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Abstract
Vanilla (Vanilla planifolia Jacks. ex Andrews), faces a problem of "premature fruit drop" little studied in orchids. Since auxins have a specific participation in the regulation of transition from flower to fruit, and specifically that the ARF8 gene regulates the expression of genes related to ovules maturity and fruit development, the objective of the present study was to analyze the expression levels of ARF8 gene during the critical 45 days post-pollination (dpp) in the CH-I and CH-VI genotypes of V. planifolia. The results show significant differences in the levels of ARF8 transcripts from 25 dpp, and indicate that the ovules of the CH-I genotype mature earlier than those of CH-VI. Because fertilization occurs between 25 and 45 ddp in the CH-I genotype, whereas in the CH-VI genotype fertilization does not occur until after day 45. For this reason, the CH-VI genotype is more susceptible to the “fruit drop". From the results it is concluded that there is no fruit when there is abscission, so that biologically the phenomenon corresponds to a process of “abscission of unfertilized flowers”.