Sliwinski Marek K, Bosch Justin A, Yoon Ho-Sung, Balthazar Maria von, Baum David A
Department of Botany, University of Wisconsin, Madison, WI 53706, USA.
Plant J. 2007 Jul;51(2):211-9. doi: 10.1111/j.1365-313X.2007.03148.x. Epub 2007 Jun 8.
Idahoa scapigera produces solitary flowers in the axils of rosette leaves without elongation of the shoot axis, a rosette-flowering architecture. Previous work with one of the two I. scapigera LFY paralogs, IscLFY1, showed that this gene caused aerial flowering rosettes in Arabidopsis thaliana. In this paper, we report that after three generations IscLFY1 transgenic lines are phenotypically indistinguishable from wild-type Arabidopsis, indicating that IscLFY1 protein is able to replace normal LFY function. Additionally, we found that ectopic LFY expression late in development can phenocopy aspects of the aerial rosette phenotype, suggesting that shoot compression caused by IscLFY1 could be caused by localized overexpression of a functional IscLFY protein. We also characterized the expression and function of the second I. scapigera LFY paralog, IscLFY2, in A. thaliana. In contrast to IscLFY1, this paralog was expressed in floral meristems and the shoot apical meristem (SAM). In I. scapigera, LFY-specific antibodies detected high protein levels in developing flowers but not in the apex, suggesting trans-regulatory differences between I. scapigera and A. thaliana. Most IscLFY2 transgenic A. thaliana plants were indistinguishable from wild type, but in a minority of lines the SAM was converted to a terminal flower as would be expected from the reporter-expression pattern. Taken together these results show that both I. scapigera paralogs have conserved LFY function, both proteins can rescue lfy and both can modify inflorescence architecture in an A. thaliana background: either by affecting internode elongation (IscLFY1) or by causing homeotic conversion of shoots into flowers (IscLFY2).
具柄爱达荷芥在莲座叶腋处产生单花，茎轴不伸长，呈莲座状开花结构。先前对具柄爱达荷芥两个LFY旁系同源基因之一IscLFY1的研究表明，该基因可使拟南芥产生地上莲座状花。在本文中，我们报道，经过三代培养后，IscLFY1转基因系在表型上与野生型拟南芥无差异，这表明IscLFY1蛋白能够替代正常的LFY功能。此外，我们发现发育后期异位表达LFY可模拟地上莲座状表型的某些方面，这表明IscLFY1导致的茎压缩可能是由功能性IscLFY蛋白的局部过表达引起的。我们还对具柄爱达荷芥的第二个LFY旁系同源基因IscLFY2在拟南芥中的表达和功能进行了表征。与IscLFY1不同，这个旁系同源基因在花分生组织和茎尖分生组织（SAM）中表达。在具柄爱达荷芥中，LFY特异性抗体在发育中的花中检测到高蛋白水平，但在顶端未检测到，这表明具柄爱达荷芥和拟南芥之间存在反式调控差异。大多数IscLFY2转基因拟南芥植株与野生型无差异，但在少数株系中，SAM转变为顶花，这与报告基因表达模式预期一致。综合这些结果表明，具柄爱达荷芥的两个旁系同源基因都具有保守的LFY功能，两种蛋白都可以挽救lfy，并且都可以在拟南芥背景下改变花序结构：要么通过影响节间伸长（IscLFY1），要么通过使茎发生同源异型转变为花（IscLFY2）。
