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Guard cells control hypocotyl elongation through HXK1, HY5, and PIF4
Gilor Kelly1, Danja Brandsma1, Aiman Egbaria2
1Institute of Plant Sciences, Agricultural Research Organization, The Volcani Center, Rishon LeZion, Israel.
Communications Biology
|June 22, 2021
Summary
Guard cells coordinate seedling growth by sensing sugar. Sugar and HXK1 promote hypocotyl elongation, opposing light
Area of Science:
- Plant Biology
- Molecular Biology
- Developmental Biology
Background:
- Seedling hypocotyl elongation is regulated by light and sugar.
- Photoreceptors halt elongation by stabilizing HY5 and inhibiting PIFs.
- The roles of sugar and specific cell types in hypocotyl elongation are unclear.
Purpose of the Study:
- Investigate how sugar influences hypocotyl elongation.
- Determine which cell types regulate hypocotyl elongation.
- Elucidate the interplay between sugar, light, and growth regulators in guard cells.
Main Methods:
- Overexpression of Arabidopsis hexokinase 1 (HXK1) in guard cells.
- Analysis of PIF4 and HY5 expression and activity in guard cells.
- Genetic manipulation of HY5 and PIF4 in guard cells and other tissues.
Main Results:
- Overexpressing HXK1 in guard cells promotes hypocotyl elongation via PIF4 under light.
- PIF4 expression in guard cells promotes light-induced hypocotyl elongation.
- HY5 expression in guard cells inhibits hypocotyl elongation, even in a hy5 mutant.
Conclusions:
- Guard cells coordinate hypocotyl elongation.
- Sugar and HXK1 oppose light's effect on hypocotyl elongation, converging at PIF4.
- HY5 in guard cells inhibits elongation and induces auto-activation in other tissues.
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