To gain more insight into the evolutionary development of orchid flowers and fruits, the orchid species Erycina pusilla was studied. The evolutionary origin of the median petaloid sepal, the callus... Show moreTo gain more insight into the evolutionary development of orchid flowers and fruits, the orchid species Erycina pusilla was studied. The evolutionary origin of the median petaloid sepal, the callus on the labellum, and the stelidia was studied. These organs were found to be derived from a sepal, a stamen that gained petal identity, and stamens that became staminodes, respectively. The “Oncidiinae” model was proposed, explaining the duplications, diversifying selection and changes in spatial expression of different MADS-box genes that shaped the perianth, enabling the rewardless flowers of E. pusilla to mimic an unrelated rewarding flower for pollinator attraction.After pollination the inferior orchid ovary develops into a fruit. This process is described for E. pusilla up to fruit dehiscence. The fruit associated MADS-box genes and proteins together with other dehiscence-related genes were analyzed in order to propose a first “orchid fruit developmental protein and gene network” model. Fruit development was further studied by transcriptome analyses presenting data obtained from different developmental phases.By analyzing the anatomy of ripe fruits of different orchid species, possible correlations were found between fruit valve lignification patterns, life form, growth strategy, ecology, fruit orientation, dehiscence type, number of valves and slits, and phylogenetic relationships. Show less
