Development and Utilization of Genetic Diversity Based Ethiopian Chickpea (Cicer arietinum L.) Germplasm Core Collection for Association Mapping

Abstract

Chickpea (Cicer arietinum L) is one of the most important cool season grain legume crops grown in semi- arid tropics and Mediterranean regions. Terminal drought stress is one of the limiting factors for chickpea production. Utilizing of germplasm collections are the main gateway to improve the stagnant production of chickpea in semi arid tropics. Hence, the objectives of this study were to i) Preliminary phenotyping and genotyping of germplasms collections for diversity assessment; ii) Development of chickpea core collection based on diversity analysis; iii) Identification of desirable accessions for drought tolerance from core set by proper phenotyping; iv) Large scale genotyping of the core collections by SNP markers; v) Large scale genotyping of the core collections by SNP markers; vi) Identification and establishing marker trait associations using appropriate association genetic approaches; vii) Quantification of population structure and relationship of Ethiopian chickpea collection. The phenotypic evaluation in contrasting environment and SNP marker data analysis revealed that there is significant phenotypic and genotypic variability in Ethiopian chickpea germplasm for drought tolerance and other agronomic traits. The population structure and relationship analysis also revealed strong subpopulation fixation and differentiation which was significantly different from the original population. High allelic and gene diversity were observed in the entire collection with common and rare alleles. Trait marker association analysis showed markers which are strongly associated with maturity related traits and high linkage disequilibrium observed for the polymorphic markers. Core collection for Ethiopian chickpea germplasm were developed and validated for different validation parameters such as percent mean difference (MD %), percent variance difference (VD %), analysis of variance, coincidence rate of range (CR %), variable rate of coefficient of variance (VR %) and genetic diversity index. The result of validation showed better correspondence between the core set and the entire set which had avoided germplasm duplication and representing the whole collection economically in time and money with few numbers of accessions. Drought tolerant accessions were also identified in the preliminary field screening which needs further confirmation