Shafi Amrina, Gill Tejpal, Zahoor Insha, Ahuja Paramvir Singh, Sreenivasulu Yelam, Kumar Sanjay, Singh Anil Kumar
Department of Biotechnology, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh, India.
Biotechnology Department, University of Kashmir, Srinagar, 190006, Jammu & Kashmir, India.
Mol Biol Rep. 2019 Apr;46(2):1985-2002. doi: 10.1007/s11033-019-04648-3. Epub 2019 Jan 31.
Hydrogen peroxide (HO) is known to accumulate in plants during abiotic stress conditions and also acts as a signalling molecule. In this study, Arabidopsis thaliana transgenics overexpressing cytosolic CuZn-superoxide dismutase (PaSOD) from poly-extremophile high-altitude Himalayan plant Potentilla atrosanguinea, cytosolic ascorbate peroxidase (RaAPX) from Rheum australe and dual transgenics overexpressing both the genes were developed and analyzed under salt stress. In comparison to wild-type (WT) or single transgenics, the performance of dual transgenics under salt stress was better with higher biomass accumulation and cellulose content. We identified genes involved in cell wall biosynthesis, including nine cellulose synthases (CesA), seven cellulose synthase-like proteins together with other wall-related genes. RNA-seq analysis and qPCR revealed differential regulation of genes (CesA 4, 7 and 8) and transcription factors (MYB46 and 83) involved in secondary cell wall cellulose biosynthesis, amongst which most of the cellulose biosynthesis gene showed upregulation in single (PaSOD line) and dual transgenics at 100 mM salt stress. A positive correlation between cellulose content and HO accumulation was observed in these transgenic lines. Further, cellulose content was 1.6-2 folds significantly higher in PaSOD and dual transgenic lines, 1.4 fold higher in RaAPX lines as compared to WT plants under stress conditions. Additionally, transgenics overexpressing PaSOD and RaAPX also displayed higher amounts of phenolics as compared to WT. The novelty of present study is that HO apart from its role in signalling, it also provides mechanical strength to plants and aid in plant biomass production during salt stress by transcriptional activation of cellulose biosynthesis pathway. This modulation of the cellulose biosynthetic machinery in plants has the potential to provide insight into plant growth, morphogenesis and to create plants with enhanced cellulose content for biofuel use.
已知过氧化氢（H₂O₂）在非生物胁迫条件下会在植物中积累，并且还作为一种信号分子发挥作用。在本研究中，培育了过表达来自多极端嗜性的喜马拉雅高海拔植物紫花金露梅的胞质铜锌超氧化物歧化酶（PaSOD）、来自掌叶大黄的胞质抗坏血酸过氧化物酶（RaAPX）的拟南芥转基因植株，以及同时过表达这两个基因的双转基因植株，并在盐胁迫下进行了分析。与野生型（WT）或单转基因植株相比，双转基因植株在盐胁迫下表现更好，生物量积累和纤维素含量更高。我们鉴定了参与细胞壁生物合成的基因，包括9种纤维素合酶（CesA）、7种纤维素合酶样蛋白以及其他与细胞壁相关的基因。RNA测序分析和定量PCR揭示了参与次生细胞壁纤维素生物合成的基因（CesA 4、7和8）和转录因子（MYB46和83）的差异调控，其中大多数纤维素生物合成基因在100 mM盐胁迫下在单转基因（PaSOD株系）和双转基因植株中上调。在这些转基因株系中观察到纤维素含量与H₂O₂积累之间呈正相关。此外，在胁迫条件下，PaSOD和双转基因株系中的纤维素含量比WT植株显著高1.6至2倍，RaAPX株系中的纤维素含量比WT植株高1.4倍。此外，过表达PaSOD和RaAPX的转基因植株与WT相比，还表现出更高含量的酚类物质。本研究的新颖之处在于，H₂O₂除了其信号传导作用外，还通过转录激活纤维素生物合成途径为植物提供机械强度，并有助于盐胁迫期间植物生物量的产生。植物中纤维素生物合成机制的这种调节有可能为植物生长、形态发生提供见解，并创造出纤维素含量更高的植物用于生物燃料。
