Barkla Bronwyn J, Vera-Estrella Rosario, Raymond Carolyn
Southern Cross Plant Science, Southern Cross University, Lismore, NSW 2480, Australia.
Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, MOR, México.
BMC Plant Biol. 2016 May 10;16(1):110. doi: 10.1186/s12870-016-0797-1.
Epidermal bladder cells (EBC) are large single-celled, specialized, and modified trichomes found on the aerial parts of the halophyte Mesembryanthemum crystallinum. Recent development of a simple but high throughput technique to extract the contents from these cells has provided an opportunity to conduct detailed single-cell-type analyses of their molecular characteristics at high resolution to gain insight into the role of these cells in the salt tolerance of the plant.
In this study, we carry out large-scale complementary quantitative proteomic studies using both a label (DIGE) and label-free (GeLC-MS) approach to identify salt-responsive proteins in the EBC extract. Additionally we perform an ionomics analysis (ICP-MS) to follow changes in the amounts of 27 different elements. Using these methods, we were able to identify 54 proteins and nine elements that showed statistically significant changes in the EBC from salt-treated plants. GO enrichment analysis identified a large number of transport proteins but also proteins involved in photosynthesis, primary metabolism and Crassulacean acid metabolism (CAM). Validation of results by western blot, confocal microscopy and enzyme analysis helped to strengthen findings and further our understanding into the role of these specialized cells. As expected EBC accumulated large quantities of sodium, however, the most abundant element was chloride suggesting the sequestration of this ion into the EBC vacuole is just as important for salt tolerance.
This single-cell type omics approach shows that epidermal bladder cells of M. crystallinum are metabolically active modified trichomes, with primary metabolism supporting cell growth, ion accumulation, compatible solute synthesis and CAM. Data are available via ProteomeXchange with identifier PXD004045.
表皮膀胱细胞（EBC）是大型单细胞、特化且经过修饰的毛状体，存在于盐生植物冰花的地上部分。最近开发的一种简单但高通量的从这些细胞中提取内容物的技术，为在高分辨率下对其分子特征进行详细的单细胞类型分析提供了机会，以便深入了解这些细胞在植物耐盐性中的作用。
在本研究中，我们使用标记（DIGE）和无标记（GeLC-MS）方法进行大规模的互补定量蛋白质组学研究，以鉴定EBC提取物中的盐响应蛋白。此外，我们进行了离子组学分析（ICP-MS）以追踪27种不同元素含量的变化。使用这些方法，我们能够鉴定出54种蛋白质和9种元素，它们在盐处理植物的EBC中显示出具有统计学意义的变化。基因本体论（GO）富集分析鉴定出大量转运蛋白，以及参与光合作用、初级代谢和景天酸代谢（CAM）的蛋白质。通过蛋白质免疫印迹、共聚焦显微镜和酶分析对结果进行验证，有助于加强研究结果，并进一步加深我们对这些特化细胞作用的理解。正如预期的那样，EBC积累了大量的钠，然而，最丰富的元素是氯，这表明将这种离子隔离到EBC液泡中对耐盐性同样重要。
这种单细胞类型的组学方法表明，冰花的表皮膀胱细胞是代谢活跃的修饰毛状体，初级代谢支持细胞生长、离子积累、相容性溶质合成和CAM。数据可通过ProteomeXchange获得，标识符为PXD004045。
