Peach In China Research Articles

Identification and Characterization of Botryosphaeria spp. Causing Gummosis of Peach Trees in Hubei Province, Central China

Peach (Prunus persica) is one of the most important and widely grown fruit trees in China; however, perennial gummosis on trunks and branches is a major problem in peach orchards of Hubei Province, one of the most important peach production areas of China. In order to identify the gummosis-causing agents, diseased trunks and branches were collected from 11 peach orchards in Hubei Province. Fungal isolates were obtained from these samples, yielding three species: Botryosphaeria dothidea (anamorph Fusicoccum aesculi), B. rhodina (anamorph Lasiodiplodia theobromae), and B. obtusa (anamorph Diplodia seriata). They were identified based on conidial morphology and cultural characteristics, as well as analyses of nucleotide sequences of three genomic regions: the internal transcribed spacer region, a partial sequence of the β-tubulin gene, and the translation elongation factor 1-α gene. Fusicoccum aesculi was found in all 11 orchards but L. theobromae was found only in Shayang County in the Jingmen region and D. seriata only in Gong'an County in the Jingzhou region. Via artificial inoculation using mycelia on wounded twigs or branches, these three species were all found to be pathogenic, causing dark lesions on the twigs and branches and, sometimes, gum exudation from diseased parts. Isolates of L. theobromae were the most virulent and caused the largest lesions and most copious gummosis, and D. seriata had less gum than the other two species. This report represents the first description of L. theobromae and D. seriata as causal agents of gummosis on peach in China.

Monilinia species causing brown rot of peach in China.

In this study, 145 peaches and nectarines displaying typical brown rot symptoms were collected from multiple provinces in China. A subsample of 26 single-spore isolates were characterized phylogenetically and morphologically to ascertain species. Phylogenetic analysis of internal transcribed spacer (ITS) regions 1 and 2, glyceraldehyde-3-phosphate dehydrogenase (G3PDH), β-tubulin (TUB2) revealed the presence of three distinct Monilinia species. These species included Monilinia fructicola, Monilia mumecola, and a previously undescribed species designated Monilia yunnanensis sp. nov. While M. fructicola is a well-documented pathogen of Prunus persica in China, M. mumecola had primarily only been isolated from mume fruit in Japan. Koch's postulates for M. mumecola and M. yunnanensis were fulfilled confirming pathogenicity of the two species on peach. Phylogenetic analysis of ITS, G3PDH, and TUB2 sequences indicated that M. yunnanensis is most closely related to M. fructigena, a species widely prevalent in Europe. Interestingly, there were considerable differences in the exon/intron structure of the cytochrome b (Cyt b) gene between the two species. Morphological characteristics, including spore size, colony morphology, lesion growth rate, and sporulation, support the phylogenetic evidence suggesting the designation of M. yunnanensis as a new species. A new multiplex PCR method was developed to facilitate the detection of M. yunnanensis and differentiation of Monilinia spp. causing brown rot of peach in China.