Vesicular-arbuscular mycorrhizal fungi can affect the water balance of both amply watered and droughted host plants. This review summarizes these effects and possible causal mechanisms. Also discussed are host drought resistance and the influence of soil drying on the fungi.

Water relations, drought and vesicular-arbuscular mycorrhizal symbiosis

Disease resistance strategies are powerful approaches to sustainable agriculture because they reduce chemical input into the environment. Recently, Piriformospora indica, a plant-root-colonizing basidiomycete fungus, has been discovered in the Indian Thar desert and was shown to provide strong growth-promoting activity during its symbiosis with a broad spectrum of plants [Verma, S. et al. (1998) Mycologia 90, 896-903]. Here, we report on the potential of P. indica to induce resistance to fungal diseases and tolerance to salt stress in the monocotyledonous plant barley. The beneficial effect on the defense status is detected in distal leaves, demonstrating a systemic induction of resistance by a root-endophytic fungus. The systemically altered “defense readiness” is associated with an elevated antioxidative capacity due to an activation of the glutathione-ascorbate cycle and results in an overall increase in grain yield. Because P. indica can be easily propagated in the absence of a host plant, we conclude that the fungus could be exploited to increase disease resistance and yield in crop plants.

https://www.pnas.org/content/pnas/102/38/13386.full.pdf

The endophytic fungus Piriformospora indica reprograms barley to salt-stress tolerance, disease resistance, and higher yield

The loss of carbon from roots (rhizodeposition) and the consequent proliferation of microorganisms in the surrounding soil, coupled with the physical presence of a root and processes associated with nutrient uptake, gives rise to a unique zone of soil called the rhizosphere. In this review, we bring together evidence to show that roots can directly regulate most aspects of rhizosphere C flow either by regulating the exudation process itself or by directly regulating the recapture of exudates from soil. Root exudates have been hypothesized to be involved in the enhanced mobilization and acquisition of many nutrients from soil or the external detoxification of metals. With few exceptions, there is little mechanistic evidence from soil-based systems to support these propositions. We conclude that much more integrated work in realistic systems is required to quantify the functional significance of these processes in the field. We need to further unravel the complexities of the rhizosphere in order to fully engage with key scientific ideas such as the development of sustainable agricultural systems and the response of ecosystems to climate change. Contents I. Introduction 460 II. What is rhizodeposition? 460 III. Regulation of rhizodeposition 460 IV. How large is the root exudation C flux? 463 V. How responsive is the root exudation C flux? 463 VI. How responsive is the microbial community to root exudation? 464 VII. The role of root exudates in nutrient acquisition 464 VIII. Mycorrhizal fungi and rhizodeposition 471 IX. Future thoughts 474 Acknowledgements 474 References 474.

https://nph.onlinelibrary.wiley.com/doi/epdf/10.1111/j.1469-8137.2004.01130.x

Plant and mycorrhizal regulation of rhizodeposition

Inoculants of plant growth-promoting bacteria for use in agriculture

An in vitro system using Ri T-DXA transformed roots and the vesicular-arbuscular mycorrhizal fungus Gigaspora margarita Becker & Hall has been developed to study the initial events of mycorrhiza formation. Sucrose, sodium and phosphorus were found to be critical components of the medium used to establish the dual culture. Using a single spore as inoculum it was consistently possible to obtain colonization of a preselected point on the root and to time the colonization process (within 5 days). Abundant viable and aseptic spores can be obtained. The system is especially appropriate for studying the triggering of the fungal biotrophy towards the root.

https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-8137.1988.tb03698.x

Early events of vesicular-arbuscular mycorrhiza formation on Ri T-DNA transformed roots

In AM, the fungi obtain carbohydrates from the plant for vegetative growth and spore Schenck NC, Perez Y. Manual for identification of VA mycorrhizal fungi. Manual for the Identification of Va Mycorrhizal Fungi. Front Cover. Norman Carl Schenck, Yvonne Perez. INVAM, 1987 Mycorrhizas 245 pages. A study on diversity of vesicular-arbuscular mycorrhizal fungi associated with Centella asiatica L Manual for the identification of VA mycorrhizal fungi. 3rd ed.

Manual for the identification of va mycorrhizal fungi

Methods and principles of mycorrhizal research

Additional New and Unreported Species of Mycorrhizal Fungi (Endogonaceae) from Florida

The yearly incidence of root colonization and extramatrical spores of vesicular-arbuscular (-VA) mycorrhizal fungi were determined for six agronomic crops grown in monoculture for 7 yr on a newly c...

Incidence of mycorrhizal fungi on six field crops in monoculture on a newly cleared woodland site.

In Florida 21 species of Endogonaceae forming vesicular-arbuscular mycorrhizae are reported. Eight species of the genus Glomus, including a new species G. clarus, and three species of Sclerocystis ...

N. C. Schenck

Papers

Manual for the identification of va mycorrhizal fungi

Methods and principles of mycorrhizal research

Additional New and Unreported Species of Mycorrhizal Fungi (Endogonaceae) from Florida

Incidence of mycorrhizal fungi on six field crops in monoculture on a newly cleared woodland site.

Endogonaceous Mycorrhizal Endophytes in Florida