Xia Chao, Huang Jing, Zhou Xiangjun, Payyavula Raja S, Lan Hai, Chen Li-Qing, Turgeon Robert, Zhang Cankui
Maize Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, China.
Department of Agronomy and Center for Plant Biology, Purdue University, West Lafayette, Indiana, USA.
Plant Cell Environ. 2025 Jun;48(6):4327-4340. doi: 10.1111/pce.15421. Epub 2025 Feb 17.
Mineral deficiency is a major problem in agriculture. Plant adaption to low mineral environments involves signaling between shoots and roots, via the food transport cells, the sieve elements. However, due to the sequestered position of the sieve elements in the vascular bundles, identifying shoot-to-root mobile signals is challenging. In herbaceous species, sieve elements and companion cells (CCs) are isolated from other leaf tissues. We hypothesize that phloem CCs play an essential role by synthesizing shoot-to-root signals in response to mineral deficiency. To test this hypothesis, we analyzed gene expression responses in Arabidopsis CCs under phosphorus deficiency using TRAP-Seq. Phosphorus was chosen for its importance in plant growth and the known role of shoot-to-root signaling in regulating root phosphate transporters during deficiency. Our findings revealed that CCs exhibit more dramatic molecular responses than other leaf cells. We also found that many genes altered in CCs have potential functions in regulating root growth. This is unexpected because it has been widely believed that shoot-to-root signaling is not involved in root growth regulation under P deficiency. The importance of CCs in regulating mineral deficiency may extend beyond phosphorus because shoot-to-root signaling is a common response to the deficiency of various minerals.
矿物质缺乏是农业中的一个主要问题。植物对低矿物质环境的适应涉及通过食物运输细胞（筛管分子）在地上部和根部之间进行信号传递。然而，由于筛管分子在维管束中的隐蔽位置，识别从地上部到根部的移动信号具有挑战性。在草本植物中，筛管分子和伴胞与其他叶组织分离。我们假设韧皮部伴胞通过响应矿物质缺乏合成从地上部到根部的信号发挥重要作用。为了验证这一假设，我们使用TRAP-Seq分析了拟南芥伴胞在缺磷条件下的基因表达反应。选择磷是因为其在植物生长中的重要性以及已知在缺磷期间从地上部到根部的信号传递在调节根磷酸盐转运体中的作用。我们的研究结果表明，伴胞比其他叶细胞表现出更显著的分子反应。我们还发现，许多在伴胞中发生变化的基因在调节根生长方面具有潜在功能。这是出乎意料的，因为人们普遍认为在缺磷条件下从地上部到根部的信号传递不参与根生长调节。伴胞在调节矿物质缺乏方面的重要性可能不仅限于磷，因为从地上部到根部的信号传递是对各种矿物质缺乏的常见反应。
