Phytopathology. 1998 Dec;88(12):1330-7. doi: 10.1094/PHYTO.1998.88.12.1330.
ABSTRACT A field experiment was conducted to determine the relative contributions of immigration and sexual reproduction to the genetic structure of Mycosphaerella graminicola populations during the course of an epidemic. The genetic structure of M. graminicola populations sampled from wheat plots inoculated artificially with 10 isolates was compared with control plots infected naturally by airborne ascospores. Restriction fragment length polymorphisms (RFLPs) were used to test the randomness of associations among loci, and DNA fingerprints were used to identify clones. All isolates in the control plots had unique genotypes and RFLP loci were at gametic equilibrium, findings consistent with random mating. The proportion of isolates in the inoculated plots with DNA fingerprints that differed from the 10 inoculated isolates increased from 3% in the early to 39 and 34% in the mid- and late season, respectively. The degree of gametic disequilibrium was higher in the mid-season than in the late-season population. By the end of the growing season, we estimate that 66% of the isolates in the inoculated plots were asexual progeny of the 10 inoculated isolates, 10% were immigrants, and 24% were sexual recombinants. The proportion of infections caused by ascospores increased over the growing season.
摘要 在一次疫病流行过程中，通过田间试验来确定菌系传粉和有性繁殖对麦类球腔菌群体遗传结构的相对贡献。对用 10 个分离物人工接种的小麦样地和自然感染空气传播子囊孢子的对照样地采集的麦类球腔菌群体的遗传结构进行了比较。利用限制片段长度多态性（RFLP）检测基因座间关联的随机性，并用 DNA 指纹识别克隆。对照样地中所有的分离物都具有独特的基因型，而且 RFLP 基因座处于配子平衡状态，这与随机交配的结果一致。接种样地中与 10 个接种分离物不同的 DNA 指纹的分离物的比例从早期的 3%分别增加到中期和晚期的 39%和 34%。在中期，配子的不平衡程度高于晚期群体。到生长季节末，我们估计接种样地中 66%的分离物是 10 个接种分离物的无性后代，10%是移民，24%是有性重组体。通过空气传播的子囊孢子引起的感染比例在整个生长季节中增加。
