Involvement of FLOWERING LOCUS T in microgravity response of Arabidopsis thaliana plants under long- and short-day conditions

Microgravity have an impact on growth and development of higher plants in space at both vegetative stage and reproductive stage. A great deal of information has been available on the vegetative stage in space, but relatively little is known about the influence of microgravity on plants at the reproductive stage. In this study, we constructed a transgenic Arabidopsis thaliana plants expressing flowering control gene, FLOWERING LOCUS T (FT), together with green fluorescent protein gene(GFP) under control of a heat shock-inducible promoter (HSP17.4), by which we induced FT expression inflight through remote controlling heating shock treatment. Inflight photography data showed that induction of FT expression in plants in space could counteract the impact of microgravity and promote flowering. Whole-genome microarray analysis of gene expression changes in leaves of wild-type and these transgenic plants grown under different photoperiod conditions in space indicated that the function of the photoperiod-related microgravity response genes are mainly involved in protein synthesis and post-translation protein modulation, notably protein phosphorylation. In addition, changes of circadian component gene expression in response to microgravity under different photoperiod indicated that role of circadian oscillator could act as integrators of microgravity response and photoperiodic signals in Arabidopsis plant grown in space.