Expression of flowering genes in the subtropical fruit tree Dimocarpus longan
In the subtropical fruit tree longan (Dimocarpus longan), flower induction naturally depends on low temperature, but interestingly and exclusively in longan flowering can be induced artificially by potassium chlorate application. This practice is frequently and successfully used for off-season fruit production. However, until today research on flower induction and bud development in longan has mainly focused on plant hormone regulation and knowledge on the genetic pathway is scarce. It is known from other plants that FLOWERING LOCUS T (FT) and APETALA1 (AP1) play key roles in flowering and recently orthologous genes from longan (DlFT1, DlFT2, DlFT1t, DlAP1-1, DlAP1-2) were isolated. Sequence and bioinformatic analyses suggest conserved functions within the flowering pathway, however, it was found that DlFT1 acts as a flowering time promoter, while DlFT2 and a truncated DlFT1t delay flowering time in transgenic arabidopsis. To investigate the expression pattern of the flowering genes in longan, time course experiments with chemically induced trees were performed. Reference genes were evaluated and expression of flowering genes in longan was investigated by quantitative real-time PCR. The data indicates that DlFT1 is up-regulated in leaves during the presumed time period of flower induction in agreement with changes of the cytokinin/auxin ratio, which might promote flower development and activate DlAP1 gene transcription in the bud.
Winterhagen, P., Tiyayon, P., Hegele, M. and Wünsche, J.N. (2017). Expression of flowering genes in the subtropical fruit tree Dimocarpus longan. Acta Hortic. 1178, 13-16
chemical flower induction, flowering time promoter, flowering time repressor, gene expression, quantitative real-time PCR, longan reference gene evaluation