| 1. Physiological and genetic analysis of lesion resembling disease mutants (Ird) in Oryza sativa L.Ten indica rice and eight japonica rice mutants with lesion resembling disease(Ird27~44)were obtained by gamma-ray mutagenesis of the whole genomes. These mutants exhibited diverse lesion mimic phenotypes under different growth environments (Fig. 5.1, Table 5.1), could be accordingly classified two types, sensitive and insensitive to environments. Basing on difference in development of lesion mimics, they can be divided into three categories: whole life lesion mimics (WLLM), vegetative initiation lesion mimics (VILM), and reproductive initiation lesion mimics (RILM). Lesion mimics resulted from the programmed cell death and were triggered by light, but not by wounding (Fig.5.2). The genetic analysis showed that four mutants, Ird32, Ird39, Ird40 and Ird42, were controlled by one or two recessive loci (Table 5.2). Among the 18 Ird mutants, Ird37 and Ird40 conferred non-race-specific resistance to Xanthomonas oryzae pv. oryzae (Table 5.3). Gene mapping and cloning ofLrd32 and Lrd40 are under way.2. Disease Resistance and Cytological Analyses of Lesion Resembling DiseaseMutant Ird40 in Oryza sativa L.Lesion resembling disease mutant Ird40, was obtained from gamma-ray mutagenesis a japonica rice variety Zhonghua 11, expresses whole life lesion mimic (WLLM), which is insensitive to environments. The genetic analyses of Ird40, showed that it is controlled by a single recessive locus, and non-isogenic to loci of Ird38, Ird39 and Ird42. Repeated inoculation with Xanthomonas oryzae pv. oryzae (Xoo) showed lrd40 conferred two-race specific resistance to Xoo. The results of inoculation of F2 population verified the resistance to Xoo results from the expressing of Ird40. After dye with Trypan blue and DAB in leaf of Ird40, programmed cell death and deposition of H2O2 was observed during lesion development. All these phenomena resemble the character of defense response in plant such as cell death and oxidative burst caused by hypersensitive response. The gene mapping and analyses of broad-spectrum disease resistance of lrd40 are under way.3. Distribution of rice Rim2 superfamily and development of a simple and sensitive rice fingerprint technique based on Rim2 genomic variationTo modify DNA marker technology or develop a new DNA marker is a hotspot in research of molecular markers. Based these data 230Mb in GenBank, which can act as fingerprint for research of genetics and breeding, the BACs containing Rim2 elements are download all sequenced BACs from website of Rice Genome Project, and distribution pattern of Rim2 elements in chromosomes are draw. It suggested that Rim2 elements of coding and pseudo-gene subgroups interspersed throughout all 12 chromosomes. Although Rim 2 elements distribute uneven way in chromosome and harbor in centromeric regions more than other chromosomal locations. Plentiful Rim2 elements and residing in other locations provides the possibility to us for differentiating rice varieties. Phylogenetic-relationships R963 and identification of hybrid rice are experience for hybrid rice including indica and japonica. Five primer pair detects the distinguishing difference of the R963 breeding materials, which it is possible similarity of genetic background. To evaluate the seed purity of hybrid FI, the polymorphism among F1s, and double parents are assayed using the same primer pair. Results hint that the Rim 2 elements are characteristic with higher efficiency and extensive applicability for diverse genome environments. Compared with convenient markers, we would think that Rim2 approach embodies its distinctive advantages of simplicity and sensitivity. Proposal of marker-assistant breeding or other application of DNA markers basis on Rim 2 elements are put forward to enrich the DNA markers family. |
PDF Full Text Request