Abiotic Stress Tolerance in Brassica Species: From Molecular Laboratories to Field Trials

Autophagy is an important degradation pathway that maintains cellular homeostasis in living organisms and plays a key role in plant fitness and immunity. To date, more than 30 autophagy-related genes (ATGs) have been identified in model plants such as Arabidopsis. However, autophagy in Chinese cabbage, the largest cultivated vegetable crop in China, has scarcely been studied. We identified 64 Chinese cabbage autophagy-associated genes, named BrATGs, at the genome-wide level. The majority of the BrATGs were highly conserved over a long evolutionary period, and the expression patterns indicated that BrATGs were most highly expressed in the healing tissues and flowers. Furthermore, BrATGs responded to the stresses of the heavy metal Cd, drought, salt, and low and high temperatures to varying degrees. Among them, BrATG8c/8j was specifically induced in response to drastic temperature changes; BrATG4c was upregulated only in response to drought and salt stress; and BrATG8f/10/VTI12C was highly expressed only in response to Cd stress. This work will advance the understanding of the molecular mechanisms underlying the abiotic stress response in Chinese cabbage. Full article

Screening and breeding elite varieties with rapid germination and uniform seedling emergence under low temperature is an effective strategy to deal with the cold climate occurring under late sowing conditions in the Yangtze River basin. This study focused on the performance of seven functional traits, including percentage of germination, percentage of emergence, mean germination time, mean emergence time, total seedling length, total dry weight, and seedling vigor index of 436 natural rapeseed populations under normal-temperature (25/20 °C) and low-temperature (15/10 °C) conditions. Furthermore, ten genotypes were screened to verify their low-temperature tolerance based on cultivar traits in a pot experiment. The results show that the germination- and emergence-related functional traits of rapeseed genotypes exhibit rich genotypic diversity in response to low-temperature stress; the variation among these traits ranged from 1–25% under normal-temperature and 10–49% under low-temperature conditions. Variation in seed characteristics also affected the capacity for low-temperature tolerance in the process of seed germination and seedling emergence, and could explain 22% of the total variance for low-temperature stress tolerance indices. There existed high correlations between the stress tolerance index of total dry weight (STI_TDW) and thousand-seed weight, and between the stress tolerance index of emergence percentage (STI_PE) and oil content. The contents of erucic acid, glucosinolate, and eicosenoic acid were positively correlated with the stress tolerance index of mean germination time (STI_MGT) and mean emergence time (STI_MET). The D-CRITIC (distance-based intercriteria correlation) weight method was selected in this experiment to calculate each variety’s comprehensive low-temperature stress tolerance index by integrating the standard deviation and distance correlation coefficient of each index. The genotypes with large comprehensive low-temperature stress tolerance index also had higher low-temperature stress tolerance index of biomass and yield in the pot experiment, indicating that the comprehensive low-temperature stress tolerance index has high reliability and applicability. This study could provide a theoretical basis for the utilization of low-temperature-tolerant germplasm resources, as well as a reference for the cold resistance and yield stability under late- and direct-sowing conditions of rapeseed in the Yangtze River basin and other similar environments around the world. Full article