Sugars, Hormones & Plant Growth

image descriptionSugars, Hormones, and Plant growth

A plant's eventual size depends on the integration of its genetic program with environmental cues, which vary on a daily basis. Both efficient carbon metabolism and the plant hormone gibberellin are required to guarantee optimal plant growth. Yet, little is known about the interplay between carbon metabolism and gibberellins that modulates plant growth. Here, we show that sugar starvation in Arabidopsis thaliana arising from inefficient starch metabolism at night strongly reduces the expression of ent-kaurene synthase, a key regulatory enzyme for gibberellin synthesis, the following day. Our results demonstrate that plants integrate the efficiency of photosynthesis over a period of days, which is transduced into a daily rate of gibberellin biosynthesis. This enables a plant to grow to a size that is compatible with its environment.



 

Why and How Do Plant Cells Sense Sugars? Read here a Review Article

image descriptionSugar effects on seedling development in Arabidopsis: Read here a Review Article

 


image descriptionThe ability to sense sugars is crucial for the modulation of gene expression in plants. Despite the importance of this phenomenon, our knowledge of sugar sensing in plants is scant. Several valuable hypotheses have been put forward based on the extensive knowledge of sugar sensing in yeast. In recent years, tests of these hypotheses have shown that hexokinase and sucrose-non-fermenting- (SNF-) related proteins appear to be involved in sugar sensing and transduction, not only in yeast but also in higher plants. However, even if plants share with yeast some elements involved in sugar sensing, several aspects of sugar perception are likely to be peculiar to higher plants. Plants should be able to sense not only glucose but also other hexoses, Such as fructose and disaccharides (sucrose, maltose and others). We have shown that comparing the molecular requirements for sucrose transport with those for disaccharide sensing suggests that these sugars are perceived possibly at the plasma membrane level independently from sucrose transport. Evidence is provided of cross-talk between the sugar-sensing pathways and the physiology of plant hormones. Turanose signaling overlaps with auxin signaling, as shown using a turanose-insensitive mutant.

Several sugar regulated genes were identified by transcript profiling of sucrose-treated arabidopsis seedlings. Among sucrose-regulated genes we identified MYB75 as a transcription factor regulating the sucrose-dependent synthesis of anthocyanins. Plant hormones interfere with the sucrose-signaling pathway triggering the induction of anthocyanins.

Additionally, cross-talk between the anaerobic and sugar signaling pathways contribute to the acclimation mechanisms in rice.

A review on sugar sensing in plants can be downloaded here.

A review on the effects of sugars on the erly development of Arabidopsis seedlings can be downloaded here.