<i>BROTHER OF FT AND TFL1</i> (<i>BFT</i>) has <i>TFL1</i>&#x2010;like activity and functions redundantly with <i>TFL1</i> in inflorescence meristem development in Arabidopsis

다국어 초록 (Multilingual Abstract)

<P><B>Summary</B></P><P>The <I>FLOWERING LOCUS T</I> (<I>FT</I>)<I>/TERMINAL FLOWER 1</I> (<I>TFL1</I>) family is a small gene family that encodes important regulators that control flower development in Arabidopsis. Here, we investigated the biological role of the product of <I>BROTHER OF FT AND TFL1</I> (<I>BFT</I>), a member of this family, whose function remains unknown. Comparison of the critical residues that play a role in distinguishing <I>FT</I>‐ or <I>TFL1</I>‐like activity revealed that <I>BFT</I> is more similar to <I>FT</I>. Similar to <I>FT</I> expression, <I>BFT</I> expression showed a diurnal oscillation pattern, peaking in the evening. <I>In situ</I> hybridization revealed <I>BFT</I> expression in the shoot apical meristem, young leaf and axillary inflorescence meristem. Transgenic plants over‐expressing <I>BFT</I> exhibited delayed flowering and severe floral defects (floral indeterminacy and compact inflorescences surrounded by serrate leaves), similar to <I>35S::TFL1</I> plants. <I>LEAFY</I> (<I>LFY</I>) and <I>APETALA1</I> (<I>AP1</I>) expression was significantly reduced in <I>35S::BFT</I> plants. <I>BFT</I> over‐expression failed to rescue the terminal flower phenotype of <I>tfl1</I> mutants; however, it delayed both terminal flower formation in the primary inflorescence and axillary inflorescence development in the <I>tfl1</I> mutant background. Consistent with this, the loss‐of‐function <I>BFT</I> alleles, <I>bft‐2</I> and an <I>BFT</I> RNAi line, accelerated termination of the primary inflorescence and formation of axillary inflorescences in the <I>tfl1</I> mutant background. Taken together, our results suggest that, despite similarities in the critical residues of BFT and FT, <I>BFT</I> possesses a <I>TFL1</I>‐like activity and functions redundantly with <I>TFL1</I> in inflorescence meristem development, and possibly contributes to the regulation of plant architecture.</P>