西府海棠(Malus micromalus)MaMAPK基因的克隆及表达特性

依据高等植物MAPK基因的保守区设计简并引物,用 RT-PCR方法,首次从西府海棠幼苗叶片中克隆了促分裂原活化蛋白激酶(mitogen-activated protein kinase,MAPK)基因(MaMAPK)的cDNA全序列.Southern杂交结果表明在西府海棠中存在一个小的MAPK基因家族.20%PEG处理西府海棠幼苗不同时间后的Northern杂交分析表明,该基因在根系和叶片中均有表达,随着胁迫时间延长表达量增加,说明西府海棠MaMAPK基因在转录水平上受水分胁迫诱导表达.

Cloning and Expression Characteristics of MaMAPK Gene of Malus micromalus

A full cDNA sequence of MAPK (mitogen activated protein kinase) gene was cloned from Malus micromalus seedling leaves by RT PCR. It was named MaMAPK , and the accession number in GenBank was AF435805. It was about 1.5 kb long and encoded 417 amino acid. There were eleven conserved subdomains and phosphorylation site "TEY" in the cDNA sequence, which is the typical characteristics of MAPK family (Fig.1). Sequence alignment suggests that it has the highest homology with alfalfa ( Medicago sativa) MMK4 gene(X82270). It shares 81% and 82% identity in nucleotide and amino acid with alfalfa, respectively. Results of Southern blotting suggest that there is a small gene family and MaMAPK gene may be small copies in genomic DNA of M. micromalus (Fig.3). Northern blotting result showed that MaMAPK gene could be expressed in roots and leaves of MAPK of four members in M.micromalus after being treat with 20% PEG for different time (Fig.4). The expression level in roots was higher than that of in leaves. There was slender expression both in roots and leaves. These results indicate that the expression of MaMAPK gene is induced by water stress.