Application of HL type male sterile cytoplasm in japonica hybrid rice breeding.

For investigating the feasibility of applying HL type male sterile cytoplasm to japonica hybrid rice breeding,a set of isonuclear alloplasmic cytoplasmic male sterile(CMS) lines(A lines) of Liuqianxin,including four different cytoplasms from Indian Chinsurah BoroⅡ(BT type),Hainan red awned wild rice(HL type),Hunan Chaling wild rice(CL type) and Hainan male sterile wild rice (WA type),and the maintainer line(B line),were used to make testcross F1 with 181 japonica parents including BT type restorer lines(R lines),wide compatible restorer lines(WCR lines),wide compatible varieties(WCVs),Yunnan rice landraces and other japonica varieties/lines.According to the spikelet fertility of testcross F1,japonica R lines for HL type male sterile cytoplasm had been selected.Then,the selected japonica R lines were testcrossed with three HL type CMS lines(including Liuqianxin A,Lingxiang A and Zhen 5A) and used to make japonica hybrid rice combinations.The results showed that the HL type CMS line and CL type CMS line were most similar on restorer-maintainer relationship with a significant correlation between the spikelet fertility of testcross F1 of HL Liuqianxin A and that of CL Liuqianxin A.The HL type and CL type japonica A lines showed worse restored ability than BT type CMS line,but better than WA type japonica CMS line.With the standard that the spikelet fertility of testcross F1 over 85%,25 HL type (CL type) japonica R lines were selected from BT type R lines and WCR lines.The nuclear background of CMS lines affected the fertility of F1.As to the restored ability,HL Liuqianxin A was the best,HL Lingxiang A the second,HL Zhen 5A the worst.The spikelet fertilities of F1s derived from HL type and CL type CMS lines were less stable than that from BT type CMS line.Japonica hybrid rice combinations derived from HL type,BT type,and WA type CMS lines had no significant difference in days from sowing to heading,plant height,yield and rice quality traits.On seed-setting percentage,japonica hybrid rice combinations of HL Lingxiang A/SJR4822-1 and BT Lingxiang A/SJR4822-1 had no significant difference,but HL Zhen 5A/SJR4822-1 was higher than WA Zhen 5A/SJR4822-1.Accordingly,it is feasible to apply HL type male sterile cytoplasm in japonica hybrid rice breeding.