Light- and Phytochrome-Dependent Regulation of Hypocotyl Elongation in Arabidopsis thaliana. Arabidopsis thaliana

To identify and characterize genes required for tissue-specific phytochrome responses during hypocotyl development in far-red-light grown bvr lines, we performed gene transcriptional profiling using bvr lines with mesophyll-specific phytochrome inactivation (cab3: :pBVR2). We identified several candidate genes whose expression is significantly altered in lines with mesophyll tissue-specific BVR expression (Cab3::pBVR2), compared to constitutive phytochrome inactivation lines, i.e. 35S-driven BVR lines (35S::pBVR3). No-0 is used as wild-type (WT) Overall design: Seeds of No-0 WT, 35S::pBVR3 and CAB3::pBVR2 on MS plates were exposed to Red (R) light of 75 µmol m-2 s-1 for 5 min and imbibing seeds were cold-stratified at 4 °C in darkness for 3 d. Seedlings were grown under continuous far-red illumination for 7 d. Seven-day-old vegetative whole seedlings (300 – 500 mg) were quickly (<1 min) harvested and immediately frozen in liquid nitrogen inside the FR chamber. Seedlings were grown under continuous far-red illumination for 7 d.

为鉴定并表征远红光培养的bvr株系下，下胚轴发育过程中组织特异性光敏色素（phytochrome）反应所需的基因，我们采用叶肉组织特异性光敏色素失活的bvr株系（cab3::pBVR2）开展基因转录谱（transcriptional profiling）分析。相较于组成型光敏色素失活株系（即35S驱动的BVR株系35S::pBVR3），我们在叶肉组织特异性表达BVR的株系Cab3::pBVR2中鉴定到多个表达显著改变的候选基因。本研究以No-0作为野生型（wild-type, WT）。实验总体设计如下：将No-0野生型、35S::pBVR3及CAB3::pBVR2的种子接种于MS培养基平板，先经75 µmol·m⁻²·s⁻¹的红光照射5分钟，随后将吸胀的种子置于4℃黑暗环境中冷层积3天。将幼苗置于连续远红光光照下培养7天，快速（<1分钟）收取7日龄营养生长期的完整幼苗（重量300–500 mg），并立即在远红光培养箱内将样品置于液氮中速冻。