A new species of <Emphasis Type="Italic">Brasiliomyces</Emphasis> (Erysiphaceae) on <Emphasis Type="Italic">Dalbergia cultrata</Emphasis> var. <Emphasis Type="Italic">cultrata</Emphasis> from Thailand

A powdery mildew fungus on leaves of Dalbergia cultrata var. cultrata (Fabaceae) collected at the Queen Sirikit Botanical Garden in northern Thailand is proven to be a new species of the genus Brasiliomyces and is described as B. chiangmaiensis sp. nov. with light and SEM micrographs. Differences in known Brasiliomyces species are discussed, and a key to species of this genus is provided.     

Molecular phylogenetic analyses reveal a close relationship between powdery mildew fungi on some tropical trees and Erysiphe alphitoides, an oak powdery mildew

To investigate the phylogenetic relationships among the powdery mildew fungi of some economically important tropical trees belonging to Oidium subgenus Pseudoidium, we conducted molecular phylogenetic analyses using 30 DNA sequences of the rDNA internal transcribed spacer (ITS) regions and 26 sequences of the domains D1 and D2 of the 28S rDNA obtained from the powdery mildews on Hevea brasiliensis (para rubber tree), Anacardium occidentale (cashew), Bixa orellana, Citrus spp., Mangifera indica (mango), and Acacia spp. The results indicate that the powdery mildew fungi isolated from these tropical trees are closely related to one another. These powdery mildews are also closely related to E. alphitoides (including Erysiphe sp. on Quercus phillyraeoides). Because of the obligate biotrophic nature of the powdery mildew fungi, the relationship between powdery mildews and their host plants is conservative. However, the present study suggests that a particular powdery mildew species has expanded its host ranges on a wide range of the tropical trees. This article also suggests that a powdery mildew fungus distributed in temperate regions of the Northern Hemisphere expanded its host ranges onto tropical plants and may be a good example of how geographical and host range expansion has occurred in the Erysiphales.     

The teleomorph of Leptographium yunnanense, discovered in crosses among isolates from Thailand, China, and Japan

A teleomorph was discovered in crosses among isolates of Leptographium yunnanense isolated from Pinus spp. originating in Thailand, China, and Japan. The ascocarps are black, globose to subglobose, and lacking necks. Ascospores are hyaline, 1-celled, surrounded by hyaline sheaths, and appear cucullate in side view, quadrangular in face view, and triangular in end view. Three species were known to have teleomorphs morphologically similar to the present fungus. However, their anamorphs were distinguishable from L. yunnanense. Thus, this teleomorph is described as Grosmannia yunnanensis. Contribution No. 214, Laboratory of Plant Parasitic Mycology, Graduate School of Life & Environmental Sciences, University of Tsukuba.     

Identification of Japanese Astraeus, based on morphological and phylogenetic analyses

To clarify the diversity of Astraeus in Japan, 35 collections of Astraeus basidiomata from Japan and Thailand were examined for their morphological characteristics and the nucleotide sequences of the rDNA ITS region and compared with several worldwide Astraeus species. Japanese Astraeus specimens were separated into two groups based on basidiome size, shape of exoperidium, and ornamentation and size of basidiospores. The phylogenetic tree analyses supported the separation, and the morphological groups belonged to different clades. The Japanese Astraeus group 1, morphologically matched to Astraeus hygromerticus var. koreanus, showed the closest phylogenetic relationship with Astraeus hygrometricus from North American and Mediterranean regions, suggesting that the Astraeus group 1 can be indentified as A. hygrometricus var. koreanus. Another Astraeus group, group 2, morphologically matched to A. hygrometricus s.l., showed a distinct monophyletic clade that was separated from A. hygrometricus complexes, indicating an undescribed species.     

Effects of methylation-sensitive enzymes on the enrichment of genic SNPs and the degree of genome complexity reduction in a two-enzyme genotyping-by-sequencing (GBS) approach: a case study in oil palm (<Emphasis Type="Italic">Elaeis guineensis</Emphasis>)

Advances in next generation sequencing have facilitated a large-scale single nucleotide polymorphism (SNP) discovery in many crop species. Genotyping-by-sequencing (GBS) approach couples next generation sequencing with genome complexity reduction techniques to simultaneously identify and genotype SNPs. Choice of enzymes used in GBS library preparation depends on several factors including the number of markers required, the desired level of multiplexing, and whether the enrichment of genic SNP is preferred. We evaluated various combinations of methylation-sensitive (AatII, PstI, MspI) and methylation-insensitive (SphI, MseI) enzymes for their effectiveness in genome complexity reduction and enrichment of genic SNPs. We discovered that the use of two methylation-sensitive enzymes effectively reduced genome complexity and did not require a size selection step. On the contrary, the genome coverage of libraries constructed with methylation-insensitive enzymes was quite high, and the additional size selection step may be required to increase the overall read depth. We also demonstrated the effectiveness of methylation-sensitive enzymes in enriching for SNPs located in genic regions. When two methylation-insensitive enzymes were used, only 16% of SNPs identified were located in genes and 18% in the vicinity (± 5 kb) of the genic regions, while most SNPs resided in the intergenic regions. In contrast, a remarkable degree of enrichment was observed when two methylation-sensitive enzymes were employed. Almost two thirds of the SNPs were located either inside (32–36%) or in the vicinity (28–31%) of the genic regions. These results provide useful information to help researchers choose appropriate GBS enzymes in oil palm and other crop species.     

Two species of <Emphasis Type="Italic">Leptographium</Emphasis> isolated from blue-stained sapwood of <Emphasis Type="Italic">Pinus khasya</Emphasis> and bark beetles in Thailand

Two species of Leptographium were isolated from blue-stained sapwood of Pinus khasya and bark beetle galleries in pine trees near Chiang Mai, Thailand. Based on morphological observations, these two species were identified as L. pini-densiflorae and L. yunnanense. This is the first record of these fungi in Thailand. Leptographium yunnanense appeared to be associated with Polygraphus major. This is contribution No. 206, Laboratory of Plant Parasitic Mycology, Graduate School of Life & Environmental Sciences, University of Tsukuba