Abstract

BONILLA-SANCHEZ, Adriana Paola  and  MOSQUERA-MOSQUERA, Hilda Rocío. Viability and in vitro germination of taxa from Cymbidieae and Epidendreae tribes (subfamily Epidendroideae, Orchidaceae). Rev. acad. colomb. cienc. exact. fis. nat. [online]. 2019, vol.43, n.168, pp.494-501. ISSN 0370-3908.  https://doi.org/10.18257/raccefyn.888.

The pollen in Epidendroideae orchids is organized in pollinia with different degrees of compaction; each pollinium can contain up to 4 million pollen grains. In the present study, we analyzed the effect of the compaction of the pollinium on the viability and germinative capacity of the pollen. We evaluated the pollen quality of seven taxa from two tribes using ex vitro palynological methods (staining with acetocarmine glycerol 2%) and direct methods (in vitro germination) in three media: M1, M2, and M3. Viability with acetocarmine was over 85% in the seven taxa studied. The highest percentage of in vitro germination was obtained in Catasetum tabulare with 16%; in the rest of the taxa, the values oscillated between 2% and 5% at 72 h of observation. The M3 medium was the most successful with 18% and 20% germination in the taxa studied. Although the viability of pollen is high, it has very low germination rates probably affected by the high degree of compaction and the absence of openings, which makes germination in artificial media slow and ineffective. The results confirm that not all viable pollen can germinate and that there is a high degree of specificity and dependence on the stimulating substances for the germination of pollen present in the stigma of the orchids, which makes it necessary to continue deepening in the analysis of the pollen biology of the subfamily Epidendroideae to understand a little more its processes of natural multiplication.

Keywords : Pollen biology; Pollen tube; Pollinium; Tetrads.

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