Evidence that<i>Xylella fastidiosa</i>Can Cause Leaf Scorch Disease of Pecan

Sanderlin, R. S.; Heyderich-Alger, K. I.

doi:10.1094/pdis.2000.84.12.1282

Cited by 40 publications

(16 citation statements)

References 25 publications

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“…It grows optimally from 26 to 28°C and is described as ''nutritionally fastidious,'' requiring specialized media for growth in the laboratory. Sanderlin and Heyderich-Alger (2000) reported that X. fastidiosa causes leaf scorch in pecan, which has become known as Pecan Bacterial Leaf Scorch (PBLS). A disease screen of commercial cultivars for susceptibility to PBLS (Sanderlin, 2005) reported variable expression of leaf scorch, with all susceptible to infection and symptom development.…”

Section: Threats Of Genetic Erosion In Situmentioning

confidence: 99%

Crop Vulnerability: Carya

Grauke¹,

Wood²,

Harris³

2016

horts

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Long-established native tree populations reflect local adaptations. Representation of diverse populations in accessible ex situ collections that link information on phenotypic expression to information on spatial and temporal origination is the most efficient means of preserving and exploring genetic diversity, which is the foundation of breeding and crop improvement. Throughout North America, sympatric Carya species sharing the same ploidy level tend to hybridize, permitting gene flow that contributes to regional diversity and adaptation. The topographic isolation of many fragmented populations, some of which are small, places native Carya populations of United States, Mexico, and Asia in a vulnerable position and justifies systematic collection and characterization. The characterization of indigenous Mexican pecan and other Carya populations will facilitate use for rootstocks and scion breeding and will contribute to pecan culture. The Asian species, as a group, are not only geographically isolated from North American species, but also occur in disjunct, fragmented populations isolated from other Asian species. Section Sinocarya includes the members of the genus most vulnerable to genetic loss. With all species, recognition of utility based on characterization of ex situ collections may contribute to the establishment of in situ reserves. Global Carya genetic resources should be cooperatively collected, maintained, characterized, and developed. The integration of crop wild relatives into characterization and breeding efforts represents a challenging opportunity for both domestic and international cooperation. Genomic tools used on the accessible collections of the National Collection of Genetic Resources for Pecans and Hickories (NCGR-Carya) offer great potential to elucidate genetic adaptation in relation to geographic distribution. The greatest progress will be made by integrating the disciplines of genetics, botany, pathology, entomology, ecology, and horticulture into internationally cooperative efforts. International germplasm exchange is becoming increasingly complicated by a combination of protectionist policies and legitimate phytosanitary concerns. Cooperative international evaluation of in situ autochthonous germplasm provides a valuable safeguard to unintended pathogen exchange associated with certain forms of germplasm distribution, while enabling beneficial communal exploration and directed exchange. This is threatened by the “proprietary” focus on intellectual property. The greatest risk to the productive development of the pecan industry might well be a myopic focus on pecan production through the lens of past practice. The greatest limitation to pecan culture in the western United States is reduced water quantity and quality; in the eastern United States the challenge is disease susceptibility; and insufficient cold hardiness in the northern United States. The greatest benefit for the entire industry might be achieved by tree size reduction through both improved rootstocks and scions, which will improve both nut production and tree management, impacting all areas of culture. This achievement will likely necessitate incorporation of crop wild relatives in breeding, broad cooperation in the testing leading to selection, and development of improved methods linking phenotypic expression to genomic characterization. The development of a database to appropriately house information available to a diverse research community will facilitate cooperative research. The acquisition of funds to pursue development of those tools will require the support of the pecan industry, which in the United States, is regionally fragmented and focused on marketing rather than crop development.

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Section: Threats Of Genetic Erosion In Situmentioning

confidence: 99%

Crop Vulnerability: Carya

Grauke¹,

Wood²,

Harris³

2016

horts

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“…These include PD in grapevines (Davis et al ., 1981; Hopkins and Purcell, 2002), leaf scorches in pecan (Sanderlin and Heyderich-Alger, 2000; Sanderlin and Melanson, 2006), pear (Leu and Su, 1993), plum (Raju et al ., 1983), almond (Mircetich et al ., 1976), mulberry (Kostka et al ., 1986), elm, sycamore, oak (Hearon et al ., 1980), maple (Sherald et al ., 1987), coffee (de Lima et al ., 1998), oleander and olives (Saponari et al ., 2013), as well as alfalfa dwarf (Goheen et al ., 1979), phony peach disease (Wells et al ., 1981), periwinkle wilt (McCoy et al ., 1978), and citrus variegated chlorosis (Chang et al ., 1993; Hartung et al ., 1994). Strains of X. fastidiosa have a wide host range in the native flora, where they exist without inducing symptoms of disease, and they are transmitted by common sharpshooter insects (Freitag, 1951; Freitag and Frazier, 1954).…”

Section: The Plant Pathogen Xylella Fastidiosamentioning

confidence: 99%

The diversity of citrus endophytic bacteria and their interactions with Xylella fastidiosa and host plants

2016

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The bacterium Xylella fastidiosa is the causal agent of citrus variegated chlorosis (CVC) and has been associated with important losses in commercial orchards of all sweet orange [Citrus sinensis (L.)] cultivars. The development of this disease depends on the environmental conditions, including the endophytic microbial community associated with the host plant. Previous studies have shown that X. fastidiosa interacts with the endophytic community in xylem vessels as well as in the insect vector, resulting in a lower bacterial population and reduced CVC symptoms. The citrus endophytic bacterium Methylobacterium mesophilicum can trigger X. fastidiosa response in vitro, which results in reduced growth and induction of genes associated with energy production, stress, transport, and motility, indicating that X. fastidiosa has an adaptive response to M. mesophilicum. Although this response may result in reduced CVC symptoms, the colonization rate of the endophytic bacteria should be considered in studies that intend to use this endophyte to suppress CVC disease. Symbiotic control is a new strategy that uses symbiotic endophytes as biological control agents to antagonize or displace pathogens. Candidate endophytes for symbiotic control of CVC must occupy the xylem of host plants and attach to the precibarium of sharpshooter insects to access the pathogen. In the present review, we focus on interactions between endophytic bacteria from sweet orange plants and X. fastidiosa, especially those that may be candidates for control of CVC.

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“…The previously mentioned symptoms were inconsistent with any previously reported blueberry disease. It was noticed, however, that the symptoms were similar to diseases caused by X. fastidiosa in other plants in south Georgia such as plum leaf scald (Raju et al, 1982;Wells et al, 1987) or pecan bacterial leaf scorch (Sanderlin and Heyderick-Alger, 2000). This observation prompted the initiation of testing to determine whether X. fastidiosa could cause these symptoms, and subsequent death, of blueberry plants.…”

mentioning

confidence: 99%

Bacterial Leaf Scorch, a New Blueberry Disease Caused by Xylella fastidiosa

Chang¹,

Donaldson²,

Brannen³

et al. 2009

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Since 2004, growers and scientists have observed a disorder described as “yellow twig” or “yellow stem” affecting a major selection of southern highbush blueberry, FL 86-19, in the south Georgia blueberry production region. The initial symptom observed was leaf marginal chlorosis and subsequent necrosis, which eventually progressed throughout the whole leaf resulting in early leaf fall. Thin, yellow twigs or yellow stems became evident on some cultivars. The described symptoms on blueberry were similar to those exhibited on grapes with Pierce's disease and on plum with leaf scald disease. This prompted the enzyme-linked immunosorbent assay (ELISA) tests and isolations of Xylella fastidiosa, which is the causal agent of the previously mentioned grape and plum diseases. Two leaf and two root tissue samples were collected from a diseased FL 86-19 plant for isolation and ELISA testing on 2 Mar. 2006. ELISA results indicated all four tissues tested positive for the bacterial pathogen, X. fastidiosa, whereas only the two root tissues provided positive isolations. One leaf and one root tissue sample were later collected from each of five additional diseased plants for isolation and ELISA testing. Both isolation and ELISA testing methods obtained positive results. Cultures were multiplied to inoculate seedlings of three cultivars: ‘Southern Belle’ (eight plants), ‘Premier’ (six), and ‘Powderblue’ (six) on 23 May 2006 and one selection, FL 86-19 (eight), on 31 May 2006. Two FL 86-19 plants started to show symptoms of marginal necrosis 54 days postinoculation, whereas one plant each of ‘Southern Belle’ and ‘Powderblue’ started to show symptoms of marginal necrosis 63 days postinoculation and ‘Premier’ stayed symptomless. All eight culture-inoculated FL 86-19 plants (100%) showed symptoms 72 days postinoculation, but no symptoms were observed on the control plants. One hundred twenty-six days postinoculation, two ‘Powderblue’ and four ‘Southern Belle’ plants showed mild symptoms, whereas all ‘Premier’ plants were asymptomatic. Positive reisolations of the bacteria from the inoculated symptomatic plants, not from asymptomatic plants, fulfilled Koch's postulates, which confirmed X. fastidiosa was the causal bacterium of the new blueberry disorder, the bacterial leaf scorch of blueberry.

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Evidence thatXylella fastidiosaCan Cause Leaf Scorch Disease of Pecan

Cited by 40 publications

References 25 publications

Crop Vulnerability: Carya

Crop Vulnerability: Carya

The diversity of citrus endophytic bacteria and their interactions with Xylella fastidiosa and host plants

Bacterial Leaf Scorch, a New Blueberry Disease Caused by Xylella fastidiosa

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