Occurrence and etiology of Alternaria leaf blotch and fruit spot of apple caused by Alternaria alternata f. sp. mali on cv. Pink lady in Israel

Gur, Lior; Reuveni, M.; Cohen, Yigal

doi:10.1007/s10658-016-1037-0

Cited by 46 publications

(48 citation statements)

References 27 publications

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“…There are two types of diseases caused by A. alternata on apple fruit, core rot (moldy core) and fruit spot. The A. alternata that causes apple core rot does not have the AMT gene found in the A. alternata apple pathotype (Reuveni et al, 2007;Gur et al, 2017); A. alternata strains without AMT can cause apple fruit spot as well as those with AMT (Rotondo et al, 2012;Harteveld et al, 2014;Gur et al, 2017). From an evolutionary perspective, our finding on sorbitol-modulated resistance to A. alternata R2 would be consistent with a scenario where, prior to gaining sorbitol-synthesizing capacity, apple leaves were susceptible to A. alternata R2, but gaining the capacity has allowed apples to fend off its attack on the leaves.…”

Section: Discussionmentioning

confidence: 99%

“…From an evolutionary perspective, our finding on sorbitol-modulated resistance to A. alternata R2 would be consistent with a scenario where, prior to gaining sorbitol-synthesizing capacity, apple leaves were susceptible to A. alternata R2, but gaining the capacity has allowed apples to fend off its attack on the leaves. On the Alternaria side, presence of abundant sorbitol in the leaves of apple might have prompted the evolution of new pathogenicity factors such as AM-toxin as found in A. alternata apple pathotype, a major pathogen causing leaf blotch of many apple varieties worldwide (Johnson et al, 2000;Rotondo et al, 2012;Li et al, 2013;Gur et al, 2017). As deletion of HRIP1 in A. alternata R2 enables gain of virulence on the leaves of wild-type 'Greensleeves' apple with normal sorbitol levels, this could be another evolutionary route for A. alternata to cope with sorbitol-modulated resistance in apple leaves.…”

Section: Discussionmentioning

confidence: 99%

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Sorbitol Modulates Resistance to Alternaria alternata by Regulating the Expression of an NLR Resistance Gene in Apple

et al. 2018

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In plant-microbe interactions, plant sugars produced by photosynthesis are not only a carbon source for pathogens, but may also act as signals that modulate plant defense responses. Here, we report that decreasing sorbitol synthesis in apple () leaves by antisense suppression of () leads to downregulation of 56 () genes and converts the phenotypic response to from resistant to susceptible. We identified a resistance protein encoded by the apple gene and a small protein encoded by the fungal gene that interact in both a yeast two-hybrid assay and a bimolecular fluorescence complementation assay. Deletion of in enables gain of virulence on the wild-type control plant. Overexpression of in two antisense lines increases resistance, whereas RNAi suppression of in the wild-type control decreases resistance against MdWRKY79 transcriptionally regulates by binding to the promoter of in response to sorbitol, and exogenous sorbitol feeding partially restores resistance of the antisense lines to These findings indicate that sorbitol modulates resistance to via the MdNLR16 protein that interacts with the fungal effector in a classic gene-for-gene manner in apple.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Sorbitol Modulates Resistance to Alternaria alternata by Regulating the Expression of an NLR Resistance Gene in Apple

et al. 2018

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“…Multiple Alternaria species have been implicated to cause leaf blotch and fruit spot of apple in many parts of the world (Filajdic and Sutton 1991;Gur et al 2017;Harteveld et al 2013;Rotondo et al 2012). In Australia, four species groups were found to be associated with these diseases, including the Alternaria arborescens, Alternaria tenuissima/Alternaria mali, Alternaria alternata/A.…”

Section: Discussionmentioning

confidence: 99%

Identification of Alternaria spp. as causal agent of dead flower buds disease of pear (Pyrus communis) in the Netherlands and methods for disease control

et al. 2019

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The occurrence of dead dormant flower buds is a common phenomenon of economic importance in the major pear production areas of Europe. Thus far, the cause of dead flower buds disease remained unknown. Several causes have been proposed, including insufficient tree chilling, unmet dormancy requirements, incompatibility between scion and cultivar, but also various biotic stress agents such as pathogens and pests. In this study, we tested the relationship between reduction of tree growth and dead flower bud incidences, but found no indication that growth regulation can prevent the occurrence of dead flower buds. It has been proposed that the bacterium Pseudomonas syringae pv. syringae may be the causal agent of dead flower buds of pear. However, although we found the bacterium as epiphyte and even as endophyte on and in flower buds, our findings argue that P. syringae pv. syringae is not the causal agent of dead flower buds disease in the Netherlands. In our research, Alternaria spp. were consistently found in diseased flower buds, and strong correlations between dead dormant flower buds and infection rates of flower buds with Alternaria spp. were recorded. The isolated Alternaria species were identified as A. arborescens SC and A. alternata SC. Field experiments for disease control showed that the disease may be controlled by specific fungicide applications. Thus, we propose that dead flower buds of pear in the Netherlands should be regarded as a fungal disease caused by A. alternata SC and potentially also A. arborescens SC.

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“…According to Gur et al. (), small‐spored Alternaria carrying the gene for AM ‐toxin biosynthesis are present in Israel. The pests (as A. mali ) are also present in Pakistan (CABI, )…”

Section: Pest Categorisationmentioning

confidence: 99%

Pest categorisation of small‐spored Alternaria carrying the genes for the AM‐ or AK‐toxin biosynthesis

Jeger¹,

Bragard²,

Caffier³

et al. 2017

EFS2

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The Panel on Plant Health performed a pest categorisation of small-spored Alternaria carrying the genes for the AM-or AK-toxin biosynthesis, for the EU. The identity of the pests is clearly defined and reliable methods exist for their detection/identification. They are listed in Annex IIAI of Directive 2000/29/EC as Alternaria alternata (non-European pathogenic isolates). Their distribution in the EU is restricted though with some uncertainty. The AM-toxin producer Alternaria affect Malus spp. and Pyrus communis (European pear), whereas the AK-toxin producer affect Pyrus pyrifolia, Pyrus bretschneideri and Pyrus ussuriensis (Asian pears). The pests could potentially enter the EU on host-planting material and fruit originating in infested countries. There are no biotic/abiotic factors limiting their potential establishment and spread in the EU, as their epidemiology is similar to that of other well-established Alternaria spp. Apples and European pears are widespread in the EU; Japanese pears are also present, but no data was found on their abundance/distribution. In the infested areas, the pests cause premature defoliation, fruit spotting and rot resulting in yield/quality losses. It is expected that the introduction and spread of the pests in the EU could impact apple and pear production, although the magnitude is unknown. Cultural practices and chemical measures may reduce the inoculum and the disease, but they cannot eliminate the pests. Phytosanitary measures are available to mitigate the risk of introduction and spread of the pests. The pests do not meet all the criteria assessed by EFSA for consideration as potential Union quarantine pests, as they are not under official control in those EU restricted areas where they have been found. The pests do not meet all the criteria assessed by EFSA to consider them as Union regulated non-quarantine pests, as host plants for planting are not the main means of pest spread.

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Occurrence and etiology of Alternaria leaf blotch and fruit spot of apple caused by Alternaria alternata f. sp. mali on cv. Pink lady in Israel

Cited by 46 publications

References 27 publications

Sorbitol Modulates Resistance to Alternaria alternata by Regulating the Expression of an NLR Resistance Gene in Apple

Sorbitol Modulates Resistance to Alternaria alternata by Regulating the Expression of an NLR Resistance Gene in Apple

Identification of Alternaria spp. as causal agent of dead flower buds disease of pear (Pyrus communis) in the Netherlands and methods for disease control

Pest categorisation of small‐spored Alternaria carrying the genes for the AM‐ or AK‐toxin biosynthesis

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