腐霉的生长温度与分类

 本文主要报道菌丝生长对温度的反应在腐霉分类鉴定上的意义。研究结果表明:种间对温度的反应差异明显;种内则基本相同,特别是在最高温度方面,按照菌丝生长的最高温度可将中国的腐霉分为4群:32℃群,36℃群,40℃群和44℃群。这可作为鉴定种的重要辅助性状,但由于与其它性状缺乏相关性,因此在系统分类上的意义不明显。

Growth Temperature and Classification in Pythium

The temperature response of the mycelia in all the Chinese species of the genus Pythium collected by the authors was studied. Representative isolates of the species of China were grown in 9cm diam. Petri dishes containing 12ml CMA. Plates were inoculated with a 5mm disc of inoculum and were first left at 10～12℃ for 10～14hrs. They were then incubated for 24hrs at temperatures ranging from 4 to 44℃ at 4℃ intervals. Petri dishes can be replaced by glass tubes of 20×2cm while the procedures are the same. Cardinal temperatures of 105 isolates of 37 Chinese Pythium species are determined. The results indicated: (1) Isolates within the same species listed in table 1 according to their localities, from northern province to the southern ones. No matter in what climates the localities are (for example, it is cold temperate in Heilongjiang, mild temperate in Shaanxi and tropical in Yunnan), the maximum temperatures for mycelial growth within species are the same. Mycelial responses to optimum and minimum temperatures within species are not necessarily the same. (2) Maximum growth temperatures of Chinese Pythium species can be divided into four groups: 32℃ Group, 36℃ Group, 40℃ Group, and 44℃ Group. Species in each group do not show morphological consistency but physiological similarities. Grouping of species does not seem to have systematic significance but helps with identification. Pythium amasculinum is a species published by the senior author (Yu 1973). Plaats-Niterink(1981) temporarily cited it as a possible synonym of P. oligandrum. In comparison of these two species the authors re-examined the isolates (including CBS 530.74) and noticed that they are different in not only their antheridial characters, but also the size of oogonia, oospores, sporangia, and cardinal temperatures as well. The maximum growth temperature is 40℃ in P. amasculinum and 44℃ in P. oligandrum, which confirms his aforementioned identification, i. e. PYTHIUM AMASCULINUM YU IS A GOOD SPECIES.