Molecular Plant Physiology and Proteomics Laboratory, Department of Botany, University of Delhi, India.
Molecular Plant Physiology and Proteomics Laboratory, Department of Botany, University of Delhi, India.
Gene. 2019 May 5;695:32-41. doi: 10.1016/j.gene.2019.02.005. Epub 2019 Feb 8.
C-repeat binding factor (CBF) dependent cold stress signaling cascade is well studied in the model plant arabidopsis but is relatively lesser studied in the crop plants. In the present study, two novel isoforms of an upstream regulator of CBF, Inducer of CBF expression (ICE), BjICE46 (1314 bp, accession number HQ446510) and BjICE53 (1494 bp, accession number HQ857208) were isolated from Brassica juncea seedlings. Genomic clones of both the isoforms (accession numbers HQ433510 and JX571043) showed three introns, out of which one intron was spanning the bHLH (basic helix-loop-helix) domain. Interestingly, the constitutive expression of BjICE53 was 21 fold higher than BjICE46. Real time quantitative expression (RT-qPCR) showed BjICE53 to be cold induced but non-responsive to phytohormones. Interestingly, BjICE46 was salinity stress induced and showed upregulation with methyl jasmonate (MeJa) and abscisic acid (ABA). This was supported by the presence of ABA, MeJa and defense related cis- acting regulatory elements in the promoter region of BjICE46. The downstream transcription factor BjCBF (645 bp) was also isolated. The promoter region of BjCBF showed three E-boxes, the binding site for ICE. BjCBF was expressed and purified from E. coli and binding of purified BjCBF with the DRE/CRT elements (present in the promoter of cold responsive genes) was EMSA confirmed. Overall, this study shows that ICE-CBF pathway is conserved in Brassica juncea along with the differential regulation of the ICE isoforms indicating cross-talk between cold and defense signaling.
C-重复结合因子（CBF）依赖的冷胁迫信号级联在模式植物拟南芥中研究得很好，但在作物植物中相对研究较少。在本研究中，从芥菜幼苗中分离出 CBF 上游调节剂诱导型 CBF 表达因子（ICE）的两个新同工型，BjICE46（1314 bp，登录号 HQ446510）和 BjICE53（1494 bp，登录号 HQ857208）。两个同工型的基因组克隆（登录号 HQ433510 和 JX571043）均显示有三个内含子，其中一个内含子跨越 bHLH（碱性螺旋-环-螺旋）结构域。有趣的是，BjICE53 的组成型表达比 BjICE46 高 21 倍。实时定量表达（RT-qPCR）显示 BjICE53 受冷诱导，但对植物激素无反应。有趣的是，BjICE46 受盐胁迫诱导，并在茉莉酸甲酯（MeJa）和脱落酸（ABA）的作用下上调。BjICE46 启动子区存在 ABA、MeJa 和防御相关顺式作用调控元件，支持这一观点。下游转录因子 BjCBF（645 bp）也被分离出来。BjCBF 启动子区显示有三个 E 盒，是 ICE 的结合位点。BjCBF 从大肠杆菌中表达和纯化，并用 EMSA 证实了纯化的 BjCBF 与 DRE/CRT 元件（存在于冷响应基因的启动子中）的结合。总的来说，这项研究表明 ICE-CBF 途径在芥菜中是保守的，同时 ICE 同工型的差异调节表明冷和防御信号之间存在串扰。
