| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 2003: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2002: ¥800,000 (Direct Cost: ¥800,000)
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| Research Abstract |
Like some gram-negative plant-pathogenic bacteria, Xanthomonas oryzae pv. oryzae possesses hrp genes, which encode components of the type III secretion system. Several reports suggest that virulence proteins against susceptible rice cultivars and resistance-inducing proteins against resistant rice cultivars and nonhost plants are secreted via the secretion system. Previously we constructed a medium to induce expression of X. oryzae pv. oryzae hrp genes, which are naturally induced only in plants. In this study, we identified three hrp dependent type III secretory proteins using the medium. Two of them, HrpE1 and HrpF, were essential for pathogenicity against susceptible rice cultivars and induction of resistant response in resistant rice cultivars and nonhost plants. The other protein, Hpal, was shown to be involved in aggressiveness of the bacteria to host, plants.
A product of hrpXo is reported to be hrp regulatory protein, and to function as a transactivator for hrp genes and genes whose products are secreted through the type III secretion system. In this study we also showed that HrpXo regulates not only expression of hrp genes and type III secretory protein genes but also that of type II secretory proteins. And we identified one of them as a cystein protease homolog.
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