Indexing Resilience to Heat and Drought Stress in the Wild Relatives of Rapeseed-Mustard

SIMPLE SUMMARY: Wild species are weedy relatives and ancestors of domesticated crops that store economically important traits. Due to their natural tolerance to many biotic and abiotic stresses, they are widely used in plant breeding and crop improvement programs. Using a source of tolerance from crop wild relatives (CWRs), and introgressing the genetic factors into elite cultivars may improve resilience in modern crop cultivars. However, the lack of best practices and opportunities to systematically assess CWRs limits their use in crop improvement programs. The current study was conducted with Brassica’s wild and U-triangle species, which varied in their potential to withstand heat and drought stress, in an attempt to identify genotypes with a high degree of tolerance to abiotic stresses. Screening was performed at the germination and early seedling stages, for which morphological data and biochemical analyses were conducted. ABSTRACT: Wild species are weedy relatives and progenitors of cultivated crops, usually maintained in their centres of origin. They are rich sources of diversity as they possess many agriculturally important traits. In this study, we analysed 25 wild species and 5 U triangle species of Brassica for their potential tolerance against heat and drought stress during germination and in order to examine the early seedling stage. We identified the germplasms based on the mean membership function value (MFV), which was calculated from the tolerance index of shoot length, root length, and biochemical analysis. The study revealed that B. napus (GSC-6) could withstand high temperatures and drought. Other genotypes that were tolerant to the impact of heat stress were B. tournefortii (RBT 2002), D. gomez-campoi, B. tournefortii (Rawa), L. sativum, and B. carinata (PC-6). C. sativa resisted drought but did not perform well when subjected to high temperatures. Tolerance to drought was observed in B. fruticulosa (Spain), B. tournefortii (RBT 2003), C. bursa-pastoris (late), D. muralis, C. abyssinica (EC694145), C. abyssinica (EC400058) and B. juncea (Pusa Jaikisan). This investigation contributes to germplasm characterization and the identification of the potential source of abiotic stress tolerance in the Brassica breeding programme. These identified genotypes can be potential sources for transferring the gene(s)/genomic regions that determine tolerance to the elite cultivars.