Novel species of Botryosphaeriaceae associated with shoot blight of pistachio

Abstract

Various species of phytopathogenic Botryosphaeriaceae were identified previously from pistachio trees worldwide. Disease symptoms caused by pathogens in Botryosphaeriaceae on pistachio include panicle and shoot blight, leaf defoliation, fruit discoloration and decay. In this study species of Botryosphaeriaceae were collected from blighted pistachio shoots in Arizona, USA, and Greece. The aims of this study were to identify these Botryosphaeriaceae isolates and to test their pathogenicity to pistachio. The fungi were identified based on comparisons of DNA sequence data of the nuclear rDNA internal transcribed spacer region (ITS), a partial translation elongation factor 1-alpha gene (TEF1), a partial β-tubulin gene (TUB2) and morphological characteristics. Results indicated that some isolates collected from pistachio represent two previously undescribed species, which we described here as Lasiodiplodia americana sp. nov. from the United States and Neofusicoccum hellenicum sp. nov. from Greece. Field inoculations of L. americana and N. hellenicum on branches of four pistachio cultivars showed that both L. americana and N. hellenicum are pathogenic on pistachio. The four pistachio cultivars differed in their susceptibility to the Botryosphaeriaceae species. Results of this study suggested that the two new species of Botryosphaeriaceae need to be monitored carefully to determine the distribution of these pathogens and the possible spread to other areas.

• Lasiodiplodia
• Neofusicoccum
• pathogenicity
• shoot blight
• tree disease

Acknowledgments

The research was financially supported by the Fundamental Research Funds for the Central Non-profit Research Institution of CAF (project CAFYBB2014MA018), the National Natural Science Foundation of China (NSFC) (project 31400546), International Science & Technology Cooperation Program of China ( 2012DFG31830) and the California Pistachio Research Board. We are grateful for valuable assistance in the field by Mr David Morgan at the University of California at Davis/Kearney Agricultural Research and Extension Center. We thank Dr Mark Doster from the Department of Plant Pathology, University of California at Davis to review the manuscript and improve the writing.