以加工型黄瓜材料NW99为对象,利用RT-PCR技术克隆黄瓜多聚半乳糖醛酸酶抑制蛋白基因(PGIP),并分析其基因编码序列、组织表达特异性和诱导表达模式.结果表明:(1)从黄瓜中克隆到一个PGIP基因,命名为CsPGIP；CsPGIP基因全长1 026 bp,读码框987 bp,无内含子,编码328个氨基酸残基,具有xxLxLxxNxLt/sGxIPxxLxxLxxL结构域,属于Pgip基因家族.(2)CsPGIP基因与甜瓜PGIP基因同源性最高,与十字花科Pgip基因同源性较高.(3) CsPGIP在黄瓜各个器官都表达,但表达水平具有组织特异性,在嫩叶中表达量最高,在茎中表达量最低；该基因表达明显受到水杨酸诱导,可能在抵御外界病原菌入侵过程中起重要作用.%Polygalacturonase-inhibiting protein (PGIP) can inhibit the activity of pathogen PG and improve the plant resistance level. (DA novel PGIP gene designated as CsPGIP was isolated and characterized in Cucumis sativus L. The cDNA of this gene was 1 026 bp with an open reading frame of 987 bp encoding a 328-animo acid polypeptide. The deduced amino acid sequence of the gene contained the typical domain of xxLxLxxNxLt/sGxIPxxLxxLxxL and belonged to Pgip gene family. (2)Phylogenetic analysis revealed the significant evolutionary homologous in the sequences of melon PGIP gene and PGIP genes in Cruciferae. (3)Real-time quantitative PCR analysis showed that CsPGIP transcripts were expressed in all tissues, but the transcripts were most abundantly expressed in the young leaf but much less in stem. The expression level of the mRNA could be up-regulated significantly after treated with pathogen and salicylic acid (SA) compared to the normal growth environment. The results indicated that CsPGIP might play an important role on host resistance against pathogen.
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