Cloning and expression analysis of major allergen(Ppmal) from Sand Pear(Pyrus pyrifolia Nakai)

【Objective】The aim of this study was to isolate a major allergen gene from sand pear(Ppmal,Gen Bank accession number: KP008110) and explore its role during the development of pear.【Methods】Under the treatment of gibberellin about one month after full flowering,Ppmal was cloned from‘Cui-guan'by homologous cloning and RACE technology,and the expression patterns of the gene in differenttissues and the development of pear were studied using real-time fluorescence quantitative PCR(q RT-PCR).【Results】A 906 bp sequence was cloned and named as Ppmal. The open reading frame(ORF) was480 bp,encoding 159 amino acids with a molecular weight of 17.56 k D,and its p I is 5.62. Bioinformaticanalysis showed that the protein had no signal peptide sequence or transmembrane domain,and it was hy-drophilic. It shares high nucleotide sequence homology with those of other reported plants,and has97.48% and 96.23% amino acids homology with Malus domestica and Pyrus communis respectively. Phylo-genetic tree analysis indicated that Ppmal is most related to apple. At the same time,The quantitative re-sult showed that the expression of Ppmal in the fruit after treatment by GA presented a first decreased andthen increased trend with the growth and development of the fruit. What's more,Ppmal had the characteristic of differential distribution in various tissues,and the expression from high to low order was flowers,new shoots,leaves and shoots.【Conclusion】The full length of Ppmal was cloned and the results revealedthat this gene was controlled by GA and presented overexpression during the fruit enlargment in pear.