Coping with the Canadian extremes, breeding for freezing and heat tolerance in chickpea – with Bunyamin Tar’an

Developing freezing and heat-resilient cultivars is essential for sustainable chickpea production in Canada. We explored the wild progenitor of chickpea, Cicer reticulatum, which can survive under suboptimal conditions as potential source for tolerance to freezing and heat stress in chickpea. Transcriptome analyses of C. reticulatum accession (Kesen_075) and cultivar CDC Consul subjected to freezing stress revealed that the expression of CBF pathway-related genes play a critical role to alleviate the damage caused by freezing stress in Kesen_075.  Bulk DNA sequencing of an F₂ population derived from a cross between CDC Consul and Kesen_075 identified genomic regions associated with tolerance to freezing stress on chromosomes Ca3, Ca4, Ca6, Ca7, Ca8. A total of 58 DEGs in Kesen_075 were located within these QTLs.  We evaluated 200 inbred lines derived from crossing of elite kabulicultivar and accessions of wild Cicer reticulatum for tolerance to heat stress using controlled heatwave simulations during flowering (35°C/29°C). Selected tolerant and sensitive lines were further tested under more severe conditions (40°C/25°C). Seed production stability was influenced by both the developmental stage exposed to heat stress and the nighttime recovery temperatures. Heat-tolerant lines maintained their productivity, while cultivated checks and sensitive lines experienced major yield losses. Most flower loss (~90%) occurred after pollination, with the sensitive line exhibiting poor pollen viability and structural defects. Analyses of photosynthetic efficiency, pigment levels, osmoprotectants, membrane stability, and antioxidants revealed distinct heat mitigation strategies among tolerant lines. Genome-wide association analyses revealed regions on chromosome 4 significantly associated with seed yield-related traits under heat stress. These works provide wide-ranging information that helps in understanding the mechanism of chickpea response to freezing and heat stress and provides potential candidate genes to target in the breeding program to develop freezing-and heat stress tolerant varieties.

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