Sector analysis reveals patterns of cambium differentiation in poplar tree stems

First author: Gerd Bossinger; Affiliations: University of Melbourne (墨尔本大学): Melbourne, Australia

Corresponding author: Gerd Bossinger 

We used sector analysis to study cambium development and dynamics and to test if fundamental developmental and functional differences exist between cambial initials as true ‘stem cells’ and more differentiated mother cells. In many higher plants, a cylindrical lateral meristem (环柱侧分生组织), the vascular cambium (维管形成层), forms along the plant axis. Most notably in stems of perennial tree species, this meristem gives rise to xylem (wood) towards the inside of the trunk (树干) and phloem (bark) towards the outside. As such, the vascular cambium is responsible for the production of most of the planet’s forest biomass, significantly contributing to the global carbon cycle. Using the bacterial uid A reporter gene (细菌uidA报告基因) in Agrobacterium-based (基于农杆菌的) in vivo stem transformation experiments in poplar trees we created 379 cambium sectors that originated from the transformation of individual cells. Results from our analysis of sector frequency and patterns are consistent with the poplar cambium featuring a single layer of true cambial initials (being able to divide both anti- and periclinally 垂周分裂和平周分裂). We show that initials are frequently lost from the cambium, that such cell loss rarely occurs at mother cell level, that phloem and xylem differentiation are controlled independently, and that the frequency of mother cell replenishment (补充) is not predetermined (预先决定的).

作者通过扇区分析研究了杨树形成层的动态发育过程，以测试形成层原始细胞作为“干细胞”与已经分化了的母细胞之间发育和功能分化的差异。在许多高等植物中，维管形成层作为环柱侧分生组织，沿着植物轴分布。在多年生的林木物种茎干中，形成层的作为主要是向内分化形成木质部，向外分化形成韧皮部。因此，维管形成层贡献了全球的森林生物量，并显著作用于全球的碳循环。作者通过基于农杆菌的体内遗传转化系统利用细菌uidA作为报告基因，在杨树中构建了379个形成层扇区，每个扇区都起源于单个转基因的细胞。作者有关扇区的频率和模式的研究结果与杨树单层形成层细胞原始细胞的特性一致，能够进行垂周分裂和平周分裂。本文的结果还表明形成层经常会丢失原始细胞，这些细胞丢失极少发生在母细胞水平，并且木质部和韧皮部的分化是独立控制的，母细胞补充的频率并不是事先预定好的。

通讯：Gerd Bossinger(https://www.findanexpert.unimelb.edu.au/display/person1603)

研究方向：发育遗传学（性别决定）；林木遗传改良（选择与育种）。

doi: https://doi.org/10.1093/jxb/ery230

Journal: Journal of Experimental Botany

Published date: 20 June, 2018

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