Advances in the genetic regulating pathways of plant flowering time

Abstract

Aims: Flowering time is critical for plant reproductive success. Plant species, especially which are widely distributed, are observed to exhibit significant differentiation in flowering time to maximize their fitness. In order to explore the molecular mechanism of adaptive differentiation of flowering time in plants, it is essential to clarify the regulating pathways of flowering. This paper summarizes the genetic pathways that regulate flowering time in various groups of plants, which can provide important reference for molecular mechanism research of adaptive differentiation of flowering time. Progresses: As a vital transition from vegetative growth to reproduction in plants, the flowering time has been reported to be regulated by both extrinsic and intrinsic factors. Based on researches of the model plant Arabidopsis thaliana and other taxa, six pathways that regulate flowering time have been identified. The light-dependent pathway, vernalization pathway, and temperature pathway refer to the regulation of flowering time in response to day length or quality of light, a long period of cold exposure, and external high or low temperature, respectively. While the gibberellin pathway, the age pathway and the autonomic pathway are the endogenous pathways. Signals from the six upstream flowering regulation pathways are transmitted to the downstream flowering integrators FT (FLOWERING LOCUS T) and SOC1 (SUP-PRESSOR OF OVEREXPRESSION OF CONSTANS 1), assembled by these two integrators, and transmitted to the downstream flowering meristem where flowering initiates. In addition, most recent studies have shown that non-coding RNA and transposable elements also play important roles in the regulation of flowering time. Prospect: The researches on the regulation of plant flowering have studied more than a hundred years ago, forming many mature theories. However, there are still many controversial and unresolved problems, such as the expression ways of flowering genes, the special regulatory mechanism of flowering, and the adaptive significance of differentiated flowering time, which require further study.