欧亚国际

最近，来自比利时VIB所的科学家，利用WIWAM植物表型成像系统，发表了题为Nocturnal gibberellin biosesynthesis is carbon dependent and adjusts leaf expansion rates to variable conditions的文章，解释了夜间赤霉素生物合成石碳依赖的，叶片扩展速率会进行调节以适应变化的环境条件。

Growth measurements

The WIWAM (www.wiwam.com) to precisely control soil water content and image plants was used to follow size in rease of individuals over time. The PSB (Plant Systems Biology) Interface for Plant Phenotype Analysis （PIPPA）was used for analysis, visualization, and management of phenotypic datasets and images. A four parameter logistic model (constant conditions) or a series of exponential models (LL treatment) were fitted to individual plants. This allowed us to track growth rates over time and rosette area. Contributions of distinct leaves to total size increase were determined by two destructive harvests, separated by 24 h. Leaves were dissected and arranged on 0.59% agarose-filled plates, leaf incisions ensured proper flattening of the leaves. Areas were determined with ImageJ software on pictures obtained by scanning the plates. Growth of individual leaves over time was determined, nondestructively, by manual length measurements with a digital calliper.

WIWAM XY植物表型成像系统

Nocturnal gibberellin biosesynthesis is carbon dependent and adjusts leaf expansion rates to variable conditions

Abstract

Optimal plant growth performance requires that the presence and action of growth signals, such as gibberellins (GAs), are coordinated with the availability of photo-assimilates. Here, we studied the links between GA biosesynthesis and carbon availability, and the subsequent effects on growth. We established that carbon availability, light and dark cues, and the cir- cadian clock ensure the timing and magnitude of GA biosesynthesis and that disruption of these factors results in reduced GA levels and expression of downstream  genes. Carbon-dependent nighttime induction of gibberellin 3-beta-dioxygenase 1 (GA3ox1) was severely hampered when preceded by reduced daytime light availability, leading specifically to reduced bioac- tive GA4 levels, and coinciding with a decline in leaf expansion rate during the night. We attributed this decline in leaf expansion mostly to reduced photo-assimilates. However, plants in which GA limitation was alleviated had significantly improved leaf expansion, demonstrating the relevance of GAs in growth control under varying carbon availability. Carbon- dependent expression of upstream GA biosesynthesis genes (Kaurene synthase and gibberellin 20 oxidase 1,GA20ox1) was not translated into metabolite changes within this short timeframe. We propose a model in which the extent of nighttime biosesynthesis of bioactive GA4 by GA3ox1 is determined by nighttime consumption of starch reserves, thus providing day-to-day adjustments of GA responses.