美国密歇根科技大学的科学家发现了杨树的一种适应土壤环境变化的新分子机理，也就是一些控制此过程的部分基因开关。研究者希望通过利用生物技术及选择性育种的方式改变杨树的抗胁迫能力。
"我们希望理解其中的发生机制，我们能娴熟的操作此系统使植物能更快更好的适应客观条件"，来自密歇根科技大学森林与环境科学的副教授Victor Busov说道。Victor Busov为此文的通讯作者。此研究成果发表于2010年3月份的The Plant Cell 杂志上。参与该研究的还有美国乔治亚大学，俄勒冈州立大学以及北京林业大学的研究人员。杨树是目前唯一一个全基因组测序完成的树种。他们分析了杨树基因组中数以千计的基因。研究者正在寻求一种调控机制。这种机制直接关系着植物是在地面部分的繁盛以及合适的恰当的土壤条件充分补充其地下部分根系的发达程度。
赤霉素（Gibberellins，简称GAs）在其中扮演了关键的角色。"在根的发育过程中，赤霉素的作用了解的不多"，Busov说到，"特别是关于赤霉素对侧根的影响的研究更是少。"Busov解释说，"侧根如同海绵，在土壤中吸收着养料和水份。"
研究发现赤霉素与其他植物激素相互作用，共同决定了植物的根应该是向地上生长还是向地下生长。"从分子水平来看，赤霉素和生长素有着自己的通信方式"，Busov称，通过与正常野生型杨树的对比试验，他们发现赤霉素浓度越多，其茎长得越好，而侧根发育则差。当通过突变相关基因或者RNAi技术等使植株不产生赤霉素时，植株显得非常矮小，但是他们的侧根长得繁盛。、人工添加赤霉素作用于缺乏赤霉素而弱小的杨树时，结果恰好颠倒了过来。这些杨树长得非常高，而侧根基本上就没有发育。
"显然，缺少赤霉素的杨树，其地下部分长得好，赤霉素促进了地上部分的生长"，Busov说，"关于这个自然规律，我们知道的并不多。它总是在地下生长和地上生长之间寻求一种平衡。一般来说，这种平衡获得了很好的维系。只是有时会在地下受到土壤环境的一些影响。"The Plant Cell科学编辑Kathleen Farquharson在同期发出评论文章中写道："此研究为如何利用激素控制侧根发育提供了新方向"。
原文出处：
The Plant Cell doi：10.1105/tpc.109.073239
Gibberellins Regulate Lateral Root Formation in Populus through Interactions with Auxin and Other Hormones
Jiqing Gou a, Steven H. Strauss b, Chung Jui Tsai c, Kai Fang d, Yiru Chen a, Xiangning Jiang d and Victor B. Busov a
a School of Forest Resources and Environmental Science, Michigan Technological University, Houghton, Michigan 49931-1295
b Department of Forest Ecosystems and Society, Oregon State University, Corvallis, Oregon 97331-5752
c Warnell School of Forestry and Natural Resources, Department of Genetics, University of Georgia, Athens, Georgia 30602-2152
d National Engineering Laboratory for Tree Breeding, College of Life Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, People's Republic of China
The role of gibberellins (GAs) in regulation of lateral root development is poorly understood. We show that GA-deficient (35S:PcGA2ox1) and GA-insensitive (35S:rgl1) transgenic Populus exhibited increased lateral root proliferation and elongation under in vitro and greenhouse conditions, and these effects were reversed by exogenous GA treatment. In addition, RNA interference suppression of two poplar GA 2-oxidases predominantly expressed in roots also decreased lateral root formation. GAs negatively affected lateral root formation by inhibiting lateral root primordium initiation. A whole-genome microarray analysis of root development in GA-modified transgenic plants revealed 2069 genes with significantly altered expression. The expression of 1178 genes, including genes that promote cell proliferation, growth, and cell wall loosening, corresponded to the phenotypic severity of the root traits when transgenic events with differential phenotypic expression were compared. The array data and direct hormone measurements suggested crosstalk of GA signaling with other hormone pathways, including auxin and abscisic acid. Transgenic modification of a differentially expressed gene encoding an auxin efflux carrier suggests that GA modulation of lateral root development is at least partly imparted by polar auxin transport modification. These results suggest a mechanism for GA-regulated modulation of lateral root proliferation associated with regulation of plant allometry during the stress response.
