Orchids are diverse members of one of the largest plant families, the Orchidaceae. These plants are extremely diverse and species rich
and apparently the major causes of their diversification can be attributed to their pollination mechanism, symbiotic relationship, and shift in
their trophic modes. Starting from fully autotrophic to holomycoheterotrophic (MH) forms, these plants show a clear transition, with
evolutionary gene loss, mainly in photosynthetic genes (ndh-family) and subsequent a few housekeeping genes. On the other hand, fungal
partners have also lost a few essential genes for their pathogenicity and became completely adapted to symbiosis with, often, reversal of
nutrient flow. The physiological impact of gene loss is enumerated to be quite profound on hosts, which is yet to be learnt. During the
course of evolution of MH, orchids have also evolved many pseudogenes, which probably helped in their diversification. The present
communication attempts to compile the fungal-mediated diversification of orchids with a view to understanding the process.