Archivio Journal of Plant Pathology

Abstract:

Mango (Mangifera indica) is an economically important fruit crop in southern China, and gummosis is one of the most important of its diseases. Under severe conditions, the outer wood of branches cracks, and exudes a yellow to brown gum, and the whole plant declines. In June, 2012, symptomatic mango branches were collected in Guangxi province. On potato dextrose agar, isolates of similar morphological characteristics were consistently recovered, with 80% isolation rate from 45 surface-sterilized branch pieces. Conidia were hyaline, aseptate, and fusiform, and measured 18-28×4-6 μm. The fungus was identified as Botryosphaeria dothidea based on morphological characteristics (Lazzizera et al., 2008). The rDNA internal transcribed spacer region (ITS), the β-tubulin gene, and the translation elongation factor 1-α gene of one isolate (L15,) showed 99-100% identity to B. dothidea, (Gen- Bank accession Nos. GQ421485, JF441083 and HQ660485). Pathogenicity of three isolates was tested on three green twigs and three 3-year-old branches in mango orchards in Nanning (Guangxi). Three wounds were made for each location with a sterilized needle. Mycelial plugs were placed on the wounds and wrapped with parafilm. Two weeks later, typical brown lesions were observed on the branches, and gum exuded from infected tissues, but no symptoms were seen on controls inoculated with sterile agar plugs. Koch’s postulates were fulfilled by reisolation of B. dothidea from diseased branches. In China, the main causal agent of mango gummosis has been identified as Lasiodiplodia theobromae (Li et al., 2013). However, to our knowledge, this is the first report of B. dothidea causing mango gummosis in the country.