The desmidclosterium pusillumHantzsch from two terraqueous habitats, with observations on asexual spore production

1992 ◽  
Vol 27 (4) ◽  
pp. 409-416 ◽  
Author(s):  
A.J. Brook
Keyword(s):  
Spore Production ◽  
Asexual Spore

scholarly journals Endogenous Lipogenic Regulators of Spore Balance in Aspergillus nidulans

2004 ◽  
Vol 3 (6) ◽  
pp. 1398-1411 ◽  
Author(s):  
Dimitrios I. Tsitsigiannis ◽  
Terri M. Kowieski ◽  
Robert Zarnowski ◽  
Nancy P. Keller
Keyword(s):  
Transcription Factors ◽  
Fatty Acid ◽  
Aspergillus Nidulans ◽  
Filamentous Fungus ◽  
Spore Production ◽  
Feedback Loops ◽  
Data Support ◽  
Asexual Spore ◽  
Genes Encoding

ABSTRACT The ability of fungi to produce both meiospores and mitospores has provided adaptive advantages in survival and dispersal of these organisms. Here we provide evidence of an endogenous mechanism that balances meiospore and mitospore production in the model filamentous fungus Aspergillus nidulans. We have discovered a putative dioxygenase, PpoC, that functions in association with a previously characterized dioxygenase, PpoA, to integrate fatty acid derived oxylipin and spore production. In contrast to PpoA, deletion of ppoC significantly increased meiospore production and decreased mitospore development. Examination of the PpoA and PpoC mutants indicate that this ratio control is associated with two apparent feedback loops. The first loop shows ppoC and ppoA expression is dependent upon, and regulates the expression of, nsdD and brlA, genes encoding transcription factors required for meiospore or mitospore production, respectively. The second loop suggests Ppo oxylipin products antagonistically signal the generation of Ppo substrates. These data support a case for a fungal “oxylipin signature-profile” indicative of relative sexual and asexual spore differentiation.

scholarly journals Influence of physiological factors on growth, sporulation and ochratoxin A/B production of the new Aspergillus ochraceus grouping

2009 ◽  
Vol 2 (4) ◽  
pp. 429-434 ◽  
Author(s):  
A. Abdel-Hadi ◽  
N. Magan
Keyword(s):  
Ochratoxin A ◽  
Maximum Growth ◽  
Spore Production ◽  
Aspergillus Ochraceus ◽  
Optimum Temperature ◽  
Physiological Factors ◽  
Large Numbers ◽  
Asexual Spore ◽  
The Impact ◽  
First Time

Recently, new species within the Aspergillus section Circumdati group responsible for ochratoxin production were reported. This study has examined the impact of interactions between water activity (aw, 0.99-0.90), temperature (20-35 °C) on growth, asexual spore production and ochratoxin A and B (OTA and OTB) on strains of each of the three species from this new grouping (A. ochraceus, A. steynii, and A. westerdijkiae) for the first time. The maximum growth occurred at 0.95 aw and 30 °C for both A. ochraceus and A. westerdijkiae, while it was at 0.99 aw and 30 °C for A. steynii. No conidial spore production occurred at 0.99 aw in cultures of A. ochraceus and A. steynii but large numbers of spores (2.3×107/cm2) were produced by A. westerdijkiae. Optimum temperature for spore production was 0.95 aw and 30 °C for A. westerdijkiae and A. ochraceus, and 0.95 aw and 35 °C for A. steynii. Quantification of OTA showed that optimum was produced at 0.99 aw, by A. steynii at 30 °C, for A. westerdijkiae at 25 °C and for A. ochraceus at 20 °C. As water stress was imposed (0.95 aw), the temperature for maximum OTA production changed. For example, for A. steynii and A. westerdijkiae this was at 35 °C, for A. ochraceus, 25 °C. Much less OTB was produced relative to OTA, but the production followed the same pattern at all aw levels and temperatures. This is the first detailed study to examine the similarities and differences in ecology of these related species in this important mycotoxigenic group.

scholarly journals Sporogenic Effect of Polyunsaturated Fatty Acids on Development of Aspergillus spp

1999 ◽  
Vol 65 (8) ◽  
pp. 3668-3673 ◽  
Author(s):  
Ana M. Calvo ◽  
Lori L. Hinze ◽  
Harold W. Gardner ◽  
Nancy P. Keller
Keyword(s):  
Fatty Acids ◽  
Linoleic Acid ◽  
Aspergillus Parasiticus ◽  
Spore Production ◽  
Fungal Colonization ◽  
Fungal Development ◽  
Spore Development ◽  
Environmental Signals ◽  
Asexual Spore ◽  
Sclerotium Production

ABSTRACT Aspergillus spp. are frequently occurring seed-colonizing fungi that complete their disease cycles through the development of asexual spores, which function as inocula, and through the formation of cleistothecia and sclerotia. We found that development of all three of these structures in Aspergillus nidulans,Aspergillus flavus, and Aspergillus parasiticusis affected by linoleic acid and light. The specific morphological effects of linoleic acid include induction of precocious and increased asexual spore development in A. flavus and A. parasiticus strains and altered sclerotium production in someA. flavus strains in which sclerotium production decreases in the light but increases in the dark. In A. nidulans, both asexual spore production and sexual spore production were altered by linoleic acid. Spore development was induced in all three species by hydroperoxylinoleic acids, which are linoleic acid derivatives that are produced during fungal colonization of seeds. The sporogenic effects of these linoleic compounds on A. nidulans are similar to the sporogenic effects of A. nidulans psi factor, an endogenous mixture of hydroxylinoleic acid moieties. Light treatments also significantly increased asexual spore production in all three species. The sporogenic effects of light, linoleic acid, and linoleic acid derivatives on A. nidulans required an intactveA gene. The sporogenic effects of light and linoleic acid on Aspergillus spp., as well as members of other fungal genera, suggest that these factors may be significant environmental signals for fungal development.

Mechanism for the Suppression of pea (Pisum sativum) Root Rot by Dinitroaniline Herbicides

Weed Science ◽  
1979 ◽  
Vol 27 (2) ◽  
pp. 195-201 ◽  
Author(s):  
J. R. Teasdale ◽  
R. G. Harvey ◽  
D. J. Hagedorn
Keyword(s):  
Pisum Sativum ◽  
Root Rot ◽  
Solution Culture ◽  
Spore Production ◽  
Aphanomyces Euteiches ◽  
Sensitive Stage ◽  
Zoospore Production ◽  
Asexual Spore ◽  
Pea Roots ◽  
Dinitroaniline Herbicides

Pea (Pisum sativumL. ‘Elf’) root rot suppression by dinitroaniline herbicides could not be explained by a direct effect on the host. Pre-incubation of pea roots with 0.1 ppmw of oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide) or trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) in solution culture did not alter their resistance to root rot. Furthermore, 0.1 ppmw of oryzalin or trifluralin did not alter the exudation of electrolytes or α-amino compounds from pea roots. Most of the dinitroaniline herbicides significantly inhibited mycelial radial growth of pathogen,Aphanomyces euteichesDrechs., at 1.0 ppmw and inhibited asexual spore production at 0.1 to 1.0 ppmw. Dinitramine (N4,N4-diethyl-α,α,α-trifluoro-3,5-dinitrotoluene-2,4-diamine), fluchloralin [N-(2-chloroethyl)-2,6-dinitro-N-propyl-4-(trifluoromethyl)aniline], and oryzalin inhibitedA. euteichesmycelial growth and asexual reproduction more effectively than the other dinitroaniline herbicides studied. The production of motile zoospores, the infecting propagule of the pathogen, was the most sensitive stage in the life cycle and was completely inhibited by 0.01 ppmw of all dinitroaniline herbicides tested. Since this concentration is below that estimated in the soil solution at registered rates of application, inhibition of motile zoospore production is sufficient to explain root rot suppression. Inhibition of pathogen motility resulted in a 2-week delay in the infection of pea roots. This delay allowed sufficient additional plant growth that the peas could better withstand the effects of subsequent disease development.

scholarly journals Primary Characterization of a Life-Cycle Mutant akasusabi of the Red Alga Neopyropia yezoensis

Phycology ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 14-26
Author(s):  
Koji Mikami ◽  
Takaharu Matsumura ◽  
Yuji Yamamoto
Keyword(s):  
Life Cycle ◽  
Red Alga ◽  
Spore Production ◽  
Red Seaweed ◽  
Timing Of Reproduction ◽  
Male And Female ◽  
Trade Off ◽  
Highly Sensitive ◽  
Asexual Spore

Gametophyte-to-sporophyte transition in the haploid-diploid life cycle depends on fertilization of male and female gametes. We describe here a mutant of the marine red seaweed Neopyropia yezoensis, designated akasusabi (aks), where the gametophyte-to-sporophyte transition occurs independently of fertilization. Although conchocelis filaments were produced from carpospores, severe defects in the maturation of carposporangia via mitosis to generate conchospores were observed. In the aks mutant, however, somatic cells of gametophytic thalli were able to produce conchocelis filaments without fertilization. Thus, apogamy occurs in aks. In addition, aks was highly sensitive to wounding that promotes both asexual and apogamous reproductive responses by producing spores, which develop either into blades or conchocelis filaments, indicating that aks responds to wounding by enhanced reproduction. These findings indicated that the aks mutation enables the transformation of vegetative cells to carpospores to produce sporophytes by apogamy and wound-inducible life cycle trade-off, stimulating a reset of the timing of reproduction during the life cycle. Therefore, AKS is involved in regulations of the gametophyte-to-sporophyte transition and asexual spore production in N. yezoensis.

scholarly journals A Small Horizontally Transferred Gene Cluster Contributes to the Sporulation of Alternaria alternata

2019 ◽  
Vol 11 (12) ◽  
pp. 3436-3444 ◽  
Author(s):  
Mingshuang Wang ◽  
Huilan Fu ◽  
Ruoxin Ruan
Keyword(s):  
Gene Cluster ◽  
Alternaria Alternata ◽  
Phylogenetic Trees ◽  
Single Gene ◽  
Growth Stress ◽  
Spore Production ◽  
Brown Spot ◽  
Plant Materials ◽  
Asexual Spore ◽  
Protein Encoding

Abstract Horizontal gene transfer (HGT) has been identified as an important source of genomic innovation in fungi. However, how HGT drove the evolution of Alternaria alternata, a necrotrophic fungus which can be ubiquitously isolated from soil and various plants and decaying plant materials is largely known. In this study, we identified 12 protein-encoding genes that are likely acquired from lineages outside Pezizomycotina. Phylogenetic trees and approximately unbiased comparative topology tests strongly supported the evolutionary origin of these genes. According to their predicted functions, these HGT candidates are involved in nitrogen and carbohydrate metabolism. Especially, five genes of them were likely transferred as a physically linked cluster from Tremellales (Basidiomycota). Functionally knocking out the five-gene cluster in an A. alternata isolate causing citrus brown spot resulted in an 80% decrease in asexual spore production in the deletion mutant. We further knocked out each of these five genes in this cluster and the resultant single-gene deletion mutants exhibited a various degree of reduction in spore production. Except for conidiation, functions of these genes associated with vegetative growth, stress tolerance, and virulence are very limited. Our results provide new evidence that HGT has played important roles over the course of the evolution of filamentous fungi.

scholarly journals Outbreak of Leaf Spot and Fruit Rot in Florida Strawberry Caused by Neopestalotiopsis spp.

Plant Disease ◽  
2021 ◽  
pp. PDIS-06-20-1290
Author(s):  
Juliana S. Baggio ◽  
Bruna B. Forcelini ◽  
Nan-Yi Wang ◽  
Rafaela G. Ruschel ◽  
James C. Mertely ◽  
...  
Keyword(s):  
Internal Transcribed Spacer ◽  
Phylogenetic Analyses ◽  
Morphological Characteristics ◽  
Taxonomic Status ◽  
Spore Production ◽  
Potato Dextrose Agar ◽  
Fruit Rot ◽  
Low Genetic Diversity ◽  
Pathogenicity Tests ◽  
A New Species

Pestalotiopsis-like species have been reported affecting strawberry worldwide. Recently, severe and unprecedented outbreaks have been reported in Florida commercial fields where leaf, fruit, petiole, crown, and root symptoms were observed, and yield was severely affected. The taxonomic status of the fungus is confusing because it has gone through multiple reclassifications over the years. Morphological characteristics, phylogenetic analyses, and pathogenicity tests were evaluated for strawberry isolates recovered from diseased plants in Florida. Phylogenetic analyses derived from the combined internal transcribed spacer, β-tub, and tef1 regions demonstrated that although there was low genetic diversity among the strawberry isolates, there was a clear separation of the isolates in two groups. The first group included isolates recovered over a period of several years, which was identified as Neopestalotiopsis rosae. Most isolates recovered during the recent outbreaks were genetically different and may belong to a new species. On potato dextrose agar, both groups produced white, circular, and cottony colonies. From the bottom, colonies were white to pale yellow for Neopestalotiopsis sp. and pale luteous to orange for N. rosae. Spores for both groups were five-celled with three median versicolored cells. Mycelial growth and spore production were higher for the new Neopestalotiopsis sp. isolates. Isolates from both groups were pathogenic to strawberry roots and crowns. However, the new Neopestalotiopsis sp. proved more aggressive in fruit and leaf inoculation tests, confirming observations from the recent outbreaks in commercial strawberry fields in Florida.

Dimorphic spore production in the genus Acaulospora

Mycoscience ◽  
2014 ◽  
Vol 55 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Andrew Taylor ◽  
Christopher Walker ◽  
Gary D. Bending
Keyword(s):  
Spore Production
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