Constitutive expression of the Poplar FD‐like basic leucine zipper transcription factor alters growth and bud development

Abstract

SummaryIn poplar, the CO/FT regulatory module mediates seasonal growth cessation. Although FT interacts with the basic leucine zipper transcription factor FD, surprisingly little is known about the possible role of FD in bud development and growth cessation in trees. In this study, we examined the expression and localization of the poplar FD homolog, PtFD1, during short-day (SD)-induced bud development, and the consequences of overexpressing PtFD1 on bud development and shoot growth. PtFD1 was primarily expressed in apical and axillary buds and exhibited a transient increase in expression during the initial stages of SD-induced bud development. This transient increase declined with continued SD treatment. When PtFD1 was overexpressed in poplar, SD-induced growth cessation and bud formation were abolished. PTFD1 overexpression also resulted in precocious flowering of juvenile plants in long-day (LD) photoperiods. Because the phenotypes associated with overexpression of PtFD1 are similar to those observe when poplar FT1 is overexpressed (Science, 312, 2006(Science, 312, , 1040, the expression and diurnal patterns of expression of both poplar FT1 and FT2 were characterized in PtFD1 overexpression poplars and found to be altered. DNA microarray analysis revealed few differences in gene expression between PtFD1 overexpressing poplars in LD conditions while extensive levels of differential gene expression occur in SD-treated plants. These results enforce the connection between the regulation of flowering and the regulation of growth cessation and bud development in poplar.

Modulation of Dormancy and Growth Responses in Reproductive Buds of Temperate Trees

“…Also the FT / TERMINAL FLOWER1-Like2 ( PaFTL2 ) gene induces bud set under transgenic inducible expression in the conifer Norway spruce ( Picea abies ), resembling the FT -antagonistic role of TERMINAL FLOWER1 ( TFL1 ) in Arabidopsis ( Karlgren et al, 2013 ). Finally, further evidences of the functional diversification of CO / FT module in flowering and dormancy processes arise from the study of other components of the pathway: the FT protein interactor gene FLOWERING LOCUS D is involved in growth cessation and bud formation ( Tylewicz et al, 2015 ; Parmentier-Line and Coleman, 2016 ); and both overexpression and RNAi studies show that a tree ortholog of the flowering pathway integrator APETALA1 ( AP1 ) mediates photoperiod-dependent growth cessation in hybrid aspen ( Azeez et al, 2014 ).…”

Identification of a Major Locus for Flowering Pattern Sheds Light on Plant Architecture Diversification in Cultivated Peanut

“…FT also interacts with the basic leucine zipper transcription factor FD. FT and FD interaction can promote flowering, and overexpression of FD leads to branched sympodial growth (26). It was suggested that the domestication of many wild exotic plants into crops with desired growth habit might have resulted from the FT/TFL1 balances (23, 27–29).…”

Strategies for Engineering Reproductive Sterility in Plantation Forests

“…Flowering time genes are attractive targets because prevention of flowering is easier to monitor (e.g., no need to demonstrate flowers are sterile) and to prevent resource allocation to reproduction. However, accumulating evidence supports that tree homologs of various flowering time and floral meristem identity genes have roles in both vegetative and reproductive phenology ( Bohlenius et al, 2006 ; Bielenberg et al, 2008 ; Hoenicka et al, 2008 ; Mohamed et al, 2010 ; Hsu et al, 2011 ; Azeez et al, 2014 ; Tylewicz et al, 2015 ; Parmentier-Line and Coleman, 2016 ). Targeting such genes for manipulation can thus result in undesired vegetative effects, such as delayed bud flush, in addition to predicted effects on flowering or no effect on flowering ( Hoenicka et al, 2012 ).…”