生物谷Bioon.com 訊 壓力不只是人類的專利,。樹(shù)木也同樣需要面對(duì)壓力,。干旱和水澇,，喪失養(yǎng)分，環(huán)境污染及氣候改變等問(wèn)題,，對(duì)于樹(shù)木而言都是壓力,，學(xué)術(shù)界稱之為脅迫,。如何幫助樹(shù)木和農(nóng)作物迅速而有效的適應(yīng)脅迫，是從事植物科學(xué)研究者急需解決的迫切任務(wù),。
美國(guó)密歇根科技大學(xué)的科學(xué)家發(fā)現(xiàn)了楊樹(shù)的一種適應(yīng)土壤環(huán)境變化的新分子機(jī)理,，也就是一些控制此過(guò)程的部分基因開(kāi)關(guān)。研究者希望通過(guò)利用生物技術(shù)及選擇性育種的方式改變楊樹(shù)的抗脅迫能力,。
"我們希望理解其中的發(fā)生機(jī)制,，我們能嫻熟的操作此系統(tǒng)使植物能更快更好的適應(yīng)客觀條件"，來(lái)自密歇根科技大學(xué)森林與環(huán)境科學(xué)的副教授Victor Busov說(shuō)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(guó)喬治亞大學(xué),，俄勒岡州立大學(xué)以及北京林業(yè)大學(xué)的研究人員,。楊樹(shù)是目前唯一一個(gè)全基因組測(cè)序完成的樹(shù)種。他們分析了楊樹(shù)基因組中數(shù)以千計(jì)的基因,。研究者正在尋求一種調(diào)控機(jī)制,。這種機(jī)制直接關(guān)系著植物是在地面部分的繁盛以及合適的恰當(dāng)?shù)耐寥罈l件充分補(bǔ)充其地下部分根系的發(fā)達(dá)程度,。
赤霉素（Gibberellins,，簡(jiǎn)稱GAs）在其中扮演了關(guān)鍵的角色。"在根的發(fā)育過(guò)程中,，赤霉素的作用了解的不多",，Busov說(shuō)到，"特別是關(guān)于赤霉素對(duì)側(cè)根的影響的研究更是少,。"Busov解釋說(shuō),，"側(cè)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(yīng)該是向地上生長(zhǎng)還是向地下生長(zhǎng)。"從分子水平來(lái)看,，赤霉素和生長(zhǎng)素有著自己的通信方式",，Busov稱，通過(guò)與正常野生型楊樹(shù)的對(duì)比試驗(yàn),，他們發(fā)現(xiàn)赤霉素濃度越多,，其莖長(zhǎng)得越好，而側(cè)根發(fā)育則差,。當(dāng)通過(guò)突變相關(guān)基因或者RNAi技術(shù)等使植株不產(chǎn)生赤霉素時(shí),，植株顯得非常矮小，但是他們的側(cè)根長(zhǎng)得繁盛,。,、人工添加赤霉素作用于缺乏赤霉素而弱小的楊樹(shù)時(shí),，結(jié)果恰好顛倒了過(guò)來(lái)。這些楊樹(shù)長(zhǎng)得非常高,，而側(cè)根基本上就沒(méi)有發(fā)育,。
"顯然，缺少赤霉素的楊樹(shù),，其地下部分長(zhǎng)得好,，赤霉素促進(jìn)了地上部分的生長(zhǎng)"，Busov說(shuō),，"關(guān)于這個(gè)自然規(guī)律,，我們知道的并不多。它總是在地下生長(zhǎng)和地上生長(zhǎng)之間尋求一種平衡,。一般來(lái)說(shuō),，這種平衡獲得了很好的維系。只是有時(shí)會(huì)在地下受到土壤環(huán)境的一些影響,。"The Plant Cell科學(xué)編輯Kathleen Farquharson在同期發(fā)出評(píng)論文章中寫(xiě)道："此研究為如何利用激素控制側(cè)根發(fā)育提供了新方向",。（生 物 谷Bioon.com）
更多閱讀
PBJ：沉默赤霉素失活霉能加快植物生長(zhǎng)
Nature：赤霉素受體的晶體結(jié)構(gòu)
JIPB：一氧化碳如何誘導(dǎo)油菜側(cè)根形成
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.
