Kenji Suetsugu, Hidehito Okada, Shun K Hirota, Yoshihisa Suyama
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引用次数: 0
Abstract
Background and aims: Mycoheterotrophy is a nutritional strategy in which plants obtain carbon and essential nutrients from fungal partners. Comparative studies of closely related taxa differing in mycoheterotrophic dependency offer important insights into the evolutionary transitions underlying this lifestyle.
Methods: We integrated stable isotope (δ¹³C and δ15N) analyses, MIG-seq-based phylogenetics, and fungal metabarcoding to investigate the physiological ecology and evolutionary history of three Odontochilus taxa: the large-leaved O. fissus, the small-leaved O. nakaianus (including albino, chlorophyll-deficient variants), and the very small-leaved O. aff. fissus. Morphologically, O. aff. fissus differs from O. fissus in having reduced, often reddish scale leaves and coralloid rhizomes, which are traits commonly observed in fully mycoheterotrophic orchids or mixotrophic orchids with high heterotrophy.
Key results: Albino individuals and protocorms of O. nakaianus exhibited isotope signatures characteristic of full mycoheterotrophy, whereas normal individuals of O. fissus, O. nakaianus, and O. aff. fissus displayed isotopic patterns indicative of partial mycoheterotrophy, with fungal dependence likely inversely correlated with leaf size. Metabarcoding revealed that all taxa consistently associated with Ceratobasidiaceae OTUs, suggesting that similar rhizoctonia fungi support varying degrees of mycoheterotrophy. MIG-seq analysis confirmed that O. aff. fissus, O. fissus, and O. nakaianus form distinct genetic clusters, while albino O. nakaianus individuals were genetically indistinguishable from their green counterparts.
Conclusions: These findings provide evidence of both genetic and nutritional divergence between O. fissus and O. aff. fissus. The results expand our understanding of the mycoheterotrophic continuum in Odontochilus species associated with rhizoctonia fungi.
期刊介绍：
Annals of Botany is an international plant science journal publishing novel and rigorous research in all areas of plant science. It is published monthly in both electronic and printed forms with at least two extra issues each year that focus on a particular theme in plant biology. The Journal is managed by the Annals of Botany Company, a not-for-profit educational charity established to promote plant science worldwide.
The Journal publishes original research papers, invited and submitted review articles, ''Research in Context'' expanding on original work, ''Botanical Briefings'' as short overviews of important topics, and ''Viewpoints'' giving opinions. All papers in each issue are summarized briefly in Content Snapshots , there are topical news items in the Plant Cuttings section and Book Reviews . A rigorous review process ensures that readers are exposed to genuine and novel advances across a wide spectrum of botanical knowledge. All papers aim to advance knowledge and make a difference to our understanding of plant science.
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