Nitrogen uptake between fungi and orchids

March 7, 2017, DOE/Joint Genome Institute
Nitrogen uptake between fungi and orchids
Researchers investigated Tulasnella calospora as both a free-living mycelium and in symbiosis with the photosynthetic orchid long-lipped serapias. Credit: Ziegler175, Wikimedia Commons, CC BY-SA 3.0

Orchids are an example of an experimentally tractable plant that is highly dependent on its relationship with its mycorrhizal fungal partners for nutrient supply. In this recent study, researchers for the first time identified some genetic determinants potentially involved in nitrogen uptake and transfer in orchid mycorrhizas.

This study provides a model system amenable to experimental manipulation, for plant-fungi nutrient exchanges on a symbiotic level and offers insights into how host plants benefit from the mutualistic relationships formed with which can expand their habitat range. Understanding these vital relationships may shed light on microbial symbioses applicable to growing bioenergy feedstock plants.

Orchids, like the majority of terrestrial plants, form symbiotic relationships between their plant roots and soil fungi, known as mycorrhizal association. However, unlike other terrestrial plants, orchids rely on their mycorrhizal fungal partners for nutrient supply during the feed germination and development stages. Following this stage, most orchid species develop leaves and are capable of self-nourishment whereas some species continue to rely on their fungal partners for an organic carbon supply. In this study, published in the January 2017 issue of New Phytologist, a team led by University of Turin researchers investigated the orchid mycorrhizal fungus Tulasnella calospora as both a free-living mycelium and in symbiosis with the photosynthetic orchid long-lipped serapias, or Serapias vomeracea. For the first time, researchers looked at the fungal genes that may have been involved in both the uptake and transfer of nitrogen to the host plant. RNA sequencing for the project was performed at the U.S. Department of Energy Joint Genome Institute (DOE JGI), a DOE Office of Science User Facility, as part of the 2013 Community Science Program portfolio.

The team also used the DOE JGI fungal genome database MycoCosm to identify coding for proteins that were involved in nitrogen uptake and transfer. They found that the Tulasnella calospora genome has two genes coding for ammonium transporters and several genes coding for amino acid transporters, proteins that play roles in the nitrogen nutrient pathway. Overall, the orchid mycorrhizal fungi's use of nitrogen may broaden the habitat ranges of orchids, allowing them to grow in a variety of soil types. Of more general interest to the DOE, this study provides important insights for this process, and furthers understanding of plant-microbial symbioses that are vital for plant health and may inform understanding of microbial symbioses relevant to bioenergy feedstock plants.

Explore further: Orchids and fungi: An unexpected case of symbiosis

More information: Valeria Fochi et al. Fungal and plant gene expression in the-symbiosis provides clues about nitrogen pathways in orchid mycorrhizas, New Phytologist (2017). DOI: 10.1111/nph.14279

Related Stories

Orchids and fungi: An unexpected case of symbiosis

July 12, 2011

The majority of orchids are found in habitats where light may be a limiting factor. In such habitats it is not surprising that many achlorophyllous (lacking chlorophyll), as well as green, orchids depend on specific mycorrhizal ...

Why are orchids so successful?

September 13, 2011

In terms of diversity, orchids are one of the most successful groups of flowering plants, with over 22,000 species. Both pollinating animals and mycorrhizal fungi are believed to have been important in the diversification ...

Microbes rule in 'knee-high tropical rainforests'

January 12, 2017

Rainforests on infertile wet soils support more than half of all plant species. Shrublands on infertile dry soils in southwestern Australia, jokingly called "knee-high tropical rainforests", support another 20 percent of ...

Bacterial tenants in fungal quarters

May 29, 2015

Ludwig Maximilian University of Munich researchers have sequenced the genome of a bacterial symbiont hosted by a mycorrhizal fungus. Analysis of the symbiont's genetic endowment reveals previously unknown facets of the partnership ...

Recommended for you

How do horses read human emotional cues?

June 21, 2018

Scientists have demonstrated for the first time that horses integrate human facial expressions and voice tones to perceive human emotion, regardless of whether the person is familiar or not.

Fish's use of electricity might shed light on human illnesses

June 21, 2018

Deep in the night in muddy African rivers, a fish uses electrical charges to sense the world around it and communicate with other members of its species. Signaling in electrical spurts that last only a few tenths of a thousandth ...

Not junk: 'Jumping gene' is critical for early embryo

June 21, 2018

A so-called "jumping gene" that researchers long considered either genetic junk or a pernicious parasite is actually a critical regulator of the first stages of embryonic development, according to a new study in mice led ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.