two lines, the detected resistance gene was shown to be race-specific.     

Screening for resistance against rhopalosiphum padi (L.). I. avena species and breeding lines

Summary Thirty-two accessions of Avena species and breeding lines were evaluated for resistance, primarily antibiosis, to the aphid Rhopalosiphum padi (L.) in greenhouse and growth room tests. The highest levels of resistance were found in A. barbata and in the perennial species A. macrostachya. One breeding line, Obee, was also found to have interesting resistance characters. Resistance in A. macrostachya is discussed in relation to perenniality. A different screening method for rapid testing of large collections of varieties is evaluated.