Physiological and molecular mechanisms of flooding tolerance in plants

Abstract

Flooding is a crucial factor affecting crop growth and yield in low-lying rainfed areas. Systematic investigation of fl ooding survival mechanisms in tolerant species has deciphered molecular, physiological, and developmental basis of soil fl ooding (waterlogging) and submergence survival. Flood escape and quiescence strategies of deepwater and submergence- tolerant rice (Oryza sativa) plants are regulated by ethylene-responsive factor (ERF) transcriptional activators. Ethylene induces genes of enzymes associated with aerenchyma formation, glycolysis, and fermentation pathway. Nonsymbiotic hemoglobin (NSHb) and nitric oxide (NO) have also been suggested as an alternative to fermentation to maintain lower redox potential (low NADH/NAD ratio). In rice (Oryza sativa L.), a calcineurin B-like interacting binding kinase (CIPK; OsCIPK15) is also involved in hypoxia tolerance. Detailed investigation revealed that ERFs are targets of a highly conserved O 2 -sensing protein turnover mechanism in Arabidopsis thaliana. Transcriptome and metabolome profi ling of waterlogging- tolerant plant species reveals survival strategies that may be utilized through crop molecular breeding to develop tolerant cultivars.