[Marker-assisted selection and pyramiding for three blast resistance genes, Pi-d(t)1, Pi-b, Pi-ta2, in rice].

G46B is a promising holding line used for three-lines breeding strategy in hybrid rice, but it is susceptible to blast disease caused by Pyricularia grisea. To improve its blast resistance, three rice varieties, Digu, BL-1, and Pi-4, with blast resistance genes, Pi-d(t), Pi-b, and Pi-ta2, respectively, were used to be crossed with G46B, and 15 plants with these three blast resistance genes, Pi-d(t)1, Pi-b, and Pi-ta2, were selected from their F2 and B1C1 populations via a marker-aided crossing procedure. Among them, four plants were heterozygotes in the three resistance genes, with the genotype of Pi-d(t)1 pi-d(t)/Pi-b pi-b/ Pi-ta2 pi-ta2; ten plants were heterozygotes in two of the three resistance genes, of which six with the genotype of Pi-d(t)1 Pi-d(t)1/Pi-b pi-b/Pi-ta2 pi-ta2, three with the genotype of Pi-d(t)1 pi-d(t)1/Pi-b pi-b/Pi-ta2 Pi-ta2, and one with the genotype of Pi-d(t)1pi-d(t)1/Pi-b Pi-b/Pi-ta2 pi-ta2; and only one plant was homozygote in two of the three resistance genes with the genotype of Pi-d(t)1 Pi-d(t)/Pi-b pi-b/Pi-ta2 Pi-ta2. These results demonstrate the capacity of maker-assisted selection (MAS) in gene pyramiding for rice blast resistance and its enhancement for the efficiency in rice resistance breeding.

[Study on transgenic elite indica container line D297B containing foreign insect-resistant gene gna].

It was reported in this article that the transgenic elite indica container line D297B containing snowdrop lectin (Galanthus nivalis agglutinin, GNA) gene gna was obtained by biolisties. PCR, Southern blotting and Western blotting indicated that the transgenes were integrated into the genome of D297B and expressed in transgenic plants. Analysis of protein activity showed that product of transgene had activity of agglutinin. Resistance of transgenic seeds to Hygromycin B suggested that the transgenes were integrated in a single locus and inherited according to the pattern of 3:1 in most of transgenic plants. In addition, the PCR analysis revealed that the insect-resistant gene gna and selective marker gene hpt were co-integrated and co-inherited.

[Anther culture generated stem borer-resistance DH lines of Minghui 81(Oryza sativa L. subsp. indica) expressing modified cry1Ac gene].

2600 Anthers from T0 modified cry1 Ac-transgenic rice lines of Minghui 81, an elite restoring line of commercial CMS indica hybrid rice, were cultured on SK3 media. 83 green plantlets were recovered, 43 double haploid (DH) and 40 haploid among them. Results of PCR analyzes indicated that 55 plants of 83 were harbored the cry1Ac gene, and the ratio of cry1Ac-positive against cry1Ac-negative was 2:1 (55/28). 36 putative transgenic DH plants were further confirmed by Southern blot. ELISA detection showed that Cry1Ac level in different transgenic rice plants of the same cry1Ac-DH clone was almost equal and the highest one amount to 0.25% of the total soluble protein. Pest insect-resistant bioassay at field trials demonstrated that some of the homozygous cry1Ac-transgenic rice plants not only showed high-level resistance against striped stem borer (Chilo suppressalis) but also retained elite agronomy characters. These results demonstrated that rice anther culture has a great value in rice molecular breeding.

[Genetic analysis and molecular tagging of a gene for non-palea in rice].

The mutants involved in the development of floral organ are good material for understanding the molecular genetic mechanisms of floral development. A rice mutant, that lacks palea in its florets, was derived from a spontaneous mutation in an indica line, SAR III-93-369. Genetic analyses in three F2 populations from the mutant crossed with three rice varieties, Sheng 47, N625 and CDR22, respectively, showed that the mutant trait is controlled by a single recessive gene. In the F2 population from npa-1/Sheng47 the gene for the non-palea trait was mapped between two restriction fragment length polymorphism markers, C498 and RZ450, with distances of 7.5 cM and 2.4 cM, respectively. The tagged recessive non-palea gene is temporarily designated npa-1.

[Obtaining stem borer-resistant homozygous transgenic lines of Minghui 81 harboring novel cry1Ac gene via particle bombardment].

A modified cry1Ac gene was generated by fusing with Lys-Asp-Glu-Lue (KDEL), an endoplasmic reticulum retention signal at the 3'-ends, with signal peptide coding sequence of Soybean kunitz trypsin inhibitor (SKTI) at the 5'-ends. Vector containing the modified cry1Ac gene coding region flanked by the corn ubiquitin 1 promoter and the nopaline synthase gene (nos) terminator with Hygromycin Phosphotransferase (hpt) gene as a plant selection marker was constructed. The modified cry1Ac gene in which toxic protein targeted to endoplasmic retention was successfully transferred into Minghui 81 (Oryza sativa L. subsp. indica), an elite restoring line of commercial CMS indica hybrid rice, through particle bombardment and obtained fertile transformants. Homozygous transgenic rice lines were obtained in the third generation exploiting self-seed set reproduction and HygromycinB selection. These transgenic lines were confirmed with polymerase chain reaction (PCR) amplification, Southern blotting and ELISA detection. Pest insect-resistant bioassay indicated that some of the homozygous cry1Ac-transgenic rice plants of T2 progeny showed high-level resistance against striped stem borer (Chilo suppressalis) at field trials.