Salt stress is a major limiting factor that severely affects the survival and growth of crops. It is important to understand the salt tolerance ability of Brassica napus and explore the underlying related genetic resources. We used a high-throughput phenotyping platform to quantify 2,111 image-based traits (i-traits) of a natural population under 3 different salt stress conditions and an intervarietal substitution line (ISL) population under 9 different stress conditions to monitor and evaluate the salt stress tolerance of B. napus over time. We finally identified 928 high-quality i-traits associated with the salt stress tolerance of B. napus. Moreover, we mapped the salt stress-related loci in the natural population via a genome-wide association study (GWAS) and performed a linkage analysis associated with the ISL population, respectively. The results revealed 234 candidate genes associated with salt stress response, and two novel candidate genes, BnCKX5 and BnERF3, were experimentally verified to regulate the salt stress tolerance of B. napus. This study demonstrates the feasibility of using high-throughput phenotyping-based QTL mapping to accurately and comprehensively quantify i-traits associated with B. napus. The mapped loci could be used for genomics-assisted breeding to genetically improve the salt stress tolerance of B. napus.
Deregulation of reduction-oxidation (redox) metabolism under environmental stresses results in enhanced production of intracellular reactive oxygen species (ROS), which ultimately leads to posttranslational modifications (PTMs) in structure and molecular function of responsive proteins. Redox PTMs are important mediators of cellular signalling and regulation and several proteomic approaches attempted to quantify them under various stresses in plants. We aimed to generate large-scale redox proteomics data in response to short-term salt stress in Brassica napus by analyzing reversible cysteine modification. We employed iodoTMT approach to analyze the redox proteome of Brassica napus seedlings under control and salt stress conditions. We identified 2,010 peptides in 1,017 proteins, of which 1,821 sites in 912 proteins had oxidative modification. The redox homeostasis of biology processes in chloroplast and cytoplasm were mainly affected and the modification levels of proteins involved in photosynthesis and glycolysis pathways were significantly changed. Two oxidatively modified proteins were selected from the candidates and their in vitro activity under oxidative stress was assayed and validated the findings of this proteomics study. This targeted approach should contribute to the understanding of redox-based molecular changes prevailing in Brassica napus proteome subjected to salt stress and the mechanism adopted to cope with it.