Proteomic, biochemical and peptidomics based analysis reveals heat responsive changes in the seedlings of Brassica juncea

Heat stress at seedling stage has a crucial impact on Indian mustard growth and productivity. Identifying heat stress responsive proteins can be crucial to understand the heat stress adaptive mechanisms. In this work, biochemical, proteomic, and peptidomics response of the thermotolerant genotype, BPR 543-2 was investigated in the early seedlings of mustard under heat stress treatment. A total of 403, 328 and 369 number of proteins were identified to be expressed exclusively during 0, 4 and 8 h of heat-stress while 89, 119 and 81 were differentially accumulated during 0–4 h, 4 h-8 h and 0–8 h using LC–MS/MS based analysis. Notably, BPR 543-2 expressed elevated levels of heat shock proteins, chaperones, enzymes involved in the metabolism of carbohydrate and energy, cell wall modifications and transcription factors. In addition, using MALDI-TOF-MS, overexpressed proteins involved in DNA repair, signal transduction and metabolic adaptation were identified during different time point of heat stress. Moreover, biochemical analysis revealed high TAC, TF and less turbulence in photosynthetic pigments in stressed samples. Through combined analysis of biochemical, proteomics and peptidomics approaches, it was observed that BPR 543-2 was more resilient to heat stress and experienced fewer significant metabolic disruptions in stressed samples, demonstrating its adaptability to heat stress at early seedling stage. The proteins with differential abundance were functionally annotated in-silico for their subcellular localization, biological and molecular functions. This work demonstrates the usefulness of proteomics and peptidomics-based approaches by providing fresh insights into the mechanism behind the heat-stress adaption mechanisms in Indian mustard. The identified critical proteins provide intriguing targets for developing stress tolerance in heat-sensitive brassica crops.