Phytophthora nicotianae: a new threat to Sanhua plum (Prunus salicina) causing shoot blight in China

• Published in: European journal of plant pathology Vol. 166; no. 3; pp. 329 - 339
• Main Authors: Wen, Ke, Chen, Xin-Xin, Zhou, Xue, Huang, Sheng-Jun, Liu, Yun-Hao, Jin, Jing-Hao, Cheng, Bao-Ping, Chen, Xiao-Ren
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.07.2023; Springer Nature B.V
• Subjects: Agriculture; Biomedical and Life Sciences; Blight; Crop yield; Cultural characteristics; Dieback; Disease; Ecology; Fruit trees; Fruits; Leaf blight; Life Sciences; Morphology; Orchards; Pathogenicity; Pathogens; Phylogeny; Physical characteristics; Phytophthora nicotianae; Plant Pathology; Plant Sciences; Polls & surveys; Prunus salicina; Ribosomal DNA; Shoot blight; Shoots; Signs and symptoms; Spacer region; Threats; Trees; China; Guangdong China; Combined gene analysis; Pathogenicity; Sanhua plum; Shoot blight
• ISSN: 0929-1873; 1573-8469
• DOI: 10.1007/s10658-023-02665-4

Sanhua plum ( Prunus salicina ), native to Guangdong Province, China, is a highly valued fruit tree because of the fruit's characteristic taste and excellent nutritional properties. A severe blighting of shoots of Sanhua plum was observed at local Sanhua orchards in Guangdong Province from 2019 to 2021, which weakens the tree vigour and reduces the fruit yield. This study aimed to characterize the symptoms of Sanhua plum leaf blight and shoot dieback, evaluate the incidence and impact, and identify the causal agent and evaluate its pathogenicity. The disease was present in all three Sanhua orchards surveyed (a total of 29 hectares), but incidence varied with locations and years, ranging from 0.4% to 3.7%. An oomycete species was isolated from symptomatic shoots collected from the surveyed fields. Based on morphological and cultural characteristics and combined phylogenetic analysis of two molecular markers, including the internal transcribed spacer regions (ITS) of rDNA and Ras-related Ypt1 gene, 15 isolates were identified as belonging to the species Phytophthora nicotianae . The isolates were pathogenic to Sanhua plum plants in nursery experiments, and symptoms identical to that observed in the fields were reproduced. The pathogen was isolated consistently from the inoculated plants, confirming Koch's postulates. Shoot blight caused by P. nicotianae represents a new threat to Sanhua plum productivity and longevity in southern China.