Amend Anthony, Keeley Sterling, Garbelotto Matteo
University of California Berkeley, Department of Plant and Microbial Biology, 321 Koshland Hall, Berkeley, CA 94720, USA.
Mycol Res. 2009 May;113(5):541-51. doi: 10.1016/j.mycres.2009.01.005. Epub 2009 Jan 22.
Examining the fine-scale spatial structure of fungal populations can tell us much about how individual species reproduce and disperse throughout natural landscapes. Here we study the fine-scale genetic structure of Tricholoma matsutake, a prized edible and medicinal mushroom, by systematic sampling of mycorrhizas within fairy rings in 50-y-old and old-growth forests in two villages. Using single nucleotide polymorphism DNA markers we show that mycorrhizas in both forest age classes in both villages showed high levels of genotypic diversity, consistent with a reproductive life history predominated by outcrossing via basidiospore dispersal. Both the percentage of polymorphic loci within fairy rings, as well as genotype diversity were higher in old-growth compared to 50-y-old forests. Fifty-year-old forests showed significant spatial autocorrelation between pairs of mycorrhizas up to 42m, and a pattern consistent isolation-by-distance structure. Spatial patterns in old-growth forests were random. Furthermore, AMOVA analysis indicates that 11% of molecular variance in 50-y-old forests is partitioned between villages, whereas no significant variance is partitioned between villages in old-growth forests. We conclude that populations of T. matsutake in 50-y-old forests are the result of a founder effect maintained by local inoculation sources. This pattern attenuates as forests age and accumulate inocula from more distance sources. We speculate on how genetic mosaicism within T. matsutake fairy rings may structure populations within a chronosequence. Finally, we discuss how population spatial dynamics and dispersal strategy in T. matsutake contrast with other ectomycorrhizal species.
研究真菌种群的精细空间结构可以让我们深入了解单个物种是如何在自然景观中繁殖和扩散的。在这里，我们通过系统采样两个村庄中50年树龄和老龄森林中仙女环内的菌根，研究了珍贵的食用和药用蘑菇松茸的精细遗传结构。使用单核苷酸多态性DNA标记，我们发现两个村庄中两个林龄类别的菌根都表现出高水平的基因型多样性，这与通过担孢子扩散进行异交为主的繁殖生活史一致。与50年树龄的森林相比，老龄森林中仙女环内的多态位点百分比和基因型多样性都更高。50年树龄的森林中，菌根对之间在长达42米的距离内表现出显著的空间自相关性，以及与距离隔离结构一致的模式。老龄森林中的空间模式是随机的。此外，AMOVA分析表明，50年树龄森林中11%的分子变异在村庄之间进行分配，而老龄森林中村庄之间没有显著的变异分配。我们得出结论，50年树龄森林中的松茸种群是由当地接种源维持的奠基者效应的结果。随着森林年龄的增长和积累来自更远距离来源的接种体，这种模式会减弱。我们推测了松茸仙女环内的遗传镶嵌如何在时间序列中构建种群结构。最后，我们讨论了松茸的种群空间动态和扩散策略与其他外生菌根物种的对比。
