High Genetic Diversity and Species Complexity of Diaporthe Associated With Grapevine Dieback in China

Grapevine trunk diseases have become one of the main threats to grape production worldwide, with <i>Diaporthe</i> species as an emerging group of pathogens in China. At present, relatively little is known about the taxonomy and genetic diversity of Chinese <i>Diaporthe</i> populations, including their relationships to other populations worldwide. Here, we conducted an extensive field survey in six provinces in China to identify and characterize <i>Diaporthe</i> species in grape vineyards. Ninety-four isolates were identified and analyzed using multi-locus phylogeny. The isolates belonged to eight species, including three novel taxa, <i>Diaporthe guangxiensis (D. guangxiensis), Diaporthe hubeiensis (D. hubeiensis), Diaporthe viniferae (D. viniferae)</i>, and three new host records, <i>Diaporthe gulyae (D. gulyae), Diaporthe pescicola (D. pescicola)</i>, and <i>Diaporthe unshiuensis (D. unshiuensis)</i>. The most commonly isolated species was <i>Diaporthe eres (D. eres)</i>. In addition, high genetic diversity was observed for <i>D. eres</i> in Chinese vineyards. Haplotype network analysis of <i>D. eres</i> isolates from China and Europe showed a close relationship between samples from the two geographical locations and evidence for recombination. In comparative pathogenicity testing, <i>D. gulyae</i> was the most aggressive taxon, whereas <i>D. hubeiensis</i> was the least aggressive. This study provides new insights into the <i>Diaporthe</i> species associated with grapevines in China, and our results can be used to develop effective disease management strategies.