Giraud T
Ecologie, Systématique et Evolution, UMR 8079 CNRS-UPS, Bâtiment 360, Université Paris-Sud, F-91405 Orsay cedex, France.
Heredity (Edinb). 2004 Dec;93(6):559-65. doi: 10.1038/sj.hdy.6800554.
This study explores the patterns of dispersal and mating of the anther smut Microbotryum violaceum, a model species in genetics and evolutionary biology. A French metapopulation of the fungus collected from its caryophyllaceous host Silene latifolia was analysed using microsatellites. The genetic diversity was low, populations were strongly differentiated, and there was no pattern of isolation by distance among populations. There was a strong deficit in heterozygotes, confirming the high self-fertilisation rates suggested by previous studies. Within populations there was a strong pattern of isolation by distance, with identical genotypes being highly clustered. This indicates that fungal spores are dispersed mostly between adjacent plants, and such local dispersal is important for understanding the dynamics and evolution of this disease. Local clusters of identical heterozygous genotypes did not contain significantly fewer individuals than did clusters of homozygous genotypes. As selfing between products of independent meiotic events (intertetrad selfing) rapidly reduces heterozygosity, this suggests that intratetrad matings are frequent, which helps to explain the puzzling maintenance of a sex-ratio distortion in M. violaceum.
本研究探讨了花药黑粉菌（Microbotryum violaceum）的传播和交配模式，该菌是遗传学和进化生物学中的一个模式物种。利用微卫星对从其石竹科寄主宽叶蝇子草（Silene latifolia）上采集的法国真菌复合种群进行了分析。遗传多样性较低，种群间差异很大，且种群间不存在距离隔离模式。杂合子严重不足，证实了先前研究提出的高自交率。在种群内部存在很强的距离隔离模式，相同基因型高度聚集。这表明真菌孢子大多在相邻植物之间传播，这种局部传播对于理解这种疾病的动态和进化很重要。相同杂合基因型的局部聚类所含个体数量并不比纯合基因型的聚类显著少。由于独立减数分裂事件的产物之间的自交（四分体间自交）会迅速降低杂合性，这表明四分体内交配很频繁，这有助于解释花药黑粉菌中性别比例扭曲现象令人费解的维持情况。
