Department of Biology & Chemistry, Texas A&M International University, Laredo, TX, USA.
Department of Biology, University of Louisiana at Lafayette, Lafayette, LA, USA.
Plant Signal Behav. 2023 Dec 31;18(1):2217389. doi: 10.1080/15592324.2023.2217389.
Plants require sunlight, carbon dioxide, water and mineral ions for their growth and development. Roots in vascular plants sequester water and ions from soil and transport them to the aboveground parts of the plant. Due to heterogeneous nature of soil, roots have evolved several regulatory barriers from molecular to organismic level that selectively allows certain ions to enter the vascular tissues for transport according to the physiological and metabolic demands of plant cell. Current literature profusely elaborates about apoplastic barriers, but the possibility of the existence of a symplastic regulation through phosphorous-enriched cells has not been mentioned. Recent investigations on native ion distribution in seedling roots of several species ( and ) identified an ionomic structure termed as "P-ring". The P-ring is composed of a group of phosphorous-rich cells arranged in radial symmetry encircling the vascular tissues. Physiological investigations indicate that the structure is relatively inert to external temperature and ion fluctuations while anatomical studies indicates that they are less likely to be apoplastic in nature. Furthermore, their localization surrounding vascular tissues and in evolutionarily distinct plant lineages might indicate their conserved nature and involvement in ion regulation. Undoubtedly, this is an interesting and important observation that has significant merit for further investigations by the plant science community.
植物的生长和发育需要阳光、二氧化碳、水和矿物质离子。维管植物的根从土壤中摄取水分和离子，并将其输送到地上部分。由于土壤的非均质性，根在分子到个体水平上进化出了几种调节屏障，根据植物细胞的生理和代谢需求，选择性地允许某些离子进入维管组织进行运输。目前的文献大量阐述了质外体屏障，但关于通过富含磷的细胞存在共质体调节的可能性尚未提及。最近对几种物种（和）幼苗根中天然离子分布的研究发现了一种称为“P 环”的离子组构。P 环由一组呈径向对称排列的富含磷的细胞组成，环绕着维管束。生理研究表明，该结构对外界温度和离子波动相对不敏感，而解剖学研究表明，它们不太可能是质外体。此外，它们在维管束周围的定位以及在进化上不同的植物谱系中可能表明它们具有保守性和参与离子调节。毫无疑问，这是一个有趣且重要的观察结果，对植物科学界进一步的研究具有重要意义。
