蝉棒束孢交配型基因MAT的群体分布特征

Population Distribution Characteristics of Mating Type Gene MAT in Isaria cicadae

【目的】探明药用真菌蝉棒束孢Isaria cicadae的交配型基因MAT的群体分布特征及其对蝉花有性生殖的影响,为提高蝉花的生殖率提供参考。【方法】从全国7省12市采集的100份蝉花标本中分离培养菌种,经形态观察、显微鉴定和ITS序列分析,获得各蝉花的无性型菌株;从各菌株DNA中克隆并分析MAT1-1-1和MAT 1-2-1序列的结构和分布特征。【结果】在100株菌株中,13株菌株仅有1 MAT1-1-1,79株菌株仅有MAT1-2-1,8株菌株兼有2个序列。2MAT 1-1-1(缺HMGɑ-box)极少与1 MAT1-1-1共存,常与MAT 1-2-1伴存,但FJDH7和FJDH9菌株同时存在1 MAT1-1-1、2MAT1-1-1和MAT1-2-1序列。聚类分析未发现MAT基因的地域分布相关性。【结论】群体中不同蝉棒束孢菌株的MAT基因有4种可能,兼有3种序列菌株的检出率极低,推测与蝉花有性生殖概率极低的现状有关。

【Objective】The population distribution of mating type gene MAT of Isaria cicadae and the effect of Cordyceps cicadae on sexual reproduction are explored to provide a reference for increasing reproduction rate of C.cicadae.【Method】The asexual strains of C.cicadae from each sample of 100 samples collected from 12 cities of seven provinces in China are obtained by morphological observation,microscopic identification and ITS sequence analysis.The structure and distribution of MAT 1-1-1 and MAT 1-2-1 of each strain are analyzed by cloning DNA of each strain.【Result】There are 13 strains with 1 MAT 1-1-1,79 strains with MAT 1-2-1 and 8 strains with 1 MAT 1-1-1and MAT 1-2-1 among 100 strains.2 MAT 1-1-1(lacking HMGɑ-box)coexists with 1 MAT 1-1-1 rarely and with MAT 1-2-1 often but FJDH 7 and FJDH 9 strains both have 1 MAT 1-1-1,2 MAT 1-1-1 and MAT 1-2-1 sequence.The clustering analysis shows there is no regional distribution correlation of MAT gene.【Conclusion】There are 4 possible MAT genes in different strains of I.cicadae population.The detection rate of strains with 1 MAT 1-1-1,2 MAT 1-1-1 and MAT 1-2-1 sequences is very low,which may be related to extremely low sexual reproduction rate of C.cicadae.