QTL Mining for Sheath Blight Resistance Using the Backcross Selected Introgression Lines for Grain Quality in Rice

Abstract

QTLs for disease scale (DS), relative lesion height (RH) and plant height (PH) were mapped using the four introgression lines selected against grain quality from the four introgression populations between two elite varieties, IR64 and Teqing as recurrent parents and two tall varieties, Tarom Molaii and Binam with high grain quality and sheath blight resistance (SBR) as donors. DS had high significant positive correlation with RH, and both of them were significantly negatively correlated with PH. DS, RH and PH presented wide segregations even in the relative small (28–60) introgression populations, including some semidwarf plants segregated with overparent SBR. Ten, eight, eight, and six QTLs for the three traits were identified in IR64/Tarom Molaii, Teqing/Tarom molaii, IR64/Binam and Teqing/Binam, respectively by one way ANOVA analysis. The two donor alleles at most QTLs reduced DS and RH as well as increased PH. No any a common QTL for each of the three traits was detected in the populations of the same donor in the two different backgrounds, indicating there was a obvious genetic background effect on expression of SBRand PH-QTLs. QTLs linked to the same marker loci between PH and DS, and PH and RH accounted for 38% and 52% of total QTLs for the two traits, respectively, indicating SBR had tight relationship with PH and both of them shared some linked loci. As compared with the previous QTL mapping results of grain quality in the same populations, most QTLs for grain quality and SBR distributed in different chromosome regions and independently inherited. Efficiency, influencing factors and its application in breeding of QTL mapping for non-target traits using introgression lines selected against the target trait were