ABSTRACT Pseudomonas syringae pv. actinidiae (Psa), the causal agent of kiwifruit bacterial canker, poses a severe threat to the global kiwifruit industry. Among its variants, Psa biovar 3 (Psa 3) is particularly virulent and widespread. Effective disease control relies on the rapid and accurate identification of pathogens. However, a convenient barcode gene for differentiating Psa biovars remains elusive, and current rapid detection methods frequently exhibit inadequate specificity and cross‐reactivity with non‐target bacteria. In this study, comparative genomics was employed to screen for diagnostic molecular markers. We identified the CN228₁7360 gene as a target within the P. syringae Genomospecies 8 (GS8) genome and designed the primer pair GS8‐F/R. This primer pair was developed to distinguish Psa biovars via amplicon sequencing. Furthermore, we comprehensively evaluated widely used Psa and Psa 3 detection primers, revealing significant specificity issues. To address this, we identified a unique Psa 3‐specific gene, CN228₀1300, and developed a new primer pair, Psa3‐F/Psa3‐R. The newly developed Psa3‐F/Psa3‐R primers demonstrated excellent specificity and elevated sensitivity in subsequent applications, enabling the accurate detection of Psa 3 in both infected plant materials and bacterial isolates. Thus, we establish a robust toolkit for Psa detection and classification. The identification of a reliable barcode gene allows for accurate biovar typing combined with sequencing, while the development of the Psa 3‐specific primers provides a rapid and precise method for monitoring the high‐risk Psa 3 variant in the field.
Zhang et al. (Fri,) studied this question.