Poster: Plant Pathogen/Symbiont Interactions

Abs # 704: Broad spectrum disease resistance of rice (Oryza sativa L.) by Brassicaceae defensin gene.

Presenter:	Kawata, Motoshige , kawata@affrc.go.jp
Authors	Kawata, Motoshige  (A) (B)  Toshihiko, Nakajima  (A)   Koichi, Mori  (A)   Shigeru, Kuroda  (A)
Affiliations:	(A): National Agricultural Research Center (B): Graduate School of Natural Science and Technology, Niigata University

Antimicrobial peptides from a variety of organisms are known to inhibit the growth of pathogens. Plant defensin is one of the pathogenesis-related proteins. They have antimicrobial properties and are characteristics to small, basic, and cysteine rich. In order to develop transgenic rice plants with broad spectrum rice disease resistance, we have focused on the defensin gene family in Brassicaceae. We have cloned defensin genes from eight vegetables of Brassicaceae, and have estimated the structural difference between them. Four types of defensin genes, that is, from B. oleracea, B. campestris, and modified genes by making substitution of one amino acid on each original ones, were prepared for introduction into rice japonica cultivar Dontokoi. Transgenic rice plants that expressed one of these defensin genes constitutively throughout the plant tissues were tested for disease reaction to Magnaporthe grisea and Xanthomonas oryzae at first. 43 of over 1200 transgenic plants with highly enhanced resistance to M. grisea and X. oryzae were successfully obtained. For further analysis, representative lines from eight independent transformants were selected and disease reaction tests were carried out, demonstrating that highly enhanced resistance to M. grisea and X. oryzae were stably inherited. Transgenic plants with highly resistance to M. grisea and X. oryzae showed highly resistance to other seed-transmitted phytopathogenic bacteria, Burkholderia plantarii and B. glumae. It was also demonstrated that highly enhanced resistance to each race of rice blast was obtained by introduction of defensin gene. These results indicate that the Brassicaceae defensin effectively works in rice plants against broad spectrum of pathogen attack.