近日，国际著名杂志Nature在线刊登了诺丁汉大学等研究机构研究人员的最新研究成果“A novel sensor to map auxin response and distribution at high spatio-temporal resolution”，研究人员在文章中人们长久以来的疑问：为什么植物根茎向下生长，而不是向上生长？
对于植物来说，向下生长的根茎可以深入土壤并最大化对水分的吸收。但是“为什么”这个问题一直让回答了让达尔文以来的无数科学家着迷。如今诺丁汉大学的科学家们找到了答案。
重力对植物生长的作用是举足轻重的。但是来自英国，德国，法国，比利时，瑞典和美国的科学家组成的研究小组在多年研究后最终确定了植物生长的整个过程。在生物技术和生物科学研究理事会(BBSRC)的资助下，诺丁汉大学植物科学教授和植物结合生物学中心生物学主任 Malcolm Bennett采用新技术探索植物根茎向下生长时发生的状况。他说： “这项研究真正体现了利用跨学科的方法探讨植物科学问题的价值。通过数学模型和试验生物学家的结合，我们可采用一系列的工具研究根系生长的问题。”
科学家们很早就发现植物因重力原因弯曲是由于根尖植物激素的再分配。这项研究结合DII-VENUS新技术（诺丁汉大学的另一项合作研究项目），运用数学模型呈现出根茎在出现90度弯曲时生长素开始重新分配，并且比之前认为的要迅速很多。
这种跨学科的研究方法揭示了生长素在弯曲90度后迅速重新分配到了正在生长的根部的低端。这表明根尖到达与水平方向呈40度的“转折点”时，生长素梯度将迅速消失。这是导致根茎弯曲的“开关”。（生物谷Bioon.com）
doi:10.1038/nature10791
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A novel sensor to map auxin response and distribution at high spatio-temporal resolution
Géraldine Brunoud,1 Darren M. Wells,2, 5 Marina Oliva,1, 5 Antoine Larrieu,2, 3, 5 Vincent Mirabet,1 Amy H. Burrow,4 Tom Beeckman,3 Stefan Kepinski,4 Jan Traas,1 Malcolm J. Bennett2 & Teva Vernoux1
Auxin is a key plant morphogenetic signal1 but tools to analyse dynamically its distribution and signalling during development are still limited. Auxin perception directly triggers the degradation of Aux/IAA repressor proteins2, 3, 4, 5, 6. Here we describe a novel Aux/IAA-based auxin signalling sensor termed DII-VENUS that was engineered in the model plant Arabidopsis thaliana. The VENUS fast maturing form of yellow fluorescent protein7 was fused in-frame to the Aux/IAA auxin-interaction domain (termed domain II; DII)5 and expressed under a constitutive promoter. We initially show that DII-VENUS abundance is dependent on auxin, its TIR1/AFBs co-receptors4, 5, 6, 8 and proteasome activities. Next, we demonstrate that DII-VENUS provides a map of relative auxin distribution at cellular resolution in different tissues. DII-VENUS is also rapidly degraded in response to auxin and we used it to visualize dynamic changes in cellular auxin distribution successfully during two developmental responses, the root gravitropic response and lateral organ production at the shoot apex. Our results illustrate the value of developing response input sensors such as DII-VENUS to provide high-resolution spatio-temporal information about hormone distribution and response during plant growth and development.
