Extension Specialist III Texas AgriLife Extension College Station, Vermont
Body of Abstract: In 2022, we published “the first report of bacterial leaf scald of plum (PLS) caused by Xylella fastidiosa susp. multiplex (Xfm) in Texas”. The previous study was conducted in Central Texas as part of the Texas Stone Fruit Survey (SFS) in FY2020-2021. During the 2021-2022 SFS, we surveyed Central and East Texas counties and detected the presence of PLS in East Texas counties and additional Central Texas counties. We identified 16 Xylella fastidiosa susp. multiplex isolates from samples obtained of trees exhibiting PLS symptoms based on 16S rRNA sequencing. To further validate subspecies identification and allocate sequence type (ST) to isolates, we used the Xf multi-locus sequence typing (MLST) primers that target seven housekeeping loci, including holC, nuoL, leuA, gltT, cysG, petC, and lacF. MLST sequences were blasted against the Xf typing database, PubMLST; all isolates were identified as ST26 (Xf multiplex Type 26), which is the same sequence type reported for California isolates, in contrast to Georgia isolates that were identified as ST10. This study extends the geographical range of this important bacterial disease and provides insights into the genetic diversity among isolates of the causal agent of PLS in the Southern United States.