| Budget Amount *help |
¥16,100,000 (Direct Cost: ¥16,100,000)
Fiscal Year 2001: ¥7,200,000 (Direct Cost: ¥7,200,000)
Fiscal Year 2000: ¥8,900,000 (Direct Cost: ¥8,900,000)
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| Research Abstract |
The mannose-binding rice lectin (MRL) is induced by some stresses of drought, disease and wound. MRL has a potential activity to agglutinate spores and protoplasts of Magnaporthe girisea and also intact cells of Xanthomonas oryzae, and also accumulated around the infection sites. MRL is composed of some isolectins ; 2 major ones have pi 4.85 and 4.74, the minor pi 4.66, 4.56, and 4.44, whereas all ones have about MW 15,000 as a single peptide. We have already isolated and identified the major one corresponding to pI4.85, named MRL4.85. Analysis of the MRL4.85 gene and the genome structures suggested that (1) MRL4.85 is almost identical to salt and drought stress-inducible salT gene products in rice plant, (2) MRL4 85 gene is transcribed to at least 5 mRNAs by alternative splicing ; one lacks 8 amino acid residues without flame | shift and the other differ in the length of 3'-UTR, (3) the 5'-UTR regulating the transcripts of MRL4.85 differs in length and lack the part of sequence contai
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ned in one of the salT gene. Further, screening of BAG library and the data of the rice genome project suggested that MRL4.85 gene is located at the first chromosome in rice plant and the similar sequence corresponding to an isolectin exists at about 130kb upstream of MRL4.85.
To verify our hypotheses that MRL may function as plant antibodies or receptors in host-parasite interaction, we have tried to obtain the transformants of rice plant to express excessively or suppressively the MRL4.85 product, using the binary vector pC1304E with CaMV 35S promoter in which the positive or negative strands are integrated. And some ten transformants are obtained at callus level.
Con A-binding glycoproteinis secreted from germinating conidia of M. grisea, which potentially interact with MRL and have activity to promote appressorium formation and growth of infection hyphae in planta, are purified by Con A affinity chromatography and HPLC. The major glycoprotein is MW 28k and modified by sugar chains at many AA residues, provably not by N-glycosylation but by O-glycosylation. Less
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