International Society for Plant Anaerobiosis

International Society for Plant Anaerobiosis - flooded Rumex crispus (c) Ole Pedersen


CONFERENCES - International Society for Plant Anaerobiosis (ISPA)


Mechanisms of submergence tolerance in lowland rice


Ismail A1, Septiningsih E1 &  Mackill D1


1) International Rice Research Institute, Philippines


Hydrological conditions in flood-prone rice ecosystems are harsh and unpredictable, leading to low and unstable productivity, as most modern varieties are sensitive to flooding. Major constraints include poor crop establishment, high mortality after complete submergence and low yield in partially or stagnant flooded areas. Prospects for enhancing yields in these lands are becoming evident with the recent progress in genetics and physiology of tolerance. Tolerance of anaerobic conditions during germination is important because of increasing interest in direct seeding. Traits associated with tolerance were studied and major QTLs were identified and are being fine-mapped for gene cloning and for use in breeding. Considerable progress was made in understanding tolerance during vegetative stage after cloning of the Submergence-1A (SUB1A) gene. Submergence induces SUB1A expression by ethylene, which interrupts the elongation escape strategy by limiting ethylene-induced GA-promoted elongation. This conditional induction allows SUB1 to substantially enhance tolerance without changing the original traits of the popular varieties into which it is introduced. Rice accessions with reasonable tolerance of stagnant floods were recently identified and are being studied. An update on current progress will be presented. Traits associated with tolerance of excess water stress offer considerable opportunities for developing resilient rice varieties to cope with current problems and with the progressively worsening conditions credited to climate changes.