First Report of Pseudomonas Grapevine Bunch Rot Caused by <i>Pseudomonas syringae</i> pv. <i>syringae</i>

Abstract

<i>Pseudomonas syringae</i> pv. <i>syringae</i>, a Gammaproteobacterium belonging to genomospecies 2 within the <i>P. syringae</i> complex, is distributed worldwide, and it is responsible for bacterial canker on >100 different hosts, including the grapevine. <i>P. syringae</i> pv. <i>syringae</i> induces necrotic lesions in the leaf blades, veins, petioles, shoots, rachis, and tendrils on grapevine cultivars in different areas. <i>P. syringae</i> pv. <i>syringae</i> has been associated with severe economic losses in different grape cultivars in Australia, where it causes inflorescence rot. In midsummer to late summer 2017, symptoms of berry rots differing from those caused by the common berry rots agents were observed in different cultivar Red Globe vineyards of Apulia (southern Italy). As proven by fulfillment of Koch's postulates, these symptoms were caused by a bacterium that, according to the results of biochemical, physiological, nutritional, antimicrobial activity, and pathogenicity tests and sequencing of <i>16S ribosomal DNA</i>, <i>gyrB</i>, <i>rpoB</i>, and <i>rpoD</i> genes, was identified as <i>P. syringae</i> pv. <i>syringae</i>. This is the first report of <i>Pseudomonas</i> grapevine bunch rot.