Cytokinin signaling localized in phloem non‐cell‐autonomously regulates cambial activity during secondary growth of Populus stems

第一作者：Xiaokang Fu

第一单位：西南大学

通讯作者：Keming Luo

 Abstract 

背景回顾：The regulation of cytokinin on secondary vascular development has been uncovered by modulating cytokinin content.

提出问题：However, it remains unclear how cytokinin enriched in developing secondary phloem regulates cambium activity in poplar.

主要研究：Here, we visualized the gradient distribution of cytokinin with a peak in the secondary phloem of poplar stem via immunohistochemical imaging, and determined the role of phloem‐located cytokinin signaling during wood formation.

结果1-干扰韧皮部中CK分布：We generated transgenic poplar harboring CKX2, a gene encoding a cytokinin degrading enzyme, driven by the phloem‐specific CLE41b promoter, indicating that the disruption of cytokinin gradient pattern restricts the cambial activity.

结果2-减弱/增强韧皮部中CK信号：The RNA interference‐ased knockdown of the histidine kinase (HK) genes encoding cytokinin receptors specifically in secondary phloem significantly compromised the division activity of cambial cells, whereas the phloem‐specific expression of a type‐B response regulator (RR) transcription factor stimulated cambial proliferation, providing evidence for the non‐cell‐autonomous regulation of local cytokinin signaling on the cambial activity.

结果3-减弱形成层中CK信号：Moreover, the cambium‐specific knockdown of HKs also led to the restricted cambial activity, and the defects was aggravated by the reduced cytokinin accumulation.

结论：Our results showed that local cytokinin signaling in secondary phloem regulates cambial activity non‐cell‐autonomously, and coordinately with its local signaling in cambium.

 摘 要 

doi: https://doi.org/10.1111/nph.17255

Journal: New Phytologist

Published date: Feb 04, 2021