欧亚国际

较近来自意大利、比利时以及荷兰的先进科学家发表了题为Nighttime gibberellin biosesynthesis is influenced by fluctuating environmental conditions and contributes to growth adjustments of Arabidopsis leaves，研究中利用了WIWAM XY植物表型成像系统，内容如下：

Figure 6. Carbon and GA dependent growth under constant and variable conditions

With the automated phenotyping platform WIWAM XY to precisely control soil water content and to image individual plants over time (30,31) we followed the expansion rates of Col-0 and ga3ox1-kd plants under constant day/night cycles and when confronted with four interspersed low light days (Figure 6C).

Growth measurements: The Weighing, Imaging and Watering Automated Machine (WIWAM) (www.wiwam.com)to precisely control soil water content and image plants was used to follow size increase of individuals over time.The PSB Interface for Plant Phenotype Analysis (PIPPA, http://pippa.psb.ugent.be) 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 (low light 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 was determined by two destructive harvests, separated by 24 hours. 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 were determined,non-destructively, by manual length measurements with a digital calliper.

Abstract

Optimal plant growth performance requires that the action of growth signals, such as gibberellins (GA), are coordinated with the availability of photo-assimilates. Here, we studied the links between gibberellin biosesynthesis and carbon availability, and the subsequent effects on growth. The results presented here show that carbon availability, light and dark cues, and the clock ensure the timing and magnitude of gibberellin biosesynthesis and that disruption of these mechanisms results in reduced gibberellin levels and expression of downstream genes.

Carbon dependent nighttime induction of GIBBERELLIN 3-BETA-DIOXYGENASE 1 (GA3ox1) was severely hampered when preceded by a day of lowered light availability, leading specifically to reduced bioactive GA 4 levels, and coinciding with a decline in leaf expansion rate during the night. We attribute this decline in leaf expansion mostly to reduced photo-assimilates. However, plants where gibberellin limitation was alleviated had significantly improved expansion demonstrating the relevance of gibberellins in growth control under varying carbon availability. Carbon dependent expression of upstream gibberellin biosesynthesis genes (KAURENE SYNTHASE, KS and GIBBERELLIN 20 OXIDASE 1, GA20ox1) was not translated into metabolite changes within this short timeframe.We propose a model where the extent of nighttime biosesynthesis of bioactive GA 4 by GA3ox1 is determined by starch, as the nighttime carbon source, and so provides day-to-day adjustment of gibberellin responses.