围小丛壳Glomerella cingulata子囊孢子交配繁殖、生物学特性及致病性

炭疽叶枯病（Glomerella leaf spot）是我国苹果上新发现的一种病害。为了解围小丛壳Glomerella cingulata子囊孢子的交配方式、生物学特性和致病性,从安徽砀山、山东牟平等地采集病害样品,经分离培养和纯化获得单孢菌株。在适宜条件下单孢菌株可产生子囊和子囊孢子,经过毛细管破子囊壁后单孢分离,获得12个子囊,每个子囊有8个子囊孢子。其中10个子囊中有4个“正”孢子（+）和4个“负”孢子（-）,2个子囊中只有“负”孢子。子囊孢子单孢菌株培养72h,“正”菌株菌落白色,以营养生长为主;“负”菌株菌落灰白色,直径略小于正菌株,菌丝稀疏,边缘菌丝白色,中部有大量橙色的分生孢子堆。“正”、“负”菌株异宗配合后,可产生大量可育子囊壳;单独的“正”菌株有性生殖产生稀疏丛簇状的可育子囊壳;单个的“负”菌株只能产生分散且不育的子囊壳。“正”、“负”菌株菌落的生长速度没有差异,对温度、营养、光照和pH值的敏感性也没有差异,但“正”、“负”菌株的致病性存在差异。正菌株的有性生殖没有导致rDNA-ITS、β-tubulin基因碱基序列变异。

Sexual reproduction,biological characteristics and pathogencity of ascospores of Glomerella cingulata

Glomerella leaf spot, an apple disease caused by Glomerella cingulata, is newly found in China. In order to understand the sexual reproduction, biological characteristics and pathogenicity of the fungal ascospores, diseased leaves were sampled from Dangshan of Anhui and Muping of Shandong, and mono-conidium cultures were obtained. The mono-conidium cultures produced asci on PDA and each had 8 ascospores. Twelve asci were separated from cultures, of which 10 asci crowded 4 spores with “+” mating type and 4 spores with “-” mating types, and the remainder 2 asci produced only spores with “-” mating type. After 72 hours’ single ascospore cultivation, colonies of “+” type strains were white and the mycelia were flourishing. The colonies of “-” type strains were gray with white edge and a large number of orange conidia on center. Colony diameter of “-” strains was slightly smaller and the mycelia were thinner than those of “+” strain. Heterothallism of “+” and “-” strains produced abundant perithecia at the junction of the two colonies. The colonies of “+” strains produced sparse fertile perithecia, while, single “-” strain only produced sterile perithecia. There were no significant difference in growth rate between “+” and “-” strains and in sensitivity to temperature, nutrition, illumination and pH. Sexual reproduction of “+” strain did not result in variation of sequences of rDNA-ITS and β-tubulin genes.