Gharat Sachin Ashruba, Parmar Shaifaly, Tambat Subodh, Vasudevan Madavan, Shaw Birendra Prasad
Environmental Biotechnology Laboratory, Institute of Life Sciences, Bhubaneswar, 751023, Odisha, India.
Bionivid Technology Private Limited, 3rd Floor, 4C-209, 4th Cross, Near New Horizon College, Kasturi Nagar, Bangalore, 560043, Karnataka, India.
PLoS One. 2016 Sep 28;11(9):e0163485. doi: 10.1371/journal.pone.0163485. eCollection 2016.
Although salt tolerance is a feature representative of halophytes, most studies on this topic in plants have been conducted on glycophytes. Transcriptome profiles are also available for only a limited number of halophytes. Hence, the present study was conducted to understand the molecular basis of salt tolerance through the transcriptome profiling of the halophyte Suaeda maritima, which is an emerging plant model for research on salt tolerance. Illumina sequencing revealed 72,588 clustered transcripts, including 27,434 that were annotated using BLASTX. Salt application resulted in the 2-fold or greater upregulation of 647 genes and downregulation of 735 genes. Of these, 391 proteins were homologous to proteins in the COGs (cluster of orthologous groups) database, and the majorities were grouped into the poorly characterized category. Approximately 50% of the genes assigned to MapMan pathways showed homology to S. maritima. The majority of such genes represented transcription factors. Several genes also contributed to cell wall and carbohydrate metabolism, ion relation, redox responses and G protein, phosphoinositide and hormone signaling. Real-time PCR was used to validate the results of the deep sequencing for the most of the genes. This study demonstrates the expression of protein kinase C, the target of diacylglycerol in phosphoinositide signaling, for the first time in plants. This study further reveals that the biochemical and molecular responses occurring at several levels are associated with salt tolerance in S. maritima. At the structural level, adaptations to high salinity levels include the remodeling of cell walls and the modification of membrane lipids. At the cellular level, the accumulation of glycinebetaine and the sequestration and exclusion of Na+ appear to be important. Moreover, this study also shows that the processes related to salt tolerance might be highly complex, as reflected by the salt-induced enhancement of transcription factor expression, including hormone-responsive factors, and that this process might be initially triggered by G protein and phosphoinositide signaling.
尽管耐盐性是盐生植物的一个典型特征，但植物领域关于这一主题的大多数研究都是在甜土植物上进行的。转录组图谱也仅在有限数量的盐生植物中可用。因此，本研究通过对盐生植物盐地碱蓬进行转录组分析来了解耐盐性的分子基础，盐地碱蓬是一种新兴的耐盐性研究植物模型。Illumina测序揭示了72,588个聚类转录本，其中27,434个通过BLASTX进行了注释。施加盐分导致647个基因上调2倍或更多，735个基因下调。其中，391种蛋白质与COG（直系同源簇）数据库中的蛋白质同源，大多数被归类为功能未知类别。大约50%分配到MapMan通路的基因与盐地碱蓬中的基因具有同源性。这类基因大多数代表转录因子。还有一些基因参与细胞壁和碳水化合物代谢、离子关系、氧化还原反应以及G蛋白、磷酸肌醇和激素信号传导。对大多数基因使用实时PCR来验证深度测序结果。本研究首次在植物中证明了蛋白激酶C的表达，它是磷酸肌醇信号中甘油二酯的作用靶点。本研究进一步揭示，在几个层面上发生的生化和分子反应与盐地碱蓬的耐盐性相关。在结构层面，对高盐度的适应包括细胞壁的重塑和膜脂的修饰。在细胞层面，甘氨酸甜菜碱的积累以及Na+的隔离和排除似乎很重要。此外，本研究还表明，耐盐相关过程可能非常复杂，盐诱导的转录因子表达增强（包括激素响应因子）就反映了这一点，并且这个过程可能最初由G蛋白和磷酸肌醇信号触发。
