Abstract
This study aimed to characterize the new fungal disease on the stem of red-fleshed dragon fruit (Hylocereus polyrhizus) in Malaysia, which is known as gray blight through morphological, molecular and pathogenicity analyses. Nine fungal isolates were isolated from nine blighted stems of H. polyrhizus. Based on morphological characteristics, DNA sequences and phylogeny (ITS, TEF1-α, and β-tubulin), the fungal isolates were identified as Diaporthe arecae, D. eugeniae, D. hongkongensis, D. phaseolorum, and D. tectonendophytica. Six isolates recovered from the Cameron Highlands, Pahang belonged to D. eugeniae (DF1 and DF3), D. hongkongensis (DF9), D. phaseolorum (DF2 and DF12), and D. tectonendophytica (DF7), whereas three isolates from Bukit Kor, Terengganu were recognized as D. arecae (DFP3), D. eugeniae (DFP4), and D. tectonendophytica (DFP2). Diaporthe eugeniae and D. tectonendophytica were found in both Pahang and Terengganu, D. phaseolorum and D. hongkongensis in Pahang, whereas D. arecae only in Terengganu. The role of the Diaporthe isolates in causing stem gray blight of H. polyrhizus was confirmed. To date, only D. phaseolorum has been previously reported on Hylocereus undatus. This is the first report on D. arecae, D. eugeniae, D. hongkongensis, D. phaseolorum, and D. tectonendophytica causing stem gray blight of H. polyrhizus worldwide.
Highlights
Red-fleshed dragon fruit (Hylocereus polyrhizus) is one of the most highly demand varieties, grown in Malaysia owing to its nutritional value and attractive color
This study aimed to identify the causal pathogen of the stem gray blight of H. polyrhizus via morphological, molecular, and pathogenicity analyses
Α- and β-conidia, were produced from the formation of pycnidial conidiomata on carnation leaf agar (CLA). α-conidia were characterized as aseptate, hyaline, and fusiform with bi- or multi-guttulate, β-conidia were characterized as aseptate, hyaline, filiform, straight, or more often hamate, and lack guttule
Summary
Red-fleshed dragon fruit (Hylocereus polyrhizus) is one of the most highly demand varieties, grown in Malaysia owing to its nutritional value and attractive color. Dragon fruits with stem gray blight were found in two locations, namely, Bukit Kor, Terengganu, Malaysia, and the Cameron Highlands, Pahang, Malaysia, in November 2017 and July 2018, respectively. These fruits exhibited irregular gray chlorotic lesion on the stem surface and black pycnidia on the infected part. This study aimed to identify the causal pathogen of the stem gray blight of H. polyrhizus via morphological, molecular, and pathogenicity analyses
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
