中文摘要：

利用RACE-PCR技术首次从药用真菌猪苓中分离得到猪苓菌核的4个小GTPase基因。这4个基因分别命名为Pu Rho A1、Pu Rho A2、Puypt1及Pu Ras,Pu Rho A1全长698 bp,编码区共585 bp,编码194个氨基酸,推测分子量为21.75 k D,理论等电点为6.44;Pu Rho A2全长837 bp,其中编码区长585 bp,可编码194个氨基酸,计算其分子量为21.75 k D,理论等电点为6.33;Puypt1为一条896 bp的c DNA,编码区为615 bp,可编码204个氨基酸,经计算分子量为22.556 k D,理论等电点为5.75。Pu Ras的c DNA全长为803 bp,其中编码区长639 bp,编码212个氨基酸,推测分子量为23.821 k D,理论等电点为5.2。Pu Rho A1具有法尼酰转移酶催化位点（FT-Caa X）和香叶烯基转移酶催化位点（GGT1-Caa X）,而Pu Rho A2仅具有香叶烯基转移酶催化位点（GGT1-Caa X）;Puypt1具有小GTPase家族中Rab1-Ypt1的完整保守结构域;Pu Ras具有法尼酰转移酶催化位点（FT-Caa X）。系统进化树结果显示猪苓的4个小GTPase都隶属于担子菌类群。实时荧光定量PCR分析结果表明在菌核形成初期Puypt1、Pu Ras、Pu Rho A1在菌核中表达量显著高于菌丝,而Pu Rho A2在菌核中的表达量显著低于菌丝,说明这4个小GTPase基因可能参与了猪苓菌核的形态发生。

英文摘要：

Four small GTPase genes which may be relative to sclerotial development were firstly cloned from medicinal fungus Polyporus umbellatus using rapid amplification of c DNA end PCR（RACE） method. The results showed that full-length c DNA of Pu Rho A was 698 bp contained 585 bp ORF, which was predicted to encode a 194 amino acid protein with a molecular weight of 21.75 k D with an isoelectric point（p I） of 6.44; the full length c DNA of Pu Rho A2 was 837 bp in length and encoded a 194 amino acid protein with a molecular weight of 21.75 k D and an isoelectric point（p I） of 6.33; the full length c DNA of Puypt1 was 896 bp in length and encoded a 204-aa protein with a molecular weight of 22.556 k D and an isoelectric point（p I） of 5.75; the full length c DNA of Pu Ras was 803 bp in length and encoded a 212-aa protein with a molecular weight of 23.821 k D and an isoelectric point（p I） of 5.2. There are fani acyl transferase enzyme catalytic site and myrcene-transferase enzyme catalytic site in Pu Rho A1 while the Pu Rho A2 only possess myrcene-transferase enzyme catalytic site. Puypt1 contains the Rab1-Ypt1 conserved domain of small GTPase family and Pu Ras contains the fani acyl transferase enzyme catalytic site. According to the phylogenetic analysis all these four small GTPase clustered with basidiomycete group. Quantitative real-time PCR analysis revealed that Puypt1, Pu Ras and Pu Rho A1 transcripts were significantly higher in the beginning of sclerotial formation than that in the mycelia, whereas the transcripts levels of Pu Rho A2 gene were particularly lower in sclerotia than that in mycelia, suggesting that these four genes might be involved in P. umbellatus sclerotial development.