Diversity of fungi associated with plants growing in geothermal ecosystems and evaluation of their capacities to enhance thermotolerance of host plants

Abstract

Diversity and heat-adaptation of endophytic fungi (EF) and rhizospheric fungi associated with plants growing in geothermal ecosystems, Southwest China, as well as their benefit in improving host plant thermotolerances were investigated. A total of 1589 culturable fungi belonging to 38 taxa were isolated, in which Curvularia, Acrophialophora, Penicillium, and Aspergillus were the dominant genera. The Shannon indices of EF and rhizospheric fungi ranged from 1.80 to 2.56 and 0.73 to 2.11, respectively. Phylogenetic analysis indicated that the EF have a close relationship with rhizospheric fungi. However, some fungi exhibited apparently species-specific habitat distribution patterns. Growth temperature tests indicated that 60.22% of the tested isolates were thermotolerant fungi and only 39.78% were mesophiles, and the number of heat-adapted fungi increased with increasing environmental temperatures. The strain G1-29, which was isolated from the roots of Hedyotis diffusa and identified as Curvularia crepinii, significantly improved host plant thermotolerance under laboratory conditions: the death rate of endophyte-infected plants was significantly lower than that of endophyte-free plants (t-test, p = .0158, df = 4). Our results suggested that the EF and rhizospheric fungi associated with plants growing in geothermal ecosystems are diverse, and many of them have adapted to the high environmental temperatures. Some fungi have come to be the dominant endemic inhabitants of specific niches, and some played an important role in improving host plant thermotolerances.

Diversity, Phylogeny and Antagonistic Activity of Fungal Endophytes Associated with Endemic Species of Cycas (Cycadales) in China

“…Root endophytic fungi were reported in different plants across a wide range of environments. For instance, mounting evidence showed a highly diverse species of root endophytes in plants thriving in hostile environments, such as deserts [ 5 , 6 ], salt marshes [ 7 , 8 ], arid and geothermal environments [ 9 , 10 ] and karst rocks [ 11 ]. The functional symbiosis or the establishment of mutualistic relationships between root fungal endophytes with their hosts are crucial for their survival and adaptation to these extremophilic environments [ 11 ].…”

Fungal community turnover along steep environmental gradients from geothermal soils in Yellowstone National Park

“…Soil temperature is thought to be the most significant factor influencing bacterial and archaeal species composition in geothermally heated environments [21, 61, 62]. Thermophilic fungi are mostly known from studies on plant-associated fungi from geothermal environments [63] and surveys such as the YNP metagenome project [64]. There is also experimental evidence documenting previously unknown thermophilic and acidophilic fungal species from hot spring habitats (Yamazaki, Toyama and Nakagiri [65].…”

Endophytic fungal diversity ofFragaria vesca, a crop wild relative of strawberry, along environmental gradients within a small geographical area

“…Suboptimal environments offer opportunities to explore and understand the fungal diversity that could be useful for agricultural applications. For example, novel endophytes of plants growing in geothermal soils have been shown to confer high temperature tolerance to the host plants ( Rodriguez & Redman, 2008 ; Zhou et al, 2015 ). The majority of the CWRs originate from diverse habitat types, including hotspots in the subtropical and tropical regions of the world ( Castañeda-Álvarez et al, 2016 ).…”