Physiological ecology of mycoheterotrophy

Leake, Jonathan R.; Cameron, Duncan D.

doi:10.1111/j.1469-8137.2009.03153.x

Cited by 63 publications

(60 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A3). However, this should be viewed as preliminary evidence until there is better general understanding of the physiological mechanisms underpinning nutrient acquisition in orchids (Leake and Cameron 2010). A thorough investigation into how orchids compete for nutrients via mycorrhizal fungi was beyond the scope of this study, but it would be a productive avenue for future research.…”

Section: Discussionmentioning

confidence: 96%

The Effects of Above- and Belowground Mutualisms on Orchid Speciation and Coexistence

Waterman

Bidartondo

Stofberg

et al. 2011

The American Naturalist

172

153

View full text Add to dashboard Cite

Both pollination by animals and mycorrhizal symbioses with fungi are believed to have been important for the diversification of flowering plants. However, the mechanisms by which these aboveand belowground mutualisms affect plant speciation and coexistence remain obscure. We provide evidence that shifts in pollination traits are important for both speciation and coexistence in a diverse group of orchids, whereas shifts in fungal partner are important for coexistence but not for speciation. Phylogenetic analyses show that recently diverged orchid species tend either to use different pollinator species or to place pollen on different body parts of the same species, consistent with the role of pollination-mode shifts in speciation. Field experiments provide support for the hypothesis that colonization of new geographical areas requires adaptation to new pollinator species, whereas co-occurring orchid species share pollinator species by placing pollen on different body parts. In contrast to pollinators, fungal partners are conserved between closely related orchid species, and orchids recruit the same fungal species even when transplanted to different areas. However, co-occurring orchid species tend to use different fungal partners, consistent with their expected role in reducing competition for nutrients. Our results demonstrate that the two dominant mutualisms in terrestrial ecosystems can play major but contrasting roles in plant community assembly and speciation.

show abstract

Section: Discussionmentioning

confidence: 96%

The Effects of Above- and Belowground Mutualisms on Orchid Speciation and Coexistence

Waterman

Bidartondo

Stofberg

et al. 2011

The American Naturalist

172

153

View full text Add to dashboard Cite

show abstract

“…The degeneration of hyphal coils into amorphous clumps was also observed in other myco-heterotrophic AM plants (Yamato 2001;Imhof 2003Imhof , 2007, and this feature is very similar to that of orchid mycorrhizas. For the degeneration, the carbon transfer from the fungi to myco-heterotrophic plants through the digestion of hyphal coils has been suggested (Leake and Cameron 2010). The phylogenetic analysis of the plant nSSU rDNA in Pandanales confirmed that S. japonica and S. tosaensis are included in Triuridaceae.…”

Section: Discussionmentioning

confidence: 99%

Arbuscular mycorrhizal fungi in roots of non-photosynthetic plants, Sciaphila japonica and Sciaphila tosaensis (Triuridaceae)

2011

View full text Add to dashboard Cite

The mycorrhizal fungi in the roots of achlorophyllous Sciaphila japonica and S. tosaensis (Triuridaceae) were identified by molecular methods. The habitats of S. japonica were in a tree plantation of Japanese cypress, Chamaecyparis obtusa, and bamboo forests, and those of S. tosaensis were in a camellia forest and a bamboo forest. In the root cortical cells of both plants, aseptate hyphal coils were observed, which suggested the Paris-type arbuscular mycorrhiza (AM). A phylogenetic analysis based on a partial sequence of an AM fungal nuclear small subunit ribosomal RNA gene showed that the fungal DNA sequences of S. japonica were separated into three closely related clades. Those of S. tosaensis were separated into two clades, which were also closely related to each other. The AM fungi of S. japonica and S. tosaensis were completely separated in the phylogenetic tree even among those found in the same habitat, which suggests the high specificities in the plant-fungal partnerships. All the detected AM fungi in these plants belonged to Glomus-group A. Even though the habitats are in quite common environments, both plant species are known as endangered species in Japan. Such a definite specificity in AM symbioses seems to restrict the distribution of the myco-heterotrophic plants.

show abstract

“…) germination (Leake and Cameron 2010). Microspermy may predispose these plants to evolve MH nutrition in adulthood, but ancestral adaptations to photosynthesis may complicate the transition.…”

Section: Important Adaptations and Limitations For The Evolution Of Mmentioning

confidence: 99%

Why do mixotrophic plants stay green? A comparison between green and achlorophyllous orchid individuals in situ

Roy

Gonneau

Rocheteau

et al. 2013

Ecological Monographs

123

View full text Add to dashboard Cite

Abstract. Some forest plants adapt to shade by mixotrophy, i.e., they obtain carbon both from photosynthesis and from their root mycorrhizal fungi. Fully achlorophyllous species using exclusively fungal carbon (the so-called mycoheterotrophic plants) have repeatedly evolved from such mixotrophic ancestors. However, adaptations for this evolutionary transition, and the reasons why it has happened a limited number of times, remain unknown. We investigated this using achlorophyllous variants (i.e., albinos) spontaneously occurring in Cephalanthera damasonium, a mixotrophic orchid. In two populations, we compared albinos with co-occurring green individuals in situ. We investigated vegetative traits, namely, shoot phenology, dormancy, CO 2 and H 2 O leaf exchange, mycorrhizal colonization, degree of mycoheterotrophy (using 13 C abundance as a proxy), and susceptibility to pathogens and herbivores. We monitored seed production (in natural or experimental crosses) and seed germination. Albinos displayed (1) more frequent shoot drying at fruiting, possibly due to stomatal dysfunctions, (2) lower basal metabolism, (3) increased sensitivity to pathogens and herbivores, (4) higher dormancy and maladapted sprouting, and, probably due to the previous differences, (5) fewer seeds, with lower germination capacity. Over the growing season, green shoots shifted from using fungal carbon to an increasingly efficient photosynthesis at time of fruiting, when fungal colonization reached its minimum. Conversely, the lack of photosynthesis in fruiting albinos may contribute to carbon limitation, and to the abovementioned trends. With a 10 3 3 fitness reduction, albinos failed a successful transition to mycoheterotrophy because some traits inherited from their green ancestors are maladaptive. Conversely, mycoheterotrophy requires at least degeneration of leaves and stomata, optimization of the temporal pattern of fungal colonization and shoot sprouting, and new defenses against pathogens and herbivores. Transition to mycoheterotrophy likely requires progressive, joint evolution of these traits, while a sudden loss of photosynthesis leads to unfit plants. We provide explanations for the evolutionary stability of mixotrophic nutrition and for the rarity of emergence of carbon sinks in mycorrhizal networks. More broadly, this may explain what prevents the emergence of fully heterotrophic taxa in the numerous other mixotrophic plant or algal lineages recently described.

show abstract

Physiological ecology of mycoheterotrophy

Cited by 63 publications

References 24 publications

The Effects of Above- and Belowground Mutualisms on Orchid Speciation and Coexistence

The Effects of Above- and Belowground Mutualisms on Orchid Speciation and Coexistence

Arbuscular mycorrhizal fungi in roots of non-photosynthetic plants, Sciaphila japonica and Sciaphila tosaensis (Triuridaceae)

Why do mixotrophic plants stay green? A comparison between green and achlorophyllous orchid individuals in situ

Contact Info

Product

Resources

About