Biological and molecular characterization of seven Diaporthe species associated with kiwifruit shoot blight and leaf spot in China

Yamin Du,Yuhong Peng,Guoping Wang,Feng Xiao,Yashuang Guo,Xianhong Wang,Ni Hong

doi:10.36253/phyto-12013

Abstract

Diaporthe species are significant pathogens, saprobes, and endophytes, with comprehensive host association and geographic distribution. These fungi cause severe dieback, cankers, leaf spots, blights, and stem-end rot of fruits on different plant hosts. This study, explored the occurrence, diversity and pathogenicity of Diaporthe spp. associated with Actinidia chinensis and A. deliciosa in the main kiwifruit production areas of China. Diaporthe isolates (284) derived from 106 diseased leaf and branch samples were examined. Multi-locus phylogenetic analyses and morphology of 43 representative isolates revealed that seven Diaporthe species were obtained, including D. alangii, D. compactum, D. eres, D. hongkongensis, D. sojae, D. tectonae, and D. unshiuensis. Pathogenicity tests were performed on kiwifruit fruits, leaves and branches. Koch’s postulates confirmed all species were pathogenic. D. alangii and D. tectonae were the most aggressive species, followed by D. eres, D. sojae, D. hongkongensis, D. unshiuensis, and D. compactum. Host range evaluation showed that the seven Diaporthe species could also infect apricot, apple, peach, pear, and plum. This is the first report of D. alangii, D. compactum, D. sojae, D. tectonae, and D. unshiuensis infecting kiwifruit in China, increasing understanding of the Diaporthe complex causing diseases of kiwifruit plants, to assist effective disease management.

Highlights

Kiwifruit is known “the king of fruits” due to its rich nutritional content, abundant dietary fibres, balanced nutritional composition of minerals, high vitamin C content, antioxidant properties and other human health-beneficial metabolites, including carotenoids and flavonoids (Huang et al, 2013; Pan etYamin Du et alii al., 2020; Wu et al, 2020)
81 isolates were obtained from diseased leaf samples, and were identified as six species of Diaporthe (D. alangii, D. compactum, D. eres, D. hongkongensis, D. sojae, and D. unshiuensis)
203 isolates were derived from infected shoots, and were identified as seven species of Diaporthe (D. alangii, D. compactum, D. eres, D. hongkongensis, D. sojae, D. unshiuensis and D. tectonae)

Summary

Introduction

Kiwifruit is known “the king of fruits” due to its rich nutritional content, abundant dietary fibres, balanced nutritional composition of minerals, high vitamin C content, antioxidant properties and other human health-beneficial metabolites, including carotenoids and flavonoids (Huang et al, 2013; Pan etYamin Du et alii al., 2020; Wu et al, 2020). Through decades of domestication and substantial efforts for selection from wild plants, several important horticultural species have been commercially cultivated, including Actinidia chinensis, A. deliciosa, A. eriantha, and A. arguta (Huang et al, 2013; Song et al, 2020). Branch blight and leaf spot diseases are widespread and prevalent, and these diseases cause serious economic losses in China, and affect development of the kiwifruit industry. The most common disease symptoms observed in kiwifruit plantations consist of branch blight, leaf spot, bacterial blossom blight, and fruit rot. These symptoms are related to several fungi (Hawthorne et al, 1982; Pennycook, 1985; Pan et al, 2018) and bacteria (Zhang et al, 2019)

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