College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Institute of Agro-Bioengineering, College of Life Science, Guizhou University, Guiyang 550025, China.
Int J Mol Sci. 2021 Apr 15;22(8):4094. doi: 10.3390/ijms22084094.
Polyamines (PAs) dramatically affect root architecture and development, mainly by unknown mechanisms; however, accumulating evidence points to hormone signaling and reactive oxygen species (ROS) as candidate mechanisms. To test this hypothesis, PA levels were modified by progressively reducing ADC1/2 activity and Put levels, and then changes in root meristematic zone (MZ) size, ROS, and auxin and cytokinin (CK) signaling were investigated. Decreasing putrescine resulted in an interesting inverted-U-trend in primary root growth and a similar trend in MZ size, and differential changes in putrescine (Put), spermidine (Spd), and combined spermine (Spm) plus thermospermine (Tspm) levels. At low Put concentrations, ROS accumulation increased coincidently with decreasing MZ size, and treatment with ROS scavenger KI partially rescued this phenotype. Analysis of double loss-of-function mutants indicated that NADPH oxidases were not involved in HO accumulation and that elevated ROS levels were due to changes in PA back-conversion, terminal catabolism, PA ROS scavenging, or another pathway. Decreasing Put resulted in a non-linear trend in auxin signaling, whereas CK signaling decreased, re-balancing auxin and CK signaling. Different levels of Put modulated the expression of PIN1 and PIN2 auxin transporters, indicating changes to auxin distribution. These data strongly suggest that PAs modulate MZ size through both hormone signaling and ROS accumulation in .
多胺（PAs）通过未知机制显著影响根系结构和发育，但越来越多的证据表明激素信号和活性氧（ROS）是候选机制。为了验证这一假说，通过逐步降低 ADC1/2 活性和腐胺（Put）水平来改变 PA 水平，然后研究了根分生组织区（MZ）大小、ROS、生长素和细胞分裂素（CK）信号的变化。降低腐胺导致主根生长呈有趣的倒 U 型趋势，MZ 大小也呈相似趋势，腐胺（Put）、亚精胺（Spd）和精胺（Spm）加热精胺（Tspm）的水平也有差异变化。在低 Put 浓度下，ROS 积累增加，与 MZ 大小减小同时发生，用 ROS 清除剂 KI 处理部分挽救了这种表型。双功能缺失突变体的分析表明，NADPH 氧化酶不参与 HO 的积累，ROS 水平的升高是由于 PA 反向转化、末端分解代谢、PA ROS 清除或另一种途径的变化。降低 Put 导致生长素信号呈非线性趋势，而 CK 信号下降，重新平衡生长素和 CK 信号。不同水平的 Put 调节生长素转运蛋白 PIN1 和 PIN2 的表达，表明生长素分布发生变化。这些数据强烈表明，PAs 通过激素信号和 ROS 积累在 中调节 MZ 大小。
