Identification and characterization of some PR-proteins induced by kitazin and Rhizoctonia solani causing sheath...

Significant reduction (68.38%) in sheath blight disease of rice was noticed when foliar spray of a systemic fungicide, kitazin (480 micrograms mg-1), was applied twice at an interval of 2 days before inoculation. SDS-PAGE analysis of proteins of Rhizoctonia-infected rice leaf sheaths revealed the presence of 16 proteins ranging from 20 to 90 kDa (approx.). Six were identified as constitutive defense proteins (increased after infection), 6 as secondary defense proteins (formed de novo) and the rest 4 appeared non-defense proteins. Non-inoculated kitazin-treated leaf sheaths showed 15 proteins of which 5 were constitutive and 4 secondary defense proteins (both are PR-proteins). Among the PR-proteins, five beta-1,3-glucanases and one chitinase was identified and characterized. One rice chitinase (MW 20 kDa) and 2 glucanases (60 & 69 kDa) showed serological relationships with tobacco chitinase (32 kDa) and tobacco glucanase (33 kDa) respectively. The implications of results have been discussed in relation to biotic and abiotic induction of PR-proteins in rice.