Diversity and Plant Growth-Promoting Effects of Fungal Endophytes Isolated from Salt-Tolerant Plants

Abstract

Unique microecosystems within the internal tissues of plants support diverse, symbiotic microbial communities that greatly influence plant adaptation and evolution [1, 2]. These microbial associations significantly influence the ability of plants to adapt and evolve in their environment. All plants in natural ecosystems appear to develop symbiotic associations with fungi [3, 4]. These symbioses provide a buffer against biotic and abiotic stresses and are important for the survival of plant hosts and their fungal symbionts in highstress habitats [3, 4]. Both plant and fungi obtain multiple benefits from symbiotic interactions in terms of fitness. Fungal symbionts may impart beneficial (mutualism, commensalism, and parasitism), harmful (competition), or neutral (amensalism and neutralism) activities on the plant host. Concurrently, host plants can also interact beneficially (mutualism), neutrally (commensalism and neutralism), or harmfully (parasitism, competition, and amensalism) during symbiosis with the fungi [5-7]. Microbes living within plants are referred to as 'endophytes' and are host-specific fungi or bacteria, such as Actinomycetes spp. [8, 9]. Endophytes constitute a major portion of the fungal symbionts associated with the roots, stems, and leaves of plants, and generally do not impart adverse effects to the host [10, 11]. They comprise a diverse group and represent a wide taxonomical range of fungi belonging primarily to the phylum Ascomycota [12, 13]. Some fungal endophytes can synthesize plant growth hormones such as auxin, abscisic acid, and gibberellins (GAs) [14, 15]. Endophytic fungi increase the host's resistance to biotic stresses caused by insects, pests, and fungal pathogens and improve the host plant's fitness against harsh environmental factors [16]. A large percentage of the world's biodiversity is concentrated within the coastal regions, although much of it is yet to be discovered. The coastal zone is the interface between the land and sea and is characterized by interconnections among neighboring ecosystems. Coastal salt marsh wetlands, located in this transition zone between land and salt or brackish water, are among the most important and biologically productive natural ecosystems on Fungal endophytes are symbiotic microorganisms that are often found in asymptomatic plants. This study describes the genetic diversity of the fungal endophytes isolated from the roots of plants sampled from the west coast of Korea. Five halophytic plant species, Limonium tetragonum, Suaeda australis, Suaeda maritima, Suaeda glauca Bunge, and Phragmites australis, were collected from a salt marsh in Gochang and used to isolate and identify culturable, root-associated endophytic fungi. The fungal internal transcribed spacer (ITS) region ITS1-5.8S-ITS2 was used as the DNA barcode for the classification of these specimens. In total, 156 isolates of the fungal strains were identified and categorized into 23 genera and two phyla (Ascomycota and Basidiomycota), with Dothideomycetes and Sordariomycetes as the pred...

Endophytic fungus Pseudodidymocyrtis lobariellae KL27 promotes taxol biosynthesis and accumulation in Taxus chinensis

“…Endophyte and its host plants formed a harmonious symbiotic relationship during the long-term co-evolution process. Especially, increasing evidences showed that endophyte can directly and indirectly promote the growth and secondary metabolites of its host plants through various ways [ 12 – 14 ]. For example, endophyte can induced the development of its host plants by directly producing plant growth hormone themselves [ 12 ], or indirectly by promoting its host plants capacity of nutrients absorption and stress resistance [ 13 ].…”

Plant Growth Promotion by Two Volatile Organic Compounds Emitted From the Fungus Cladosporium halotolerans NGPF1

“…The genus Cladosporium is a well-known group of fungi that includes some indoor and outdoor molds. Many species of the genus Cladosporium are endophytes that live inside plants, and were found to promote plant growth rather than being pathogenic ( Khalmuratova et al, 2020 ; Sun et al, 2020 ; Faddetta et al, 2021 ; Mao et al, 2021 ; Schmidt et al, 2021 ). However, some species of Cladosporium , including C. fulvum and C. herbarum , are phytopathogenic ( Kaur and Manhas, 2014 ; Elgorban et al, 2017 ; Wang et al, 2018 ), strongly affecting plant growth and health.…”

“…Fungal VOCs that have the ability to promote plant growth can avoid potential pathogenicity problems associated with whole organisms as direct contact is not required ( Hamayun et al, 2010 ; Ghirardo et al, 2011 ; Paul and Park, 2013 ; Naznin et al, 2014 ; Li et al, 2018 ; Khalmuratova et al, 2020 ). It could be safer to only apply VOCs as bio-fungicides and growth stimulants to enhance the growth of plants.…”

Fungal Biodiversity in Salt Marsh Ecosystems

“…When compared to saprobic fungi in halophytes, few studies have been carried out on the diversity of endophytes and pathogens and their interaction in the salt marsh ecosystems. Surveys on endophytic fungi from halophytes using cultivation-dependent methods coupled with molecular approaches, showed that endophytes were dominated by Ascomycota and a few belonged to Basidiomycota and Zygomycota [168][169][170][171][172][173][174][175]. Pathogenic fungi from salt marsh ecosystems are poorly documented but play a significant role in the dynamics of the ecosystem [176][177][178].…”