Genetic management for increased tolerance to aluminium and iron toxicities in rice—A review

Abstract

Several tolerant donors were identified from rice germplasms and significant strides were made in their genetic improvement through conventional breeding during the last 40 years in Indian subcontinent. In majority of the cases the physiological mechanism governing tolerance towards Fe and Al toxicities were unzipped. It is also worth mentioning that progress in breeding largely depends upon the efficiency and effectiveness of the screening technique to identify the true tolerants, availability of the tolerant gene(s) in the germplasms and selection of desirable lines from the segregating population. With increase in Fe-toxicity level, plant height, number of ear bearing tillers, panicle length and grain yield were found decreased in rice; whereas, vegetative growth period got extended with increased spikelet sterility. Toxic concentrations of Al generally inhibit root growth, restrict water intake and nutrients uptake that lead to poor growth and low yield <i style="">per se</i>. <i style="">In vitro</i> screening for developing tolerant genotypes is relatively a straightforward and amply demonstrative method. Toxicity tolerance was also found transferable to a desirable plant type. Further, marker aided selection (MAS) would facilitate reliable selection for abiotic stress tolerant genotypes. Quantitative trait loci (QTL) for toxicity tolerance towards Fe and Al were identified and expected to help in developing tolerant, high yielding varieties through MAS. The present review deals with the possible regulatory mechanisms of Fe and Al tolerance and improvement of rice through identification of the tolerant lines with the help of efficient molecular markers <i style="">en route</i> biotechnological approaches.