Biodiversidad y Sistemática, Instituto de Ecología, A.C., P.O. Box 63, Xalapa, Veracruz 91000, México.
Mycologia. 2010 Jan-Feb;102(1):153-62. doi: 10.3852/09-010.
Ectomycorrhizal (EM) fleshy fungi are being monitored in a population of Fagus grandifolia var. mexicana persisting in a montane cloud forest refuge on a volcano in a subtropical region of central Veracruz (eastern Mexico). The population of Fagus studied represents one of the 10 recognized forest fragments still housing this tree genus in Mexico. This is the first attempt to document EM fungi associated with this tree species in Mexico. We present evidence of the ectomycorrhizal symbiosis for Lactarius badiopallescens and L. cinereus with this endemic tree. Species identification of Lactarius on Fagus grandifolia var. mexicana was based on the comparison of DNAsequences (ITS rDNA) of spatiotemporally co-occurring basidiomes and EM root tips. The host of the EM tips was identified by comparison of the large subunit of the ribulose-bisphosphate carboxylase gene (rbcL). The occurrence of Lactarius badiopallescens and L. cinereus populations in the area of study represent the southernmost record known to date of these two species in North America and are new for the Neotropical Lactarius mycota. Descriptions coupled with illustrations of macro- and micromorphological features of basidiomes as well as photographs of ectomycorrhizas are presented.
外生菌根（EM）肉质真菌正在对一个生活在中美洲韦拉克鲁斯州亚热带地区一座火山上的高山云雾森林保护区中的 Fagus grandifolia var. mexicana 种群进行监测。研究中的 Fagus 种群是墨西哥仍有 10 个被认可的森林碎片之一。这是首次尝试记录与这种树种相关的 EM 真菌。我们为 Lactarius badiopallescens 和 L. cinereus 与这种特有树种的外生菌根共生提供了证据。基于同时出现的担子果和 EM 根尖的 DNA 序列（ITS rDNA）的比较，对 Lactarius 在 Fagus grandifolia var. mexicana 上的物种鉴定。通过比较核酮糖-1,5-二磷酸羧化酶基因（rbcL）的大亚基来确定 EM 根尖的宿主。在研究区域中 Lactarius badiopallescens 和 L. cinereus 种群的出现代表了迄今为止这两个物种在北美的最南端记录，也是新的新热带 Lactarius 真菌群。本文提供了担子果的宏观和微观形态特征的描述和插图，以及外生菌根的照片。
