Salt-tolerant broomcorn millet (Panicum miliaceum L.) resists salt stress via modulation of cell wall biosynthesis and Na+ balance

Soil salinization threatens sustainable agricultural production and ecological balance in many parts of the world. Therefore, to breed plants with salt tolerance and discover the resistance genes are essential for enhancing salt tolerance adaptation. We studied phenotypic, physiological characteristics, and digital RNA sequencing of two broomcorn millet cultivars (salt tolerant cultivar, ST 47; salt sensitive cultivar, SS 212), stressed by 1% NaCl (w/w; similar to 170 mM) for 0, 12 hr, 1, 3, 7 days and subsequent re-watering 7 days (RW 7 days). By comparative phenotype and physiology analysis we suggest ST 47 showed greater salt tolerance and faster recovery after re-watering than SS 212, and lower Na+ contents and higher K+/Na+ ratio. Digital RNA sequencing analysis suggested 6,878 and 1,940 differentially expressed genes (DEGs) were detected in ST 47 at 12 hr (vs. 0 hr) and RW 7 days (vs. 0 hr), respectively, whereas 7,246 and 5,375 DEGs were identified in SS 212. DEG functional enrichments suggested ST 47 exhibited better regulation of phenylpropanoid biosynthesis, carbon metabolism, and auxin and gibberellin signal transduction in response to salt stress via enhancing the cell wall biosynthesis. Furthermore, ionic stress signaling analysis proposed ST 47 better regulation of Na+ distribution in response to salt stress. These results provide valuable information for improving salinity tolerance in plants and studying the function of candidate genes governing salt tolerance in broomcorn millet.

Automated summary

The study demonstrated that the salt-tolerant cultivar ST 47 exhibited better salt tolerance and recovery ability under salt stress, with lower Na+ content and higher K+/Na+ ratio. Digital RNA sequencing analysis revealed that ST 47 showed better gene expression regulation in response to salt stress.