Breeding for drought and salt tolerant rice (Oryza Sativa L.): Progress and perspectives

Abstract

Water shortage and salinity are the most important factors limiting rice production worldwide. No drought tolerant (DT) or salt tolerance (ST) rice varieties have been commercially released in the past, due largely to the lack of breeding efforts and partially to the complexity of genetics and physiology underlying DT/ST in rice. The real challenge facing plant breeders is how to efficiently develop high yield and DT or ST cultivars for varied stress scenarios of different rice ecosystems. Progress has been recently made in developing DT/ST rice cultivars using the conventional breeding approach at IRRI and hybrid rice cultivars tend to show high yield potential and good levels of water use efficiency or DT. Tremendous QTL mapping efforts in the past decade have identified numerous QTLs affecting DT/ST in rice, but the results have not let to any successful MAS. A new and promising strategy combining BC breeding with designed QTL pyramiding have been practiced at IRRI and in China, in which exploiting useful genetic diversity for DT/ST from the primary gene pool of rice by BC breeding and developing DT/ST introgression lines in elite genetic backgrounds, discovery, allelic mining and characterization of QTL networks for DT/ST, and directed trait improvement by designed QTL pyramiding are well designed and integrated. Many promising DT and ST rice lines have been developed using this strategy, even though the theoretical aspects underlying this strategy remain to be fully established © 2007 Springer.