ANALYSIS OF BLAST RESISTANCE GENE Pi-ta IN SOME RICE (ORYZA SATIVA L.) CULTIVARS

Abstract

Rice blast disease caused by Pyricularia grisea is one of the most devastating diseases worldwide and deeply reduced the productivity. The resistance to the pathogen is a classical gene system and Pi-ta is one of major resistance genes introgressed trom indica cuitivars, have recently been molecularly characterized. Pi-ta protein is a putative cytoplasmic receptor binded directly to the A VR Pi-ta protein from Pyricularia grisea to initiate a Pi-ta-mediated defense response. The main objective of our study was to investigate the relationship between the presence of Pi-ta gene and the fungal resistance in some indica rice (Oryza sativa L.) cultivars which have been grown in the Central of Vietnam such as HT1, X21, KDI8, TH5, IR38, 4B and 212. The presence and absence of the Pi-ta gene were confirmed by using three specific pairs of primer to the Pi-ta gene (YLI53IYLl54, YLl55IYL87 and YL1001YL102) to amplify the respective DNA fragments by polymerase chain reaction (PCR). PCR products were, then, cloned into the vector pCR2.1 for sequencing. The presence of dominant Pi-ta allele (Pi_tai) will be determined based on the type of amino acid (918) in the leucine rich region of Pi-ta protein. Our results showed that only four of seven investigated rice cultivars (TH5, IR38, 4B and 212) contain Pi-ta gene. The homology between three specific regions of Pi-ta gene (AF207842) and three PCR products is 100%. The analysis also determined the presence of the dominant Pi-to allele with alanine at 918 position in two of four indica rice cultivars containing Pi-ta gene. Thus, the PCR-based Pi-to gene markers could be useful for marker-assisted selection breeding since it is the part of resistance gene, and the technique is simple, rapid and inexpensive. In addition, the analysis can be done with a large numbers of samples