<i>Pantoea</i> -Induced Interveinal Chlorosis (PIC): A New Bacterial Disease of Corn and Sorghum Caused by <i>Pantoea agglomerans</i> Identified in the Texas Panhandle

The genus Pantoea includes bacteria that have been designated as emerging pathogens because of their increasing numbers of previously unreported hosts, as well as their multidrug-resistant traits. In corn and sorghum, members of the genus are associated with four important diseases: Stewart's wilt caused by P. stewartii, necrotic or white leaf spots or streaks and stalk rot of corn caused by P. ananatis, leaf blight and vascular wilt disease in maize and sorghum caused by P. agglomerans, and, more recently, late-season decline disease of corn and sorghum caused by P. ananatis. In 2023, bright lemon-green foliar discoloration with interveinal chlorosis was observed on wild grasses in the northwest region of the Texas Panhandle. Later in the year, identical symptoms were observed on corn and sorghum plants. Symptomatic plants were also observed to be stunted, delayed in development, including yield-limiting impairment in reproductive growth. In extreme cases, affected plants failed to reach the reproductive growth stage. Diagnosis of symptomatic tissues consistently recovered bacterial isolates that were initially only culturable using phytoplasma media. BLAST searches of 16S rRNA sequences, multilocus sequence analysis, and genome sequence analysis identified the bacterial isolates as most closely related to P. agglomerans. Investigation of a causal role of the bacteria using a representative isolate, B1714, from sorghum, relying on Koch's postulates, resulted in the successful reproduction of the symptoms observed on symptomatic field plants. Bacteria matching isolate B1714 were also successfully recovered from symptomatic tissues, thus satisfying Koch's postulates and attributing a causative role to isolate B1714.