Characterization of Japanese Rhizoctonia solani AG-2-1 isolates using rDNA-ITS sequences, culture morphology, and growth temperature

Hyphal anastomosis reactions, rDNA-internal transcribed spacer (ITS) sequences, and virulence of isolates representing Rhizoctonia solani AG-BI and six subsets of anastomosis group (AG)-2 (-2-1, -2-2 IIIB, -2-2 IV, -2-2 LP, -2-3, and -2-4) were compared. AG-2-4 is a subset described for the first time in this report. Anastomosis reactions within AG-BI and the listed subsets of AG-2 were generally strong but, between subsets, ranged from strong to a very weak “bridging” -type reaction. Anastomosis reaction alone generally did not provide adequate evidence for placement of an isolate into a subset of AG-2. Anastomosis reactions between AG-BI and the original subsets of AG-2 (-2-1 and -2-2) are very strong; for this reason, we propose that it be included as a subset of AG-2 (designation AG-2 BI). Subsets -2-3 and -2-4 show very weak bridging-type anastomosis reactions with all other subsets of AG-2 and thus may be candidates for independent AG status. Grouping within AG-2 based on rDNA-ITS sequences was consistent with the abovementioned subsets. However, grouping based on virulence as measured herein does not conform to established grouping patterns within AG-2 and does not seem useful as a group-defining criterion. A broad range of damage was observed among members of the most virulent subsets (-2-1, -2-2 IIIB, -2-2 IV, and -2-4), whereas other subsets (-2 BI, -2-2 LP, and -2-3) were similar to one another in causing a minimal level of damage. Group-specific primer pairs for each of the seven subsets of AG-2 were designed based on the abovementioned rDNA-ITS sequences. Primer pairs proved dependable and subset specific in polymerase chain reaction amplifications of purified genomic DNA from 109 isolates of R. solani and two isolates of binucleate Rhizoctonia. These primers will provide a simple and useful method for subset-specific characterization within AG-2 if further critical evaluations confirm their specificity.

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Cortinarius alpinus as an example for morphological and phylogenetic species concepts in ectomycorrhizal fungi

Sommerfeltia ◽

10.2478/v10208-011-0009-1 ◽

2008 ◽

Vol 31 (1) ◽

pp. 161-177 ◽

Cited By ~ 8

Author(s):

U. Peintner

Keyword(s):

Ectomycorrhizal Fungi ◽

Related Species ◽

Dry Weight ◽

Species Concepts ◽

Its Sequences ◽

Phylogenetic Species ◽

Closely Related Species ◽

Rdna Its ◽

Rdna Its Sequences ◽

Distinguishing Character

Cortinarius alpinus as an example for morphological and phylogenetic species concepts in ectomycorrhizal fungiExtensive morphological and molecular analyses of closely related species from alpine, subalpine and montane habitats should enable a comparison of ecological, morphological and phylogenetic species concepts in ectomycorrhizal mushrooms. One fundamental question of this study was whether alpine species really exist, and which criteria, besides the specific habitat, could reliably be used for the de-limitation of such taxa. For this reason, 56 rDNA ITS sequences were generated or downloaded from GenBank for 10 closely related species of Cortinarius subgenus Myxacium, section Myxacium. Several collections were sequenced for each of the following taxa: Cortinarius absarokensis, C. alpinus, C. favrei, C. fennoscandicus, C. grallipes, C. mucosus, C. muscigenus, C. septentrionalis, C. trivialis and C. vernicosus. Moreover, spore statistics were carried out for 38 collections of alpine and subalpine taxa. These data provide clear evidence for C. favrei being a synonym of C. alpinus. C. absarokensis and C. alpinus can clearly be delimited based on pileus diameter and average dry weight per basidiome, even in overlapping habitats, but spore size and shape is not a good distinguishing character. Phylograms have very short branches, and base differences between ITS sequences are generally very low in this group, and give no resolution for the included taxa of this section. Based on these results, species concepts of ectomycorrhizal mushrooms are discussed in detail.

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