INDUCTION OF THAUMATIN-LIKE PROTEINS (TLPS) IN RHIZOCTONIA SOLANI-INFECTED RICE AND CHARACTERIZATION OF 2 NEW CDNA CLONES

Thaumatin-like proteins (TLPs) were shown to be induced in rice plants (cv. IR58) that were infected with the sheath blight fungus, Rhizocto nia solani. Western blot analysis revealed the presence of two TLPs wi th sizes of 25 and 24 kDa which are different from a previously report ed TLP with a size of 15.6 kDa from rice plants infiltrated with the n on-pathogenic bacterium, Pseudomonas syringae pv. syringae. By probing a cDNA expression library prepared from RNA isolated from R. solani-i nfected rice plants with a TLP antibody, several putative TLP cDNA clo nes were isolated and sequenced. The cDNA clones appeared to be derive d from two different genes which shared only 77% sequence identity wit h each other and a lower percentage of sequence identity with the prev iously reported TLP cDNA clone. Southern blot analysis with the two TL P cDNAs revealed different rice genomic DNA fragments. Northern blot a nalysis also confirmed that a 1.1-kb RNA detectable by the TLP cDNA in serts was induced by fungal infection. Thus rice TLPs are encoded by a family of at least three genes which are differentially expressed in responses to bacterial or fungal pathogens.