A possible role for flowering locus T‐encoding genes in interpreting environmental and internal cues affecting olive (Olea europaea L.) flower induction

Abstract

Olive (Olea europaea L.) inflorescences, formed in lateral buds, flower in spring. However, there is some debate regarding time of flower induction and inflorescence initiation. Olive juvenility and seasonality of flowering were altered by overexpressing genes encoding flowering locus T (FT). OeFT1 and OeFT2 caused early flowering under short days when expressed in Arabidopsis. Expression of OeFT1/2 in olive leaves and OeFT2 in buds increased in winter, while initiation of inflorescences occurred i n late winter. Trees exposed to an artificial warm winter expressed low levels of OeFT1/2 in leaves and did not flower. Olive flower induction thus seems to be mediated by an increase in FT levels in response to cold winters. Olive flowering is dependent on additional internal factors. It was severely reduced in trees that carried a heavy fruit load the previous season (harvested in November) and in trees without fruit to which cold temperatures were artificially applied in summer. Expression analysis suggested that these internal factors work either by reducing the increase in OeFT1/2 expression or through putative flowering repressors such as TFL1. With expected warmer winters, future consumption of olive oil, as part of a healthy Mediterranean diet, should benefit from better understanding these factors.

High ambient temperature leads to reduced FT expression and delayed flowering in Brassica rapa via a mechanism associated with H2A.Z dynamics

“…There are also examples such as Arabidopsis Gy‐0 accession that reacts similarly to Arabidopsis Col , the main laboratory accession, regarding hypocotyl elongation, but shows a delay in flowering time when grown at 28°C (Verhage et al ., ). High temperature also delays flowering in cauliflower ( Brassica oleraceae ) (Verhage et al ., ), rice flower bush (Halevy et al ., ), olive trees (Haberman et al ., ) and some orchids (Newton and Runkle, ). Flowering time retardation by warm ambient temperature, as well as low temperature induction of FT‐ like genes, have been also described in mandarin (Nishikawa et al ., ), chrysanthemum (Nakano et al ., ) and litchi (Ding et al ., ).…”

The effects of GA3 treatment on yield, carbohydrate, and endogenous hormone changes in Memecik olive cultivar

“…This result could have been obtained due to using low-dose GA 3 ; thus, like in the experiment of El-Naby et al (2012), the effects of GA 3 changed with different doses. On the other hand, Haberman et al (2017) indicated that when potted trees were exposed to artificial cold treatments in early summer (June) or fall (September), inflorescence formation could occur before the winter season. They identified two FT-encoding genes in the olive genome and provided evidence of a dramatic increase in both genes during the winter or by artificial cold-temperature treatment in other seasons.…”

“…Furthermore, 75 ppm GA 3 treatment on the first of December increased vegetative growth, improved fruit characteristics, and increased the oil percentage. Haberman et al (2017) indicated that olive juvenility and seasonality of flowering were altered by overexpressing genes that encode flowering locus T (FT). OeFT1 and OeFT2 caused early flowering under short days when they were expressed in Arabidopsis.…”

Microbial contamination in the genome of the domesticated olive

“…Both genomes contain 23 diploid chromosomes and an estimated size between 1.38-1.48 GB of sequence (Cruz et al 2016;Unver et al 2017). The domesticated olive genome (sequenced approximately one year prior to the wild olive genome) has been used for gene identification (Haberman et al 2017), discovery of olive fruit development programs (D'Angeli and Altamura 2016), and to improve understanding of genome structure (Barghini et al 2017).…”