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Results for “oval conidia”

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4 recordsLinked to original sources
PubMed2026

Spore type-specific gene expression profiles underlying development and leaf infection processes of Colletotrichum graminicola.

Colletotrichum graminicola causes significant losses of the staple crop maize worldwide. The fungus produces two distinct asexual spore types, oval and falcate conidia, which show unique processes in development and plant interaction. Based on genome resequencing of our laboratory strain (CgM2/M1.001), we investigated the gene expression profiles of oval and falcate conidia during development and early leaf infection using RNA-seq. Our results reveal specific gene expression profiles between the two spore types, indicating fundamental differences in their developmental programs that reflect different modes of infection. We identified expression patterns discriminating both conidia types from mycelium and spore type-specific ones for genes encoding transcription factors, conserved fungal developmental genes, transporters, genes of secondary metabolite clusters, and pathogenicity-related functions, including effectors and carbohydrate-active enzymes (CAZymes). Our study shows that despite the identical genomic basis, oval and falcate conidia show unique transcriptomes across vegetative development and early plant interaction. Taking together, these results provide new insights into the molecular mechanisms determining the biology of C. graminicola and its interaction with the plant host.

Colletotrichum graminicola↗
PubMed1992

Morphological variation in pathogenic strains of Penicillium marneffei.

Penicillium marneffei is a dimorphic fungus known to be pathogenic to animals and man. The natural reservoir of this organism was known to be bamboo rats found in South Vietnam, Thailand and China. The first two human infections were reported in 1959 and 1973 from the United States. Up to 1984, five new cases of human penicillosis were reported from Thailand. Since then several more cases have been reported from different parts of the world mainly from the southern part of China. However, there are very limited mycological descriptions of this fungi. In this report, five Thai strains were studied for colonial morphology in comparison with Reference strain PLM 689. Variation in mycelial pigment was observed ranging from yellowish-green to orange with water soluble red pigment produced in every strain which can be seen early from the reverse side. Ultrastructural study by both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) was compared with that of the reference strain PLM 689. PLM 689 strain had only biverticillate penicilli, but all five strains from Thailand had both monoverticillate and biverticillate penicilli which occasionally appeared on the same branch. The conidia of the Thai isolates were oval in shape and 1.3-2 x 0.7-1.6 microns in size smaller than those of PLM 689 which were 2.5-4 x 2-3 microns. Phialides were also smaller and a little shorter but the number of phialides was similar to those of PLM 689 ranging 4-10 except for one strain which had 3-16 phialides. All Thai strains have stipes smaller and somewhat longer than those of PLM 689.(ABSTRACT TRUNCATED AT 250 WORDS)

Hospitals, University↗
PubMed1977

The relationship between conidiation and alkaloid production in saprophytic strains of Claviceps purpurea.

A direct relationship between alkaloid synthesis and conidia formation was observed in a series of mutants of the saprophytic fungus Claviceps purpurea 129 which produces high quantities of clavine alkaloids (4500 microgram-ml-1). Sclerotia-like mutants forming mostly arthrospores and only a low number of conidiospores were exceptional in that they were characterized by an inverse relationship between alkaloid synthesis and conidial formation. Conidiospores of the parent strain 129 differed both in their size and ultrastructure. They include oval microconidia (2 X 3.5 micrometer) and prolonged macroconidia (2 X 10.5 micrometer). Both conidial types originated on short lateral sporophores terminated by phialids. Most conidia were characterized by electron-dense cytoplasm with a number of lipidic inclusions; a minority of conidia contained granular cytoplasm and vacuoles with membrane invaginations. Bicellular conidia were only rarely observed.

Claviceps↗
PubMed1975

Ultrastructural and electron cytochemical studies of Entomophthora coronata.

Aspects of the fine structure as well as electron cytochemical localization studies of certain hydrolytic enzymes were examined by electron microscopy of ultrathin sections of the vegatative hyphae and conidia of the phycomycetous fungus, Entomophthora coronata. This entomogenous fungal organism is of interest since it has been increasingly implicated as the etiologic agent of phycomycosis of man and animals. On thin section, hyphal cells were frequently observed with septa while the cytoplasm was multinucleate. The conidium was bound by a multilayered cell wall. The cytoplasm of ungerminated conidia characteristically contained large numbers of a class of cytoplasmic organelle found in loose aggregates with lipid storage bodies. Similar organelles were observed in the cytoplasm of hyphal cells from 7-day old cultures. This round to oval to slightly reniform structure was bound by a single limiting membrane and composed of an electron dense, slightly granular matrix without evidence of crystalloid formation. The limiting membrane of the lipid storage bodies was observed to be intimately associated with that of one or more of these microbody-like organelles. This intimate association of the two cytoplasmic organelles suggests that the microbody-like organelle may be involved in some manner with lipid metabolism during the life cycle of the fungus. Cautious interpretations of electron cytochemical localization studies suggested that lipase, nonspecific esterase, and possibly aryl sulfatase were associated with the microbody-like organelles. Neither peroxidatic nor acid phosphatase activity could be demonstrated with these organelles of the conidial cytoplasm.

Arylsulfatases↗