Occurrence and identification of Penicillium and Talaromyces species from beach sand

Aims@#Penicillium and Talaromyces were among the species of microfungi that inhabit beach sand in Batu Ferringhi Beach, Penang Island, Malaysia. Previously, Talaromyces was described as the sexual stage of Penicillium, but both are now accepted as separate genera based on molecular phylogeny. The aim of the present study was to identify species of Penicillium and Talaromyces that are present in beach sand in Malaysia.@*Methodology and results@#Species identities were confirmed according to similarities of the internal transcribed spacer regions and β-tubulin gene sequences and a phylogenetic analysis based on both regions/gene. Nine Penicillium spp. were identified as P. georgiense, P. chermesinum, P. pimiteouiense, P. citrinum, P. oxalicum, P. daleae, P. rolfsii and Penicillium sp. and the four Talaromyces spp. were T. siamense, T. atroroseus, T. minioluteus and T. fusiformis.@*Conclusion, significance and impact of study@#These findings showed that beach sand harboured a variety of Penicillium and Talaromyces species. The occurrence of Penicillium and Talaromyces in beach sands is associated with the organic matter in the sand, which provides suitable substrates and nutrient sources. Due to this, beach sand might harbour many potentially pathogenic or opportunistic species that may pose a health concern to immunocompromised individuals.

Colletotrichum spp. associated with agricultural crops in Malaysia, causal pathogens and potential control methods

ABSTRACT@#Colletotrichum is one of the most significant and common plant pathogens, infecting many economically important crops worldwide. Colletotrichum is also one of the most studied fungal genera in Malaysia because it contains many species that infect various types of agricultural crop including fruit, vegetable and industrial crops. Studies on Colletotrichum spp. are mostly focused on the causal pathogens, the host range and disease management. Among the host crops, most studies on Colletotrichum spp. have been conducted on infection in chilli (Capsicum spp.), which, in Malaysia, first arose in the 1980s and still continues to be a problem to this day. Studies have also been conducted on Colletotrichum spp. associated with anthracnose in fruit crops including dragon fruit, papaya, banana and mango. Disease management of anthracnose pathogens postharvest has also been conducted to prolong the shelf life of these fruit crops. In this review, Colletotrichum spp. associated with chilli and several fruit crops as well as their disease management are highlighted. There have been many changes in Colletotrichum taxonomy and systematics in recent years, affecting the identification of anthracnose pathogens reported in Malaysia. Colletotrichum species identified solely by morphology or solely via the internal transcribed spacer (ITS) region should be referred to as sensu lato (in the broad sense) since many species belong to species complexes. Species within a species complex are closely related, and most are cryptic species particularly species in the C. gloeosporioides and C. acutatum complexes which are commonly associated with agricultural crops in Malaysia. Due to the importance of Colletotrichum spp. as plant pathogens, up-to-date identification methods should be used since accurate species identification of Colletotrichum is crucial for formulating suitable disease management programmes as well as for plant quarantine and biosecurity purposes. This review provides the current knowledge on the status of Colletotrichum spp. associated with agricultural crops in Malaysia and potential control methods on different types of agricultural crops.

Aspergillus species from groundnuts (Arachis hypogaea) and mycotoxin production by toxigenic species

Aims@#Groundnut is an important food crop and is susceptible to contamination by Aspergillus. The present study was conducted to identify Aspergillus spp. from groundnuts as well as to detect mycotoxin production by toxigenic species. @*Methodology and results@#Molecular identification using ITS region, β-tubulin and calmodulin genes identified six species, A. niger, A. tubingensis, A. flavus, A. aculeatus, A. sydowii and A. fumigatus. Phylogenetic tree of combined sequences showed the isolates from the same species were grouped with reference strains in the same clade, thus the species identity was confirmed. Detection of mycotoxin biosynthesis genes can give an indication of mycotoxin production. Two ochratoxin A genes, PKS15KS and PKS15C-MeT were detected in seven A. niger isolates but none of the isolates produced ochratoxin A when quantification was conducted using Ultra-High Performance Liquid Chromatography. Two aflatoxin B1 biosynthesis genes, Nor-1 (norsolorinic acid) and Ver-1 (Versicolorin) genes were detected in A. flavus but only KDH7 and KL27b isolates produced aflatoxin B1 with concentrations of 1.0 μg/g and 1.1 μg/g, respectively. @*Conclusion, significance and impact of study@#Various species of Aspergillus found on groundnuts may lead to potential mycotoxin contamination as toxigenic species were also recovered. The occurrence of Aspergillus spp. can reduce the quality of the legumes as well as reducing their shelf life.

Preliminary study on the effects of fusaric acid treated protocorm-like bodies of Dendrobium hybrid against Fusarium proliferatum and Fusarium oxysporum

Aims@#Dendrobiums are majorly affected by Fusarium proliferatum and F. oxysporum. The aim of this research was to utilise the mycotoxin, fusaric acid (FA) on Dendrobium hybrid to produce cultivars that are resistant towards these fungi. @*Methodology and results@#FA of concentrations 0.05, 0.10, 0.15 and 0.20 mM were transferred to sterilised half-strength Murashige and Skoog (MS) medium and inoculated with four weeks old thin cell layer (TCL) of protocorm-like bodies (PLBs) for eight weeks. It was deduced that PLBs treated with 0.10 mM of FA resulted in highest survival and shoot regeneration rate but the survival and regeneration rate began to decline as the concentrations of FA were increased. Histology and scanning electron microscopy (SEM) observation showed prominent cell damage and stomatal closure in PLBs treated with FA. Direct amplification of minisatellite DNA (DAMD) markers showed polymorphism in the FA treated PLBs compared to the control PLBs. In the leaf bridge bioassay, plantlets treated with 0.05 mM of FA showed most resistance towards both fungal species. @*Conclusion, significance and impact of study@#Therefore, this research is a preliminary screening study where the optimum concentration of FA was selected based on the reaction of treated TCL of PLBs towards these mutagens.

Identification and Characterization of Macrophomina phaseolina Causing Leaf Blight on White Spider Lilies (Crinum asiaticum and Hymenocallis littoralis) in Malaysia

Crinum asiaticum and Hymenocallis littoralis, commonly known as spider lilies are bulbous perennial and herbaceous plants that widely planted in Malaysia as ornamental. During 2015–2016, symptom of leaf blight was noticed on the hosts from several locations in Penang. The symptom appeared as irregular brown to reddish lesions surrounded by yellow halos. As the disease progressed, the infected leaves became blighted, dried, and fell off with the presence of black microsclerotia and pycnidia on the lesions parts. The present study was conducted to investigate the causal pathogen of leaf blight on C. asiaticum and H. littoralis. Based on morphological characteristics and DNA sequences of internal transcribed spacer (ITS) region and translation elongation factor 1-alpha (TEF1-α) gene, the causal pathogen was identified as Macrophomina phaseolina. Phylogenetic analysis of combined dataset of ITS and TEF1-α grouped the isolates studied with other isolates of M. phaseolina from GenBank. The grouping of the isolates was supported by 96% bootstrap value. Pathogenicity test proved the role of the fungus in causing leaf blight on both hosts.

The pathogen and control management of rice blast disease

Abstracts@#Outbreak of rice blast disease is a serious problem in all rice growing regions worldwide and is a threat to rice production. In Malaysia, the outbreak of rice blast is a recurrent problem where rice plant remain vulnerable to the disease. Nowadays, the generic name of rice blast pathogen is Pyricularia oryzae and Magnaporthe oryzae is the synonym. Rice pathogen infects mainly aerial parts of rice plant causing rotting and blast on the leaves, stems, peduncles, panicles and seeds leading to crop failure. Rice blast pathogen population is regarded as highly variable and consisted of multiple pathotypes which contribute to genetic diversity as well virulence diversity of the pathogen. The pathotypes can only be determined through pathogenicity test using a set of differential rice cultivars which generally differ by one or more resistance genes. Knowledge on the rice blast virulence and host resistant is important to manage the disease. Among the control methods, utilizing resistant cultivars is considered as the most effective approach to manage rice blast disease. Therefore, development of blast resistant cultivar becomes a priority.

Characterization of two xerophilic Aspergillus spp. from peanuts (Arachis hypogaea)

@#Aims: Xerophilic Aspergillus spp. promote the growth of toxigenic species. Since mycotoxins are toxic to human andanimal, identification of these species is important.Methodology and results: Two xerophilic species isolated from peanuts (Arachis hypogaea) were identified based onmorphological characteristics, molecular identification, and phylogenetic analysis using internal transcribed spacerregion, β-tubulin, and calmodulin sequences.Conclusion, significance and impact of study: The occurrence of A. chevalieri and A. amstelodami on peanutsprovides favorable growth conditions for less xerophilic Aspergillus as well as other spoilage-related fungal genera,particularly mycotoxin-producing species that could lead to mycotoxin contamination. The occurrence of A. chevalieriand A. amstelodami on peanuts might also reduce shelf life and affect the quality of the kernels. To our knowledge, thisis the first report of the occurrence of A. chevalieri and A. amstelodami on a food product in Malaysia, and the finding ofthis study contributes to the repertoire of Aspergillus species that are associated with food products.

Occurrence of microfungi on several dried fruits

Aims: Dried fruits may harbour a variety of fungi especially those that can grow in low water activity conditions. Knowledge on the occurrence of fungi on dried fruits is an important step to predict the possibility of mycotoxin contamination, thus the present study was conducted to determine the occurrence of fungi on dates, figs, kiwi and raisins. Methodology and results: Based on morphological characteristics, six genera of fungi comprising eight species, Aspergillus niger, A. flavus, Penicillium corylophilum, P. glabrum, Chaetomium globosum, Fusarium sacchari, Acremonium strictum and Mycelia sterilia were identified. Three most commonly species isolated were A. niger (19 isolates), P. corylophilum (seven isolates) and A. flavus (five isolates). The less common species were C. globosum (three isolates), Mycelia sterilia (three isolates), A. strictum (one isolate) and P. glabrum (one isolate). Conclusion, significance and impact of study: Common mycotoxin producer are the fungi from the genera Aspergillus, Penicillium and Fusarium. The occurrence of toxigenic fungi on dates, figs, kiwi and raisins suggested that some of these fungi may be an important source of mycotoxin contamination.

The First Report of Penicillium georgiense in Malaysia

Penicillium georgiense was isolated from sandy beach soil from Batu Ferringhi beach, Penang Island, Malaysia. The identification was based on morphological characteristics and phylogenetic analysis of internal transcribed spacer regions and beta-tubulin sequences. To the best of our knowledge, this is the first report of P. georgiense in Malaysia.

Fusarium species Associated with Fruit Rot of Banana (Musa spp.), Papaya (Carica papaya) and Guava (Psidium guajava)

A total of 60 isolates of Fusarium were isolated from fruit rot of banana (Musa spp.), papaya (Carica papaya) and guava (Psidium guajava). The most common species recovered from the fruit rot of the three fruit crops were F. semitectum (40 %), F. solani (38.3 %), F. verticillioides (11.7 %) and F. oxysporum (10 %). Fusarium semitectum was isolated from fruit rot of banana, papaya and guava; F. oxysporum from banana and papaya; F. solani from banana and guava and F. verticillioides from banana. From pathogenicity tests, F. solani and F. semitectum were pathogenic to both banana and papaya and F. verticillioides to banana. F. oxysporum was not pathogenic to banana and papaya and F. semitectum was not pathogenic to guava. The results of the present study showed the presence of several Fusarium spp. on fruit rot of banana, papaya and guava and several species are found to be pathogenic causing fruit rot on their hosts.