Plant biology

An Autonomous Flowering Pathway with an Autoregulator

Science's STKE  24 Jun 2003:
Vol. 2003, Issue 188, pp. tw243
DOI: 10.1126/stke.2003.188.tw243

Flowering time of plants can be controlled by pathways responsive to light or temperature, or through an autonomous pathway. The autonomous pathway promotes flowering and is especially important for Arabidopsis ecotypes that are rapid cyclers, that is, they will complete a life-cycle of vegetative and reproductive growth more than once a growing season. Quesada et al. show that an RNA-binding protein with a WW domain, FCA, which promotes flowering, regulates its own production by promoting usage of an upstream polyadenylation site located in an alternatively spliced third intron, leading to the production of truncated forms of FCA that are not functional in regulating flowering. Only intronless versions of FCA could be overexpressed, and these suppressed expression of the native, functional γ transcript and promoted the accumulation of the truncated β transcript. Expression of another truncated version that lacks the WW domain, the FCA-δ, did not alter the abundance of FCA or the pattern of transcripts produced. Thus, the WW domain is essential for the autoregulatory activity of FCA. Overexpression of the intronless FCA-γ transcript resulted in premature flowering and in transgenic plants expressing the highest levels of FCA-γ. Additional phenotypes were observed, including small stature, premature senescence and death of leaves. The authors propose that autoregulation may prevent premature flowering.

V. Quesada, R. MacKnight, C. Dean, G. G. Simpson, Autoregulation of FCA pre-mRNA processing controls Arabidopsis flowering time. EMBO J. 22, 3142-3152 (2003). [Abstract] [Full Text]