Advanced Backcross QTL Analysis for the Whole Plant Growth Duration Salt Tolerance in Rice (Oryza sativa L.)

Abstract

Salinity is a major factor limiting rice yield in coastal areas of Asia. To facilitate breeding salt tolerant rice varieties, the whole-plant growth duration salt tolerance (ST) was genetically dissected by phenotyping two sets of BC2F5 introgression lines (ILs) for four yield traits under severe natural salt stress and non-stress filed conditions using SSR markers and the methods of advanced backcross QTL (AB-QTL) analysis and selective introgression. Many QTLs affecting four yield traits under salt stress and non-stress conditions were identified, most (>90%) of which were clustered in 13 genomic regions of the rice genome and involved in complex epistasis. Most QTLs affecting yield traits were differentially expressed under salt stress and non-stress conditions. Our results suggested that genetics complementarily provides an adequate explanation for the hidden genetic diversity for ST observed in both IL populations. Some promising Huanghuazhan (HHZ) ILs with favorable donor alleles at multiple QTLs and significantly improved yield traits under salt stress and non-stress conditions were identified, providing excellent materials and relevant genetic information for improving rice ST by marker-assisted selection (MAS) or genome selection.