The taxonomy of the genus Vigna has been primarily based on morphological attributes. We have used 27 genomic clones from soybean, common bean, mungbean and cowpea to examine restriction fragment length polymorphism (RFLP) among 44 accessions of different species belonging to four subgenera of the genus Vigna. One accession each of common bean (Phaseolus vulgaris) and soybean (Glycine max) was included in the study. Total DNA from the various genotypes was digested with one restriction enzyme (Eco RV). Results of a numerical taxonomic analysis showed a high level of genetic variation within the genus with a remarkably higher amount of variation associated with Vigna sp. from Africa relative to those from Asia. The distinctness of the Asiatic grams in subgenus Ceratotropis, cowpea in section Catiang, bambara groundnut (V. subterranean) and members of the subgenus Plectotropis was elucidated by this study. Members of the subgenus Plectotropis were closer in genome homology to those of subgenus Vigna section Catiang than to those of subgenus Ceratotropis. The relative positions of some genotypes to one another on the dendrogram and minimum spanning tree were discussed in regard to hybridisations aimed generating well-saturated genomic maps and interspecies transfer of desirable genes.
Morphological studies and phylogenetic analyses of DNA sequences from three
genomic regions – the internal transcribed spacer (ITS) regions of the
nuclear ribosomal gene repeat, a partial sequence of RNA polymerase II subunit
(rpb2), and a partial sequence of translation elongation factor
(tef1) – were used to investigate the systematics of
Hypocrea citrina and related species. A neotype specimen is
designated for H. citrina that conforms to Persoon's description of a
yellow effuse fungus occurring on leaf litter. Historical information and
results obtained in this study provide the foundation for selection of a
lectotype specimen from Fries's herbarium for H. lactea. The results
indicate that (1) Hypocrea citrina and H. pulvinata are
distinct species; (2) H. lactea sensu Fries is a synonym of the older
name H. citrina; (3) H. pulvinata, H. protopulvinata, and
H. americana are phylogenetically distinct species that form a
well-supported polyporicolous clade; (4) H. citrina is situated in a
clade closely related to H. pulvinata; and (5) H.
microcitrina and H. pseudostraminea reside in a highly supported
clade phylogenetically distinct from H. citrina. Hypocrea protopulvinata,
H. microcitrina, H. megalocitrina, H. pseudostraminea, and a new species,
H. aurantiistroma, are reported and described from North America.
Variation in rpb2 and tef1 gene sequences suggests
geographical subgroupings between European and North American isolates of
H. pulvinata. The phylogenies inferred from ITS, rpb2, and
tef1 gene sequences are concordant. Hypocrea citrina var.
americana is elevated to species status, Hypocrea
americana.
Morphological studies and phylogenetic analyses of DNA sequences from the
internal transcribed spacer (ITS) regions of the nuclear ribosomal gene
repeat, a partial sequence of RNA polymerase II subunit (rpb2), and a
partial sequence of the large exon of tef1 (LEtef1) were
used to investigate the taxonomy and systematics of nine Hypocrea
species with anamorphs assignable to Trichoderma sect.
Hypocreanum. Hypocrea corticioides and H. sulphurea are
reevaluated. Their Trichoderma anamorphs are described and the
phylogenetic positions of these species are determined. Hypocrea
sulphurea and H. subcitrina are distinct species based on
studies of the type specimens. Hypocrea egmontensis is a facultative
synonym of the older name H. subcitrina. Hypocrea with anamorphs
assignable to Trichoderma sect. Hypocreanum formed a
well-supported clade. Five species with anamorphs morphologically similar to
sect. Hypocreanum, H. avellanea, H. parmastoi, H. megalocitrina, H.
alcalifuscescens, and H. pezizoides, are not located in this
clade. Protocrea farinosa belongs to Hypocrea s.s.
The new species Hypocrea virens, has been found to be the teleomorph of Trichoderma virens, a species commonly used in biological control applications. This conclusion is based on the comparison of morphological and molecular data from four isolates of T virens and a single collection and isolate of H. virens. Data for several morphological characters, including colony and growth characteristics, were collected. In addition, sequence data from ITS1, 5.8S, ITS2 rDNA and translation elongation factor (tef-la) were analyzed for the five isolates. Analysis of phenotypic characters show that cultures and microscopic characters of the anamorph of H. virens are indistinguishable from those of T virens. This is consistent with sequence data from ITS1, 5.8S, ITS2 rDNA which show that the sequence of H. virens is identical to that of the ex-type isolate of T virens. Despite minor variation in tef-la sequences, T. virens isolates and H. virens form a monophyletic group that is different from other examined species of Hypocrea; this clade is supported by a 100% bootstrap value. Molecular and morphological data confirm the connection between H. virens and T virens.
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