Transcriptomic Analysis Suggests Shoots and Roots-Specific Antioxidant Responses to Early-/Long-Term Salt Stress in...

Area of Science:

• Plant Biology
• Molecular Biology
• Genetics

Background:

• Salinity stress significantly limits rapeseed (Brassica napus) growth and yield.
• The molecular basis of rapeseed's salt tolerance, particularly differential responses between shoots and roots, is not well understood.
• Understanding these mechanisms is crucial for developing salt-tolerant varieties.

Purpose of the Study:

• To investigate the differential molecular responses of rapeseed shoots and roots to early- and long-term salt stress.
• To elucidate the regulatory mechanisms governing ion homeostasis and oxidative defense under salinity.
• To identify key genes and pathways involved in salt tolerance for breeding applications.

Main Methods:

• Comparative analysis of physiological parameters (Na+/K+ ratio, enzyme activities, MDA content) in shoots and roots.
• Transcriptome sequencing and analysis (PCA, WGCNA) to identify differentially expressed genes (DEGs) and co-expression networks.
• Identification of tissue- and time-specific gene expression patterns under salt stress.

Main Results:

• Salt stress altered Na+/K+ ratios and antioxidant enzyme activities (SOD, POD, CAT) differently in shoots and roots.
• Transcriptome analysis revealed distinct early- and long-term salt stress responses, with specific genes like SOD2, UGT72E1, CAT2, and RBOHC showing tissue-specific regulation.
• Phenylpropanoid biosynthesis genes were generally upregulated, while HCT and CSE showed tissue-specific antioxidant patterns.
• WGCNA identified hub genes (ABI5, MPK6, CAD5, NADK1, LFG2) correlated with early-term root stress responses, involved in hormone signaling and redox homeostasis.
• Specific PER genes were induced at different time points and in different tissues.

Conclusions:

• Rapeseed exhibits complex, spatiotemporal responses to salt stress involving distinct ion homeostasis and oxidative defense strategies in shoots and roots.
• Key genes and pathways, including those in phenylpropanoid biosynthesis and antioxidant defense, have been identified as critical for salt tolerance.
• The findings provide valuable genetic resources and targets for breeding salt-tolerant rapeseed varieties.