Anaerobic‐Aerobic Swerve in Arsenic‐Stressed Deepwater Rice Genotype Under Submergence

ABSTRACT Global floods in arsenic (As)‐stressed paddy fields affect rice productivity. Future predictions of flood‐related disasters provoke an urge to opt for climate‐smart varieties for a secure supply. Thus, this study is designed to present the mechanisms favoring a traditional variety Mini mansoori (M.M) to withstand the dual stress of As and submergence (Sub). The investigation involved the identification of the key attributes regulating the physio‐biochemical shifts in 3‐ and 7‐day (d) submerged plants. Our results indicated that at 3 days, gas‐film (GF) decrement correlated with reduced photosynthesis and Kreb‐cycle enzymes. This, in turn, stimulated anaerobic enzymes, salicylic acid, and gibberellic acid (SA‐GA) production, which increased glutamate metabolism through GDH enzyme, ultimately enhancing GABA and proline production to cover the energy gap. Proline dehydrogenase enzyme at 3 days monitored the stabilized proline turnover by catabolizing proline into glutamate while releasing reducing equivalents for additional ATP generation. However, at 7 days, further enhancement in GA content led to shoot elongation. The expanded GF and new leaf emergence recovered the photosynthetic machinery, TCA functioning, sugar reserves, and GABA content via proline homeostasis. This proline metabolic balance accentuated As tolerance and Sub resistance, henceforth presenting M.M. var. as climate smart for future crop improvements.