The Blast Resistance Characteristic Of Some Rice Resources And PiK Analysis

Rice is the most important grain crops for human beings, and rice blast is one of the most destructive diseases in rice for its world-wide distribution. It has been proved that breeding and planting disease-resistant cultivars is the mostefficient and environmental-protective means to control this disease. Screening and utilization of blast resistance germplasm resources is an important foundation for rice blast resistance breeding. A batch of high quality resistant source has been obtained in this research after years of field and indoor resistance screening, and these resistant sources of different agronomic traits have utilization value; disease nurseries identification of rice near-isogenic line(nil) materials containing PiK locus genes in multi-location experiment for many years indicated that PiK locus genes showed resistence in all the disease nurseries each year, Pikh and Pikm showed high and stableresistence especially, and the perennial disease nurseries identification in Pujiang, Yaan and Yingshan of Sichuan at2011indicated that Pikh and Pikm still performed high resistence, monitoring date of many years indicated that the resistence of PiK locus genes still exist in Sichuan, and these genes still has utilization value; Combination of genetic sequencing and protein sequence alignment the distribution of PiK locus genes in resistant resources were identificated and analysised, so as to more rational utilization of these germplasm resources,as well as providing basis for the distribution of rice varieties. Results obtained are as follows:1Resistance performance of5rice nils materials containing PiK genes (PiK, PiKs, PiKh, PiKm, PiKp) in Pujiang, Baoxing and Yingshan disease nurseries of Sichuan at2011were as follows:All5materials presented susceptibility in Pujiang, and among them, IR25(Pikm)presented the lowest incidence of the leaves, up to6.67%; IR25(Pikm) performed no resistance in Baoxing and Yingshan;IR4(Piks) performed susceptible in all the three disease nurseries, especially in pujiang the incidence of disease reached73.66%. IR8(Pikh)、IR25(Pikm) presented relatively low incidence of the leaves and disease index in all the three disease nurseries. In a word, Pikh、Pikm perform resistance or low susceptible, it suggests that cultivars and resistant source containing these genes still has improvement and utilization value.2. Many blast resistant resources perennial screened and preserved in two institutes (Plant Protection Institute and Rice Research institute) of Sichuan Academy of Agricultural Sciences and Sichuan Agricultural University were repetitive identified and their agronomic traits were observed in Pujiang in2009-2010. The susceptible materials were eliminated and the materials with the same agronomic traits were incorporated, finally32resistant materials were obtained, and then seedlings inoculation identification for them were done in the fall of2010. These data indicate that most of the32materials showed high resistance and broad-spectrum resistance, they also had some excellent agronomic traits, suggesting their research, utilization and transformation value, which meant that they could be used according to the different breeding objectives.3. Amplification products with total length about12.1kb were obtained with PiK gene loci primer in16varieties from the32resistant materials, and the sequence similarity between amplification products and reference sequence were all above98%, it could be deduced that PiK genes do exist in these resistant materials. According to the incidence of rice nils materials containing PiK locus gene in Sichuan province, we could deduce that these materials probably contain Pikh or Pikm. Translating the obtained full length sequences into amino acid sequence, then using the biology software MEGA5.0to build amino acid sequences homologous, results showed that the sequence similarity of amino acid of R1, R3and the reference sequence (PiKm) were99.9%, while R12, R14, R24and R32were up to100%. Therefore, it could be deduced that R1, R3, R12, R14, R24and R32probably contain Pikh or Pikm. Further research is required to find out that except PiK gene if there are any other genes playing role in their resistance to rice blast.4Through the full-length sequences comparison, there were differences between all the obtained mologous sequences and reference sequence, except R24, nucleotide polymorphism relative concentration in6000～7000bp, Through the comparison and cluster analysis, the majority of nucleotide polymorphisms were associated with the Pikm-1gene, while Pikm-2amino acid sequence were highly conservative. 5LTH is a highly susceptible cultivar to rice blast, its amplification products were obtained with PiK gene loci primer(PiKm, AB462256), and the sequence similarity to the reference sequence was98.57%, the DNA sequence was translated into two amino acid sequence LTH-1and LTH-2, and the sequence similarity to the corresponding amino acid reference sequence PiKm-1and PiKm-2were94.68%and100%respectively. Eventhough LTH contained this gene locus but showed no resisitence. Amino acid sequences alignment results showed that there were4amino acids changes in LTH-1when compared to the known PiK amino acid sequence, and the changes were at sites6,191,221and288. It is probable that the4amino acids differences is the reason why LTH showed no resistance to rice blast.