The Role of Soil Fungi in K+ Plant Nutrition

Rosario Haro,Begoña Benito

doi:10.3390/ijms20133169

Abstract

K+ is an essential cation and the most abundant in plant cells. After N, its corresponding element, K, is the nutrient required in the largest amounts by plants. Despite the numerous roles of K in crop production, improvements in the uptake and efficiency of use of K have not been major focuses in conventional or transgenic breeding studies in the past. In research on the mineral nutrition of plants in general, and K in particular, this nutrient has been shown to be essential to soil-dwelling-microorganisms (fungi, bacteria, protozoa, nematodes, etc.) that form mutualistic associations and that can influence the availability of mineral nutrients for plants. Therefore, this article aims to provide an overview of the role of soil microorganisms in supplying K+ to plants, considering both the potassium-solubilizing microorganisms and the potassium-facilitating microorganisms that are in close contact with the roots of plants. These microorganisms can influence the active transporter-mediated transfer of K+. Regarding the latter group of microorganisms, special focus is placed on the role of endophytic fungus. This review also includes a discussion on productivity through sustainable agriculture.

Highlights

After nitrogen (N) and phosphorus (P), potassium (K) is one of the main nutrients required for plant growth, since it plays roles in osmotic adjustment and the regulation of cell membrane potential and pH
There is scant information on the functional characterization of K+ transporters in fungi associated with plants, and the information that exists is basically restricted to the characterization of one K+ uptake system and one K+ efflux system, called HcTrK1 and HcTOK1, respectively, which both belong to the ectomycorrhizal fungus H. cylindrosporum [56,62]
We studied the repertoire of K+ transporters of endophytic fungi using an in silico BLASTP search, which was performed against the endophytic fungi genomes sequenced by JGI (Joint Genome Institute)

Summary

Not Only Plant Roots Live Underground

NoFtroOmnltyhePlpalnant tRpohoytssiLoilovgeiUstnsdpeorginrtooufnvdiew, soil in the natural environment provides plants with the mFinroemralthneutprliaentspnheyesdioedlofgoisrtthsepiroignrtoowftvhi.eHwo, swoeilvienr,ththeensaotiul reanlveinrovnirmonenmteins tapnraotvuirdaelsnpiclhanetws wheirteh nthuemmerionuesradlivneurstreiemnitcsronoeregdaendismfosr (teh.ge.i,rfugnrogwi, btha.ctHeroiaw, epvroerto, zthoae asnodil neenmvairtoondmese)ntht riisveaanloantugrwalitnhicthhee rwoohtesreofnpulmanetrso.uTshdeisveeorsregamniicsrmoos ragllanobistmaisn(me.gin.,efruanl gniu, tbraiecntetrsiafr,opmrothoezosaoialntod mneemetathoediersp) hthyrsiivoeloagloicnagl with the roots of plants These organisms all obtain mineral nutrients from the soil to meet their physiological requirements. They are not evenly distributed in the soil but, rather, can be found in aggregates or “patches” at certain distances to plant roots or they can establish more intimate interactions in the proximity to the root surfaces of plants, a region known as the rhizosphere. Several recent works have supported the importance of the mycobiota of the plant root for nutrition and adaptation to the environment of the host, especially the rhizosphere soil-dwelling filamentous fungi [9]

The Involvement of Soil Fungi in Plant Mineral Nutrition

Findings

Conclusions