稻瘟菌侵染诱导水稻凝集素基因的表达

利用mRNA差异显示技术（DDRT-PCR），从非亲和性稻瘟菌生理小种131侵染的水稻品种爱知旭（Oryza sati-vaL.cv.Aichi-asahi)叶片中分离了8个诱导差异表达的cDNA片段，对这8个差示片段进行了回收，重扩增和克隆，以其中一个长度为321碱基并与甘露糖结合水稻凝集素和水稻盐诱导蛋白基因高度同源的差示片段为探针。筛选水稻非亲和性cDNA文库，获得12个阳性克隆。序列测定和数据库查询表明该基因的cDNA与水稻凝集素基因的cDNA及盐诱导蛋白基因的cDNA核苷酸同源笥高达96%。推定的氨基酸序列与甘露糖结合水稻凝集素的氨基酸序列一致。与水稻盐诱导蛋白仅相差2个氨基酸。Southern杂交显示该基因在水稻基因组中有两个同源拷贝数。Northern杂交表明非亲和性稻瘟菌侵染可强烈诱导该基因表达。因此推则该基因参与了水稻对稻瘟菌侵染的防御反应。

Identification of a Lectin Gene Induced in Rice in Response to Magnaporthe grisea Infection

By mRNA differential display, eight induced cDNAs were obtained from rice leaves infected with an incompatible race 131 of Magnaporthe grisea, and one of these cDNAs was highly similar to salt-induced mannose-binding lectin gene. Using this fragment as a probe, a full length cDNA was isolated from a rice cDNA library, which was constructed using mRNA from the incompatible race-infected leaves. Sequence analysis indicates that the cDNA encodes a protein of 15 kD with 145 amino acids and shares 96% identity at nu-cleotide level with MRL and salT, but is identical to MRL at amino acid level. Genomic Southern blotting shows that there are two mannose-binding lectin genes in rice genome. Northern blotting analysis indicates that the gene was strongly and specifically induced in rice leaves infected with the incompatible race, suggesting that the lectin induction be involved in the defense of rice to M. grisea.