Du Gaigai, Tian Xin, van den Brink Daan M, Xu Jian, Visser Eric J W, Rieu Ivo
Department of Plant & Animal Biology, Radboud Institute for Biological and Environmental Sciences, Radboud University, Nijmegen, The Netherlands.
Plant Cell Environ. 2025 Aug;48(8):5861-5873. doi: 10.1111/pce.15563. Epub 2025 Apr 18.
Roots located in the upper soil layers are prone to experiencing high temperatures. Despite their importance for water and nutrient absorption, little is known about the effect of high temperature on root hairs. Here, we found that exposure of Arabidopsis thaliana seedlings to long-term mild heat suppressed root hair initiation. Epidermal patterning of hair and non-hair cells was maintained, as observed with GL2- and CPC-based marker genes, and the suppression was independent of the activity of GL2 and its upstream regulators. Instead, we found that expression of downstream RHD6 and RHD6-like bHLH transcription factor genes RSL2 and RSL4 was reduced and that overexpression of RHD6 via an inducible transgene or ethylene treatment maintained the transcriptional expression of RSL2 and RSL4 and fully rescued the root hair phenotype. We conclude that GL2-independent downregulation of RHD6 and its homologues mediates the inhibition in root hair initiation under long-term mild heat stress. This finding may contribute to the development of strategies for improving plant performance under high temperature.
位于上层土壤层的根系容易遭受高温。尽管它们对于水分和养分吸收很重要，但关于高温对根毛的影响却知之甚少。在这里，我们发现拟南芥幼苗长期暴露于温和高温下会抑制根毛起始。如基于GL2和CPC的标记基因所观察到的，毛细胞和非毛细胞的表皮模式得以维持，并且这种抑制与GL2及其上游调节因子的活性无关。相反，我们发现下游RHD6以及RHD6样bHLH转录因子基因RSL2和RSL4的表达降低，并且通过诱导型转基因或乙烯处理过表达RHD6可维持RSL2和RSL4的转录表达，并完全挽救根毛表型。我们得出结论，RHD6及其同源物的GL2非依赖性下调介导了长期温和热胁迫下根毛起始的抑制。这一发现可能有助于制定提高植物在高温下性能的策略。
