Associations of some characters with seed yield in chickpea collections

Summary Three thousand two hundred and sixty-seven kabuli chickpea (Cicer arietinum L.) germplasm accessions were grown during the spring season of 1980 at Tel Hadya, the main research station of ICARDA, Syria to determine the components of seed yield. Observations were recorded on seed yield and 14 other characters. Correlation and path coefficient analyses were done to find out associations among characters and to assess the direct and indirect contribution of each character to seed yield.Large variation was observed for all the characters studied except days to flowering, days to maturity and protein content. Correlation and path coefficient analyses showed that biological yield and harvest index were the major direct contributors to seed yield. The 100-seed weight, plant height, days to flowering and maturity, canopy width, and protein content contributed to seed yield mainly through indirect effect via biological yield and harvest index. The 100-seed weight and seed yield were major contributors to biological yield. Major contributor to protein content was days to maturity. Results indicated that selection for high biological yield and harvest index would lead to high seed yield; and selection for large seed size would lead to high biological yield. Therefore, these characters should receive the highest priority in selecting high yielding plants in chickpea breeding.     

Diallel analyses reveal the genetic control of resistance to ascochyta blight in diverse chickpea and wild Cicer species

Ascochyta blight is a major fungal disease affecting chickpea production worldwide. The genetics of ascochyta blight resistance was studied in five 5 × 5 half-diallel cross sets involving seven genotypes of chickpea (ICC 3996, Almaz, Lasseter, Kaniva, 24B-Isoline, IG 9337 and Kimberley Large), three accessions of Cicer reticulatum (ILWC 118, ILWC 139 and ILWC 184) and one accession of C. echinospermum (ILWC 181) under field conditions. Both F₁ and F₂ generations were used in the diallel analysis. The disease was rated in the field using a 1–9 scale. Almaz, ICC 3996 and ILWC 118 were the most resistant (rated 3–4) and all other genotypes were susceptible (rated 6–9) to ascochyta blight. Estimates of genetic parameters, following Hayman’s method, showed significant additive and dominant gene actions. The analysis also revealed the involvement of both major and minor genes. Susceptibility was dominant over resistance to ascochyta blight. The recessive alleles were concentrated in the two resistant chickpea parents ICC 3996 and Almaz, and one C. reticulatum genotype ILWC 118. The wild Cicer accessions may have different major or minor resistant genes compared to the cultivated chickpea. High narrow-sense heritability (ranging from 82% to 86% for F₁ generations, and 43% to 63% for F₂ generations) indicates that additive gene effects were more important than non-additive gene effects in the inheritance of the trait and greater genetic gain can be achieved in the breeding of resistant chickpea cultivars by using carefully selected parental genotypes.     

Morpho-physiological traits to complement grain yield selection under semi-arid Mediterranean conditions in each of the durum wheat types mediterraneum typicum and syriacum

Summary Some 238 landraces from Algeria and Tunisia representative of the mediterraneum typicum durum wheat type and 265 landraces from Syria and Jordan representing the syriacum type were grown in a semi-arid Mediterranean environment of Northern Syria characterized by moderate drought stress. The germplasm types were compared for mean value, level of variation and relationships with grain yield of various morpho-physiological traits possibly usable for indirect selection of best yielding materials. The syriacum germplasm showed higher yield mainly due to greater earliness of cycle, slightly longer grain filling period, shorter stature, lower early growth vigour and higher drought tolerance expressed by a visual score recorded in another, more stressful environment in the region. It also showed lower variation for all morpho-physiological characters except plant glaucousness, for which it was more variable. The wheat types differed not only for architecture but also for optima of individual morpho-physiological traits required to maximize the yield response in the given environment. Higher yield of syriacum materials was attained at same heading and three to four days delayed maturity with respect to average phenology of three well-adapted control cultivars, and it was favoured by increasing number of kernels per spike, early vigour and drought tolerance. Higher yield of mediterraneum typicum landraces was related to heading and maturity dates approaching those of the control cultivars and to increasing kernel weight, early vigour and drought tolerance. Plant stature hardly affected the yield. Both absent and strong glaucousness could confer a yield advantage in syriacum materials.     

Current status and future strategy in breeding chickpea for resistance to biotic and abiotic stresses

Chickpea (Cicer arietinum L.) production has remained static for the past two decades. One major limiting factor has been susceptibility of cultivars to several biotic and abiotic stresses that adversely affect yield. In recent years, cultivars resistant to Ascochyta blight (Ascochyta rabiei [Pass.] Lab.), Fusarium wilt (Fusarium oxysporum f. sp. ciceris), and cold have been bred and released in many countries. Some progress has been made in breeding for resistance to drought, insects, and cyst nematode, but not for viruses, heat, and salinity. Two or more stresses are of equal importance in most chickpea growing areas. Therefore, future efforts should be directed toward the development of cultivars with multiple-stress resistance. Proper understanding of important stresses in different countries and the genetics of resistance should lead to more systematic approaches to resistance breeding. Wild Cicer species hold promise and deserve attention in resistance breeding.     

Agro-morphological characterisation of common vetch and its close relatives

The Vicia sativa aggregate, which includes the common vetch, is a complex of six closely related tax a which combines cultivated, weedy and wild forms. In this study 454 accessions with an emphasis on Mediterranean and Central Asian accessions have been compared for 22 key agro-morphological and phonological characters. The agronomic potential of the different members of the aggregate is assessed and useful variation existing in the collection is determined. Geographic patterns of the agronomic variation are studied to determine sources of useful variation. In both sub sp. cordata and sub sp. sativa accessions were found which had higher yields than the checks, consisting of three promising accessions. Sub sp. macrocarpa needs a longer growing season than the other tax a to reach its full potential. The other three tax a in the aggregate all had quite low yields. Important variation in shattering of pod sand in tolerance to moderate frost and resistance to the Sitona weevil was found in most subspecies of the aggregate. Variation in phenological characters appeared to be related to the latitude from which the accession was collected. This revised version was published online in July 2006 with corrections to the Cover Date.     

Chickpea molecular breeding: New tools and concepts

Summary Chickpea is a cool season grain legume of exceptionally high nutritive value and most versatile food use. It is mostly grown under rain fed conditions in arid and semi-arid areas around the world. Despite growing demand and high yield potential, chickpea yield is unstable and productivity is stagnant at unacceptably low levels. Major yield increases could be achieved by development and use of cultivars that resist/tolerate abiotic and biotic stresses. In recent years the wide use of early maturing cultivars that escape drought stress led to significant increases in chickpea productivity. In the Mediterranean region, yield could be increased by shifting the sowing date from spring to winter. However, this is hampered by the sensitivity of the crop to low temperatures and the fungal pathogen Ascochyta rabiei. Drought, pod borer (Helicoverpa spp.) and the fungus Fusarium oxysporum additionally reduce harvests there and in other parts of the world. Tolerance to rising salinity will be a future advantage in many regions. Therefore, chickpea breeding focuses on increasing yield by pyramiding genes for resistance/tolerance to the fungi, to pod borer, salinity, cold and drought into elite germplasm. Progress in breeding necessitates a better understanding of the genetics underlying these traits. Marker-assisted selection (MAS) would allow a better targeting of the desired genes. Genetic mapping in chickpea, for a long time hampered by the little variability in chickpea’s genome, is today facilitated by highly polymorphic, co-dominant microsatellite-based markers. Their application for the genetic mapping of traits led to inter-laboratory comparable maps. This paper reviews the current situation of chickpea genome mapping, tagging of genes for ascochyta blight, fusarium wilt resistance and other traits, and requirements for MAS. Conventional breeding strategies to tolerate/avoid drought and chilling effects at flowering time, essential for changing from spring to winter sowing, are described. Recent approaches and future prospects for functional genomics of chickpea are discussed.     

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.     

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     

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.     

Evaluation of Yield Criteria for Drought and Heat Resistance in Chickpea (Cicer arietinum L.)

The chickpea (Cicer arietinum L.) is usually grown under rainfed, rather than irrigated conditions, where drought accompanied by heat stress is a major growth constraint. The aim of this study was to select chickpea genotypes having resistance to drought/heat stress and to identify the most appropriate selection criteria for this. A total of 377 chickpea accessions were sown 2 months later than normal for the Antalya region (Turkey) to increase their exposure to the drought and high‐temperature conditions of a typical summer in this part of the world. Interspersed between every 10 test genotypes as benchmark genotypes, were plants of the two known genotypes ILC 3279 (drought‐susceptible) and ILC 8617 (drought‐susceptible), while ICC 4958 (known drought‐resistant) and ICCV 96029 (known very early, double‐podded) were also sown for confirmation. All plants were subsequently screened for drought and heat stress resistance. Soon after the two known susceptible genotypes had died, evaluations of the entire trial were made visually on a scale from ‘1’ (free from drought/heat damage) to ‘9’ (all plants died from drought/heat). Yield loss in many of the test genotypes and in the two known susceptible genotypes (ILC 3279 and ILC 8617) rose to 100 %. The desi chickpeas (smaller, dark seeds) were generally more drought‐ and heat‐resistant than the kabuli chickpeas (larger, pale seeds). Two desi chickpeas, ACC 316 and ACC 317, were selected for drought and heat (>40 °C) resistance under field conditions. Seed weight was the trait least affected by adverse environmental conditions and having the highest heritability, and it should be used in early breeding selections. When breeding drought‐ and heat‐resistant chickpeas, path and multivariate analyses showed that days to the first flowering and maturity to escape terminal drought and heat stresses should be evaluated ahead of many other phenological traits, and harvest index, biological yield and pods per plant for increased yield should also be considered.     

Assessment of genetic diversity of cultivated chickpea using microsatellite-derived RFLP markers: Implications for origin

Restriction fragment length polymorphism (RFLP) analysis was performed on 30 accessions of cultivated chickpea (Cicer arietinum L.) collected from 11 different countries representing the Near East, Central Asian and Hindustani regions. A synthetic digoxygenated oligonucleotide (GATA)₄ complementary to a microsatellite DNA sequence was used as a probe. The results revealed that simple repetitive sequences are abundant and polymorphic in the chickpea genome. The fragments detected were used lo estimate the genetic diversity within accessions and a similarity index between the genotypes of the accessions. The genetic distance data were used to construct a dendrogram depicting genetic relationships among the different accessions. The results indicate that the greatest genetic diversity occurs in Pakistan, Iraq, Afghanistan, south-east Russia, Turkey and Lebanon. Lower genetic diversity was found in Iran, India, Syria, Jordan and Palestine, Based on DNA markers, it is concluded that there are three centres of diversity for chickpea: Pakistan-Afghanistan. Iraq Turkey and Lebanon. India, which was previously considered as a secondary center of diversity for chickpea, showed lower diversity than the above regions.     

Development of early-flowering Kabuli chickpea with compound and simple leaves

Terminal drought is a major constraint to chickpea (Cicer arietinum L.) production. Autumn sowing and early flowering have been suggested as ways to benefit from the winter rains in short rainy seasons under dryland cropping. High‐yielding, late‐flowering, simple‐leafed (slv/slv) chickpea cultivars with good field resistance to Ascochyta blight have been bred recently. Changing plant architecture, by altering leaf shape, may affect agronomic performance. As no information is available on the effect of leaf shape on phenology and seed yield, this study was aimed at: (i) introducing the simple leaf trait into an early‐flowering chickpea background; (ii) comparing the grain yield of the two leaf types in early vs. late flowering backgrounds and (iii) producing breeding lines combining early flowering, large seeds and Ascochyta tolerance with both leaf types. Hybrid progeny were studied from the cross of ‘Sanford’ (slv/slv) and ICC7344, (compound, SLV/SLV). Four early‐podding, F₈ breeding lines were selected with either simple or compound leaves. In three different field experiments under dryland conditions (334–379 mm), they yielded ca. 1.4 t/ha as compared with 1.0 t/ha in the standard Israeli ‘Yarden’ on one site, but no significant differences in yield were obtained in the other two experiments.     

Mapping and validation of QTLs for resistance to an Indian isolate of Ascochyta blight pathogen in chickpea

Ascochyta blight (AB) caused by Ascochyta rabiei, is globally the most important foliar disease that limits the productivity of chickpea (Cicer arietinum L.). An intraspecific linkage map of cultivated chickpea was constructed using an F₂ population derived from a cross between an AB susceptible parent ICC 4991 (Pb 7) and an AB resistant parent ICCV 04516. The resultant map consisted of 82 simple sequence repeat (SSR) markers and 2 expressed sequence tag (EST) markers covering 10 linkage groups, spanning a distance of 724.4 cM with an average marker density of 1 marker per 8.6 cM. Three quantitative trait loci (QTLs) were identified that contributed to resistance to an Indian isolate of AB, based on the seedling and adult plant reaction. QTL1 was mapped to LG3 linked to marker TR58 and explained 18.6% of the phenotypic variance (R ²) for AB resistance at the adult plant stage. QTL2 and QTL3 were both mapped to LG4 close to four SSR markers and accounted for 7.7% and 9.3%, respectively, of the total phenotypic variance for AB resistance at seedling stage. The SSR markers which flanked the AB QTLs were validated in a half-sib population derived from the same resistant parent ICCV 04516. Markers TA146 and TR20, linked to QTL2 were shown to be significantly associated with AB resistance at the seedling stage in this half-sib population. The markers linked to these QTLs can be utilized in marker-assisted breeding for AB resistance in chickpea.     

Genetic Variations and Adaptations in Chickpea

A total of 329 chickpea lines, comprising 130 kabiili and 199 desi types, originating from six regions, viz., Indian sub-continent, Middle East, North Africa, America, Europe and USSR, were sown in augmented design. The data recorded on agronomic characters on all entries from each region were evaluated in terms of group (region) means. Among the six regions, greater plant height and lateness in flowering were specific to USSR entries. Group means of USSR accessions, both desi and kabuli, differed significantly from those of Indian varieties for a majority of the characters. These observations indicate that the degree of expression of certain characters could be ascribed to specific areas, which led to area-specific adaptations. Furthermore, type-specific differentiating characters, differing in degree of expression, were observed in desi and kabuli types. For example, high mean values of characters, like branches, pods, grain yield and harvest index, were associated with desi types, and 100-seed weight with kabulis. History of cultivation and selection for specific purpose has been cited as cause for area-specific adaptations and type-specific differentiating characters.     

Current and future strategies in breeding lentil for resistance to biotic and abiotic stresses

Lentil production is limited by lack of moisture and unfavorable temperatures throughout its distribution. Waterlogging and salinity are only locally important. Progress has been made in breeding for tolerance to drought through selection for an appropriate phenology and increased water use efficiency and in breeding for winter hardiness through selection for cold tolerance.The diseases rust, vascular wilt, and Ascochyta blight, caused by Uromyces viciae-fabae, Fusarium oxysporum f. sp. lentis, and Ascochyta fabae f. sp. lentis, respectively, are the key fungal pathogens of lentil. Cultivars with resistance to rust and Ascochyta blight have been released in several countries and resistant sources to vascular wilt are being exploited. Sources of resistance to several other fungal and viral diseases of regional importance are known. In contrast, although the pea leaf weevil (Sitona spp.) and the parasitic weed broomrape (Orobanche spp.), and to a lesser extent the cyst nematode (Heterodera ciceri), are significant yield reducers of lentil, no sources of resistance to these biotic stresses have been found. Directions for future research in lentil on both biotic and abiotic stresses are discussed.     

Faba bean breeding for resistance against biotic stresses: Towards application of marker technology

Summary Faba beans are adversely affected by numerous fungal diseases leading to a steady reduction in the cultivated area in many countries. Major diseases such as Ascochyta blight (Ascochyta fabae), rust (Uromyces viciae-fabae), chocolate spot (Botrytis fabae), downy mildew (Peornospora viciae) and foot rots (Fusarium spp.) are considered to be the major constraints to the crop. Importantly, broomrape (Orobanche crenata), a very aggressive parasitic angiosperm, is the most damaging and widespread enemy along the Mediterranean basin and Northern Africa. Recent mapping studies have allowed the identification of genes and QTLs controlling resistance to some of these diseases. In case of broomrape, 3 QTLs explained more than 70% of the phenotypic variance of the trait. Concerning Ascochyta, two QTLs located in chromosomes 2 and 3 explained 45% of variation. A second population sharing the susceptible parental line also revealed two QTLs, one of them likely sharing chromosomal location and jointly contributing with a similar percentage of the total phenotypic variance. Finally, several RAPD markers linked to a gene determining hypersensitive resistance to race 1 of the rust fungus U. viciae-fabae have also been reported. The aim of this paper is to review the state of the art of gene technology for genetic improvement of faba bean against several important biotic stresses. Special emphasis is given on the application of marker technology, and Quantitative Trait Loci (QTL) analysis for Marker-Assisted Selection (MAS) in the species. Finally, the potential use of genomic tools to facilitate breeding in the species is discussed. The combined approach should expedite the future development of lines and cultivars with multiple disease resistance, one of the top priorities in faba bean research programs.     

Identification of segregation-distortion-neutral alleles to improve pollen fertility of indica-japonica hybrids in rice (Oryza sativa L.)

The genetics of resistance to Ascochyta blight (Ascochyta fabae f. sp. fabae) was studied in two populations of faba bean (Vicia faba). Plants of a resistant population, ILB 752, and a susceptible one, NEB 463, were screened for their reaction to the pathogen and the results were quantified on a scale of 0–5. Crosses were made between plants both within and between accessions and the F₁ and F₂ generations assessed in a field trial 21 and 45 days after inoculation. Disease scores were greater at 45 days than at 21 days and they were not significantly affected by the presence of susceptible spreader rows in part of the trial. ILB 752 carried a major dominant gene conferring resistance while NEB 463 carried the recessive allele for susceptibility. Furthermore, a minority of plants of NEB 463 appeared to carry at least one pair of complementary recessive genes, also conferring resistance. Most of the plants of ILB 752 were homozygous for the dominant resistance gene and a few were heterozygous. Reciprocal crosses behaved identically, indicating the absence of maternal effects in the expression of Ascochyta blight resistance in faba beans. The results show that it is important to confirm the level of heterozygosity for the resistance genes in this partially outbreeding species before crossing is commenced. The major dominant gene for resistance, identified in ILB 752, has clear potential for use in breeding for Ascochyta blight resistance. The minor genes identified in NEB 463 also show the potential for accumulating resistance through mass selection. This revised version was published online in July 2006 with corrections to the Cover Date.