Characterizing blast-tolerant transgenic rice constitutively expressing the chitinase of the beta-glucanase gene

摘要

Blast is the most devastating fungal disease of rice in Japan and other rice-growing countries. We reproduced, through Agroibaeterium-mediated transformation, the rice class I chitinase gene, Cht-2 or Cht-3, under the control of the enhanced CaMV 35Spromoter into two elite japonica varieties, Nipponbare and Koshihikari, We also reintroduced the rice 1,3-1,4-beta-glucanase gene, Gnsl. The transgenic rice plants that constitutively expressed either the chitinase gene or the glucanase gene showed a significantly higher resistance against the rice blast pathogen, Magnaporthe grisea race 007.0 and 333. A few small lesions without further expansion appeared on the inoculated leaves of the transgenic rice and the plants continued to grow normally. Especially in the glucanase rice, small brown spots appeared after inoculation. Subcellular localization of each gene product was analyzed. The Cht-2 gene product was found to accumulate intracellularly, whereas the Cht-3 gene product was excreted. The Gnsl gene product was distributed over mesophyll cells, The transgenic rice carrying chitinase genes flowered a week earlier. Also, the glucanase rice was stunted in growth.