Bacteria and phytoplasmas / Bactéries et phytoplasmes Colony morphology of Xylella fastidiosa almond leaf scorch strains
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چکیده
Xylella fastidiosa is the causal agent of almond leaf scorch disease (ALSD), which is currently reemerging in California as a potential threat to almond (Prunus dulcis) production. We previously reported the presence of different colony morphotypes of X. fastidiosa ALSD strains on periwinkle wilt medium solidified with Gelrite and their association with genotypes or pathotypes after a low number of serial transfers. The morphotypes could be differentiated by single nucleotide polymorphisms and were classified as Aand G-genotypes. The stability of colony morphology was not studied. Yet, it is an important issue in the bacterial characterization. In this project, we evaluated the variations of colony morphology through 14 subculture passages. The G-genotype strains were consistently (>99%) associated with smooth colony morphotypes. Similarly, A-genotype strains were consistently associated with rough colony morphotypes. Rough A-genotype strains reversed to smooth colony variants at a low frequency suggesting phase variation in X. fastidiosa. In an ALSD survey, we successfully used colony morphology to discern X. fastidiosa genotypes with >95% accuracy. The phenotypic traits described in this study are of value for further biological and genetic studies of X. fastidiosa.
منابع مشابه
Two Xylella fastidiosa Genotypes Associated with Almond Leaf Scorch Disease on the Same Location in California.
ABSTRACT Almond leaf scorch disease (ALSD) has recently reemerged in the San Joaquin Valley of California threatening almond production. ALSD is caused by Xylella fastidiosa, a nutritionally fastidious bacterium. Single nucleotide polymorphisms (SNPs) in the 16S rRNA gene (16S rDNA) of X. fastidiosa strains were identified to characterize the bacterial population in infected trees. Genotype-spe...
متن کاملWhole genome sequences of two Xylella fastidiosa strains (M12 and M23) causing almond leaf scorch disease in California.
Xylella fastidiosa is a Gram-negative plant-pathogenic bacterium causing many economically important diseases, including almond leaf scorch disease (ALSD) in California. Genome information greatly facilitates research on this nutritionally fastidious organism. Here we report the complete genome sequences of two ALSD strains of this bacterium, M12 and M23.
متن کاملMultilocus simple sequence repeat markers for differentiating strains and evaluating genetic diversity of Xylella fastidiosa.
A genome-wide search was performed to identify simple sequence repeat (SSR) loci among the available sequence databases from four strains of Xylella fastidiosa (strains causing Pierce's disease, citrus variegated chlorosis, almond leaf scorch, and oleander leaf scorch). Thirty-four SSR loci were selected for SSR primer design and were validated in PCR experiments. These multilocus SSR primers, ...
متن کاملPopulation Structure of Xylella fastidiosa Associated with Almond Leaf Scorch Disease in the San Joaquin Valley of California.
Xylella fastidiosa causes disease in many commercial crops, including almond leaf scorch (ALS) disease in susceptible almond (Prunus dulcis). In this study, genetic diversity and population structure of X. fastidiosa associated with ALS disease were evaluated. Isolates obtained from two almond orchards in Fresno and Kern County in the San Joaquin Valley of California were analyzed for two succe...
متن کاملXYLEM CHEMISTRY MEDIATION OF RESISTANCE TO PIERCE’S DISEASE Project Leader:
INTRODUCTION Xylella fastidiosa (Xf) is a Gram-negative xylem-limited bacterium that causes Pierce’s disease (PD), plum leaf scald, almond leaf scorch, phony peach disease and many other diseases. For many plant species there is no resistant germplasm. Xylem vessels may be filled with exopolysaccharides produced by the bacterium, and pectins, gums and tyloses produced by the plant. There has be...
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