Development Of Japonica Rice Lines And Two-line Hybrid Rice Resistance Against Lepidopteran Rice Pest

Rice, as one of the staple food crops in China, is divided into two kinds of types, indica and japonica. Japonica is mainly planted in the Northeast and North and Northwest of China. It.is suffered damage from stem borers(Chilo suppressalis, Scirpophugu incertulas and Cnaphalocrocis medinalis Guene) as same as indica in southern China. Developing japonica varieties with resistance against stem borer has been one of breeding goals for rice breeders.The objective of this study is to develop japonica breeding lines and japonica two-line hybrids which are resistant against stem borer. TIC-19, a transgenic line with crylC*gene, was used as donor parent and Wuyujing20as a recipient parent. Several new breeding lines with crylC*gene were developed through crossing, backcrossing and phenotypic selection and molecular-marker assisted selection. Then, they were crossed with three japonica PGMS lines for developing japonica two-line hybrids. The main results of this study are as follows:1. Ten japonica breeding lines which have crylC*gene and genetic background of Wuyujing20were developed through crossing, backcrossing and molecular-marker assisted selection between Wuyujing20and T1C-19. The analysis results of PCR and protein expression of crylC*showed that the ten selected breeding lines had same electrophoresis amplified bands and protein expression levels as donor parent (TIC-19).2. The results of investigating leaffroller-resistances under field conditions with not spraying any insectcides showed that the ten selected breeding lines and corresponding combinations were not damaged by leaffroller as same as TIC-19. But Wuyujing20and its combinations were damaged by leaffroller under the same conditions.3. The results of three replication expriments showed that two selected breeding lines which were desiged as LR1009and LR1010in the paper had a same performances as Wuyujing20for main agronomic traits, yield per plant and rice qualities, implying they have similar genetic background of Wuyujing20. One to three characteristics of other selected eight breeding lines were signifcant different with Wuyujing20, impying they could be applicated as new lines in breeding program.4. The results of comprehensiving leaffroller resistance, yield advantage identification and rice quality analysis showed that the japonica two-line hybrid desigened with229S/LR1010will be a promising combination.