Improving The Resistance To Brown Plant Hopper Of A Rice Restorer Line Chenghui727 By Molecular-assisted Selection

Brown planthopper is the most serious pest of rice (Nilaparvata lugens Stal) in rice-producing areas. The restorer line Chenghui727 has become a widely cultivated in hybrid rice production and the released hybrids in which Chenghui 727 was used as the male parent are actually susceptible to BPH. In this study, molecular assisted-selection designated MAS for introgression of two genes, Bph14 and Bph15, from B5 was carried on to improve the PBH resistance of Chenghui 727 and its derived hybrids. RICE6K, a whole-genome single nucleotide polymosphism (SNP) array, was used to analyze the genetic background of the newly developed breeding lines. A number of identified high-quality markers,640 out of 5102, showed polymosphism between recurrent parent, Chenghui727, and the donor parent, B5. The main results are as follows:1. Five breeding restorer lines (designed as HWQ13001-40-1, HWQ13002-16-1, HWQ13003-4-1, HWQ13004-37-1 and HWQ13005-55-2) harboring two R-genes, Bph14 and Bph15 was selected by MAS, gene pyramiding and backcross.2. Four breedings, viz. HWQ13001-40-1, HWQ13002-16-1, HWQ 13003-4-1, and HWQ 13005-55-2 showed similarities of genetic background to recurrent parent Chenghui727 by percentage means of 85.63,89.22,77.34 and 83.67, correspondingly. Further selfcrossings are needed to increase the recovery of RP background since several fragments in each line were still heterozygous.3. The results of evaluating blast resistance under natural condition in the blast epidemic area at Wuhan showed that the leaf blast score and panicle blast incidence of five breeding lines and their derived hybrids were lower than the recipient line Chenghui727.4. The results of evaluating brown planthopper showed that all five breeding lines and their derived hybrids were highly resistant to brown planthopper.5. The evaluation results of agronomic traits and grain quality of three breeding lines, viz. HWQ 13001-40-1, HWQ13002-16-1 and HWQ13003-4-1, were similar to Chenghui727.6. The results of yield evaluation of combinations in which HWQ13001-40-1, HWQ13002-16-1 and HWQ 13003-4-1 were used as male parents, non-significant difference was obtained compared with Check variety, Fengliangyou No.4.