PIF Genes Mediate the Effect of Sucrose on Seedling Growth Dynamics

Jodi L. Stewart,Julin N. Maloof,Jennifer L. Nemhauser,Mohammed Bendahmane

doi:10.1371/journal.pone.0019894

Jodi L. Stewart, Julin N. Maloof + Show 2 more

Open Access

https://doi.org/10.1371/journal.pone.0019894

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Abstract

As photoautotrophs, plants can use both the form and amount of fixed carbon as a measure of the light environment. In this study, we used a variety of approaches to elucidate the role of exogenous sucrose in modifying seedling growth dynamics. In addition to its known effects on germination, high-resolution temporal analysis revealed that sucrose could extend the number of days plants exhibited rapid hypocotyl elongation, leading to dramatic increases in ultimate seedling height. In addition, sucrose changed the timing of daily growth maxima, demonstrating that diel growth dynamics are more plastic than previously suspected. Sucrose-dependent growth promotion required function of multiple phytochrome-interacting factors (PIFs), and overexpression of PIF5 led to growth dynamics similar to plants exposed to sucrose. Consistent with this result, sucrose was found to increase levels of PIF5 protein. PIFs have well-established roles as integrators of response to light levels, time of day and phytohormone signaling. Our findings strongly suggest that carbon availability can modify the known photomorphogenetic signaling network.

Highlights

As a plant emerges from the seed, it must make an accurate and nuanced assessment of the light environment
Sucrose promotes seedling growth by extending the number of days of hypocotyl elongation The addition of 88 mM (3%) sucrose to plant media nearly doubled the height of six day old seedlings (Figure 1A), while causing a delay in germination (Figure 1C,D), consistent with previous reports [28,29,30,31]
Addition of comparable levels of mannitol caused a strong reduction in overall hypocotyl elongation (Figure S1A), and had no effect on timing of germination (Figure S1B,C), suggesting that sucrose effects were not the result of changes in osmotic potential

Summary

Introduction

As a plant emerges from the seed, it must make an accurate and nuanced assessment of the light environment. Sucrose promotes seedling growth by extending the number of days of hypocotyl elongation The addition of 88 mM (3%) sucrose to plant media nearly doubled the height of six day old seedlings (Figure 1A), while causing a delay in germination (Figure 1C,D), consistent with previous reports [28,29,30,31]. Addition of comparable levels of mannitol caused a strong reduction in overall hypocotyl elongation (Figure S1A), and had no effect on timing of germination (Figure S1B,C), suggesting that sucrose effects were not the result of changes in osmotic potential.

Results

Conclusion