Blight Sensitivity of Spanish Selections of J. Regia

Aletà, N.; Ninot, A.; Moragrega, C.; Llorente, Isidre; Montesinos, E.

doi:10.17660/actahortic.2001.544.47

Cited by 12 publications

(13 citation statements)

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“…In addition, two strains (12763 and 12785) isolated from VOC induced the same necrotic symptoms as the strain CFBP 2528 isolated from walnut blight when they were inoculated in immature fruit according to the technique described by Aletà et al. (2001).…”

Section: Resultsmentioning

confidence: 91%

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Identification of a genetic lineage within Xanthomonas arboricola pv. juglandis as the causal agent of vertical oozing canker of Persian (English) walnut in France

Hajri

Meyer

Delort³

et al. 2010

Plant Pathology

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A new bacterial disease of Persian (English) walnut (Juglans regia) has been observed in France. This disease, called vertical oozing canker (VOC), is characterized by vertical cankers on trunks and branches of affected walnut trees with oozing exudates. To determine the aetiology of the disease, a study was carried out in 79 walnut orchards and nurseries located in southeastern and southwestern France. Bacterial analysis from diseased samples yielded 36 strains identified as Xanthomonas arboricola and 32 strains identified as Brenneria nigrifluens on the basis of biochemical tests. The causal agent of VOC was identified as X. arboricola by pathogenicity tests on walnut. Fluorescent amplified fragment length polymorphism (F-AFLP) was carried out on 36 strains of X. arboricola collected in this study, 24 strains of X. arboricola pv. juglandis isolated from walnut blight symptoms and one strain of X. arboricola pv. corylina included as an outgroup. Based on cluster analysis of F-AFLP data, most X. arboricola strains responsible for main VOC outbreaks showed a high degree of similarity, forming a cluster clearly separate from strains of X. arboricola pv. juglandis isolated from walnut blight symptoms. It is suggested that VOC is caused by a distinct genetic lineage within the pathovar juglandis of X. arboricola that is also able to cause classical bacterial blight symptoms on walnut leaves and fruits.

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Section: Resultsmentioning

confidence: 91%

“…The pathogenicity of four strains (CFBP 1022, CFBP 2528, 12763 and 12785) representative of the bacterial collection was also tested on immature fruits following the technique described by Aletà et al. (2001).…”

Section: Methodsmentioning

confidence: 99%

Identification of a genetic lineage within Xanthomonas arboricola pv. juglandis as the causal agent of vertical oozing canker of Persian (English) walnut in France

Hajri

Meyer

Delort³

et al. 2010

Plant Pathology

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“…Before inoculation, fruits were disinfected with 5% sodium hypochlorite for 5 min, rinsed with distilled water three times, and dried on clean tissue paper. Inoculation was performed using a syringe with a 10 8 cfu/ml bacterial suspension of Xaj strain 417 (Pereira et al , ), grown on yeast extract peptone (YEP) medium at 28 °C for 3 days (Aleta et al , ). Fifteen fruits of each cultivar were inoculated at three locations each with Xaj and placed in plastic boxes lined with moist paper towel at 25 °C under a 16 hr light photoperiod for 8 days.…”

Section: Methodsmentioning

confidence: 99%

Functional analysis of walnut polyphenol oxidase gene (JrPPO1) in transgenic tobacco plants and PPO induction in response to walnut bacterial blight

et al. 2020

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Walnut (Juglans regia) is economically important for both its wood and nut nutritional value, but it is susceptible to diseases such as walnut bacterial blight, caused by Xanthomonas arboricola pv. juglandis (Xaj). Walnuts contain many phenolic compounds, providing a good model on which to study polyphenol oxidase (PPO). We inoculated the detached walnut fruits of cultivars Ford, Chandler, Franquette, Robert Livermore, and Payne with Xaj and measured the induction of PPO activity in infected sites and adjacent to infected sites. Compared to infected and uninfected sites, PPO activity was induced significantly in areas adjacent to infected sites in all cultivars except Ford. Ford and Franquette, presenting the lowest and highest PPO activity, showed the largest and smallest mean diameter spots in response to Xaj, respectively. Polyacrylamide gel electrophoresis confirmed monophenol oxidase activity of walnut PPO in the assessed tissues. Then, we revealed the antipathogenic potential of walnut PPO through Agrobacterium tumefaciens‐mediated walnut JrPPO1 gene transfer into tobacco (Nicotiana tabacum). Two transformed tobacco lines overexpressing the JrPPO1 gene were regenerated successfully and challenged with Pseudomonas syringae pv. tabaci. Transgenic lines showed significantly higher PPO activity and lower disease severity to the pathogen compared to the control. However, a significant difference in disease severity and PPO activity level was observed between the two transgenic lines. Our results demonstrate a potential defence‐related role of PPO in transgenic tobacco and its induction in areas adjacent to infection sites in walnut cultivars treated with Xaj.

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“…In order to determine severity, we used indexes to qualify the infection: 0 (no infection); 1 (necrosis located at the inoculation point); 2 (necrosis extending from the inoculation point through the green tissue); 3 (necrosis extending through the mesocarp and reaching the endocarp) and 4: necrosis affecting the seed. This method is described by Aletà et al [5]. In order to fulfill Koch´s postulates pieces of necrotic lesions were processed as described previously and cultured on LB and PDA, for re-isolation of bacteria and fungi, respectively.…”

Section: Molecular Methodsmentioning

confidence: 99%

“…During the last years, it has been reported a new disease that affects walnut trees causing premature fruit to drop and significant yield losses in Mediterranean regions such as Spain, France, Turkey [5,6] and Italy [7]. The typical symptoms of this pathology consist of an apical necrosis that originates at the stigmatic end of the fruits.…”

Section: Introductionmentioning

confidence: 99%

First Report of Apical Necrosis in Walnut Cultivars from Northern Argentinean Patagonia

Temperini¹,

Pardo²,

Pose³

2017

J Plant Pathol Microbiol

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Walnut blight caused by Xanthomonas arborícola pv. juglandis and apical necrosis are severe diseases that cause premature drop of walnuts all around the world. Evidence from previous studies proposes Xanthomonas arborícola pv. juglandis together with Fusarium spp. and Alternaria spp. as causal agents of apical necrosis. While walnut blight is a well-known pathology in Argentina, apical necrosis has not been reported yet in this country. However, during 2013 and 2014 seasons, serious damages were registered in the nut producing region of Río Negro Middle Valley in northern Argentinean Patagonia. Diseased fruits exhibited symptoms that matched those described for walnut blight and apical necrosis. Therefore, the aim of this study was to determine the incidence of these pathologies and the microorganisms involved in their etiology. As a result, it was possible to identify morphologically and molecularly the bacteria isolated from damaged fruits, confirming their identity as Xanthomonas arborícola pv. juglandis. Moreover, A. tenuissima was found in a high prevalence in damaged as well as in healthy fruits, whereas Fusarium spp. was isolated with a low frequency in both. When pathogenicity tests were performed, it was demonstrated the ability of the three microorganisms to produce typical lesions in healthy nuts. Thus, we can presume that both diseases occurred during this couple of years in this region. This is the first report of apical necrosis in Argentina

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Blight Sensitivity of Spanish Selections of J. Regia

Cited by 12 publications

References 0 publications

Identification of a genetic lineage within Xanthomonas arboricola pv. juglandis as the causal agent of vertical oozing canker of Persian (English) walnut in France

Identification of a genetic lineage within Xanthomonas arboricola pv. juglandis as the causal agent of vertical oozing canker of Persian (English) walnut in France

Functional analysis of walnut polyphenol oxidase gene (JrPPO1) in transgenic tobacco plants and PPO induction in response to walnut bacterial blight

First Report of Apical Necrosis in Walnut Cultivars from Northern Argentinean Patagonia

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