Morphology, DNA Phylogeny, and Pathogenicity of Wilsonomyces carpophilus Isolate Causing Shot-Hole Disease of Prunus divaricata and Prunus armeniaca in Wild-Fruit Forest of Western Tianshan Mountains, China

Abstract

Prunus divaricata and Prunus armeniaca are important wild fruit trees that grow in part of the Western Tianshan Mountains in Central Asia, and they have been listed as endangered species in China. Shot-hole disease of stone fruits has become a major threat in the wild-fruit forest of the Western Tianshan Mountains. Twenty-five isolates were selected from diseased P. divaricata and P. armeniaca. According to the morphological characteristics of the culture, the 25 isolates were divided into eight morphological groups. Conidia were spindle-shaped, with ovate apical cells and truncated basal cells, with the majority of conidia comprising 3–4 septa, and the conidia had the same shape and color in morphological groups. Based on morphological and cultural characteristics and multilocus analysis using the internal transcribed spacer (ITS) region, partial large subunit (LSU) nuclear ribosomal RNA (nrRNA) gene, and the translation elongation factor 1-alpha (tef1) gene, the fungus was identified as Wilsonomyces carpophilus. The 25 W. carpophilus isolates had high genetic diversity in phylogenetic analysis, and the morphological groups did not correspond to phylogenetic groups. The pathogenicity of all W. carpophilus isolates was confirmed by inoculating healthy P. divaricata and P. armeniaca leaves and fruits. The pathogen was re-isolated from all inoculated tissues, thereby fulfilling Koch’s postulates. There were no significant differences in the pathogenicity of different isolates inoculated on P. armeniaca and P. divaricata leaves (p > 0.05). On fruit, G053 7m3 and G052 5m2 showed significant differences in inoculation on P. armeniaca, and G010 5m2 showed extremely significant differences with G004 7m2 and G004 5m2 on P. divaricata (p < 0.05). This is the first report on shot-hole disease of P. armeniaca (wild apricot) leaves and P. divaricata induced by W. carpophilus in China.

The Self-incompatibility Locus and Chloroplast DNA Regions of Prunus domestica Reflect the Origin and Genetic Diversity of Traditional Cultivars

“…PHYLOGENETIC INFERENCE. Phylogenetic inference among the studied taxa was carried out using maximum-likelihood (ML) and Bayesian (BA) approaches. The ML and BA methods were chosen for phylogenetic analysis because of their robustness, efficiency, and demonstrated success in former studies (Xu et al 2022;Ye et al 2020). Before the analysis, the cpDNA and nuclear (nrITS) sequences were concatenated into separate matrices, then indel polymorphisms were coded following the simple gap coding algorithm developed by Simmons et al (2001) using FastGap 1.2 (Borchsenius 2009).…”

Development of PCR based SSR markers for Wilsonomyces carpophilus and a PCR based diagnosis protocol for the early detection of shot hole disease in stone fruit crops

“…The shot hole pathogen Wilsonomyces carpophilus belongs to phylum Ascomycota, class: Dothideomycetes, order: Pleosporales and family Dothidotthiaceae (1,2). Shot hole disease is one of the most economically important diseases of stone fruits worldwide.…”

Main text: Population structure of Wilsonomyces carpophilus, the shot hole pathogen of stone fruits in Kashmir, India.

“…The pathogen affects leaves, fruits, twigs, latent buds and ower calyxes (Abolfazl, 2018). Symptoms of W. carpophilus include narrow circular purple lesions with pale center that gradually became larger and necrotic in the centre until the centre fell out, imitating a shot hole and on fruits sunken necrotic lesions are formed (Ye et al, 2020). Although the studies have been conducted on W. carpophilus morphology (Adaskaveg, 1995;Ahmadpour et al, 2009a), host inoculation and varietal response (Ahmadpour et al, 2012a), disease epidemiology (Adaskaveg, 1990b), disease control and genetic diversity (Ahmadpour et al, 2012b;Nabi et al, 2018), no information is available on its genetic structure.…”

“…Seven ISSR (inter-simple sequence repeat) markers revealed a signi cant amount of polymorphism in various isolates of W. carpophilus in Kashmir, indicating that these markers were useful for examining the genetic diversity in shot-hole infections (Nabi et al, 2018). Morphological and cultural traits, as well as multilocus analysis utilizing the internal transcribed spacer (ITS) region, partial large subunit (LSU) nuclear ribosomal RNA (nrRNA) gene, and the translation elongation factor 1-alpha (tef1) gene, demonstrate substantial genetic variation in phylogentic analysis with 25 W. carpophilus isolates from Prunus armeniaca and P. divaricadiata (Ye et al, 2020).The knowledge of genetic structure provides insight into the evolutionary processes that shape the populations (Mc Donald and Linde, 2002). Thus, the objective of this study was to study the genetic structure of W. carpophilus from different geographic regions and different hosts by determining genetic diversity and genetic differentiation using ISSR markers and sequence information of ITS region of the fungus so as to analyse the possible disease management strategies.…”