Investigating host preference of Acidovorax citrulli, the causal agent of bacterial fruit blotch of cucurbits
Mei Zhao: The University of Georgia
<div><em>Acidovorax citrulli</em> causes bacterial fruit blotch of cucurbits (BFB), and can be assigned to two groups: I and II. The association of group I and II <em>A. citrulli </em>strains with different cucurbit hosts strongly suggests host preference. We observed significant differences in pathogenicity between representative group I and II <em>A. citrulli </em>strains on watermelon and melon fruits, but not on foliar tissues. Thus, we hypothesized that <em>A. citrulli </em>host specificity occurs in cucurbit fruit, but not foliar tissues. The objective of this study was to assess differences in cucurbit host preference between group I and II <em>A. citrulli</em> strains under field conditions. This is important for understanding the factors that control virulence and to develop effective strategies to manage BFB. We planted a mixed plot with four cucurbit species in Tifton, GA USA and initiated a BFB outbreak with representative group I and II <em>A. citrulli </em>strains. We observed that 30%, 60%, 67%, and 71% of <em>A. citrulli</em>-positive watermelon, melon, pumpkin, and squash leaf samples were infected with the group I strain, respectively. However, 100% of the symptomatic watermelon fruit samples were infected with the group II strain, while 86% of symptomatic melon fruits were infected with the group I strain. These data support the hypothesis of <em>A. citrulli</em> host specificity in cucurbit fruits but not foliage under natural field conditions. Further studies will confirm and explore the nature of this host specificity.</div>
|
