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The global expansion of rapeseed seed quality has been focused on maintaining glucosinolate (GSL) and erucic acid (EA) contents. However, the influence of seed GSL and EA contents on the germination process under drought stress remains poorly understood. Herein, 114 rapeseed accessions were divided into four groups based on GSL and EA contents to investigate their performance during seed imbibition under drought stress. Our results revealed significant variations in seed germination-related traits, particularly with higher GSL and EA, which exhibited higher germination % (G%) and lower mean germination time (MGT) under drought stress conditions. Moreover, osmoregulation, enzymatic system and hormonal regulation were improved in high GSL and high EA (HGHE) versus low GSL and low EA (LGLE) seeds, indicating the essential protective role of GSL and EA during the germination process in response to drought stress. The transcriptional regulation mechanism for coordinating GSL–EA-related pathways in response to drought stress during seed imbibition was found to involve the differential expression of sugar metabolism-, antioxidant-, and hormone-related genes with higher enrichment in HGHE compared to LGLE seeds. GO enrichment analysis showed higher variations in transcription regulator activity and DNA-binding transcription factors, as well as ATP and microtubule motor activity in GSL–EA-related pathways. Furthermore, KEGG analysis identified cellular processes, environmental information processing, and metabolism categories, with varied gene participation between GSL, EA and GSL–EA-related pathways. For further clarification, QY7 (LGLE) seeds were primed with different concentrations of GSL and EA under drought stress conditions. The results showed that 200 μmol/L of GSL and 400 μmol/L of EA significantly improved G%, MGT, and seedling fresh weight, besides regulating stress and fatty acid responsive genes during the seed germination process under drought stress conditions. Conclusively, exogenous application of GSL and EA is considered a promising method for enhancing the drought tolerance of LGLE seeds. Furthermore, the current investigation could provide a theoretical basis of GSL and EA roles and their underlying mechanisms in stress tolerance during the germination process. [ABSTRACT FROM AUTHOR]

Rapeseed is a valuable oil crop due to its high nutritious value and ample oil content. The current study provides a comparative analysis of 24 cultivars to better understand the performance and predict the adaptative mechanisms of drought-tolerant and drought-sensitive cultivars based on germination and morphophysiological traits during the early seedling stage using PEG-6000 simulated drought conditions. JYZ 158 and FY 520 (tolerant cultivars) and YG 2009 and NZ 1838 (sensitive cultivars) were selected to further explore the role of osmolytes and enzymatic activity in improving drought tolerance. This investigation illustrated that drought stress negatively influenced all studied cultivars; however, the degree of influence was different for each cultivar, suggesting their different potential for drought tolerance. Moreover, enzymatic and osmoregulatory mechanisms were highly efficient in tolerant cultivars compared to sensitive cultivars. Additionally, tolerant cultivars showed higher chlorophyll and lower malondialdehyde (MDA) contents versus sensitive cultivars under drought stress conditions. Higher drought tolerance coincided with higher enzymatic activity and osmolyte content. This work showed that JYZ 158 and FY 520 cultivars had higher drought tolerance, and might be a significant germplasm resource for breeding programs developing drought-tolerant rapeseed. [ABSTRACT FROM AUTHOR]