Molecular characterization of fruit-specific class III peroxidase genes in tomato

• Main Authors: Chii-Jeng Wang, 王啓正
• Other Authors: 葉開溫
• Format: Others
• Language: en_US
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/43618962616182836171

博士 === 國立臺灣大學 === 植物科學研究所 === 103 === To research the characters and function of fruit-specific class III peroxidase gene of tomato, expression of four tomato class III peroxidase (LePrx) genes, LePrx09, LePrx17, LePrx35 and LePrxA, was isolated and charactered from immature tomato fruits, and the function in the regulation of fruit growth was studied. LePrx35 and LePrxA were identified as novel peroxidase genes in tomato. Analysis of amino acid sequences revealed that these genes are belonged to class III peroxidases group and contain B, D and F conserved domains, which bind heme groups, two calcium atoms, and form a stable molecular structure by a buried salt bridge motif and four disulphide bridges. Phylogenetic analysis for 24 and 118 full-length peroxidase proteins of Solanaceae crop species show three groups constructed and some wounding, pathogen and lignin synthesis related peroxidases were grouped with the four LePrxs. The temporal expression patterns at various fruit growth stages revealed that LePrx35 and LePrxA were expressed only in immature green fruits, whereas LePrx17 and LePrx09 were expressed in both immature and mature green fruits. Cis-element analysis revealed that all the upstream of the four LePrxs have at least sugar repressive element and other wounding, pathogen and hormones related cis-elements. The promoter of LePrx09, LePrx17 and LePrxA has fruit-specific cis-elements, TGTTACA or TCCAAAA. Moreover, tissue-specific expression profiles indicated that only LePrx09 was mainly expressed in the mesocarp but not the inner tissue of immature fruits. Histochemical localization of GUS activity analysis also revealed the mesocarp-expression pattern. The effects of hormone treatments and stresses on the four genes were examined; only the expression levels of LePrx17 and LePrx09 were altered. Transcription of LePrx17 was up-regulated by jasmonic acid (JA) and pathogen infection, and expression of LePrx09 was induced by ethephon, salicylic acid (SA) and JA, in particular, as well as wounding, pathogen infection and H2O2 stress. Tomato plants over-expressing LePrx09 displaying enhanced resistance to H2O2 stress, suggesting that LePrx09 may participate in the H2O2 signaling pathway to regulate fruit growth and disease resistance in tomato fruits. Thus, if the sequences of LePrx09 promoter region and its upstream genes were involved in the stresses resistant tomato entries, it would be as a useful marker for stresses resistance breeding.