Allogamy, metaxenia and hybrids in orchids, what do we know about it?

Orchids are a diverse group of plants, also manifested in their great diversity of flowers. Despite this, orchids are pollinated either through autogamy or allogamy (geitonogamy and xenogamy). Although there are some autogamous orchids, the majority are allogamous, mainly pollinated by xenogamy since they present physical or genetic barriers that prevent self-pollination. In addition, orchids are known for their capacity for interspecific pollination, which could influence fruits (metaxenia) and seeds (xenia) production. Its capacity for hybridization represents an opportunity to produce organisms tolerant to biotic or abiotic stress, in addition to exhibiting new shapes, colors and fragrances; this would be important in horticulture, where the proper selection of parents provides those advantages to the descendant hybrids. This review addresses the characteristics of each type of reproduction systems in orchids, as well as their advantages and disadvantages. At the same time, the study of the induction effect of metaxenia and xenia in this family is proposed. Finally, the production of orchid hybrids is contextualized and the opportunities of this approach in the near future.