|Budget Amount *help
¥3,400,000 (Direct Cost : ¥3,400,000)
Fiscal Year 1998 : ¥1,800,000 (Direct Cost : ¥1,800,000)
Fiscal Year 1997 : ¥1,600,000 (Direct Cost : ¥1,600,000)
The novel mannose-binding rice lectin (MRL) finally purified by Sephadex G-50 affinity chromatography was not homogeneous, but separated completely in two dimensional polyacrylamide gel electrophoresis ; the major spots were located at pI 4.85 and 4.74, the minor at pI 4.66,4.56, and 4.44, whereas all spots distributed at about MW 45,000. In western blot analysis, all the spots reacted with the monoclonal antibodies specific to MRL.The proteins at pI 4.85,4.77,4.66, and 4.56 recovered from the gel had lectin activity, respectively. The major proteins at pI 4.85 and 4.77 had also common amino acid sequence at N-terminus, TLVKIGPWGGNGGSAQDISV, which is almost identical to salt and drought stress-inducible salT gene products in rice plant. The high homology was also conserved in both of the cDNA and genomic clones of the MRL subunit at pI 4.85. These results suggested that MRL are composed of some isolectins, if not, related proteins to remain a common epitope, and may belong to a superfamily of stress-inducible proteins.
MRL activity was found in all growth parts of seedlings in all cultivars tested, but localized at cell wall and periplasm around mesophyll and epidermal cells. The content of extractive MRL rapidly changed when inoculated with both compatible and incompatible races of M.grisea. Pre-treatment with the monoclonal antibody, a-D-mannose or 0.15M NaCi enhanced the elongation of infection hypha in the compatible rather than in the incompatible. In contrast, pre-treatment with ConA suppressed the appressorium formation and the elongation of infection hypha. Co-treatment with the monoclonal antibody and an inducer to elicit resistant reaction such as saccharin, Probenazole, or mycelial extract suppressed their inducer activity, These results strongly supported our hypotheses that MRI.may function as plant antibodies or receptors in host-parasite interaction..