Study of morphology and orchid mycorrhizal associations in Malaxis rheedei

Abstract

The mycorrhizal association in orchids is a striking example of mutualism, where the orchid and the associated mycorrhizal fungi exchange essential nutrients and support each other’s growth and reproduction. The present study focused on a selected terrestrial orchid which is noteworthy for its medicinal value. We aimed to investigate the specific mycorrhizal associations to understand how these interactions influence the morphology of their roots. The morphological characteristics of roots were studied using light microscopy. Transmission electron microscopy studies were conducted to analyze and measure fungal hyphae and peloton sizes as well as to know about fungal colonization distribution. Phylogenetic analysis was conducted to identify the mycorrhizal fungi. Colonization was seen in the 91% root cortex proving high mycorrhizal association. Hyphae appeared in the form of peloton patches at the cortex, occupying up to 62% of the cortical space. The root length with an intact peloton was noted 30% more than the degraded peloton. A single fungus, Tulasnella calospora was isolated from the roots. It was identified using phylogenetic analysis of ITS sequences. Identification of this orchid-mycorrhizal association has the potential to address ecological challenges, contribute to its conservation, and unlock the phytochemical potential of plant-fungus interactions for drug development.