Rice Genetics IV - IRRI books - International Rice Research Institute

K1 (Kiyosawa 1984) obtained Pi-ta from different sources. While Pi-ta in variety K1was introgressed from the indica variety Tadukan, the origin of Pi-ta in Yashiro-mochiappears to be an upland variety, Okaine (Rybka et al 1997). The DNA sequences ofthe genes cloned from Tadukan and K1 are identical to those of Pi-ta from Yashiromochi.In contrast, the Yashiro-mochi Pi-ta coding sequence differs by seven nucleotidesfrom the sequence present in the sensitive japonica varieties Tsuyuake,Nipponbare, and Sariceltik. The seven base pair differences in the coding region resultin five amino acid differences between the two proteins (Table 1). The amino acidsequence encoded by the susceptible indica C101A51 allele differs from the resistantprotein in only one of these five amino acid differences, serine at residue 918. Thus,direct comparison of DNA sequence for Pi-ta homologues from resistant and sensi-AN –Ala1 208 527 586 918– C928NBSLRDBPreProMatureProtease motif13 aa 34 aa176 aaVILHEMVHIIFig. 1. (A) The predicted 928-amino acid Pi-ta protein. Only the nucleotide-binding site (NBS)-containing region has homology to other R genes. The C-terminal leucine-rich domain (LRD) ofthe Pi-ta protein, with critical residue 918, has been implicated in binding to AVR-Pita. (B)Working hypothesis on the structure of the putative AVR-Pita protease. A gene that encodesthe predicted mature form of the protein was constructed and named AVR-Pita 176 .Table 1. Amino acid sequence differences among Pi-ta proteins from varieties carrying the Pi-taand Pi-ta 2 genes, and varieties with neither of these genes.ResistantAmino acid c positionVariety R gene to AVR-Pitafungus 6 148 158 176 918Yashiro-mochi a Pi-ta Yes I R H D ATetep a Pi-ta 2 Yes I R H D AC101A51 Pi-2 No I R H D STsuyuake b Pi-km No SSQ V SaAdditional Pi-ta-containing variety K1 and additional Pi-ta 2 -containing varieties Tadukan, Reiho, and Katycontain sequences identical to those of Yashiro-mochi and Tetep. b Additional susceptible japonica varietiesNipponbare and Sariceltik contain sequences identical to those of Tsuyuake. c Amino acid abbreviationsare I = isoleucine, R = arginine, H = histidine, D = aspartic acid, A = alanine, Q = glutamine, S =serine, V = valine.312 Valent et al