Molecular and Biological Characterization of Two New Species Causing Peach Shoot Blight in China.

Peach shoot blight (PSB), which kills shoots, newly sprouted leaf buds, and peach fruits, has gradually increased over the last 10 years and resulted in 30 to 50% of total production loss of the peach industry in China. has been identified as the common causal agent of this disease. In this study, two new species, (strain JW18-2) and (strain JH18-2), were also pathogens causing PSB, as determined through molecular phylogenetic analysis based on the sequences of the internal transcribed spacer (ITS) region, translation elongation factor 1-α () and beta-tubulin (), and colony and conidial morphological characteristics. Biological phenotypic analysis showed that the colony growth rate of strain JW18-2 was faster than that of strains JH18-2 and ZN32 (one of the strains that we previously found and identified). All three strains produced conidia; however, JW18-2 could not produce βconidia on alfalfa decoction and Czapek media, and the βconidia produced by strain JH18-2 were shorter in length and thicker in width than those produced by strain ZN32. Pathogenicity tests showed that JW18-2 presented the strongest pathogenicity for peach fruits and twigs and was followed by strains JH18-2 and ZN32. The results shed light on the etiology of PSB and provide a warning that or might develop into dominant species after a few years while also potentially benefitting the development of effective disease control management strategies.