三个桑树肌动蛋白基因的克隆与组织表达分析

Molecular Cloning and Tissues Expression Analysis of Three Actin Genes from Mulberry (Morus alba)

肌动蛋白基因在植物各种生理活动中具有极其重要的作用。通过同源克隆与反向PCR的方法,克隆了3个肌动蛋白基因的核心片段,其中一个为已报道的MaACT1,另2个分别被命名为MaACT2和MaACT3,进而PCR扩增获得MaACT1和MaACT2肌动蛋白全长CDS,其中MaACT2基因全长1704bp,由4个外显子和3个内含子组成,CDS为1134bp,编码377个氨基酸残基。采用RT-PCR的方法分析了3个基因在叶、茎、果、根等组织的表达情况以及在茎、叶和托叶的生长过程中的表达变化。MaACT1在茎中表达量较弱但有随着茎的生长逐渐增强的趋势,在幼叶中有较高的表达,MaACT2与MaACT3在根、茎、叶等组织中都有较高表达,MaACT3在叶、托叶和茎的各个发育时期表达都很稳定,可以作为桑树基因表达研究的内参基因。

Actins play extremely important roles in plants. To date, no full-length cDNA actin genes have been reported in mulberry. In this study, we cloned three core fragments, two full CDS, and one full-length genomic sequence of actin genes from mulberry by means of homologous cloning and PCR strategy. The three mulberry actin genes obtained were designated MaACT1, MaACT2, and MaACT3. The full length of MaACT2 is 1 704 bp, which contains four exons and three introns. A putative CDS of MaACT2 （1 134 bp in length） encodes 377 amino acid residues. The RT-PCR analysis showed that MaACT1 had lower expressions in various tissues and organs than those of MaACT2 and MaACT3. The expression level of MaACT1 in stem was very low at beginning and increased gradually with the development of stem, while its expression was relatively high in young leaf. MaACT2 and MaACT3 had high and stable expressions in root, leaf, and stem, especially MaACT3 was expressed stably at different developmental stages. Therefore, MaACT3 is considered as a good candidate of internal reference gene in mulberry.