A Survey for Strains of <i>Xylella fastidiosa</i> in Citrus Affected by Citrus Variegated Chlorosis and Citrus Blight in Brazil

Beretta, M. J. G.; Barthe, G. A.; Ceccardi, Toni L.; Lee, R. F.; Derrick, K. S.

doi:10.1094/pdis.1997.81.10.1196

Cited by 29 publications

(16 citation statements)

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“…Chemometric analysis showed that the deficiency of P and K in symptomatic trees for all orchards and high concentrations of Fe, Mn and Zn were present in chlorotic areas, although other studies revealed deficiency of zinc in leaves (Beretta et al, 1997). According to the analysis, the deficiency of P and K in symptomatic trees for all orchards and high concentrations of Fe, Mn and Zn present in chlorotic areas of symptomatic trees, may or may not be influenced by the causal agent.…”

Section: Resultsmentioning

confidence: 79%

Nutritional deficiency in citrus with symptoms of citrus variegated chlorosis disease

et al. 2009

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It is well known that citrus plants that have been infected by Xylella fastidiosa display nutritional deficiencies, probably caused by production of extracellular polymers by the bacteria that block normal nutrient flow through the xylem. The aim of this work was to study the mineral composition of specific foliar areas in different stages of infection in citrus. Thus, the concentrations of macro and micronutrients in leaves of citrus infected by X. fastidiosa were measured. Samples from four infected citrus orchards in the State of São Paulo, Brazil, were respectively collected from Santa Rita do Passa Quatro, Neves Paulista, Gavião Peixoto and Paraíso counties. The presence of X. fastidiosa in leaves was confirmed by polymerase chain reaction (PCR) using specific PCR primers. To understand the variation in leaf-nutrient content in citrus plants, we used foliar nutrient values from control (non-symptomatic) plants as a reference. Chemometric analysis showed that the deficiency of P and K in symptomatic trees for all orchards and high concentrations of Fe, Mn and Zn were observed in chlorotic areas, although other studies revealed deficiency of zinc in leaves. This is the first report showing that a correlation between chlorotic citrus leaf and higher concentrations of Fe, Mn and Zn are observed when infected and healthy plants were compared.Keywords: citrus, nutrition, Xylella fastidiosa, CVC disease, chemometry. Deficiência nutricional em citros com sintomas da doença da clorose variegada dos citros ResumoJá é bem conhecido que cultivares cítricas que foram infectadas pela bactéria Xylella fastidiosa apresentam deficiências nutricionais devido à produção de polímero extracelular por esta bactéria, o qual bloqueia o fluxo normal de nutriente pelo xilema. O objetivo deste trabalho foi o de estudar a composição mineral em áreas foliares específicas em diferentes fases de infecção na planta. Assim, as concentrações de macro e micronutrientes em folhas de citros infectados por X. fastidiosa foram quantificadas. Foram coletadas amostras de quatro pomares cítricos infectados localizados em: Santa Rita do Passa Quatro, Neves Paulista, Gavião Peixoto e Paraíso, no Estado de São Paulo. A presença de X. fastidiosa em folhas foi confirmada através de reação da polimerase em cadeia (PCR) usando iniciadores específicos. Para entender a variação no conteúdo de nutriente foliar em plantas cítricas, utilizou-se de valores de nutrientes foliares de plantas não sintomáticas (controle) como referência. A análise quimiométrica mostrou que a deficiência de P e K em plantas sintomáticas e concentrações altas de Fe, Mn e Zn foram presentes em áreas foliares cloróticas, embora outros estudos mostrem a deficiência de zinco em folhas. Este é o primeiro relato indicando que uma correlação entre folhas cítricas cloróticas e elevadas concentrações de Fe, Mn e Zn foi observada quando plantas infectadas e saudáveis foram comparadas.Palavras-chave: citros, nutrição, Xylella fastidiosa, doença do CVC, quimiometria. BIOLOGYSilva-Stenico...

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Section: Resultsmentioning

confidence: 79%

Nutritional deficiency in citrus with symptoms of citrus variegated chlorosis disease

et al. 2009

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“…Three additional plants were healthy. The bacterial presence was confirmed before and after the measurements through the polymerase chain reaction (PCR), specific for X. fastidiosa (Beretta et al, 1997).…”

Section: Methodsmentioning

confidence: 99%

CO2 assimilation, photosynthetic light response curves, and water relations of 'Pêra' sweet orange plants infected with Xylella fastidiosa

Habermann

Machado²,

Rodrigues

et al. 2003

Braz. J. Plant Physiol.

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Plants with citrus variegated chlorosis (CVC), a disease caused by the xylem-limited bacteria Xylella fastidiosa, have leaves with water deficiency symptoms and are associated with decreases on the net photosynthesis and transpiration rates. Using healthy and CVC-affected 'Pêra' sweet orange plants on 'Rangpur' lime rootstock, the leaf gas exchange variables were measured with an open-gas portable photosynthesis system. All plants were watered and the leaf water potential (Ψ w ) was measured by isopiestic thermocouple psychrometric technique. The net photosynthesis (A) vs. internal leaf CO 2 concentration (A/Ci curves) was analyzed. The relative effect of stomatal resistance on photosynthesis (S%) and the estimation of carboxylation efficiency were calculated. The rates of photosynthesis and transpiration, stomatal conductance, and internal leaf CO 2 concentration (Ci) were also measured while varying the photosynthetic photon flux density (PPFD). The S% values were approximately 30 % greater in infected plants when compared to healthy ones. The light compensation point for diseased plants was higher than in the healthy ones, and the saturation light point in plants with CVC was twofold lower. The lower Ψ w in diseased plants favours the hypothesis of xylem occlusion, which probably caused a lower water supply to the mesophyll, thus decreasing the photosynthesis and transpiration rates. Nevertheless, there was also a reduction in the photosynthetic metabolic activities, represented by lower carboxylation efficiency and photochemical disturbances that were detected in diseased plants.Key words: A/Ci curves, citrus variegated chlorosis, Citrus sinensis L. Osbeck, photosynthetic photon flux density, photosynthetic metabolism, stomata.Assimilação do CO 2 , curvas de resposta fotossintética à luz e relações hídricas de plantas da laranja doce 'Pêra' infectadas com Xylella fastidiosa: Plantas com clorose variegada dos citros (CVC), uma doença causada pela bactéria Xylella fastidiosa, restrita ao xilema, apresentam folhas com sintomas de deficiência hídrica, associados com diminuição na fotossíntese líquida e na taxa de transpiração. Utilizando-se plantas sadias e com CVC de laranjeira 'Pêra' sobre limoeiro 'Cravo', as variáveis de trocas gasosas foram medidas com sistema portátil aberto de fotossíntese. Todas as plantas foram irrigadas e o potencial da água na folha (Ψ w ) medido pela técnica psicrométrica de termopar isopiéstico. Fotossíntese líquida (A) vs. concentração interna de CO 2 na folha (curvas A/Ci) foram analisadas. O efeito relativo da resistência estomática sobre a fotossíntese (S%) e a estimativa da eficiência de carboxilação foram calculados. Taxas de fotossíntese e transpiração, condutância estomática e concentração interna de CO 2 na folha (Ci) foram também medidas quando se variou a densidade de fluxo de fótons fotossinteticamente ativos (DFFFA). Os valores de S% foram 30 % maiores nas plantas doentes, comparados às sadias, e seu ponto de compensação de luz também foi maior e o ponto de saturação de...

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“…The identity of the X. fastidiosa colonies was confirmed based on colony morphology and growth pattern. In addition, samples of single colonies were tested by PCR, using specific primers (1,21), and by ELISA with polyclonal antiserum against X. fastidiosa of citrus (SANOFI; Diagnostics Pasteur S.A., France). All colony samples visually identified as X. fastidiosa were positive in these tests.…”

Section: Methodsmentioning

confidence: 99%

“…Since X. fastidiosa was first shown to cause CVC (3,20), serological (5) and molecular methods (1,21,25) have been developed to detect the bacterium in citrus. The pathogen is naturally transmitted to citrus by sharpshooter (Cicadellinae) leafhoppers (29).…”

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confidence: 99%

Multiplication and Movement of a Citrus Strain ofXylella fastidiosaWithin Sweet Orange

et al. 2001

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Citrus variegated chlorosis (CVC), caused by the xylem-limited bacterium Xylella fastidiosa, has arisen from obscurity to become a major threat to the Brazilian citrus industry in less than 10 years. Since X. fastidiosa was first shown to cause CVC (3,20), serological (5) and molecular methods (1,21,25) have been developed to detect the bacterium in citrus. The pathogen is naturally transmitted to citrus by sharpshooter (Cicadellinae) leafhoppers (29). Transmission by natural root grafts and by top grafting with infected budsticks also were reported (10). Epidemiological studies suggest that most spread of CVC is from tree to tree within the citrus groves (19). Therefore, management of CVC is mainly based on planting healthy nursery trees, vector control, and removal of inoculum by roguing of symptomatic young plants (<2 years old) and pruning of branches with early foliar symptoms in older trees (8,30). The population behavior of X. fastidiosa within citrus is crucial to its pathology and control, but bacterial colonization of citrus has not been studied quantitatively and some characteristics of infection, movement of X. fastidiosa within citrus, and disease development remain unknown. He et al. (10) used polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) to detect movement of X. fastidiosa from scion graft to rootstock but did not quantify populations of the pathogen.A limiting factor to studies concerning X. fastidiosa is the slow growth of the pathogen on solid medium, leading to frequent contamination of culture attempts. This has hindered attempts to quantify populations of X. fastidiosa. Hopkins (14) developed a protocol to estimate population of viable X. fastidiosa cells from grapevines with Pierce's disease (PD) based on counting CFU of this bacterium on solid media by dilution plating. A modification of this technique (11) was used to study PD strains of X. fastidiosa in alternative hosts, with the bacterium reaching high populations (log 8 CFU/g of plant tissue) in grapevine, 100-fold lower populations in an asymptomatic host, Himalayan blackberry, and still lower, nonsystemic populations in water grass and mugwort. Populations of X. fastidiosa estimated by dilution plating were also correlated with vector transmission rates; bacterial populations lower than log 6 to log 7 CFU/g determined by culture in grapevine resulted in reduced transmission efficiency (13).The objective of our study was to follow the fate of a CVC strain of X. fastidiosa in citrus seedlings under greenhouse conditions and to estimate population levels of X. fastidiosa in symptomatic leaves of infected citrus trees in commercial orchards. We used culturing to quantify X. fastidiosa in leaves collected from the field and its growth and movement within citrus seedlings, following mechanical inoculation in the stem and leaf petioles with variable concentrations of live cells. We also tested different media for X. fastidiosa growth and evaluated citrus tissue homogenates for inhibition of bacterial growth i...

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A Survey for Strains of Xylella fastidiosa in Citrus Affected by Citrus Variegated Chlorosis and Citrus Blight in Brazil

Cited by 29 publications

References 14 publications

Nutritional deficiency in citrus with symptoms of citrus variegated chlorosis disease

Nutritional deficiency in citrus with symptoms of citrus variegated chlorosis disease

CO2 assimilation, photosynthetic light response curves, and water relations of 'Pêra' sweet orange plants infected with Xylella fastidiosa

Multiplication and Movement of a Citrus Strain ofXylella fastidiosaWithin Sweet Orange

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