Mycobiont diversity and first evidence of mixotrophy associated with Psathyrellaceae fungi in the chlorophyllous orchid Cremastra variabilis

• Published in: Journal of plant research Vol. 134; no. 6; pp. 1213 - 1224
• Main Authors: Yagame, Takahiro, Lallemand, Felix, Selosse, Marc-André, Funabiki, Eriko, Yukawa, Tomohisa
• Format: Journal Article
• Language: English
• Published: Singapore Springer Singapore 01.11.2021; Springer Nature B.V; Springer Verlag
• Subjects: Abundance; Autotrophs; Biomedical and Life Sciences; Colonization; Environmental conditions; Fungi; Life Sciences; Mixotrophy; Morphology; Mycobionts; Nitrogen isotopes; Nutrients; Plant Biochemistry; Plant Ecology; Plant Physiology; Plant Sciences; Psathyrellaceae; Regular Paper – Ecology/Ecophysiology/Environmental Biology; Relative abundance; Partial mycoheterotrophy; Rhizoctonias; Mycorhizomes; Orchid morphology; Psathyrellaceae; Mycorrhizae
• ISSN: 0918-9440; 1618-0860
• DOI: 10.1007/s10265-021-01337-w

Mixotrophy (MX, also called partial mycoheterotrophy) in plants is characterized by isotopic abundances that differ from those of autotrophs. Previous studies have evaluated mycoheterotrophy in MX plants associated with fungi of similar ecological characteristics, but little is known about the differences in the relative abundances of 13 C and 15 N in an orchid species that associates with several different mycobionts species. Since the chlorophyllous orchid Cremastra variabilis Nakai associates with various fungi with different ecologies, we hypothesized that it may change its relative abundances of 13 C and 15 N depending on the associated mycobionts. We investigated mycobiont diversity in the chlorophyllous orchid C. variabilis together with the relative abundance of 13 C and 15 N and morphological underground differentiation (presence or absence of a mycorhizome with fungal colonization). Rhizoctonias (Tulasnellaceae, Ceratobasidiaceae, Sebacinales) were detected as the main mycobionts. High differences in δ 13 C values (– 34.7  to – 27.4 ‰) among individuals were found, in which the individuals associated with specific Psathyrellaceae showed significantly high relative abundance of 13 C. In addition, Psathyrellaceae fungi were always detected on individuals with mycorhizomes. In the present study, MX orchid association with non - rhizoctonia saprobic fungi was confirmed, and the influence of mycobionts on morphological development and on relative abundance of 13 C and 15 N was discovered. Cremastra variabilis may increase opportunities to gain nutrients from diverse partners, in a bet - hedging plasticity that allows colonization of various environmental conditions.