Location: Southern Horticultural ResearchTitle: Genotyping Xylella fastidiosa in rabbiteye blueberry in Louisiana, USA
|FERGUSON, MARY HELEN - Louisiana State University|
|CLARK, CHRISTOPHER - Louisiana State University|
Submitted to: European Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2020
Publication Date: 6/8/2020
Citation: Ferguson, M., Clark, C.A., Smith, B.J. 2020. Genotyping Xylella fastidiosa in rabbiteye blueberry in Louisiana, USA. European Journal of Plant Pathology. 157:679-683. https://doi.org/10.1007/s10658-020-02017-6.
Interpretive Summary: The bacterium, Xylella fastidiosa, causes bacterial leaf scorch of southern highbush blueberry and has been detected in rabbiteye blueberry in several states in the southeastern U. S. Recent work showed an association between X. fastidiosa infection and yield reduction in rabbiteye blueberry. Our objectives were to determine how prevalent X. fastidiosa infections were in rabbiteye blueberry plants in Louisiana and then determine what X. fastidiosa strains were present in these rabbiteye blueberry plants. This relates to the practical questions of what plants might serve as alternative hosts for this pathogen in rabbiteye blueberry and whether rabbiteye blueberry might serve as an alternative host of the bacterium for susceptible southern highbush blueberry cultivars. One of the X. fastidiosa strains we found in rabbiteye blueberry does suggest that rabbiteye blueberry may serve as an alternative host of strains that are able to infect susceptible southern highbush blueberry cultivars. Older rabbiteye plants do not always show distinctive symptoms of X. fastidiosa infection; therefore, blueberry growers are advised to take care to use clean planting stock when introducing rabbiteye plants into orchards in which susceptible southern highbush cultivars are grown.
Technical Abstract: Rabbiteye blueberry (V. ashei Reade = V. virgatum Aiton) comprises much of the blueberry acreage in Louisiana. Testing of plants from 17 Louisiana blueberry orchards revealed the bacterium Xylella fastidiosa in only two orchards. Three genotypes of X. fastidiosa were identified from rabbiteye blueberry in these orchards by multilocus sequence typing. A genotype that was found at both orchards, sequence type (ST) 42, was identical to one previously found in southern highbush blueberry in Georgia and two non-blueberry native species in Texas. Other genotypes shared most alleles with X. fastidiosa strains considered, like ST 42, to be part of a group that is believed to have resulted from recombination between X. fastidiosa subsp. multiplex and subsp. fastidiosa. These two genotypes each also had one newly identified allele. This work suggests that a narrow range of X. fastidiosa genotypes infect rabbiteye blueberry in Louisiana, but some uncultivated native plant species, as well as southern highbush blueberry, may serve as alternative hosts. Likewise, rabbiteye blueberry may serve as an alternative host for X. fastidiosa strains that infect susceptible southern highbush cultivars.