Characterization of Chinese eggplant isolates of the fungal pathogen Verticillium dahliae from different geographic origins

Abstract

ABSTRACT. Verticillium dahliae is a fungal pathogen that causes wilt disease in a wide range of host plants. Charac terization of virulence, morphological, and molecular variations among V. dahliae isolates from different geographic origins is essential for any breeding program aimed at producing plant cultivars resistant to this disease. We characterized virulence variation among V. dahliae isolates from Chinese cultivated eggplant grown in Northeast China by pathogenicity testing on susceptible, moderately resistant, and resistant eggplant accessions in a glasshouse using a root-dipping method of infection. These isolates were also characterized for morphological features based on growth on potato dextrose agar media and for genetic variation based on ISSR markers. All 12 isolates were divided into three pathotypes based on the virulence, i.e., strong, moderate, or weak type. Three isolates were categorized as defoliating pathotypes, with strong virulence, and the rest of the isolates were categorized as non-defoliating pathotypes, with moderate to weak virulence. The eggplant isolates were classified into three morphological types or morphotypes, hypha, hypha-sclerotia, and sclerotia; no significant correlations were detected between pathotypes and morphotypes or geographic origins. ISSR fingerprinting indicated genetic diversity among isolates, ranging from 0.26 to 0.69. Specific fingerprint types were not correlated with either pathotype or morphotype. However, ISSR analyses did reveal two clusters in which the isolates in each share the same or neighboring geographic origins.

Performance of Aubergine Rootstocks against Verticillium dahliae Isolates in Southeastern Spain

“…Plants were inoculated seven days after transplanting (3-4 true leaves). Each plant was inoculated with 10 mL of conidial suspension (1 × 10 5 conidia mL −1 ), resulting in 1 × 10 6 conidia per plant [5,11]. A hole (1 cm deep) was made on each side of the plant, and the inoculum was introduced into it.…”

“…It has a broad pathogenic capacity and a degree of parasitic specialization [8,9]. The symptoms are leaf yellowing, apical wilting, defoliation, reduced growth, the browning of the vascular system and partial or total desiccation of the plant [8,[10][11][12]. In the absence of the cultivated host plant, this fungus can persist in the soil in form of microsclerotia for a long time (6 to 14 years) [11,13].…”

“…The symptoms are leaf yellowing, apical wilting, defoliation, reduced growth, the browning of the vascular system and partial or total desiccation of the plant [8,[10][11][12]. In the absence of the cultivated host plant, this fungus can persist in the soil in form of microsclerotia for a long time (6 to 14 years) [11,13]. Mild climatic conditions favour the development of the disease and the appearance of symptoms [10,14].…”

“…Mild climatic conditions favour the development of the disease and the appearance of symptoms [10,14]. The pathogenic variability of aubergine isolates is high, with different levels of aggressiveness depending on the cultivar [11] and with asymptomatic infectious isolates [4]. In Spain, symptoms of V. dahliae appear on aubergine crops in spring and autumn when temperatures are mild for approximately 3 to 4 weeks.…”

Genetic Diversity of Cercospora arachidicola Associated with Peanut Early Leaf Spot in Shandong Province of China

“…Restriction fraction length polymorphism (RFLP) (Krishnamoorthy et al 2015), amplified fragment length polymorphism (AFLP) (Onaga et al 2015), random amplification of polymorphic DNA (RAPD) (Patricia et al 2003), sequence-related amplified polymorphism (SRAP) (Mahmoud 2016) and ISSR have been widely applied to assess genetic diversity in plant pathogenic fungi. Among these molecular markers, ISSR is more sensitive, reliable and reproducible owing to higher annealing temperatures and longer primer sequences (Xu et al 2013). This technique specifically amplifies regions of the genome flanked by two inverted microsatellite repeats (Xiao and Gong 2006).…”