Toxins Produced by Valsa mali var. mali and Their Relationship with Pathogenicity

Wang, Caixia; Li, Chao; Li, Baohua; Li, Guifang; Dong, Xiangli; Wang, Guoping; Zhang, Qingming

doi:10.3390/toxins6031139

Cited by 32 publications

(41 citation statements)

References 23 publications

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“…This is different from many other Ascomycetes in which 1,8‐dihydroxynaphthalene (DHN) melanin plays a role in virulence (Langfelder et al ., ; Ludwig et al ., ; Woo et al ., ). However, some other secondary metabolites, such as 3‐( p ‐hydroxyphenyl)propanoic acid and p ‐hydroxybenzoic acid, have been shown to be involved in virulence in V. mali (Wang C. et al ., ). Therefore, whether VmVeA and VmVelB are involved in virulence in connection with these secondary metabolites requires further research.…”

Section: Discussionmentioning

confidence: 97%

Two members of the velvet family, VmVeA and VmVelB, affect conidiation, virulence and pectinase expression in Valsa mali

Xu²,

Yin³

et al. 2018

Molecular Plant Pathology

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Velvet protein family members are important fungal-specific regulators which are involved in conidial development, secondary metabolism and virulence. To gain a broader insight into the physiological functions of the velvet protein family of Valsa mali, which causes a highly destructive canker disease on apple, we conducted a functional analysis of two velvet protein family members (VmVeA and VmVelB) via a gene replacement strategy. Deletion mutants of VmVeA and VmVelB showed increased melanin production, conidiation and sensitivity to abiotic stresses, but exhibited reduced virulence on detached apple leaves and twigs. Further studies demonstrated that the regulation of conidiation by VmVeA and VmVelB was positively correlated with the melanin synthesis transcription factor VmCmr1. More importantly, transcript levels of pectinase genes were shown to be decreased in deletion mutants compared with those of the wild-type during infection. However, the expression of other cell wall-degrading enzyme genes, including cellulase, hemi-cellulase and ligninase genes, was not affected in the deletion mutants. Furthermore, the determination of pectinase activity and immunogold labelling of pectin demonstrated that the capacity for pectin degradation was attenuated as a result of deletions of VmVeA and VmVelB. Finally, the interaction of VmVeA with VmVelB was identified through co-immunoprecipitation assays. VmVeA and VmVelB play critical roles in conidiation and virulence, probably via the regulation of the melanin synthesis transcription factor VmCmr1 and their effect on pectinase gene expression in V. mali, respectively.

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Section: Discussionmentioning

confidence: 97%

Two members of the velvet family, VmVeA and VmVelB, affect conidiation, virulence and pectinase expression in Valsa mali

Xu²,

Yin³

et al. 2018

Molecular Plant Pathology

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“…Moreover, the pathogen degraded phloridzin directly for the production of toxins [i.e. phloroglucinol, protocatechuic acid, p-hydroxybenzoic acid, 3-(p-hydroxyphenyl)propanoic acid, and p-hydroxyacetophenone] that facilitated necrosis in apple bark (Koganezawa and Sakuma, 1982;Natsume et al, 1982;Wang et al, 2014). Even so, there were no clear correlations between Valsa canker resistance and phloridzin levels (Bessho et al, 1994).…”

mentioning

confidence: 99%

“…the extensive penetration of its pathogen into host phloem and xylem, Valsa canker cannot be controlled effectively with agricultural chemicals (Yin et al, 2015). To date, microRNAs (Feng et al, 2017), pathogenic effectors (Zhang et al, 2018), toxic compounds (Natsume et al, 1982;Wang et al, 2014), and cell wall-degrading enzymes (Yin et al, 2015) have been implicated in the pathogenicity of V. mali. Previous work has shed light on the management of apple Valsa canker.…”

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confidence: 99%

MdUGT88F1-Mediated Phloridzin Biosynthesis Regulates Apple Development and Valsa Canker Resistance

Zhou

et al. 2019

Plant Physiol.

103

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In apple (Malus domestica), the polyphenol profile is dominated by phloridzin, but its physiological role remains largely elusive. Here, we used MdUGT88F1 (a key UDP-glucose:phloretin 2'-O-glucosyltransferase gene) transgenic apple lines and Malus spp. germplasm to gain more insight into the physiological role of phloridzin in apple. Decreasing phloridzin biosynthesis in apple lines by RNA silencing of MdUGT88F1 led to a series of severe phenotypic changes that included severe stunting, reduced internode length, spindly leaf shape, increased stem numbers, and weak adventitious roots. These changes were associated directly with reduced lignin levels and disorders in cell wall polysaccharides. Moreover, compact organization of tissues and thickened bark enhanced resistance to Valsa canker (caused by the fungus Valsa mali), which was associated with lignin-and cell wall polysaccharide-mediated increases of salicylic acid and reactive oxygen species. Phloridzin was also assumed to be utilized directly as a sugar alternative and a toxin accelerator by V. mali in apple. Therefore, after infection with V. mali, a higher level of phloridzin slightly compromised resistance to Valsa canker in MdUGT88F1-overexpressing apple lines. Taken together, our results shed light on the importance of MdUGT88F1-mediated biosynthesis of phloridzin in the interplay between plant development and pathogen resistance in apple trees.

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“…Strains were single-hyphen propagated to obtain pure cultures on PDA medium (potato dextrose agar) and maintained on PDA slants at 4°C [8]. …”

Section: Methodsmentioning

confidence: 99%

Induction of Resistance Mediated by an Attenuated Strain ofValsa malivar.maliUsing Pathogen-Apple Callus Interaction System

Zhang

Wang

Yong

et al. 2014

The Scientific World Journal

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To study the induced resistance in apple against Valsa mali var. mali (Vmm), a Vmm–apple callus interaction system was developed to evaluate the induced resistance of an attenuated Vmm strain LXS081501 against further infection by a virulent Vmm strain LXS080601. The infection index was up to 97.32 for apple calli inoculated with LXS080601 alone at 15 days after inoculation whereas it was only 41.84 for calli pretreated with LXS081501 followed by LXS080601 inoculation. In addition, the maximum levels of free proline, soluble sugar, and protein in calli treated with LXS081501 plus LXS080601 were 2.14 to 3.47 times higher than controls and 1.42 to 1.75 times higher than LXS080601 treatment. The activities of defense-related enzymes such as phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), peroxidase (POD), and catalase (CAT) as well as β-1,3-glucanase and chitinase in apple calli inoculated with LXS080601 alone or LXS081501 plus LXS080601 increased significantly 24 hai and peaked from 48 to 120 hpi. However, in the latter treatment, the maximum enzyme activities were much higher and the activities always maintained much higher levels than control during the experimental period. These results suggested the roles of osmotic adjustment substances and defense-related enzymes in induced resistance.

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Toxins Produced by Valsa mali var. mali and Their Relationship with Pathogenicity

Cited by 32 publications

References 23 publications

Two members of the velvet family, VmVeA and VmVelB, affect conidiation, virulence and pectinase expression in Valsa mali

Two members of the velvet family, VmVeA and VmVelB, affect conidiation, virulence and pectinase expression in Valsa mali

MdUGT88F1-Mediated Phloridzin Biosynthesis Regulates Apple Development and Valsa Canker Resistance

Induction of Resistance Mediated by an Attenuated Strain ofValsa malivar.maliUsing Pathogen-Apple Callus Interaction System

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