香蕉过氧化物酶基因表达和酶活性与香蕉抗枯萎病的关系

为了获得能反应香蕉遭受枯萎病侵染的标记基因。通过随机克隆测序的方法从香蕉根系cDNA文库中获得一个过氧化物酶基因，命名为MaPOD1（GenBank登录号为KC478598）。扩增获得的cDNA序列与质粒序列一致，表明该基因是香蕉POD基因编码框全长cDNA，包含一个948 bp的最大开放阅读框，编码一个长328个氨基酸的蛋白质。蛋白质序列同源比对发现其含有过氧化物酶活性位点和亚铁血红素配体位点结构。实时荧光定量PCR分析表明该基因在香蕉根和假茎中表达量较高；在球茎中的表达量最低。在耐病和感病品种中，MaPOD1均上调表达，但在耐病品种中MaPOD1在所有时间点相对于对照增加的倍数均高于感病品种，表明在该基因在香蕉的抗病性中起着重要作用。该基因的表达与酶活变化趋势相同，基因表达滞后于酶活变化。MaPOD1可以作为一个新的响应枯萎病侵染的标记基因。

Analysis of POD Activity and Gene Expression Pattern in Banana Resistance to Fusarium Oxysporum f specialis (f. Sp) cubense Tropical Race 4

The aim of this paper is to acquire a new marker gene of banana under the infection of Foc TR4. A peroxidase gene was identified by randomly sequencing from cDNA library obtained from banana roots. This gene was called MaPOD1 (GenBank accession number is KC478598). The cDNA sequence obtained by amplifying was consistent with plasmid sequence, indicated that this gene was full-length cDNA of banana POD gene, which contained an open reading frame of 948 bp encoding a protein of 328 amino acids. Through protein sequence homologous compare, it was found that the gene contained peroxidase active site and heme binding site structure. Semi quantitative RT-PCR demonstrated that the expression of MaPOD1 was higher in banana roots and pseudostems while lower in rhizomes. In resistant and susceptible varieties of banana after inoculation Foc TR4, the expression of MaPOD1 was upregulated, but in resistant varieties the time point of MaPOD1, compared to control, increased higher than that in susceptible varieties at time points, indicated that this gene played an important role in banana resistance. The expression of this gene had the same trend with enzymatic activity change, and gene expression lagged after enzyme activity change. MaPOD1 could be a new marker gene under the infection of Foc TR4.