Molecular identification of endophytic fungi in lawn grass (Axonopus compressus) and their pathogenic ability

Abstract

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.

Identification and Characterization of Beneficial Soil Microbial Strains for the Formulation of Biofertilizers Based on Native Plant Growth-Promoting Microorganisms Isolated from Northern Mexico

“…Therefore, the following evaluation steps involved the microbial mass propagation on a commercial growth medium and further in vivo bioassay on two different plants species grown under seedbed conditions to identify plant pathogenicity or the establishment of symbiotic rhizosphere colonization capable of promoting plant growth and development, since successful plant growth promotion implies that PGPM colonized and interacted adequately with plant roots in the rhizosphere [ 28 ]. Since combined PGP traits were considered in the selection of the best strains for biofertilizer formulation, it was decided to evaluate fungi mostly as consortia since some fungal species, including species of the genera Aspergillus and Penicillium , are considered facultative microorganisms or latent plant pathogens associated with various plant diseases such as anthracnose, plant rot, leaf spot, wilt, blight, mildew, and post-harvest diseases, among others [ 29 , 30 , 31 , 32 ]. Bacterial strains individually exhibited a better combination of plant growth-promoting mechanisms, making them potential candidates for the formulation of biofertilizers.…”

Fungal Endophytes as Mitigators against Biotic and Abiotic Stresses in Crop Plants

“…Apart from the beneficial effects of fungal endophytes, some reported studies show that their adverse effects on the survival of host plants are minimal and thus could be ignored due to their lack of pathogenic properties. The result of the pathogenicity tests revealed that most of the fungal endophytes that reside inside host plant tissues can reflect their pathogenic ability with differing degrees of virulence to potentially infect both their natural hosts and non-hosts, including particularly important agricultural crop species [169][170][171]. Therefore, it was noticed that several fungal endophytes have also been reported to be part of a group of latent plant pathogens, which alter the host's physiology and render them more prone to fungal infection.…”

Plants as the Extended Phenotype of Endophytes—The Actual Source of Bioactive Compounds

“…For example, the fungus Fusarium verticillioides plays a dual role in maize, operating as both a harmful pathogen and a beneficial endophyte [ 46 ]. Pathogenicity experiments conducted on endophytic fungi isolated from a healthy Axonopus compressus plant revealed their capacity to infect both their natural hosts and non-hosts [ 47 ]. The equilibrium between these two states is determined not only by the genotype of the host, but also by the local abiotic stress factors that have a negative impact on the host fitness [ 37 ].…”