Negi Sanjana, Tak Himanshu, Ganapathi T R
Plant Cell Culture Technology Section, Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Trombay, Mumbai, India.
Homi Bhabha National Institute, AnushaktiNagar, Mumbai, India.
PLoS One. 2018 Feb 13;13(2):e0192852. doi: 10.1371/journal.pone.0192852. eCollection 2018.
Deposition of secondary cell wall in the xylem elements is controlled by a subgroup of NAC (NAM, ATAF, CUC) family, known as vascular-related NAC transcription factors (VNDs). In the present study, we analyzed the 5' upstream regulatory region of two banana NAC transcription factors (MusaVND6 and MusaVND7) for tissue specific expression and presence of 19-bp secondary-wall NAC binding element (SNBE)-like motifs. Transgenic banana plants of Musa cultivar Rasthali harboring either PMusaVND7::GUS or PMusaVND6::GUS showed specific GUS (β-D-Glucuronidase) activity in cells of the xylem tissue. Approximately 1.2kb promoter region of either MusaVND6 or MusaVND7 showed presence of at least two SNBE-like motifs. This 1.2kb promoter region was retarded in a gel shift assay by three banana VND protein (VND1,VND2 and VND3). The banana VND1-VND3 could also retard the mobility of isolated SNBE-like motifs of MusaVND6 or MusaVND7 in a gel shift assay. Transcript levels of MusaVND6 and MusaVND7 were elevated in transgenic banana overexpressing either banana VND1, VND2 or VND3. Present study suggested a probable regulation of banana VND6 and VND7 expression through direct interaction of banana VND1- VND3 with SNBE-like motifs. Our study also indicated two promoter elements for possible utilization in cell wall modifications in plants especially banana, which is being recently considered as a potential biofuel crop.
木质部细胞中次生细胞壁的沉积受NAC（NAM、ATAF、CUC）家族的一个亚组控制，该亚组被称为维管相关NAC转录因子（VNDs）。在本研究中，我们分析了两个香蕉NAC转录因子（MusaVND6和MusaVND7）的5'上游调控区域，以研究其组织特异性表达以及19bp次生壁NAC结合元件（SNBE）样基序的存在情况。携带PMusaVND7::GUS或PMusaVND6::GUS的香蕉品种Rasthali转基因植株在木质部组织细胞中表现出特异性GUS（β-D-葡萄糖醛酸酶）活性。MusaVND6或MusaVND7的约1.2kb启动子区域显示至少存在两个SNBE样基序。在凝胶迁移实验中，该1.2kb启动子区域被三种香蕉VND蛋白（VND1、VND2和VND3）阻滞。在凝胶迁移实验中，香蕉VND1-VND3也能阻滞MusaVND6或MusaVND7分离出的SNBE样基序的迁移。在过表达香蕉VND1、VND2或VND3的转基因香蕉中，MusaVND6和MusaVND7的转录水平升高。本研究表明，香蕉VND1-VND3与SNBE样基序的直接相互作用可能对香蕉VND6和VND7的表达有调控作用。我们的研究还指出了两个启动子元件，可用于植物尤其是香蕉的细胞壁修饰，香蕉最近被视为一种潜在的生物燃料作物。
