据英国《新科学家》周刊网站报道，经过７０多年的研究，植物学家可能已发现激发植物开花的分子指令。在全球变暖导致气候带向两极移动的趋势下，这一发现对科学家帮助作物适应不同纬度具有重要意义。
由德国科隆马克斯·普朗克研究所的乔治·库普兰和伦敦帝国学院的科林·特恩布尔领导的小组发现，一种被称为ＦｌｏｗｅｒｉｎｇＬｏｃｕｓ（ＦＴ）的基因所产生的蛋白质可以激发植物开花。
研究人员利用基因工程把ＦＴ基因的蛋白质加入到拟南芥的绿色荧光蛋白质标记中，随后把一种缺乏ＦＴ基因从而不能开花的突变茎嫁接到这种带有标记的作物上。结果发现，发光的ＦＴ蛋白质进入突变的茎，并促使其开花。
另一支由日本人领导的小组利用大致相同的技术，在水稻上显示了同样的过程。
专家认为，在两种远缘植物上发现相同的“促花素”，表明所有植物的机理是一样的。
研究人员早在上世纪３０年代就发现，植物的叶子通过感应日光变化判断季节，到时机成熟时，就向茎尖发出某种信号，激发开花。但是科学家始终不知道这种所谓“促花素”究竟是何种物质。
英文原文：
Botanists discover the signal that triggers flowering
12:48 20 April 2007
NewScientist.com news service
Bob Holmes
After a quest lasting more than 70 years, botanists may finally have found what one leading textbook describes as "the Holy Grail of plant biology" – the molecular command that tells a plant it is time to flower.
The discovery may help scientists tailor crops to different latitudes – an especially valuable ability as global warming begins to shift climate zones towards the poles.
Researchers have known since the 1930s that the leaves of plants perceive the seasons by sensing the amount of daylight and, when the time is right, trigger flowering by sending some sort of signal to the shoot tip. But the identity of this so-called "florigen" has remained mysterious.
Now two research teams have independently identified it. Florigen, they say, is the protein produced by a gene called Flowering locus T, or FT. One team, led by George Coupland at the Max Planck Institute for Plant Breeding Research in Cologne, Germany, and Colin Turnbull at Imperial College London in the UK, used genetic trickery to join the FT protein to a green fluorescent protein marker in Arabidopsis, or thale cress.
Green fuse
Onto this marker-enriched plant, the team grafted a mutant stem that lacked the FT gene and so was unable to flower by itself. They observed that the fluorescent FT protein crossed into the mutant stem and triggered flowering. "It's pretty unambiguous," says Turnbull.
Another team, led by Ko Shimamoto at the Nara Institute of Science and Technology in Ikoma, Japan, used much the same technique to show the same thing in rice.
Finding the same florigen in two such distantly related species suggests the mechanism is common to all plants, says Jan Zeevaart, a plant biologist at Michigan State University in East Lansing, US.
The new results are not the FT gene's first turn in the limelight. In recent years, several studies have shown that FT is turned on in leaf tissue at particular day lengths, and that the FT protein acts in the shoot tip to trigger flowering. However, no one knew whether the FT protein or some other molecule was the flowering signal that shuttled from leaf to shoot tip.
Messenger shot
In 2005, researchers in Sweden seemed to settle the question when they announced that messenger RNA from the FT gene was the mobile signal. But this week, the Swedish team formally retracted this claim.
"A guest researcher from China who had been invited to join our team manipulated the data to get false results," says Ove Nilsson at Umeå University in Sweden. The Chinese researcher, Tao Huang, who is no longer at Umeå University, still stands by his results, says Nilsson.
With the flowering signal now firmly in hand, biotechnologists have the means to tinker with a plant's flowering time to adapt it to different conditions. For example, farmers at higher latitudes might want to force crops to flower earlier so that they can mature their fruit before the first frost, suggests Brian Ayre, a plant biologist at the University of North Texas in Denton, US.
Reference: Science, doi:10.1126/science.1141752 and doi:10.1126/science.1141753; (retraction) Science, vol 316, p 367
