Construction and evaluation of near-isogenic lines for major QTLs of basal root thickness and 1000-grain-weight in lowland and upland rice

The development of near-isogenic lines (NILs) is one of the important foundations for the establishment of molecular linkage map, the mapping of quantitative trait locus(QTL) and molecular marker-assisted selection (MAS). In the present study, NILs for two major QTLs of basal root thickness(BRT) and 1000-grain-weight(TGW) were obtained through the foreground selection for the target QTL, the background selection for the genome of the recurrent parents of 3 backcross populations( BC1F1, BC2F1 and BC3F1) and phenotypic selection for the population of BC3F2. There were 9 BRT QTL-NILs with BRT ranges of 1.07~1.16 mm, over the recurrent parent by 6.11%~15.18% and an average recovering ratio of genetic background (RRGB)of 97.22%; eleven NILs of TGW QTL with ranges of 21.25～26.25 g, over the recurrent parent by 7.05%～32.16% and 95.97% of RRGB.