Beneficial Effects of Fungal Endophytes in Major Agricultural Crops

In nature, there is a wide range of microorganisms whose interaction with plants is beneficial. The role of microbes in determining the health of soils and plants is increasingly acknowledged. Plants harbor a diversity of microorganisms that may engage in a continuum of interactions ranging from beneficial to adverse interactions. Some of these interactions may be transient and occur during a specific life stage of the plants regardless of its beneficial, detrimental, or neutral impact. One of the most important microorganisms with beneficial effects on plants are endophytes, which are defined as microorganisms from bacterial, archaeal, fungal, and protist taxa which for all or part of their life cycle colonize internal tissues of the host without causing visible disease symptoms.

It has been estimated that there are approximately 1 million endophytic fungal species distributed through all ecosystems, from hot deserts to tropical forests and they may colonize roots, stems, and/or leaves. To date, all the plant taxa studied have been found to harbor at least one fungal endophyte in healthy tissues, but it is their chemical and not their biological diversity that mainly generates interest in these microorganisms.

Endophytic fungi play an important role in the physiology of the host plants and this association implies protective effects on host plants. The presence of these microorganisms may impart for the plants an increasing resistance to biotic stresses due to the production of metabolites, the induction of antimicrobial compounds by plants, or simply, by space competition with these pathogens. Furthermore, these benefits extend to an increase in the tolerance of plants to stressful factors such as salinity, drought, heavy metal presence, or low pH. However, one of the most interesting benefits of the endophytes is the host growth promotion.

At present, there is a growing global population of around 7 billion people, which is expected to reach 9.7 billion by 2050. This continuous growth of the population poses a food insecurity scenario that agriculture must face by increasing production. However, this objective is interrupted by the presence of pests and diseases that decrease crops production, the loss of fertility in agricultural soils, as well as climate change, which contributes to the problem of lower yield and decreased quality of the crops. The use of endophytic fungi, thanks to their potential to promote plant growth, could be a promising tool to increase crop yield and reduce the dependence on chemical compounds in the context of sustainable agriculture.

The objective of this Research Topic is to showcase the latest research on the beneficial effects of fungal endophytes on major food crops. We welcome submissions of original research papers, reviews, and methods, including (but not limited to) research on the following sub-themes:

• Study of the endophyte-host fungal interaction
• Plant metabolic changes by endophytic fungal tissues-colonization
• Promotion of plant growth by endophytic fungi
• Biofertilizers from endophytic fungi
• Increased tolerance to abiotic stresses by endophytic fungi
• Activation of plant defense responses by endophytic fungi
• Endophytic fungi as biological control agents against crop pathogens
• Endophytic fungi as entomopathogens
• Mycoremediation by endophytic fungi

Please note that descriptive studies and those defining gene families or descriptive collection of transcripts, proteins, or metabolites, will not be considered for review unless they are expanded and provide mechanistic and/or physiological insights into the biological system or process being studied.