Systemic Colonization of Xanthomonas fragariae Strain YL19 Causing Dry Cavity Rot of Strawberry Crown Tissue in China

Abstract

Xanthomonas fragariae usually causes angular leaf spot (ALS) of strawberry, a serious bacterial disease in many strawberry-producing regions worldwide. Recently, a new strain of X. fragariae (YL19) was isolated from strawberry in China and has been shown to cause dry cavity rot in strawberry crown. In this study, we constructed a GFP-labeled Xf YL19 (YL19-GFP) to visualize the infection process and pathogen colonization in strawberries. Foliar inoculation of YL19-GFP resulted in the pathogen migrating from the leaves to the crown, whereas dip inoculation of wounded crowns or roots resulted in the migration of bacteria from the crowns or roots to the leaves. These two invasion types both resulted in the systematic spread of YL19-GFP, but inoculation of a wounded crown was more harmful to the strawberry plant than foliar inoculation. Results increased our understanding of the systemic invasion of X. fragariae and the resultant crown cavity caused by Xf YL19.

TheXanthomonas fragariaeeffector XopK suppresses stomatal immunity by perturbing abscisic acid accumulation and signaling pathways in strawberry

“…However, a more severe dry cavity rot in the crown at 45 dpi was observed (Fig. 3), which may account for the systematic moving of the early colonized bacteria from leaves to crowns through vascular tissues as described by Wang et al (2023). The different infection outcomes with pressure or syringe-inoculation (Fig.…”

“…Xanthomonas fragariae strain YL19-GFP is grown in liquid nutrient broth (NB) or NB with agar at 25 °C (Wang et al, 2023). Escherichia coli DH5α was cultivated at 37°C in either liquid or solid Luria-Bertani medium.…”

“…The virulence of the X.fragariae YL19-GFP strain in strawberry plants was determined based on previous studies (Liang et al, 2023; Wang et al, 2023; Wei et al, 2024). The YL19-GFP was cultured in liquid NB medium to OD 600 =1.0 (10 8 cfu/ml), then resuspended in 10 mM MgCl 2 buffer with 0.01% Silwet L-77 for subsequent inoculation assay.…”

“…Xanthomonas fragariae ( Xaf ) causes bacterial angular leaf spot (ALS) in strawberries, which is one of the most severe diseases for this fruit crop (EPPO, 2023; Kim et al, 2016; Roach et al, 2016; Wang & Turechek, 2016). Recently, we isolated a Xaf new strain, YL19, which was observed to cause both typical ALS symptoms in leaves and dry cavity rot in the crown of strawberries, the first Xaf strain has both these effects in strawberries (Li et al, 2021; Wang et al, 2023). The pathogen usually enters through the leaf stomata and colonizes the parenchyma apoplast.…”

“…The genomic information of 74 Xaf strains, including the new strain YL19 (Li et al, 2021; Wang et al, 2023; Wei et al, 2022; Qiu et al, 2023), was sequentially made accessible to the public (Gétaz et al, 2017; Henry & Leveau, 2016; Vandroemme et al, 2013; Qiu et al, 2023). The virulent Xaf strain LMG25863 was predicted to contain twenty-three T3Es and several putative new effectors (Vandroemme et al, 2013).…”