The Chitinase Activities And Gene Expression Of Banana And The Ripening After Harvest

Seven SSH fragments of chitinase gene had already been obtained by constructing the SSH library of banana fruit,and found it might be associated with fruit ripening by the result of chip analysis in our laboratory,so it was very necessary to research it further.The Seven SSH fragments of chitinase gene belonged to two diffirent gene through the compareing of sequence,one is a classâ…¢acid chitinase gene named gene A,the other is a putative gene named gene B.According to the classâ…¢acide chitinase gene and on the base of the SSH fragment of RB-196,designing the PCR primers screened the classâ…¢acide chitinase gene and another 1051bp fragment of gene B by the PCR method from banana fruit cDNA library. The results of Blastx showed that it had highly homologous with Musa acuminata mRNA for putative chitinase isoform. The result of Genscan indicated that gene B included an integrated ORF and there were 317 amino acids.In order to research the relationsihip between the two chitinase gene and banana fruit ripening after harvest.Firstly,we detected the exo-and endo-chitinase activities of peel and pulp of banana fruit and which treated with 1-MCP,ethylene.The results showed that the chitinase activities of banana fruit treated with 1-MCP were obvious rising from the 12rd,reached the peak at 25rd., were later 4 days than CK and the peak value also lower than CK .By contrast ,The activities of banana fruit treated with ethylene were obvious rising from the 2rd. reached the peak at 6rd. were eralier 13 days than CK and the peak value also higher than CK. In order to further analyze the expression in different stages during the fruit ripening .,the banana friut pulp and which treated with 1-MCP of 2rd,10rd,14rd,19rd,21rd,23rd,25rd and the 27rd of only for 1-MCP, at the same time ,the banana friut pulp treated with ethylene of 2rd,4rd,6rd,8rd and 10rd,were selected as materials,and then extracted the RNA of all and reverse transcripted them to cDNA as the templates for RT-PCR. The results of RT-PCR indicated that the expression is discrepant in different stages during the fruit ripening.It was rising during process of postharvest from the 2rd. And reached the peak at 21-25rd(which treated with ethylene at 6rd)and then descend. which were consistant with the the change curve of chitinase activities .Those...