Understanding the intricate interplay between plants and bacteria is paramount for elucidating mechanisms of immunity and disease. This review synthesizes current knowledge on the role of flagella in bacterial motility and host recognition, shedding light on the molecular mechanisms underlying plant immunity and bacterial pathogenicity. We delve into the sophisticated signaling network of plants, highlighting the pivotal role of pattern recognition receptors (PRRs) in detecting conserved molecular patterns known as microbe-associated molecular patterns (MAMPs), with a particular focus on flagellin as a key MAMP. Additionally, we explore recent discoveries of solanaceous-specific receptors, such as FLAGELLIN SENSING 3 (FLS3), and their implications for plant defense responses. Furthermore, we examine the role of bacterial motility in host colonization and infection, emphasizing the multifaceted relationship between flagella-mediated chemotaxis and bacterial virulence. Through a comprehensive analysis of flagellin polymorphisms within the genus Xanthomonas, we elucidate their potential impact on host recognition and bacterial pathogenicity, offering insights into strategies for developing disease-resistant crops. This review is intended for professionals within the fields of crops sciences and microbiology.

Bacterial spot disease of cucurbits, caused by Xanthomonas cucurbitae , is a major problem in cucurbit‐growing areas worldwide. In the Midwestern region of the United States, pumpkin and squash fields can have greater than 90% infected fruits, leading to high yield losses. While reference genomes are available for this bacterial species, the genetic diversity between different strains and populations is unknown. After performing restriction‐site associated DNA sequencing (RAD‐seq) analysis of X . cucurbitae isolates collected from the Midwestern region, we selected five representative isolates for further characterization, which included whole‐genome sequencing and in vitro enzyme and in planta virulence assays. Our results suggest that minimal genetic diversity exists between these isolates, and that the isolates have differential virulence on different cucurbit host plants. This study contributes to our understanding of X . cucurbitae population dynamics in the Midwestern region and may assist with developing additional management strategies for controlling bacterial spot disease of cucurbits.