Screening of EMS-Induced Drought-Tolerant Sugarcane Mutants Employing Physiological, Molecular and Enzymatic Approaches

Drought stress is one of the major agronomic concerns that lead towards a sharp decline in sugarcane yield. An urgent demand to overcome drought is critical to ensure sugarcane production. Mutation breeding is one of the promising tools available to produce stress-resistant plants, with the induction of new alleles due to point mutation within existing sugarcane germplasm. The current study was directed to chemically mutagenize the calli of two sugarcane cultivars (ROC22 and FN39) via 0.1% EMS, with focus on inducing mutations in their genome. The 1644 regenerated plants of ROC22 and 1398 of FN39 were exposed to 28% PEG-6000 stimulated osmotic stress. Eighteen plants of ROC22 and 2 plants of FN39, that survived after in vitro osmotic stress treatment, were then subjected to preliminary greenhouse pot trials to confirm drought tolerance by analyzing them using various physiological parameters, including photosystem II (PSII) photochemical efficiency (Fv/Fm), leaf chlorophyll content, and photosynthetic rate. The genetic diversity among drought-resistant mutant lines was further assessed by 15 pairs of simple sequence repeat (SSR) markers amplification and CEL (Celery) I endonuclease digestion, to investigate the mutated sites. Mutant lines of ROC22 (i.e., MR22-15 and MR22-20) were found to be promising for future drought resistance breeding, due to better physiological adaptation under drought stress.