生物谷Bioon.com 訊 壓力不只是人類的專利,。樹木也同樣需要面對壓力。干旱和水澇,，喪失養(yǎng)分,，環(huán)境污染及氣候改變等問題，對于樹木而言都是壓力,，學術界稱之為脅迫,。如何幫助樹木和農(nóng)作物迅速而有效的適應脅迫，是從事植物科學研究者急需解決的迫切任務,。
美國密歇根科技大學的科學家發(fā)現(xiàn)了楊樹的一種適應土壤環(huán)境變化的新分子機理,，也就是一些控制此過程的部分基因開關。研究者希望通過利用生物技術及選擇性育種的方式改變楊樹的抗脅迫能力,。
"我們希望理解其中的發(fā)生機制,，我們能嫻熟的操作此系統(tǒng)使植物能更快更好的適應客觀條件"，來自密歇根科技大學森林與環(huán)境科學的副教授Victor Busov說道,。Victor Busov為此文的通訊作者,。此研究成果發(fā)表于2010年3月份的The Plant Cell 雜志上。參與該研究的還有美國喬治亞大學,，俄勒岡州立大學以及北京林業(yè)大學的研究人員,。楊樹是目前唯一一個全基因組測序完成的樹種,。他們分析了楊樹基因組中數(shù)以千計的基因。研究者正在尋求一種調控機制,。這種機制直接關系著植物是在地面部分的繁盛以及合適的恰當?shù)耐寥罈l件充分補充其地下部分根系的發(fā)達程度,。
赤霉素（Gibberellins，簡稱GAs）在其中扮演了關鍵的角色,。"在根的發(fā)育過程中,，赤霉素的作用了解的不多"，Busov說到,，"特別是關于赤霉素對側根的影響的研究更是少,。"Busov解釋說，"側根如同海綿,，在土壤中吸收著養(yǎng)料和水份,。"
研究發(fā)現(xiàn)赤霉素與其他植物激素相互作用，共同決定了植物的根應該是向地上生長還是向地下生長,。"從分子水平來看,，赤霉素和生長素有著自己的通信方式"，Busov稱,，通過與正常野生型楊樹的對比試驗,，他們發(fā)現(xiàn)赤霉素濃度越多，其莖長得越好,，而側根發(fā)育則差,。當通過突變相關基因或者RNAi技術等使植株不產(chǎn)生赤霉素時，植株顯得非常矮小,，但是他們的側根長得繁盛,。、人工添加赤霉素作用于缺乏赤霉素而弱小的楊樹時,，結果恰好顛倒了過來,。這些楊樹長得非常高，而側根基本上就沒有發(fā)育,。
"顯然,，缺少赤霉素的楊樹，其地下部分長得好,，赤霉素促進了地上部分的生長",，Busov說，"關于這個自然規(guī)律,，我們知道的并不多,。它總是在地下生長和地上生長之間尋求一種平衡。一般來說，這種平衡獲得了很好的維系,。只是有時會在地下受到土壤環(huán)境的一些影響。"The Plant Cell科學編輯Kathleen Farquharson在同期發(fā)出評論文章中寫道："此研究為如何利用激素控制側根發(fā)育提供了新方向",。（生 物 谷Bioon.com）
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Bioon.com推薦原文出處：
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.
