scholarly journals Role of Chitosan Extracted from Shrimp Waste in Controlling Tomato Blackmold Disease Caused by Alternaria alternata

2016 ◽  
Vol 5 (1) ◽  
pp. 47-57
Author(s):  
Ahmed Zian
Keyword(s):  
Alternaria Alternata ◽  
Shrimp Waste

scholarly journals The YAP1 Homolog–Mediated Oxidative Stress Tolerance Is Crucial for Pathogenicity of the Necrotrophic Fungus Alternaria alternata in Citrus

2009 ◽  
Vol 22 (8) ◽  
pp. 942-952 ◽  
Author(s):  
Ching-Hsuan Lin ◽  
Siwy Ling Yang ◽  
Kuang-Ren Chung
Keyword(s):  
Oxidative Stress ◽  
Alternaria Alternata ◽  
Critical Role ◽  
Disease Process ◽  
Brown Spot ◽  
Null Mutant ◽  
Wild Type ◽  
Protein Fusion ◽  
Fungal Pathogenicity

Citrus brown spot disease is caused by the necrotrophic fungus Alternaria alternata. Its pathogenic capability has been thought to depend exclusively on the production of host-selective ACT toxin. However, circumvention of plant defenses is also likely to be important for the disease process. To investigate the fungal response to host-generated reactive oxygen species (ROS), we cloned and characterized the AaAP1 gene of A. alternata, which encodes a polypeptide resembling yeast YAP1-like transcriptional activators implicated in cellular responses to stress. Expression of the AaAP1 gene in a wild-type strain was primarily induced by H2O2 or ROS-generating oxidants. Using a loss-of-function mutation in the AaAP1 gene, we demonstrated an essential requirement for oxidative tolerance during the host invasion step. Mutants lacking AaAP1 showed increased sensitivity to H2O2 and loss of fungal pathogenicity. The ΔAaAP1 null mutant did not cause any visible necrotic lesions on wounded or unwounded leaves of citrus cv. Minneola. Compared with the wild type, the null mutant displayed lower catalase, peroxidase, and superoxide dismutase activities. All mutant phenotypes were restored to the wild type in fungal strains expressing a functional copy of AaAP1. Upon exposure to H2O2, the AaAP1::sGFP (synthetic green fluorescent protein) fusion protein became localized in the nucleus. Inoculation of the mutant with NADPH oxidase inhibitors partially restored fungal pathogenicity. Our results highlight the global regulatory role of a YAP1 homolog in response to oxidative stress in A. alternata and provide insights into the critical role of ROS detoxification in the pathogenicity of A. alternata.

scholarly journals Effects of methyl jasmonate and gums formed in stone fruit trees on in vitro ethylene production by mycelium of verticillium dahliae and alternaria alternata

2013 ◽  
Vol 21 (2) ◽  
pp. 87-93
Author(s):  
Elżbieta Węgrzynowicz-Lesiak ◽  
Anna Jarecka Boncela ◽  
Justyna Góraj ◽  
Marian Saniewski
Keyword(s):  
Methyl Jasmonate ◽  
Verticillium Dahliae ◽  
Ethylene Production ◽  
Alternaria Alternata ◽  
Pathogenic Fungi ◽  
Fruit Trees ◽  
Stone Fruit ◽  
Mycelium Growth

ABSTRACT The knowledge about the role of jasmonates in ethylene production by pathogenic fungi is ambiguous. In this study, we describe the effect of methyl jasmonate (JA-Me) and gums formed in stone fruit trees on the growth and in vitro ethylene production by mycelium of Verticillium dahliae and Alternaria alternata. Methyl jasmonate at concentrations of 100, 250 and 500 μg·cm-3 inhibited the mycelium growth of V. dahliae and A. alternata, proportionally to the concentrations used. After 8 days of incubation, JA-Me at concentration of 500 μg·cm-3 limited the area of mycelium of these pathogens by 7-8 times but did not entirely inhibited the pathogen growth. Addition of gums produced by trees of cherry and peach to a medium containing 40 μg·cm-3 JA-Me did not influence the mycelium growth of V. dahliae, but gums of plum and apricot trees stimulated mycelium growth, in comparison to JA-Me only. Methyl jasmonate at concentrations of 2 and 40 μg·cm-3 stimulated the ethylene production by mycelium of V. dahliae and A. alternata. It is possible that methyl jasmonate stimulated ethylene production in mycelium of these pathogens through interaction with some fractions of galactans formed during hydrolysis of agar. The lack of interaction of JA-Me with polysaccharides of stone fruit trees gums concerning ethylene production was documented and it needs further explanation.

scholarly journals Phenylpropanoid metabolism enzyme activities and gene expression in postharvest melons inoculated with Alternaria alternata

2021 ◽  
Vol 64 (1) ◽  
Author(s):  
Yujia Bai ◽  
Zuoshan Feng ◽  
Maerhaba Paerhati ◽  
Jin Wang
Keyword(s):  
Gene Expression ◽  
Alternaria Alternata ◽  
Storage Period ◽  
Phenylpropanoid Metabolism ◽  
Lesion Diameter ◽  
Metabolism Enzymes ◽  
Coenzyme A Ligase ◽  
Metabolism Enzyme ◽  
Better Than

AbstractThis study explored the mechanism of melon resistance to Alternaria alternata (A. alternata) infection in Jiashi and 86-1 melons. Melons were inoculated with A.alternata and the change in lesion diameter was measured. The changes in cinnamic acid-4-hydroxylase (C4H), phenylalanine ammonia lyase (PAL), and 4-coumaric acid coenzyme A ligase (4CL) activity and gene expression were studied in the pericarp tissues of Jiashi and 86-1 melons. The lesion diameter was smaller in Jiashi melon than in 86-1 melon, and the pericarp lesions were smaller than pulp lesions, indicating that Jiashi melon can resist A. alternata infection better than 86-1 melon. After inoculation with A. alternata, the C4H, PAL, and 4CL activities of Jiashi and 86-1 melons peaked in the middle and late storage period, and the peak was higher in Jiashi melons. The gene expression changes were consistent with the enzyme activity. The C4H, PAL, and 4CL gene expression was significantly higher in Jiashi melon pericarp than in 86-1 melon, and the C4H, PAL, and 4CL activities in Jiashi melon were positively correlated with their gene expression, confirming the role of phenylpropanoid metabolism enzymes in resistance to A. alternata.

scholarly journals Histone acetyltransferases and deacetylases are required for virulence, conidiation, DNA damage repair, and multiple stresses resistance of Alternaria alternata

2021 ◽  
Author(s):  
Haijie Ma ◽  
Lei Li ◽  
Yunpeng Gai ◽  
Xiaoyan Zhang ◽  
Yanan Chen ◽  
...  
Keyword(s):  
Dna Damage ◽  
Carbon Source ◽  
Alternaria Alternata ◽  
Gene Deletion ◽  
Dna Damage Repair ◽  
Histone Acetyltransferases ◽  
Deletion Mutants ◽  
Multiple Stresses ◽  
Damage Repair

Histone acetylation, which is critical for transcriptional regulation and various biological processes in eukaryotes, is a reversible dynamic process regulated by HATs and HDACs. This study determined the function of 6 histone acetyltransferases (HATs) (Gcn5, RTT109, Elp3, Sas3, Sas2, Nat3) and 6 histone deacetylases (HDACs) (Hos2, Rpd3, Hda1, Hos3, Hst2, Sir2) in the phytopathogenic fungus Alternaria alternata by analyzing targeted gene deletion mutants. Our data provide evidence that HATs and HDACs are both required for mycelium growth, cell development and pathogenicity as many gene deletion mutants (ΔGcn5, ΔRTT109, ΔElp3, ΔSas3, ΔNat3, ΔHos2, and ΔRpd3) displayed reduced growth, conidiation or virulence at varying degrees. In addition, HATs and HDACs are involved in the resistance to multiple stresses such as oxidative stress (Sas3, Gcn5, Elp3, RTT109, Hos2), osmotic stress (Sas3, Gcn5, RTT109, Hos2), cell wall-targeting agents (Sas3, Gcn5, Hos2), and fungicide (Gcn5, Hos2). ΔGcn5, ΔSas3 and ΔHos2 displayed severe growth defects on sole carbon source medium suggesting a vital role of HATs and HDACs in carbon source utilization. More SNPs were generated in ΔGcn5 in comparison to wild-type when they were exposed to ultraviolet ray. Moreover, ΔRTT109, ΔGcn5 and ΔHos2 showed severe defects in resistance to DNA-damaging agents, indicating the critical role of HATs and HDACs in DNA damage repair. These phenotypes correlated well with the differentially expressed genes in ΔGcn5 and ΔHos2 that are essential for carbon sources metabolism, DNA damage repair, ROS detoxification, and asexual development. Furthermore, Gcn5 is required for the acetylation of H3K4. Overall, our study provides genetic evidence to define the central role of HATs and HDACs in the pathological and biological functions of A. alternata.

Role of Seed Mycoflora on Seed Germination of Oroxylum indicum (L.) Vent. in Kumaun region of Indian Central Himalaya

2013 ◽  
Vol 36 (1) ◽  
pp. 83-89
Author(s):  
Bhawana Pande ◽  
R. Gupta
Keyword(s):  
Aspergillus Niger ◽  
Seed Germination ◽  
Trichoderma Harzianum ◽  
Fusarium Solani ◽  
Alternaria Alternata ◽  
Alternaria Solani ◽  
Central Himalaya ◽  
Oroxylum Indicum ◽  
Indian Central

A number of fungus was isolated from the seeds of Oroxylum indicum (L.) Vent. The mycoflora associated with the seeds of this tree have not been previously reported from Kumaun region of Indian Central Himalaya. During the course of study mycoflora such as Fusarium solani, Aspergillus niger, Aspergillus nidulens, Penicillium sp., Trichoderma harzianum, Alternaria solani, Alternaria alternata, Curvolaria lunata., Stachybotryis chartarum, Acremonium sp., Rhizoctonia solani, Chaetomium globosum, Cladosporium cladoporoides and Torula allii were isolated from the seeds.

scholarly journals Calcineurin phosphatase and phospholipase C are required for developmental and pathological functions in the citrus fungal pathogen Alternaria alternata

Microbiology ◽  
2014 ◽  
Vol 160 (7) ◽  
pp. 1453-1465 ◽  
Author(s):  
Hsieh-Chin Tsai ◽  
Kuang-Ren Chung
Keyword(s):  
Phospholipase C ◽  
Alternaria Alternata ◽  
Dynamic Equilibrium ◽  
Wild Type ◽  
Targeted Gene Disruption ◽  
Conidial Formation ◽  
Calcineurin Phosphatase ◽  
Cellular Ca ◽  
Type Infection

Excessive Ca2+ or compounds interfering with phosphoinositide cycling have been found to inhibit the growth of the tangerine pathotype of Alternaria alternata, suggesting a crucial role of Ca2+ homeostasis in this pathotype. The roles of PLC1, a phospholipase C-coding gene and CAL1, a calcineurin phosphatase-coding gene were investigated. Targeted gene disruption showed that both PLC1 and CAL1 were required for vegetative growth, conidial formation and pathogenesis in citrus. Fungal strains lacking PLC1 or CAL1 exhibited extremely slow growth and induced small lesions on calamondin leaves. Δplc1 mutants produced fewer conidia, which germinated at slower rates than wild-type. Δcal1 mutants produced abnormal hyphae and failed to produce any mature conidia, but instead produced highly melanized bulbous hyphae with distinct septae. Fluorescence microscopy using Fluo-3 dye as a Ca2+ indicator revealed that the Δplc1 mutant hyphae emitted stronger cytosolic fluorescence, and the Δcal1 mutant hyphae emitted less cytosolic fluorescence, than those of wild-type. Infection assessed on detached calamondin leaves revealed that application of CaCl2 or neomycin 24 h prior to inoculation provided protection against Alt. alternata. These data indicate that a dynamic equilibrium of cellular Ca2+ is critical for developmental and pathological processes of Alt. alternata.

A novel role of ammonia in appressorium formation of Alternaria alternata (Fries) Keissler, a tobacco pathogenic fungus

2010 ◽  
Vol 117 (3) ◽  
pp. 112-116 ◽  
Author(s):  
W. J. Duan ◽  
X. Q. Zhang ◽  
T. Z. Yang ◽  
X. W. Dou ◽  
T. G. Chen ◽  
...  
Keyword(s):  
Alternaria Alternata ◽  
Pathogenic Fungus ◽  
Appressorium Formation

scholarly journals Endopolygalacturonase Is Essential for Citrus Black Rot Caused by Alternaria citri but Not Brown Spot Caused by Alternaria alternata

2001 ◽  
Vol 14 (6) ◽  
pp. 749-757 ◽  
Author(s):  
Atsunori Isshiki ◽  
Kazuya Akimitsu ◽  
Mikihiro Yamamoto ◽  
Hiroyuki Yamamoto
Keyword(s):  
Cell Wall ◽  
Alternaria Alternata ◽  
Biochemical Properties ◽  
Brown Spot ◽  
Black Rot ◽  
Citrus Peel ◽  
Degrading Enzyme ◽  
Cell Wall Degrading Enzyme ◽  
A Cell

Alternaria citri, the cause of Alternaria black rot, and Alternaria alternata rough lemon pathotype, the cause of Alternaria brown spot, are morphologically indistinguishable pathogens of citrus: one causes rot by macerating tissues and the other causes necrotic spots by producing a host-selective toxin. To evaluate the role of endopolygalacturonase (endoPG) in pathogenicity of these two Alternaria spp. pathogens, their genes for endoPG were mutated by gene targeting. The endoPGs produced by these fungi have similar biochemical properties, and the genes are highly similar (99.6% nucleotide identity). The phenotypes of the mutants, however, are completely different. An endoPG mutant of A. citri was significantly reduced in its ability to cause black rot symptoms on citrus as well as in the maceration of potato tissue and could not colonize citrus peel segments. In contrast, an endoPG mutant of A. alternata was unchanged in pathogenicity. The results indicate that a cell wall-degrading enzyme can play different roles in the pathogenicity of fungal pathogens. The role of a cell wall-degrading enzyme depends upon the type of disease but not the taxonomy of the fungus.

scholarly journals Effectiveness of mycorrhizal fungi in the protection of juniper, rose, yew and highbush blueberry against Alternaria alternata

2019 ◽  
Vol 31 (1) ◽  
pp. 117-127 ◽  
Author(s):  
Stanisław Mazur ◽  
Małgorzata Nadziakiewicz ◽  
Halina Kurzawińska ◽  
Jacek Nawrocki
Keyword(s):  
Alternaria Alternata ◽  
Mycorrhizal Fungi ◽  
Morphological Characteristics ◽  
Protective Role ◽  
Highbush Blueberry ◽  
Pathogenicity Test ◽  
Growth Substrate ◽  
Whole Plants ◽  
Pathogenic Effects

AbstractAfter conducting two-year observations in nurseries in the Małopolska province, Poland, the species of shrubs on which symptoms of discoloration and withering of the leaves/needles and shoots, and sometimes of whole plants, occurred most frequently were selected for further study. The species included juniper (Juniperus horizontalis ‘Wiltonii’, rose (Rosa ‘Star Profusion’), yew (Taxus × media ‘Hillii’) and highbush blueberry (Vaccinum corymbosum ‘Patriot’). The predominant fungus isolated from the diseased plants was Alternaria alternata (Fr.) Keissl. A pathogenicity test performed in the laboratory confirmed the pathogenic effects of A. alternata on all of the tested species of shrubs. In 2011-2014, a field experiment was conducted with A. alternata inoculum introduced into the growth substrate. The presence of the pathogen reduced considerably the annual growth of all the shrubs tested. The applied mycorrhizal inocula had an effect on some morphological characteristics of plants, such as height and number of shoots. Moreover, the plants whose roots had been treated with the mycorrhizal inocula and were grown in the substrate inoculated with the pathogen also achieved greater increases in growth in comparison with the plants treated with the pathogen as well as relative to the control. The protective role of mycorrhizal inocula against the damaging effects of the pathogen was evident in all the species of shrubs.

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