JGG 2002, 29(11): 1028-1033 DOI:   ISSN: 1673-8527 CN: 11-5450/R           

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Cloning and Characterization of a Homologous Gene of Plant Class V Chitinase from Balsampear, Momordica charantia Linn.

XIAO Yue-Hua;HOU Lei;YUAN Xiao-Hong; YANG Xing-Yong; PEI Ying; LUO Xiao-Ying; PEI Yan

Biotechnology Research Center, Southwest Agricultural University ,Chongqing 400716; China

Abstract

Balsampear (M. charantia Linn.) is a vegetable crop, highly resistant to pathogens. Chitinases were proposed to play an important role in the defense response of this crop. Based on the N-terminal sequence of a purified balsampear chitinase, a fragment (ChitB), similar to the tabacco class V chitinase gene, was amplified from the leaf RNA using 3’RACE, and the corresponding 5’ sequence was further amplified by the Y-RACE method. By joining the two amplified fragments, the full-length cDNA of M.charatica homologous gene of plant class V chitinase (McChi5) was obtained. The 1348bp cDNA contained an ORF of 1044bp, which coded for a polypeptid of 347 amino acids. The deduced polypeptide had a predicted molecular weight of 38.3kD and a pI of 5.77. Homology analysis demonstrated that, McChi5 protein, which contained a conserved domain of family 18 glycosyl hydrolyse, had the sequence similar to tabacco class V chitinases, several putative chitinases and chitinase-like proteins of Arabidopsis thiliania, and some chitinases from mammals, insects and bacteria. Southern blotting suggested that two copies of McChi5 gene and several homologous genes existed in the M.charatica genome. By RNA dot blotting analysis, expression of the McChi5 gene was detected in cotyledons, roots,stems, and leaves, and it was not induced by wounding treatment. The biological functions and the potential applications of Mcchi5 gene were discussed.

Keywords balsampear (M.charantia)   RAGE   chitinase   class V  
Received 1900-01-01 Revised 1900-01-01 Online 2002-11-10 
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