小麦条锈菌相对寄生适合度继代测定方法的探讨

 将小麦条锈菌条中28号与条中27号小种等量混合,分别接种在铭贤169和东方红3号小麦品种的麦苗上。繁殖5个夏孢子世代并逐代检测混合群体中2小种所占比例。结果表明:随着世代数的增加,条中28号小种的比例均逐代上升,而且在东方红3号上上升速度更快。按照Leonard等人(1969)的公式,求得条中27号在2品种上的相对寄生适合度分别为0.7028和0.5807(以条中28号的适合度为1)。另外证明选择适当的鉴别寄主,依据病点数推测混合群体中小种比例的方法是可行的。最后,就相对寄生适合度测定方法进行了讨论。

ESTIMATION OF RELATIVE PARASITIC FITNESS BY DETECTING THE PROPORTING OF RACES IN POPULATION

Seedlings of cv. Mingxian 169 and Dongfanghong 3 were inoculated with spore mixture composed of equal amount of wheat yellow rust race CY28 and CY27. One proportion of the reproduced urediospores was inoculated onto differential hosts to detect the ratio of races and the other part inoculated the seedlings of the two tested cultivars mentioned above. This process was carried out on 5 successive generations. Results indicated that the ratio of CY28 increased in the population of the fungus, and the rate of increase was higher on Dongfanghong 3 than that of on Mingxian 169. By using the equation proposed by Leonard et al. (1969), the relative parasitic fitness of CY27 and of CY28 were estimated as 0.7028 and 0.5807 on two cultivars, respectively. Provided proper differential hosts are selected, it may be feasible to estimate the proportion of races in the population of wheat rust according to the number of infection sites on the leaves of differential host. Different methods commonly used for estimating relative parasitic fitness were also discussed.