Department of Forest and Rangeland Stewardship, Colorado State University, Fort Collins, CO, USA.
Water Management and Systems Research Unit, USDA-ARS, Fort Collins, CO, USA.
J Plant Physiol. 2024 May;296:154209. doi: 10.1016/j.jplph.2024.154209. Epub 2024 Mar 5.
While there are many theories and a variety of innovative datasets contributing to our understanding of the mechanism generating root pressure in vascular plants, we are still unable to produce a specific cellular mechanism for any species. To discover these mechanisms, we used RNA-Seq to explore differentially expressed genes in three different tissues between individual Zea mays plants expressing root pressure and those producing none. Working from the perspective that roots cells are utililizing a combination of osmotic exudation and hydraulic pressure mechanisms to generate positively-pressured flow of water into the xylem from the soil, we hypothesized that differential expression analysis would yield candidate genes coding for membrane transporters, ion channels, ATPases, and hormones with clear relevance to root pressure generation. In basal stem and coarse root tissue, we observed these classes of differentially expressed genes and more, including a strong cytoskeletal remodeling response. Fine roots displayed remarkably little differential expression relevant to root pressure, leading us to conclude that they either do not contribute to root pressure generation or are constitutively expressing root pressure mechanisms regardless of soil water content.
虽然有许多理论和各种创新的数据集有助于我们理解在维管植物中产生根压的机制，但我们仍然无法为任何物种确定具体的细胞机制。为了发现这些机制，我们使用 RNA-Seq 技术在表达根压和不产生根压的个体玉米植株的三个不同组织中探索差异表达基因。从根部细胞利用渗透渗出和液压机制的组合将水从土壤中正向压入木质部的观点出发，我们假设差异表达分析将产生与根压产生相关的候选基因，这些基因编码膜转运蛋白、离子通道、ATP 酶和激素。在基部茎和粗根组织中，我们观察到了这些差异表达基因类别，以及更多的基因，包括强烈的细胞骨架重塑反应。细根显示出与根压相关的差异表达非常少，这使我们得出结论，它们要么不参与根压的产生，要么无论土壤含水量如何，它们都在持续表达根压机制。
