Genetics of resistance to ascochyta blight in chickpea (Cicer arietinum L.)

Summary Six chickpea lines resistant to Ascochyta rabiei (Pass.) Lab. were crossed to four susceptible cultivars. The hybrids were resistant in all the crosses except the crosses where resistant line BRG 8 was involved. Segregation pattern for diseases reaction in F₂, BCP₁, BCP₂ and F₃ generations in field and glasshouse conditions revealed that resistance to Ascochyta blight is under the control of a single dominant gene in EC 26446, PG 82-1, P 919, P 1252-1 and NEC 2451 while a recessive gene is responsible in BRG 8. Allelic tests indicated the presence of three independently segregating genes for resistance; one dominant gene in P 1215-1 and one in EC 26446 and PG 82-1, and a recessive one in BRG 8.Research paper No. 3600     

The origin of chickpea Cicer arietinum L.

Summary Species relationship between the cultivated chickpea Cicer arietinum and the two newly discovered wild species C. echinospermum and C. reticulatum were assessed through breeding experiments and cytological examination of the hybrids.The two wild species differed from each other by a major reciprocal translocation and their hybrid was completely sterile. The wild species C. echinospermum also differed from the cultivated species by the same translocation and their hybrid was highly sterile. The other wild species, C' reticulatum, was crossed readily with the cultivated chickpea. Meiosis of the hybrids, involving 4 different C. arietinum lines, was normal, and they were fertile. This wild species therefore can be considered as the wild progenitor of the cultivated chickpea.     

Variation in Cicer arietinum L.

Summary A collection of populations and cultivars of Cicer arietinum L. were studied to obtain phenotypic, genotypic and environmental correlation coefficients, and broad sense heritabilities. Principal Component Analyses were performed on phenotypic, genotypic and environmental matrices. Data and phase obtained on a pure morphological basis, as well as on quantitative genetic studies and geographical distribution support the existence of two complexes within the cultivated chickpea, macrosperma and microsperma. These taxa differ in a cluster of complex characters associated with seed. pod and leaf morphology, and they differ in distribution. There is no taxonomic basis to treat these as subspecies. We propose to include C. reticulatum Lad., the wild chickpea, as a subspecies of C. arietinum, with the cultivated kinds recognized as subspecies arietinum. Race macrosperma was derived from race microsperma through selection during relatively recent times of the evolutionary history of the chickpea.     

Induction and inheritance of determinate growth habit in chickpea (Cicer arietinum L.)

Summary The character of determinate plant growth has not been reported for chickpea and has not been observed in the world germplasm collection at ICRISAT, Patancheru, India. A determinate growth habit would be desirable where growing conditions often lead to excessive vegetative growth. We attempted to generate this trait by mutation breeding. Seeds of the cultivar ICCV 6 were exposed to varying irradiation treatments, M₁ and M₂ populations were raised, and in the latter one plant was detected that showed the determinate growth habit and female sterility. The character of determinate growth segregated in a postulated digenic epistatic 3:13 fashion in the F₂ and confirmed its digenic mode of inheritance in the F₃ and F₄. The symbol cd is proposed for the allele conditioning for determinancy and Dt for the allele expressing the determinate trait. Continued mutation breeding with this and other material may result in identifying fully fertile, determinate plant types.Abbreviations DT - determinate - IDT - indeterminate ICRISAT Journal Article No. 1396.     

Genetics for speed of plumule emergence in chickpea (Cicer arietinum L.)

Summary Genetics for speed of plumule emergence was studied using six generations (P₁, P₂, F₁, BC₁(P₁), BC₂(P₂) and F₂) in three crosses. Two of the crosses which had parents of different emergence speed were controlled by two genes with duplicate epistasis. The third cross which involved parents of little difference for speed, indicated incomplete dominance for one gene of bit fast parent over the slow one. In all the crosses F₂ segregation pattern was confirmed by the segregation pattern of back crosses. The gene symbols were designated as Sp1Sp1 Sp2Sp2 for fast speed parents: sp1sp1 sp2sp2 for slow parent and sp1sp1 Sp2Sp2 for the parent with bit fastness for speed of plumule emergence.     

Distribution of qualitative traits in the world germplasm of chickpea (Cicer arietinum L.)

Summary The chick pea germplasm collection maintained at ICRISAT Center, Patancheru, India, is the largest collection of this crop available in one place. This collection was grown in instalments and described for qualitative and agronomical traits. The importance and distribution of six qualitative traits, namely flower colour, plant colour, growth habit, seed shape, seed surface and seed colour have been discussed.Approved as J. A. No. 365 by the International Crops Research Institute for the Semi-Arid Tropics (ICRI-SAT).     

Cultivar identification and genetic relationship among selected breeding lines and cultivars in chickpea (Cicer arietinum L.)

Twenty two RAPD and 22 ISSR markers were evaluated for their potential use in determination of genetic relationships in chickpea (Cicer arietinum L.) cultivars and breeding lines. We were able to identify six chickpea cultivars/breeding lines by cultivar-specific markers. All of the cultivars tested displayed a different phenotype generated either by the RAPD or ISSR primers. Though ISSR primers generated less markers than RAPD primers, the ISSR primers produced higher levels of polymorphism (% of polymorphic markers per primer) than RAPD primers. A high level of within cultivar homogeneity was observed in chickpea. Cultivars/breeding lines originating from a common genetic background showed closer genetic relationship. Chickpea lines with similar seed type(kabuli or desi) had a tendency to cluster together. This revised version was published online in August 2006 with corrections to the Cover Date.     

Leaf types and their genetics in chickpea (Cicer arietinum L.)

Summary Commonly the chickpea leaf is uni-imparipinnate, having 9–15 leaflets. However, certain variants have been reported; these are available in the chickpea collection at ICRISAT and were re-examined. Based on the lamina differentiation, three major classes of leaf type can be recognized: uni-imparipinnate (normal), multipinnate and simple (leaf). (Certain other leaf forms reported earlier are not classes of leaf type though they are distinct variants). It was determined that the leaf type differences are governed by two genes (mlsl), which show supplementary gene action. The multipinnate leaf is formed when the first gene is dominant (ml⁺sl/.sl). Whereas the simple leaf occurs when the first gene is recessive and the second gene is in either form (ml./ml.), the normal leaf is expressed when both dominant genes are present (ml⁺sl⁺/..).Submitted as J.A. No. 814 by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).     

Quantitative resistance to Botrytis cinerea from Solanum neorickii

Tomato (Solanum lycopersicum) is susceptible to gray mold (Botrytis cinerea). Quantitative resistance to B. cinerea was previously identified in a wild relative, S. neorickii G1.1601. The 122 F₃ families derived from a cross between the susceptible S. lycopersicum cv. Moneymaker and the partially resistant S. neorickii G1.1601 were tested for susceptibility to B. cinerea using a stem bioassay. Three putative quantitative trait loci (pQTL) were detected: pQTL3 and pQTL9 reducing lesion growth (LG) and pQTL4 reducing disease incidence (DI). For each pQTL, a putative homologous locus was identified recently in another wild tomato relative, S. habrochaites LYC4. pQTL3 was confirmed by assessing disease resistance in BC₃S₁ and BC₃S₂ progenies of S. neorickii G1.1601. pQTL4 was not statistically confirmed but the presence of the S. neorickii resistance allele reduced DI in all three tested populations. The reduction in LG of pQTL9 was not confirmed but rather, this locus conferred a reduced DI, similar to observations in the QTL study using S. habrochaites. The results are discussed in relation to other disease resistance loci identified in studies with other wild tomato relatives.     

Inheritance of a plant type mutant and its utilization in chickpea

Summary A macro-mutant, E 100Y(M) in chickpea (Cicer arietinum L.) was found to affect several plant and seed characters. For plant type monogenic inheritance was observed. A single pair of recessive genes pt/pt was ascribed to this mutant. The mutant locus seemed to be exerting pleiotropic action. The utilization of this mutant for chickpea improvement has been discussed.     

Selection of diverse parents of chickpea (Cicer arietinum L.) by multivariate analysis and the degree of heterosis of their F1 hybrids

Summary Studies on genetic diversity in chickpea (Cicer arietinum L.) indicated the existence of considerable amount of variation for grain yield and its components in the material. One hundred and thirty two genotypes fell into eight clusters. The covariation structure studied by means of factor analysis indicated the possibility of obtaining, through hybridization, genotypes physiologically and morphologically more efficient. Multivariate analysis of data from 7 parents and 21 F1 hybrids indicated weak correspondence between D²-analysis and canonical variate analysis. As there was no relationship between heterosis over midparent and genetic distance between the parents, so the traditional approach of making a large number of crosses is being suggested.     

DAF marker tightly linked to a major locus for Ascochyta blight resistance in chickpea (Cicer arietinum L.)

Resistance of chickpea against the disease caused by the ascomycete Ascochyta rabiei is encoded by two or three quantitative trait loci, QTL1, QTL2 and QTL3. A total of 94 recombinant inbred lines developed from a wide cross between a resistant chickpea line and a susceptible accession of Cicer reticulatum, a close relative of cultivated chickpea, was used to identify markers closely linked to QTL1 by DNA amplification fingerprinting in combination with bulked segregant analysis. Of 312 random 10mer oligonucleotides, 3 produced five polymorphic bands between the parents and bulks. Two of them were transferred to the population on which the recent genetic map of chickpea is based, and mapped to linkage group 4. These markers, OPS06-1 and OPS03-1, were linked at LOD-scores above 5 to markers UBC733B and UBC181A flanking the major ascochyta resistance locus. OPS06-1 mapped at the peak of the QTL between markers UBC733B (distance 4.1 cM) and UBC181A (distance 9.6 cM), while OPS03-1 mapped 25.1 cM away from marker UBC733B on the other flank of the resistance locus. STMS markers localised on this linkage group were transferred to the population segregating for ascochyta resistance. Three of these markers were closely linked to QTL1. Twelve of 14 STMS markers could be used in both populations. The order of STMS markers was essentially similar in both populations, with differences in map distances between them. The availability of flanking STMS markers for the major resistance locus QTL1 will help to elucidate the complex resistance against different Ascochyta pathotypes in future. This revised version was published online in August 2006 with corrections to the Cover Date.     

Development of methods using phytoalexin (resveratrol) assessment as a selection criterion to screen grapevine in vitro cultures for resistance to grey mould (Botrytis cinerea)

Summary The purpose of this research was, firstly to determine the ability of grapevine in vitro cultures to synthesize resveratrol, a stilbene-type phytoalexin that is considered to be a good marker for resistance of grapevines to Botrytis cinerea, the causal organism for grey mould. Secondly, this study sought to establish the relationship between phytoalexin production potential and resistance to Botrytis cinerea in grapevines. In this aim, resveratrol production was assessed in 13 Vitis species or cultivars. A good correlation appeared between resveratrol production by grapevine in vitro cultures and grey mould resistance except for two Vitis spp. for which no correlation was observed, thus suggesting that resistance of grapevines may sometimes be associated with factors other than stilbene phytoalexins. In view of the results obtained, the potential use of resveratrol induction and of in vitro methods as a tool for screening grapevines for resistance to B. cinerea was discussed.     

The use of allozymes at three life stages influences genetic variation analysis and clustering in Cicer arietinum germplasm collections

Levels of genetic variation using 6 enzyme systems for a total of 11 interpretable loci were examined in chickpea (Cicer arietinum) originating from 9locations in Bangladesh. The measurement of genetic variation at enzyme loci was carried out on the seed embryo, on the early leaves of seedlings and on the mature leaves at the vegetative stage. A total of 592individuals, including 240 seeds, 200 seedlings and152 mature leaves were investigated. Using electrophoretic data, chickpea was found to express higher percentages of polymorphic loci at the seed stage (36–64%) than at seedling (22–56%) or the vegetative stage (11–44%). The proportion of mean number of alleles and the average mean observed heterozygosity also were higher at the seed stage when compared to the seedling and vegetative stages. Unique alleles were absent, and only differences infrequencies could be noticed. Positive values of the fixation index were noted for pgm-1 and 6pg-1 for all stages and in both mnr loci for the seed embryo's. A trend towards lower genetic distances of all possible pairs of populations could be observed when comparing those of seed embryo's with seedlings or mature leaves. This trend was even more pronounced when pooling the data of 9 populations into their 3regions. Slight differences in genetic distances caused a separative clustering of population 3 at seed embryo, of population 2 at seedling and of population5 at vegetative stages. It is suggested that careful examination of enzyme polymorphisms at different developmental stages is a prerequisite before drawing conclusions on the genetic distance between germplasm collections from different origins since small differences in the data entry for clustering results in ties that may affect tree topologies. This revised version was published online in July 2006 with corrections to the Cover Date.     

Inheritance of Dry Root Rot (Rhizoctonia bataticola) Resistance in Chickpea (Cicer arietinum)

The inheritance of resistance to dry root rot of chickpea caused by Rhizoctonia bataticola was studied. Parental F₁ and F₂ populations of two resistant and two susceptible parents, along with 49 F₁ progenies of one of the resistant × susceptible crosses were rested for their reaction to dry root rot using the blotting-paper technique. All F, plants of the resistant × susceptible crosses were resistant; the F₂ generation fitted a 3 resistant: 1 susceptible ratio indicating monogenic inheritance, with resistance dominant over susceptibility. F³ family segregation data confirmed the results. No segregation occurred among the progeny of resistant × resistant and susceptible × susceptible crosses.     

Pollen grain germination and pollen tube growth following in vivo and in vitro self and interspecific pollinations in annual Cicer species

Summary Germination of pollen grains and growth of pollen tubes were studied to determine the cause of barreness in crosses among annual Cicer species. In vivo and in vitro time-course studies and fluorescent microscopy revealed no pollination incompatibility among the selfs, crosses and reciprocals of C. arietinum L., C. reticulatum Lad. and C. cuneatum Rich. In general, Cicer pollen grains germinated and grew on styles of Cicer species. Pollen tube growth was characterized by irregularly spaced and intermittent callose deposits. Failure of seed formation in interspecific pollinations may be attributed to the slowness of pollen tube growth or collapse of fertilized ovules. In addition to these causes, shortness of stamens and sparsity of pollen grains were responsible for flower drop in natural selfs. Although the number of pollen tubes entering the micropyle in interspecific pollinations was low, it may be possible to grow the fertilized ovules on an artificial medium to obtain F₁ plants.     

Cross compatibility between chickpea and its wild relative,Cicer echinospermum Davis

Summary Cicer echinospermum, a wild relative of chickpea (Cicer arietinum L.), has traits that can be used to improve the cultivated species. It is possible to obtain successful crosses between the two species, even though their cross progenies have reduced fertility. The reasons for this low fertility could be due to the two species differing in small chromosome segments or at genic level. Another limitation to the use ofC. echinospermum at ICRISAT Asia Center is that the species is not adapted to the short photoperiod which prevails during the chickpea cropping season at Patancheru, Andhra Pradesh, India. Future work will include screening the segregating progenies for monitoring traits from both the species through isozyme analysis and to incorporate these into good agronomic backgrounds following backcrosses.Submitted as JA 1669 by ICRISAT     

Estimation of Outcrossing Rate in Chickpea (Cicer Arietinum L.) Sown in Autumn

Gene flow via outcrossing from transgenic plants to relatives will be one of the most important concerns to grow of the transgenic chickpea (Cicer arietinum L.) in European Union (EU). This report is therefore focused on spontaneous outcrossing rate in chickpea. A total of 39 kabuli type mutants with white flower and one desi type with pink flower were grown to estimate spontaneous outcrossing rate. Outcrossing rate ranged from 0.0 to 1.25% in mutant materials. Since labelling threshold for transgenic contamination in food and feed in European Union (EU) is 0.9%, outcrossing rate of 1.25% is higher than threshold of 0.9% in EU, and this result suggests that cultivation of transgenic chickpea will be under high risk to be contaminated chickpeas in neighbourhood fields.     

Two new traits - open flower and small leaf in chickpea (Cicer arietinum L.)

Two new traits – open flower and small leaf in chickpea are discussed. Open flower, a natural mutant in a good agronomic background is reported for the first time, small leaf trait has been reported earlier, and has now been studied by breeders. Both useful traits were found to be monogenic recessive. The joint F₂ segregation data revealed no linkage between flower colour and flower type, but flower type and leaf size showed some linkage. Open flower could contribute to a higher rate of cross pollination and utilization of heterosis. The small leaf allows light to penetrate the crop canopy, and could be useful in designing a physiologically efficient plant type in chickpea. This revised version was published online in July 2006 with corrections to the Cover Date.     

Inheritance of Seed Coat Thickness in Chickpea (Cicer arietinum L.) and its Evolutionary Implications

The desi and kabuli chickpeas are characterized, among other things, by their seed coats being thicker in the desi than in the kabuli type. The inheritance of seed coat thickness, and its relation to flower colour and seed size, was studied. Seed coat thickness exhibits monogenic inheritance, the thin kabuli seed coat being the recessive character. Linkage was found between seed coat thickness and flower colour, the recombinant fraction being 0.19. No relationship was found between seed coat thickness and seed size. The role of these characters in the evolution of the chickpea is discussed.