Anaerobic-Aerobic Swerve in Arsenic-Stressed Deepwater Rice Genotype Under Submergence.

Area of Science:

• Agricultural Science
• Plant Physiology
• Environmental Science

Background:

• Global floods in arsenic-stressed paddy fields threaten rice productivity.
• Climate-smart crop varieties are crucial for ensuring food security amidst increasing flood predictions.

Purpose of the Study:

• To elucidate the physio-biochemical mechanisms enabling the traditional rice variety Mini mansoori (M.M.) to tolerate combined arsenic (As) and submergence (Sub) stress.
• To identify key attributes regulating stress responses in M.M. at 3 and 7 days of submergence.

Main Methods:

• Investigated physio-biochemical shifts in Mini mansoori under 3-day and 7-day submergence.
• Analyzed gas-film (GF) levels, photosynthesis, Kreb-cycle enzymes, anaerobic enzymes, salicylic acid (SA), gibberellic acid (GA), glutamate dehydrogenase (GDH), proline, and proline dehydrogenase.

Main Results:

• At 3 days, reduced GF correlated with decreased photosynthesis and Kreb-cycle activity, triggering anaerobic pathways, SA-GA production, and enhanced glutamate metabolism via GDH, boosting GABA and proline for energy.
• Proline dehydrogenase at 3 days stabilized proline turnover, aiding ATP generation.
• At 7 days, increased GA promoted shoot elongation, expanded GF, and new leaf emergence, restoring photosynthesis, TCA function, sugar reserves, and GABA via proline homeostasis, enhancing As tolerance and Sub resistance.

Conclusions:

• Mini mansoori exhibits a climate-smart profile due to its ability to balance proline metabolism under dual As and Sub stress.
• The identified physio-biochemical mechanisms in M.M. offer a basis for developing climate-resilient rice varieties for future crop improvement.