Department of Biological Science, Sungkyunkwan University, Suwon, Korea.
PLoS Genet. 2011 Jan 6;7(1):e1001263. doi: 10.1371/journal.pgen.1001263.
Sugars are evolutionarily conserved signaling molecules that regulate the growth and development of both unicellular and multicellular organisms. As sugar-producing photosynthetic organisms, plants utilize glucose as one of their major signaling molecules. However, the details of other sugar signaling molecules and their regulatory factors have remained elusive, due to the complexity of the metabolite and hormone interactions that control physiological and developmental programs in plants. We combined information from a gain-of-function cell-based screen and a loss-of-function reverse-genetic analysis to demonstrate that fructose acts as a signaling molecule in Arabidopsis thaliana. Fructose signaling induced seedling developmental arrest and interacted with plant stress hormone signaling in a manner similar to that of glucose. For fructose signaling responses, the plant glucose sensor HEXOKINASE1 (HXK1) was dispensable, while FRUCTOSE INSENSITIVE1 (FINS1), a putative FRUCTOSE-1,6-BISPHOSPHATASE, played a crucial role. Interestingly, FINS1 function in fructose signaling appeared to be independent of its catalytic activity in sugar metabolism. Genetic analysis further indicated that FINS1-dependent fructose signaling may act downstream of the abscisic acid pathway, in spite of the fact that HXK1-dependent glucose signaling works upstream of hormone synthesis. Our findings revealed that multiple layers of controls by fructose, glucose, and abscisic acid finely tune the plant autotrophic transition and modulate early seedling establishment after seed germination.
糖是进化上保守的信号分子，可调节单细胞和多细胞生物的生长和发育。作为产生葡萄糖的光合生物，植物将葡萄糖用作其主要信号分子之一。然而，由于控制植物生理和发育程序的代谢物和激素相互作用的复杂性，其他糖信号分子及其调节因子的细节仍然难以捉摸。我们结合了功能获得型基于细胞的筛选和功能丧失型反向遗传分析的信息，证明果糖在拟南芥中作为信号分子发挥作用。果糖信号诱导幼苗发育停滞，并以类似于葡萄糖的方式与植物应激激素信号相互作用。对于果糖信号反应，植物葡萄糖传感器己糖激酶 1（HXK1）是可有可无的，而假定的果糖-1,6-二磷酸酶 FRUCTOSE INSENSITIVE1（FINS1）则起着至关重要的作用。有趣的是，FINS1 在果糖信号中的功能似乎与其在糖代谢中的催化活性无关。遗传分析进一步表明，尽管 HXK1 依赖的葡萄糖信号在激素合成之前起作用，但 FINS1 依赖的果糖信号可能作用于脱落酸途径的下游。我们的研究结果表明，果糖、葡萄糖和脱落酸的多层控制可精细调节植物自养转变，并调节种子萌发后幼苗的早期建立。
