Abstract
The local environment has a substantial impact on early seedling development. Applying excess carbon in the form of sucrose is known to alter both the timing and duration of seedling growth. Here, we show that sucrose changes growth patterns by increasing auxin levels and rootward auxin transport in Arabidopsis (Arabidopsis thaliana). Sucrose likely interacts with an endogenous carbon-sensing pathway via the PHYTOCHROME-INTERACTING FACTOR (PIF) family of transcription factors, as plants grown in elevated carbon dioxide showed the same PIF-dependent growth promotion. Overexpression of PIF5 was sufficient to suppress photosynthetic rate, enhance response to elevated carbon dioxide, and prolong seedling survival in nitrogen-limiting conditions. Thus, PIF transcription factors integrate growth with metabolic demands and thereby facilitate functional equilibrium during photomorphogenesis.
Highlights
The local environment has a substantial impact on early seedling development
We show that supplemental Suc stimulates an endogenous carbon-sensing pathway that regulates hypocotyl elongation through altered auxin levels and distribution in Arabidopsis (Arabidopsis thaliana)
We found that supplemental Suc promoted hypocotyl elongation through altered auxin levels and distribution (Figs. 1 and 2)
Summary
The local environment has a substantial impact on early seedling development. Applying excess carbon in the form of sucrose is known to alter both the timing and duration of seedling growth. Nutrient and energy availability are key factors controlling growth in all organisms This is true of sessile plants, which use growth patterns to optimally exploit their local environment. A model has recently been proposed to explain how dual control by light and the circadian clock produces peaks and troughs in hypocotyl growth rates Both cues converge on the PHYTOCHROME-INTERACTING FACTOR (PIF) family of transcription factors, with clock regulation of PIF transcription and light regulation of PIF protein stability (Nozue et al, 2007). While light promotes PIF protein turnover, Suc increases PIF abundance (Stewart et al, 2011) Identified by their ability to directly bind with phytochrome photoreceptors, PIF transcription factors are known to act as key growth regulators in response to a variety of environmental conditions
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