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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.

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Crop wild relatives (CWRs) belonging to the Brassicaceae family possess extensive genetic diversity and have frequently been utilized in the enhancement of cultivated Brassica species. However, their tolerance to glyphosate, a widely used herbicide, has remained unknown. Our study examined the glyphosate response of 20 genotypes from the Brassicaceae family, which included genotypes within the U triangle and their wild relatives. We evaluated their behaviour based on morpho-biochemical responses, specifically focusing on the traits of germination percentage, root length, and survival percentage. By calculating the mean membership function value (MFV) for each genotype’s response to these traits, we classified them into three distinct groups: susceptible, moderately tolerant, and tolerant. Among these genotypes, Brassica rapa (NRCPB rapa 8) demonstrated tolerance to glyphosate, as indicated by their mean MFV value of 0.68. Moderate tolerance to glyphosate was observed in Brassica juncea (Pusa Jaikisan) with a mean MFV of 0.52. Conversely, Diplotaxis catholica, Diplotaxis muralis, and Enarthrocarpus lyratus were susceptible, with mean MFV values of 0.37, 0.35, and 0.34, respectively. These findings revealed varying levels of response to glyphosate among these genotypes, with some displaying significant tolerance. The study provides valuable insights into the herbicide tolerance of Brassica CWRs and emphasizes the potential use of phenotypic and biochemical markers in evaluating herbicide tolerance.

The existing resistance genes against white rust disease are often ineffective due to racial variation of the causal fungal pathogen, Albugo candida. Therefore, new sources of resistance effective against multiple races are needed for durable resistance. Large-scale phenotyping of advanced introgressed (ILs), mutant, and resynthesized (RBJ) lines of Brassica juncea L., under artificial inoculation at cotyledonary and true leaf stages, against thirteen diverse isolates of Albugo candida and simultaneously at the adult plant stage under multi-location field evaluation from 2019–2022, revealed significant differences in white rust reactions. Amongst 194 introgressed lines, three lines, namely ERJ 39, ERJ 12, and ERJ 15, and three lines among 90 resynthesized and 9 mutant lines, including RBJ 18, DRMR 18-36-12, and DRMR 18-37-13, were identified as potential sources of resistance against multiple isolates at all three developmental stages of the plant. Furthermore, correlation and principal component analysis revealed a positive correlation between white rust resistance at true leaf and adult plant stages for ILs as well as mutant and RBJ lines. These novel sources of host resistance will play vital roles are required for the mustard improvement program and to establish a strong genetic and molecular foundation for identifying white rust resistance linked marker(s), QTLs, or gene(s) for sustainable disease management in India.