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.
Lawn grass (Axonopus compressus) is a widely distributed grass species from the family Poaceae that is ubiquitous in Malaysia. We isolated endophytic fungi from the leaves of A. compressus and molecularly identified them as Fusarium parceramosum, Colletotrichum siamense, C. gigasporum, C. endophyticum, Curvularia lunata, Stagonospora bicolor, Calonectria gracilis, and Albifimbria verrucari. These fungal endophytes are considered host generalists, as they have been isolated from other plants and have also been reported to be latent plant pathogens. We tested the pathogenicity of selected endophytic fungal isolates on A. compressus leaves, chili (Capsicum annum), and tomato (Solanum lycopersicum), and found that they were pathogenic to wounded A. compressus leaves with low to moderate virulence, and several were pathogenic to wounded and unwounded chili and tomato fruits. This indicated that the endophytes could infect both vegetable fruits with low to very high virulence. Pathogenicity tests demonstrated that endophytic fungi from the leaves of A. compressus can become pathogenic and infect the host and other plant species. The findings also indicated that leaves of A. compressus may harbor pathogens with latent ability that can become active due to changes in environmental conditions, thereby disrupting the balance between host-endophyte antagonism.
Fusarium proliferatum is a well-known plant pathogenic fungus-infected many crops. The present study was carried out to molecularly identified and characterized morphologically identified F. proliferatum from various hosts and substrates. The species identity of the isolates was verified as F. proliferatum based on TEF-1α sequences and phylogenetic analysis indicated high intraspecific variations. RFLP-IGS analysis also indicated high intraspecific variations of which the isolates were clustered into three RFLP Groups (I, II, and III) comprising 67 IGS haplotypes. Seventy isolates were crossed-fertile and proven to be members of mating population D (MP-D) of Gibberella fujikuroi while four isolates were infertile. A high level of intraspecific variations is vital for F. proliferatum adaptation and survival in the host and environment. Correct species identification of F. proliferatum is important as the fungus is a well-known plant pathogen and mycotoxin producer. Correct species identity is also essential to strategize suitable disease control methods as well as to predict their host range and mycotoxin production.
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.
Fusarium isolates from highland areas in Malaysia were mostly recovered from two species of grasses, Elyhordeum montanense and Paspalum conjugatum. The isolates were grouped into four morphological groups. Based on TEF-1α sequences, morphotype 1 isolates were molecularly identified as F. graminearum species complex, morphotype 2 as F. venenatum, morphotype 3 as F. avenaceum and morphotype 4 as F. kyushuense. Restriction analysis of the Intergenic Spacer region showed high levels of genetic diversity of isolates in F. graminearum species complex and F. venenatum. For mycotoxin analysis, only F. avenaceum and F. kyushuense produced beauvericin and moniliformin (0.869 & 0.321 µg/kg, respectively). Zearalenone was produced by 32 isolates of F. graminearum species complex (0.002 – 0.437 µg/kg), two isolates of F. venenatum (0.006 - 0.014 µg/kg) and F. kyushuense (0.006 µg/kg). Only F. avenaceum isolate produced fumonisin B1 (0.001 µg/kg). The present study indicates the occurrence of Fusarium species commonly reported in highland areas in Malaysia where the weather is cooler and the temperature is lower than in the lowland areas. To our knowledge, this is the first report on the occurrence of phylogenetic species within F. graminearum species complex, F. venenatum, F. avenaceum and F. kyushuense in Malaysia.
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