Junichi Kashiwagi

Genetic variability of drought-avoidance root traits in the mini-core germplasm collection of chickpea (Cicer arietinum L.).

Extensive and deep root systems have been recognized as one of the most important traits for improving chickpea (Cicer arietinum L.) productivity under progressively receding soil moisture conditions. However, available information on the range of variation for root traits is still limited. Genetic variability for the root traits was investigated using a cylinder culture system during two consecutive growth seasons in the mini-core germplasm collection of ICRISAT plus several wild relatives of chickpea. The largest genetic variability was observed at 35 days after sowing for root length density (RLD) (heritability, h2 = 0.51 and 0.54) across seasons, and followed by the ratio of plant dry weight to root length density with h2 of 0.37 and 0.50 for first and second season, respectively. The root growth of chickpea wild relatives was relatively poor compared to C. arietinum, except in case of C. reticulatum. An outstanding genotype, ICC 8261, which had the largest RLD and one of the deepest root system, was identified in chickpea mini-core germplasm collection. The accession ICC 4958 which was previously characterized as a source for drought avoidance in chickpea was confirmed as one with the most prolific and deep root system, although many superior accessions were also identified. The chickpea landraces collected from the Mediterranean and the west Asian region showed a significantly larger RLD than those from the south Asian region. In addition, the landraces originating from central Asia (former Soviet Union), characterized by arid agro-climatic conditions, also showed relatively larger RLD. As these regions are under-represented in the chickpea collection, they might be interesting areas for further germplasm exploration to identify new landraces with large RLD. The information on the genetic variability of chickpea root traits provides valuable baseline knowledge for further progress on the selection and breeding for drought avoidance root traits in chickpea.

Improving drought-avoidance root traits in chickpea (Cicer arietinum L.) - current status of research at ICRISAT

Abstract Chickpea (Cicer arietinum L.), an important food legume grown in the semi-arid tropical and Mediterranean regions, suffers substantial yield loss due to drought at the end of the growing season (terminal drought), as the crop is largely grown rainfed in post-rainy season on progressively receding soil moisture conditions. Root traits have been identified to postpone dehydration (drought avoidance hereafter) under moisture stress. The root length density (RLD) in the relatively shallow soil layers and the maximum root depth (RDp) were found to positively influence the seed yield under terminal drought environments. Considerable progress has been made to improve the methodology for sampling and analysis of roots. Using a PVC cylinder technique, the mini-core collection (n=211) of chickpea germplasm was evaluated for a number of root traits, including root biomass, RLD and RDp. A few germplasm accessions were identified to have a more prolific root system than the previously identified germplasm line ICC 4958, the best-known source of high root biomass. The germplasm accession ICC 8261 was identified to have the best combination of both RLD and RDp. Molecular markers have been identified for one major quantitative trait locus (QTL) that accounts for about one-third of the variation in root biomass (as measured by total root dry matter) and RDp from study of recombinant inbred lines (RILs) derived from a cross between ICC 4958 and Annigeri. New RIL populations, developed from two other crosses (ICC 8261 × ICC 283 and ICC 4958 × ICC 1882) involving parents having larger variation for root traits than between Annigeri and ICC 4958, are being studied to identify additional QTLs for root traits. Marker-assisted breeding for improvement of root traits in chickpea is expected to promote the development of varieties with greater drought avoidance.

Chickpea Individual and consensus genetic maps for ICC 283 x ICC 826, ICC 4958 x ICC 1882

Analysis of phenotypic data for 20 drought tolerance traits in 1–7 seasons at 1–5 locations together with genetic mapping data for two mapping populations provided 9 QTL clusters of which one present on CaLG04 has a high potential to enhance drought tolerance in chickpea improvement. CMap Visualization Links: ICC 283 x ICC 8261 ICC 4958 x ICC 1882 Consensus map