Colletotrichum species associated with fig (Ficus carica L.) in Malaysia
Graphical abstract
Introduction
Fig (Ficus carica L.) is a deciduous tree that grows 10–30 feet tall. This edible fruit belongs to Moraceae which can be consumed either fresh or dried. The family Moraceae (mulberry family) comprises 53 genera and 1400 species, about 800 of which are in the genus Ficus. Among the members of the family include trees, shrubs, lianes, and herbs that commonly produce lacticifers with latex (Mabberley, 1997). Fig originates from the eastern Mediterranean region and nowadays, it has been widely cultivated throughout the world, including Malaysia. This ancient fruit has gained a lot of interest among growers due to its unique characteristics, nutritional value, and medicinal properties.
Figs are soft and dense woody plants, while the bark is commonly gray, smooth, and without fissures. It has thick spreading branches and stems, and fibrous roots (Dominguez, 1990). The leaves are palmate, large, petiolate with three to seven lobes, thick and rough on the upper surface but soft and hairy on the lower surface (Ferguson et al., 1990; Crisosto et al., 2011). Leaves are a distinctive feature to distinguish fig varieties. The fruit is synconium, obovoid, turbinate, or pear-shaped, 1–4 inches long and varies in color from yellowish green to coppery, bronze, or dark purple depending on the variety (McGovern, 2002; Salma et al., 2020). The skin of the fruit is thin and perishable especially during ripening. Apart from being a unique fruit, it is a nutritious fruit rich in fiber, potassium, calcium, iron, antioxidant polyphenols, proteins, sugars, and organic acids (Slatnar et al., 2011). Ficus carica demonstrates various pharmacological compounds that are valuable as antipyretic, anti-inflammatory, anticonstipation, anticancer, antiviral, and antimutagenic effects (Badgujar et al., 2014).
Regrettably, like other deciduous plants, every part of the fig is susceptible to fungal diseases. This problem causes important repercussions in fig production. According to Michailides (2003), fungal diseases are responsible for the loss of up to 50% of total fig production in California. However, scientific studies on F. carica fungal diseases in Malaysia, even in the world, are still lacking. The first fungal diseases on F. carica recently reported in Malaysia were leaf blight and stem canker caused by Lasiodiplodia theobromae and L. brasiliensis, and fruit rot caused by L. theobromae (Nur-Shakirah et al., 2022). Other previous studies have shown the occurrence of fungi and fungal-like organisms causing multiple diseases on fig plants, including Cercospora fici and Bipolaris sorokiniana causing leaf spot (Schubert et al., 1999; Atashi and Fotouhifar, 2022); L. theobromae and Neoscytalidium dimidiatum causing canker, shoot blight, and stem dieback (Ray et al., 2010; Çeliker and Michailides, 2012; Güney et al., 2022); Ceratocystis ficicola causing stem wilt (Kajii et al., 2013); Colletotrichum gloeosporioides causing anthracnose fruit rot (Choi et al., 2013); Cerotelium fici causing leaf rust (Solano-Báez et al., 2017); Neocosmospora caricae sp. nov. and N. metavorans causing stem and trunk canker (Bolboli et al., 2022); and Phytophthora palmivora causing fruit rot (Michailides, 2003).
Samplings conducted from September 2018 to March 2019 manifested the occurrence of leaf blight, stem canker, and anthracnose fruit rot of F. carica in nurseries in various states in Malaysia. Observations during sampling showed that the disease incidence of leaf blight, stem canker, and anthracnose fruit rot in fig nurseries was 15%, 20%, and 25%, which could threaten the fig cultivation and production. Symptomatic samples of leaves, stems, and fruits were collected and brought back to the laboratory for further analysis. This study aims to determine the causal pathogens of leaf blight, stem canker, and anthracnose fruit rot of F. carica in Malaysia through morphological, molecular, and pathogenicity analyses.
Section snippets
Sample collection and fungal isolation
From September 2018 to March 2019, samplings were conducted during rainy seasons at different nurseries in seven states in Malaysia, including, Perlis, Kedah, Penang, Perak, Selangor, Terengganu, and Pahang. A total of 57 plants of F. carica from the Super Jumbo variety were sampled consisting of 28 blighted leaves, 11 cankered stems, and 18 anthracnose-rotted fruits. Symptomatic leaves showed blight symptoms, including circular to irregular brownish lesions, which then enlarged gradually,
Fungal isolation and morphological characterization
A total of 39 fungal isolates were isolated from symptomatic leaves (19 isolates), stems (eight isolates), and fruits (12 isolates) of F. carica in Malaysia. Based on morphological characterization, the fungal isolates were assigned into three different morphotypes, A (one isolate), B (30 isolates), and C (eight isolates). Isolate from morphotype A produced dense, off-white to slightly gray aerial mycelium (Fig. 2.A), whereas isolates from morphotype B produced whitish aerial mycelium, cottony,
Discussion
The present study discovered three Colletotrichum species namely C. fructicola, C. siamense, and C. truncatum associated with fig (F. carica) in Malaysia. Colletotrichum is considered as one of the 10 most important genera of phytopathogens in the world causing multiple diseases in a wide range of economically important plants, including F. carica (Tan et al., 2022). Ficus carica has been grown in Malaysia since the 2000s (Moniruzzaman et al., 2020). Some growers grow F. carica as their hobby
Credit authorship contribution statement
Abdul Omar Nur-Shakirah: Conceptualization, Methodology, Formal Analysis, Investigation, Writing – original draft. Mohd Safie Khadijah, Yee Jia Kee: Conceptualization, Field observation, Sample collecting, Methodology, Investigation. Bee Lynn Chew: Conceptualization, Field observation, Sample collecting. Latiffah Zakaria, Nik Mohd Izham Mohamed Nor, Sreeramanan Subramaniam, Yin-Hui Leong: Conceptualization, Methodology. Masratul Hawa Mohd: Writing-Reviewing & Editing, Supervision.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
This work was supported by Research University Grant (1001/PBIOLOGI/8011061) from Universiti Sains Malaysia.
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