Magliano Teresa M Alconada, Botto Javier F, Godoy A Veronica, Symonds V Vaughan, Lloyd Alan M, Casal Jorge J
IFEVA, Facultad de Agronomía, Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas, 1417 Buenos Aires, Argentina.
Plant Physiol. 2005 Jun;138(2):1126-35. doi: 10.1104/pp.104.059071. Epub 2005 May 20.
We used 52 Arabidopsis (Arabidopsis thaliana) accessions and developed a new set of 137 recombinant inbred lines between Landsberg erecta (Ler) and Nossen (No-0) to explore the genetic basis of phytochrome-mediated responses during deetiolation. Unexpectedly, most accessions showed weak or moderate hypocotyl growth and cotyledon unfolding responses to pulses of far-red light (FR). Crosses between Columbia and No-0, two accessions with poor response, segregated seedlings with unfolded cotyledons under pulsed FR, suggesting the occurrence of accession-specific loci in the repression of morphological responses to weak light signals. Confirming the latter expectation, mapping of responses to pulsed FR in the Ler x No-0 lines identified novel loci. Despite its weak response to pulsed FR, No-0 showed a response to continuous FR stronger than that observed in Ler. By mapping the differential effect of pulsed versus continuous FR, we identified two high-irradiance response loci that account for the steeper response to continuous FR in No-0. This underscores the potential of the methodology to identify loci involved in the regulation of the shape of signal input-output relationships. Loci specific for a given phytochrome-mediated response were more frequent than pleiotropic loci. Segregation of these specific loci is predicted to yield different combinations of seedling responsivity to light. Such flexibility in combination of responses is observed among accessions and could aid in the adjustment to different microenvironments.
我们使用了52个拟南芥（Arabidopsis thaliana）生态型，并在直立型兰茨贝格（Landsberg erecta，Ler）和诺森（Nossen，No-0）之间构建了一组新的137个重组自交系，以探究脱黄化过程中光敏色素介导反应的遗传基础。出乎意料的是，大多数生态型对远红光（FR）脉冲显示出弱或中等的下胚轴生长及子叶展开反应。两个反应较差的生态型哥伦比亚和No-0之间的杂交，产生了在脉冲FR下子叶展开的幼苗，这表明在对弱光信号形态反应的抑制中存在生态型特异性位点。对Ler×No-0系中脉冲FR反应的定位证实了后一种预期，鉴定出了新的位点。尽管No-0对脉冲FR反应较弱，但它对连续FR的反应比Ler中观察到的更强。通过定位脉冲与连续FR的差异效应，我们鉴定出了两个高辐照度反应位点，它们解释了No-0对连续FR更陡峭的反应。这突出了该方法在鉴定参与调节信号输入-输出关系形状的位点方面的潜力。特定于给定光敏色素介导反应的位点比多效性位点更常见。预计这些特定位点的分离会产生幼苗对光反应性的不同组合。在生态型之间观察到这种反应组合的灵活性，这可能有助于对不同微环境的适应。
