National Key Laboratory of Plant Molecular Genetics and CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
Plant Biotechnol J. 2018 Mar;16(3):808-817. doi: 10.1111/pbi.12830. Epub 2017 Nov 18.
Wood production is dependent on the activity of the vascular cambium, which develops from the fascicular and interfascicular cambia. However, little is known about the mechanisms controlling how the vascular cambium is developed in woody species. Here, we show that PtrHB4, belonging to the Populus HD-ZIP III family, plays a critical role in the process of vascular cambium development. PtrHB4 was specifically expressed in shoot tip and stem vascular tissue at an early developmental stage. Repression of PtrHB4 caused defects in the development of the secondary vascular system due to failures in interfascicular cambium formation. By contrast, overexpression of PtrHB4 induced cambium activity and xylem differentiation during secondary vascular development. Transcriptional analysis of PtrHB4 repressed plants indicated that auxin response and cell proliferation were affected in the formation of the interfascicular cambium. Taken together, these results suggest that PtrHB4 is required for interfascicular cambium formation to develop the vascular cambium in woody species.
木材的生产依赖于维管形成层的活动，维管形成层由束间形成层和束内形成层发育而来。然而，关于控制木质植物维管形成层发育的机制知之甚少。在这里，我们表明属于杨树 HD-ZIP III 家族的 PtrHB4 在维管形成层发育过程中起着关键作用。PtrHB4 在早期发育阶段特异性表达于茎尖和茎的维管组织中。PtrHB4 的抑制导致次生维管系统的发育缺陷，因为束间形成层的形成失败。相比之下，PtrHB4 的过表达诱导了次生维管发育过程中的形成层活性和木质部分化。对 PtrHB4 抑制植物的转录分析表明，在束间形成层的形成过程中，生长素反应和细胞增殖受到影响。总之，这些结果表明 PtrHB4 对于束间形成层的形成以及木质植物维管形成层的发育是必需的。
