Symbiotic Interaction Enhances the Recovery of Endangered Tree Species in the Fragmented Maulino Forest

Abstract

Beneficial plant-associated microorganisms, such as fungal endophytes, are key partners that normally improve plant survival under different environmental stresses. It has been shown that microorganisms from extreme environments, like those associated with the roots of Antarctica plants, can be good partners to increase the performance of crop plants and to restore endangered native plants. Nothofagus alessandrii and N. glauca, are among the most endangered species of Chile, restricted to a narrow and/or limited distributional range associated mainly to the Maulino forest in Chile. Here we evaluated the effect of the inoculation with a fungal consortium of root endophytes isolated from the Antarctic host plant Colobanthus quitensis on the ecophysiological performance [photosynthesis, water use efficiency (WUE), and growth] of both endangered tree species. We also, tested how Antarctic root-fungal endophytes could affect the potential distribution of N. alessandrii through niche modeling. Additionally, we conducted a transplant experiment recording plant survival on 2 years in order to validate the model. Lastly, to evaluate if inoculation with Antarctic endophytes has negative impacts on native soil microorganisms, we compared the biodiversity of fungi and bacterial in the rhizospheric soil of transplanted individuals of N. alessandrii inoculated and non-inoculated with fungal endophytes. We found that inoculation with root-endophytes produced significant increases in N. alessandrii and N. glauca photosynthetic rates, water use efficiencies and cumulative growth. In N. alessandrii, seedling survival was significantly greater on inoculated plants compared with non-inoculated individuals. For this species, a spatial distribution modeling revealed that, inoculation with root-fungal endophytes could potentially increase the current distributional range by almost threefold. Inoculation with root-fungal endophytes, did not reduce native rhizospheric microbiome diversity. Our results suggest that the studied consortium of Antarctic root-fungal endophytes improve the ecophysiological performance as well as the survival of inoculated trees and can be used as a biotechnological tool for the restoration of endangered tree species.

Early Effects of Mycorrhizal Fungal Inoculum and Fertilizer on Morphological and Physiological Variables of Nursery-Grown Nothofagus alessandrii Plants

“…Few studies have measured photosynthesis in N. alessandrii . Torres-Díaz et al [ 79 ] evaluated the effect of inoculation with a fungal consortium of root endophytes isolated from the Antarctic host plant Colobanthus quitensis on ecophysiological performance (photosynthesis, water use efficiency, and growth) in N. alessandrii and Nothofagus glauca (Phil.) Krasser.…”

Extreme environments as sources of fungal endophytes mitigating climate change impacts on crops in Mediterranean‐type ecosystems

“…However, Penicillium species found in Antarctica may already be present in South America, since this cosmopolitan genus, which forms tiny (typically <6 μm × <4 μm) dry spores, is apparently capable of intercontinental dispersal, with all three operational taxonomic units of the genus recorded in Antarctic soils also being found in soils on other continents (Cox et al, 2019). Nevertheless, in order to avoid inadvertent introductions of pathogens into agricultural soils, we advocate the thorough identification of Antarctic endophytic fungi based on DNA sequence data (Torres‐Díaz et al, 2021) and stringent tests of the effects of these fungi on crop performance. It has also been suggested that the introduction of endophytes from Antarctica to South America could alter native soil communities (Núñez et al, 2015).…”

“…It has also been suggested that the introduction of endophytes from Antarctica to South America could alter native soil communities (Núñez et al, 2015). However, the inoculation of Nothofagus with Antarctic isolates of P. rubens and P. bialowiezense has no apparent effects on the diversity or abundance of native rhizosphere bacteria or fungi (Torres‐Díaz et al, 2021), suggesting that these endophytes pose negligible risks to soil microbiome composition. Further research is needed to confirm whether or not the four other endophytes studied here affect native microbiomes and to determine potential shifts in the efficacy of extremophile endophytes in the less extreme habitats of MTEs, which could potentially lead to their decreased effectiveness over time or even switching to negative impacts on host plants under altered environmental conditions (Giauque et al, 2019).…”

“…The endophytes selected for study were Penicillium fuscoglaucum and Penicillium glabrum from Distichlis spicata in the Atacama Desert, Penicillium thomii and Penicillium crustosum from Hordeum comosum in the High Andes and Penicillium rubens and Penicillium bialowiezense from Deschampsia antarctica in maritime Antarctica (Figure 1). The endophytes, which had been isolated from surface‐sterilised root fragments of each plant species, were identified through sequencing of the partial internal transcribed spacer region and large subunit genes (Torres‐Díaz et al, 2021). Previous studies have shown that each of the six isolates colonises the roots of lettuce ( Lactuca sativa ), tomato ( Solanum lycopersicum ) and bell pepper ( Capsicum annuum ) grown in monoculture (Acuña‐Rodríguez et al, 2019; Molina‐Montenegro et al, 2016, 2020), with hyphae growing on root surfaces and apoplastically between epidermal cells (Acuña‐Rodríguez et al, 2020).…”

“…Plant response to a commercial product was also assessed by inoculating 100 seedlings of each crop species with Sáfer Mycorrizas M.A. (Agrobiological Sáfer, Medellin, Colombia), a mixture of the arbuscular mycorrhizal fungi (AMF) Glomus , Scutellospora , Acaulospora and Entrophospora spp., which has been shown to improve crop growth and stress tolerance (Torres‐Díaz et al, 2021). Finally, 100 control plants of each crop species were mock inoculated with approximately 2 mL of distilled, filtered (0.45 μm) water.…”