Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Apartado Postal 70-275, Ciudad Universitaria, México, D.F. 04510, México.
Mycologia. 2003 Sep-Oct;95(5):846-59. doi: 10.1080/15572536.2004.11833044.
Lophodermium comprises ascomycetous fungi that are both needle-cast pathogens and asymptomatic endophytes on a diversity of plant hosts. It is distinguished from other genera in the family Rhytismataceae by its filiform ascospores and ascocarps that open by a longitudinal slit. Nucleotide sequences of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA were used to infer phylogenetic relationships within Lophodermium. Twenty-nine sequences from approximately 11 species of Lophodermium were analyzed together with eight sequences from isolates thought to represent six other genera of Rhytismataceae: Elytroderma, Lirula, Meloderma, Terriera, Tryblidiopsis and Colpoma. Two putative Meloderma desmazieresii isolates occurred within the Lophodermium clade but separate from one another, one grouped with L. indianum and the other with L. nitens. An isolate of Elytroderma deformans also occurred within the Lophodermium clade but on a solitary branch. The occurrence of these genera within the Lophodermium clade might be due to problems in generic concepts in Rhytismataceae, such as emphasis on spore morphology to delimit genera, to difficulty of isolating Rhytismataceae needle pathogens from material that also is colonized by Lophodermium or to a combination of both factors. We also evaluated the congruence of host distribution and several morphological characters on the ITS phylogeny. Lophodermium species from pine hosts formed a monophyletic sister group to Lophodermium species from more distant hosts from the southern hemisphere, but not to L. piceae from Picea. The ITS topology indicated that Lophodermium does not show strict cospeciation with pines at deeper branches, although several closely related isolates have closely related hosts. Pathogenic species occupy derived positions in the pine clade, suggesting that pathogenicity has evolved from endophytism. A new combination is proposed, Terriera minor (Tehon) P.R. Johnst.
石细胞包含子囊菌，既是针叶小蠹的病原体，也是多种植物宿主的无症状内生菌。它与 Rhytismataceae 科的其他属的区别在于其丝状的子囊孢子和通过纵向裂缝打开的子囊果。核核糖体 DNA 的内部转录间隔区（ITS）区域的核苷酸序列用于推断石细胞内的系统发育关系。分析了来自大约 11 种石细胞的 29 个序列，以及来自被认为代表 Rhytismataceae 科的其他六个属的 8 个序列：Elytroderma、Lirula、Meloderma、Terriera、Tryblidiopsis 和 Colpoma。两个假定的 Meloderma desmazieresii 分离株存在于石细胞分支内，但彼此分开，一个与 L. indianum 分组，另一个与 L. nitens 分组。Elytroderma deformans 的一个分离株也存在于石细胞分支内，但在单独的分支上。这些属在石细胞分支内的出现可能是由于 Rhytismataceae 科的属概念存在问题，例如强调孢子形态来界定属，或者难以从也被石细胞定殖的材料中分离出 Rhytismataceae 针叶病原体，或者这两个因素的结合。我们还评估了宿主分布和 ITS 系统发育上的几个形态特征的一致性。来自松宿主的石细胞物种形成了一个单系姐妹群，与来自南半球更远宿主的石细胞物种形成了一个单系姐妹群，但与 Picea 的 L. piceae 没有形成一个单系姐妹群。ITS 拓扑结构表明，石细胞在更深的分支上与松树没有严格的共进化，尽管几个密切相关的分离株有密切相关的宿主。致病性物种占据了松树分支的衍生位置，这表明致病性是从内生性进化而来的。提出了一个新的组合，Terriera minor (Tehon) P.R. Johnst.
