Transcriptional reprogramming and enhanced photosynthesis drive inducible salt tolerance in sugarcane mutant line M4209

• Published in: Journal of experimental botany Vol. 71; no. 19; pp. 6159 - 6173
• Main Authors: Negi, Pooja, Pandey, Manish, Dorn, Kevin M, Nikam, Ashok A, Devarumath, Rachayya M, Srivastava, Ashish K, Suprasanna, Penna
• Format: Journal Article
• Language: English
• Published: England 07-10-2020
• Subjects: Photosynthesis; Plant Leaves; Saccharum - genetics; Salinity; Salt Tolerance - genetics; salt tolerance; redox homeostasis; Photosynthesis efficiency; transcriptional reprogramming; sugarcane
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/eraa339

Sugarcane (Saccharum officinarum) is a globally cultivated cash crop whose yield is negatively affected by soil salinity. In this study, we investigated the molecular basis of inducible salt tolerance in M4209, a sugarcane mutant line generated through radiation-induced mutagenesis. Under salt-contaminated field conditions, M4209 exhibited 32% higher cane yield as compared with its salt-sensitive parent, Co86032. In pot experiments, post-sprouting phenotyping indicated that M4209 had significantly greater leaf biomass compared with Co86032 under treatment with 50 mM and 200 mM NaCl. This was concomitant with M4209 having 1.9-fold and 1.6-fold higher K+/Na+ ratios, and 4-fold and 40-fold higher glutathione reductase activities in 50 mM and 200 mM NaCl, respectively, which suggested that it had better ionic and redox homeostasis than Co86032. Transcriptome profiling using RNA-seq indicated an extensive reprograming of stress-responsive modules associated with photosynthesis, transmembrane transport, and metabolic processes in M4209 under 50 mM NaCl stress. Using ranking analysis, we identified Phenylalanine Ammonia Lyase (PAL), Acyl-Transferase Like (ATL), and Salt-Activated Transcriptional Activator (SATA) as the genes most associated with salt tolerance in M4209. M4209 also exhibited photosynthetic rates that were 3-4-fold higher than those of Co86032 under NaCl stress conditions. Our results highlight the significance of transcriptional reprogramming coupled with improved photosynthetic efficiency in determining salt tolerance in sugarcane.