Research Paper

Histological and ultrastructural perspectives on the mycorrhizal root in the Snow-White Venus’s Slipper Orchid (Paphiopedilum niveum (Rchb.f.)Stein)

Pornsawan Sutthinon, Anawat Padpaiboon, Nopparat Thawinwathin, Sutthinut Soonthornkalump

Published on: 02 April 2026

Page: 303 - 313

DOI: 10.6165/tai.2026.71.303

Abstract

Paphiopedilum niveum (Rchb.f.) Stein, commonly known as the "Lady's Slipper" orchid, is an endangered species highly prized for its beauty. Efforts to utilize orchid-mycorrhizal associations in this species have been made to reduce the mortality rate of new in vitro seedlings. Although some fungal groups have recently been identified in this orchid, data on host cells and cell walls features during colonization in this plant remain limited. This research aimed to provide detailed cellular and sub-cellular observations of mycorrhizal roots of P. niveum. Histological and ultrastructural analyses revealed that the outer cortex was the most common site of colonization. Callose wall deposition was observed in the exodermis, endodermis, some sclerenchyma cells in the pith, and peloton clump. Significant cellular changes, such as plasma membrane invagination, intact nuclei with condensed heterochromatin, hyphal vacuolization, and lipid droplet formation were shown. These observations enhance our understanding of the cellular characteristics involved in orchid-fungus interactions.

Keyword: callose wall, lady's slipper orchid, lignin, mycorrhiza, root anatomy

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