Characterization of white rot fungi from wood decayed for lignin degradation.

The present study was conducted to isolate and identify white rot fungi (WRF) from wood decayed and to determine their ability to produce lignin-modifying enzymes (LMEs), specifically laccase (Lac), lignin peroxidase (LiP), and manganese peroxidase (MnP), on solid and liquid media supplemented with synthetic dyes namely 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), azure B, and phenol red. A total of 23 isolates of WRF were isolated from decayed wood and identified as eight different species namely Phanerochaete australis, Perenniporia tephropora, Lentinus squarrosulus, Ganoderma australe, Trametes polyzona, Lentinus sajor-caju, Gymnopilus dilepis, and Fomitopsis palustris based on morphological characteristics, DNA sequences of the internal transcribed spacer (ITS) region, and phylogenetic inference. The fungal isolates can be divided into four groups based on the type of LMEs produced, namely A (Lac-LiP-MnP) with 16 isolates, B (Lac-MnP) (three isolates), C (Lac) (three isolates), and D (MnP) (one isolate). This study highlights P. australis (BJ38) as the best producer of Lac and LiP, while L. squarrosulus (IPS72) is the best producer of MnP. The present study is the first reported P. australis as an efficient lignin degrader by demonstrating the highest activity of two important LMEs.

Evaluation of the pathogenicity of endophytic fungi isolated from spines of rattan (Calamus castaneus) against other plant hosts.

AIMS: In this study, we sought to determine the pathogenic ability of endophytic fungi recovered from the spines of Calamus castaneus, a common rattan palm growing in the forests of Peninsula Malaysia. METHODS AND RESULTS: Ten endophytic fungal isolates were selected for pathogenicity tests: Colletotrichum boninense, Colletotrichum fructicola, Colletotrichum cliviae, Diaporthe hongkongensis, Diaporthe arengae, Diaporthe cf. nobilis, Neopestalotiopsis saprophytica, Neopestalotiopsis formicarum, Fusarium solani and Fusarium oxysporum. These endophytes were tested against leaves of bertam (Eugeissona sp.), oil palm (Elaeis guineensis) and mango (Mangiferae indica) and the fruits of chilli (Capsicum annum), tomato (Solanum lycopersicum) and banana (Musa acuminata). The fungal isolates showed infectivity against bertam, oil palm and mango leaves with degrees of virulence ranging from low to moderate, whereas infectivity against chilli, tomato and banana ranged from low to very high. CONCLUSIONS: Fungal endophytes isolated from the spines of C. castaneus are pathogenic to different crop plants with differing degrees of virulence or aggressiveness. SIGNIFICANCE AND IMPACT OF THE STUDY: Spines of C. castaneus can harbour fungal pathogens of a number of different crops as endophytes. The ability of the fungal endophytes to colonize and infect different crops demonstrate their importance towards agricultural crops. There is a possibility the endophytes behave as latent pathogen. When conditions become favourable, the fungal endophytes transform to pathogenic form and potentially infect other plants.

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

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), ß-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.

Molecular Phylogeny of Endophytic Fungi from Rattan (Calamus castaneus Griff.) Spines and Their Antagonistic Activities against Plant Pathogenic Fungi.

Calamus castaneus is a common rattan palm species in the tropical forests of Peninsular Malaysia and is noticeable by the yellow-based spines that cover the stems. This study aimed to determine the prevalence of fungal endophytes within C. castaneus spines and whether they inhibit the growth of fungal pathogens. Twenty-one genera with 40 species of fungal endophytes were isolated and identified from rattan palm spines. Based on molecular identification, the most common isolates recovered from the spines were Colletotrichum (n = 19) and Diaporthe spp. (n = 18), followed by Phyllosticta spp., Xylaria sp., Trichoderma spp., Helminthosporium spp., Penicillium spp., Fusarium spp., Neopestalotiopsis spp., Arthrinium sp., Cyphellophora sp., Cladosporium spp., Curvularia sp., Bionectria sp., and Acremonium spp. Non-sporulating fungi were also identified, namely Nemania primolutea, Pidoplitchkoviella terricola, Muyocopron laterale, Acrocalymma fici, Acrocalymma medicaginis, and Endomelanconiopsis endophytica. The isolation of these endophytes showed that the spines harbor endophytic fungi. Most of the fungal endophytes inhibited the growth of several plant pathogenic fungi, with 68% of the interactions resulting in mutual inhibition, producing a clear inhibition zone of <2 mm. Our findings demonstrate the potential of the fungal endophytes from C. castaneus spines as biocontrol agents.

Fusarium Species in Mangrove Soil in Northern Peninsular Malaysia and the Soil Physico-Chemical Properties.

Fusarium genus comprises important saprophytic and phytopathogenic fungi and is widespread in nature. The present study reports the occurrence of Fusarium spp. in soils from two mangrove forests in northern Peninsular Malaysia and analyzed physico-chemical properties of the mangrove soil. Based on TEF-1α sequences, nine Fusarium species were identified: Fusarium solani species complex (FSSC) (n = 77), Fusarium verticillioides (n = 20), Fusarium incarnatum (n = 10), Fusarium proliferatum (n = 7), Fusarium lateritium (n = 4), Fusarium oxysporum (n = 3), Fusarium rigidiuscula (n = 2), Fusarium chlamydosporum (n = 1), and Fusarium camptoceras (n = 1); FSSC isolates were the most prevalent. Phylogenetic analysis of the combined TEF-1α and ITS sequences revealed diverse phylogenetic affinities among the FSSC isolates and potentially new phylogenetic clades of FSSC. Soil analysis showed varied carbon content, pH, soil moisture, and salinity, but not nitrogen content, between sampling locations. Regardless of the physico-chemical properties, various Fusarium species were recovered from the mangrove soils. These were likely saprophytes; however, some were well-known plant pathogens and opportunistic human pathogens. Thus, mangrove soils might serve as inoculum sources for plant and human pathogenic Fusarium species. The present study demonstrates the occurrence of various Fusarium species in the extreme environment of mangrove soil, thereby contributing to the knowledge on species diversity in Fusarium.

Diaporthe species causing stem gray blight of red-fleshed dragon fruit (Hylocereus polyrhizus) in Malaysia.

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 ß-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.

Characterisation and Pathogenicity of Aspergillus tamarii Causing Banana Fruit Rot.

Banana fruit rot is a common postharvest disease of the banana fruit. The appearance of rot symptoms on the surface of the fruits reduces the quality and marketability of banana. From rot lesions on banana fruits, three Aspergillus isolates were isolated. Based on morphological characteristics and sequences of Internal Transcribed Spacer, ß-tubulin and calmodulin, the isolates were identified as A. tamarii. Pathogenicity tests of the isolates, conducted using mycelial plugs with wounded and unwounded treatments, showed A. tamarii as the pathogen of banana fruit rot. Rot symptoms were highly severe on wounded banana fruits compared to unwounded fruits, and therefore, wounded banana fruits are more susceptible to A. tamarii infection. To the best of our knowledge, this is the first report of A. tamarii as a causal pathogen of banana fruit rot. This study indicated A. tamarii is one of postharvest rot pathogens of banana.

Reput buah pisang merupakan penyakit lepas tuai yang lazim pada buah pisang. Kemunculan gejala reput pada permukaan buah mengurangkan kualiti dan kebolehpasaran buah pisang. Dari lesi reput pada buah pisang, tiga pencilan Aspergillus telah dipencilkan. Berdasarkan ciri-ciri morfologi dan jujukan Trankripsi Penjarak Dalaman (ITS), ß-tubulin dan kalmodulin, pencilan tersebut dikenal pasti sebagai A. tamarii. Ujian kepatogenan yang dilakukan menggunakan palam miselium dengan rawatan luka dan tidak luka, menunjukkan A. tamarii merupakan patogen reput buah pisang. Gejala reput amat teruk pada buah pisang yang luka berbanding buah yang tidak luka. Oleh itu, buah pisang yang luka lebih mudah dijangkiti A. tamarii. Pada pengetahuan kami, ini adalah laporan pertama A. tamarii sebagai patogen penyebab reput buah pisang. Kajian ini menunjukkan A. tamarii merupakan salah satu patogen reput pisang lepas tuai.

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.