Lasiodiplodia theobromae as a causal pathogen of leaf blight, stem canker, and pod rot of Theobroma cacao in Malaysia

Abstract

Symptoms of leaf blight, stem canker, and pod rot were observed on T. cacao during a series of samplings conducted in several states of Malaysia from September 2018 to March 2019. The identity of the pathogen that was responsible for the diseases was determined using morphological characteristics, DNA sequences, and phylogenetic analyses of multiple genes, namely, internal transcribed spacer (ITS), elongation translation factor 1-alpha (tef1-α), β-tubulin (tub2), and RNA polymerase subunit II (rpb2). A total of 57 isolates recovered from diseased leaves of T. cacao (13 isolates), stems (20 isolates), and pods (24 isolates) showed morphological features that resembled Lasiodiplodia sp. The identity of the isolates was further determined up to the species level by comparing DNA sequences and phylogenetic analyses of multiple genes. The phylogenetic analysis of the combined dataset of ITS, tef1-α, tub2, and rpb2 elucidated that all of the isolates obtained were Lasiodiplodia theobromae as supported by 97% bootstrap value. The results of pathogenicity tests revealed L. theobromae as the causal pathogen of leaf blight, stem canker, and pod rot of T. cacao.

Biological and molecular characterization of Lasiodiplodia theobromae causing dieback disease of strawberry in Thailand

“…Lasiodiplodia theobromae , a member of Botryosphaeriaceae , is a well‐known pathogenic fungus and soil‐borne saprophyte that infects a wide range of host plants, both pre‐ and post‐harvest (Domasch et al, 1980; Lawrence et al, 2016). L. theobromae occurs throughout tropical and subtropical regions (Ismail et al, 2012), and more than 500 host plants such as almonds, blueberries, cocoa, grapevines, mangos, olives, bananas, anthurium, cotton, apple and peanut have been reported (Alves et al, 2008; Daengsuwan et al, 2019; Galvez et al, 2016; Hong et al, 2012; Ismail et al, 2012; Kuswinanti et al, 2019; Nam et al, 2016; Naz et al, 2021; Salaemae et al, 2022; Shakirah et al, 2022). The fungus has been associated with several disease symptoms on import commercial crops, including dieback, fruit rot, stem end rot, pod rot, panicle brown rot, decline, twig and stem blight and stem canker (Amrutha & Vijayaraghavan, 2020; Daengsuwan et al, 2019; Galvez et al, 2016; Hong et al, 2012; Mehmood et al, 2021; Nam et al, 2016; Naz et al, 2021; Shakirah et al, 2022; Yildiz et al, 2014).…”

Untitled

“…The first report of dieback in Strawberry plants in Kenya reveals that the symptoms of dieback began on runners, causing black rot on roots and necrotic discolouration in the crown of the plants [27]. In Theobroma cocoa of Malasia, the isolates of L. theobromae were responsible to cause leaf blight, stem canker and pod rot [24]. Shahbaz [26] found that L. theobromae was associated with the decline of mango trees.…”

“…The infected areas appear to be oval shaped, with blackish centres and brownish margins [23]. The literature reveals L. theobromae fungal pathogen causing dieback in various other plant species like cocoa [24], mango [25,26], strawberry [27] etc. The temperature of 25 °C-30 °C and relative humidity of 80-85% favours the development of the dieback disease in plants.…”

Potential of Omics to Control Diseases and Pests in the Coconut Tree

“…In Brazil, the fungus Lasiodiplodia theobromae is an important pathogen, that causes leaf blight disease. The pathogen invades the rachis to the petiole of the coconut palm, causing necrosis accompanied by gum liberation, which drives early defoliation and loss of bunches, leading to an important loss of coconut fruit yield [23]. This pathogen is widely distributed in India, and it is associated with the postharvest nut rot of coconut [24].…”