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科学家首次确定导致植物开花的信号蛋白

来源:生物谷 2007-06-13 09:18

    最近来自UC  Davis,Arizona大学Tucson分校的科学家通过和新西兰及墨西哥的同事合作,确定了导致植物开花的信号蛋白。

    UC  Davis植物生物学教授William  J.  Lucas表示:“这是植物生物学中最重要的领域。”Lucas是发表在5月份的Plant  Cell上的文章的主要作者。

    通过研究南瓜,Lucas实验室的访问博士后Ming-Kuem  Lin和同事发现一种被称为FT的蛋白通过植物体韧皮部的树液传送到生长点来触发植物开花。

    很多植物,包括一些重要的农作物——例如大米、玉米和小麦等都是对春季或是秋季的白昼时间变化做出反应从而开花的。科学家认为成花激素是随着日长改变而在树叶中形成,然后通过韧皮部输送到分裂组织或是生长点。韧皮部主要负责从植物中心将水、糖分以及其它分子输送到周边组织。

    Lucas小组分析了常见的南瓜(Cucurbita  maxima),因为它能产生大量的树液。但是一般的南瓜不会对白昼长度改变做出反应。因此小组寻找了超过一百种相关的南瓜种类,最终找到了一种野生南瓜(Cucurbita  moschata),它只在短日照情况下开花。

    当C.  moschata感染了携带FT基因的病毒后,它开花变得不受日长影响。这种病毒只存在于叶子和茎中,而不在花蕾中。当将C.  moschata嫁接到C.  maxima上后,植物又开花了,因为信号从C.  maxima叶子中传递到了C.  moschata分裂组织。其中FT蛋白从韧皮部中被分离出来。

    这一结果证明FT蛋白是成花激素。Lucas认为,对于植物自身调控方式的了解能在农业上有很广泛的应用。(引自教育部科技发展中心)

英文原文:

physorg.com

Published: 07:06 EST, June 09, 2007

Flowering Signal Found

The signal that causes plants to flower, or "florigen," has been identified by researchers at UC Davis, the University of Arizona, Tucson, and collaborators in New Zealand and Mexico.

 

"This is the Holy Grail of plant biology," said William J. Lucas, professor of plant biology at UC Davis and senior author on the paper published in the May issue of the journal Plant Cell.

Working with pumpkins and squash, Ming-Kuem Lin, a visiting postdoctoral researcher in Lucas' lab and colleagues showed that a protein, FT, is transported through the phloem sap from the body of the plant to the growing tips to trigger flowering.

Many plants, including important crops such as rice, maize and wheat, flower in response to lengthening days in the spring or shortening days in fall. Researchers thought that florigen is made in the leaves as the length of the day changes and it is transported to the meristems, or growing tips of the plant, through the phloem network, which actively transports water, sugars and other molecules from the center of the plant to the periphery.

Lucas' research group works with common pumpkins (Cucurbita maxima), because of the large amount of sap they produce. But pumpkins do not flower in response to day length. So the team searched more than a hundred strains of related plants to find a wild squash, Cucurbita moschata, which flowers only in short days.
When the C. moschata plants were infected with a virus carrying the FT gene, they flowered regardless of day length. The viruses were found only in the leaves and stems, but not in the flowering buds, ruling out another possible candidate, the RNA produced by the FT gene.

The researchers grafted C. moschata onto C. maxima. Again, the plants flowered, as the signal was carried from the C. maxima leaves to the C. moschata meristems. The pumpkin FT protein was isolated from the phloem.

The experiments provide absolute, direct evidence that the FT protein moving through the phloem is the florigen, Lucas said. Phloem contains about 1,900 other proteins, many of which are also likely to be signals of one kind or another, he said.

In addition to opening up new ways to understand how plants regulate themselves, the findings could eventually have widespread applications in agriculture, Lucas said.

Source: UC Davis
 
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