Leaf shape is highly variable within and among plant species,ranging from slender to oval shaped.This is largely determined by the proximodistal axis of growth.However,little is known about how proximal–distal growth...Leaf shape is highly variable within and among plant species,ranging from slender to oval shaped.This is largely determined by the proximodistal axis of growth.However,little is known about how proximal–distal growth is controlled to determine leaf shape.Here,we show that Arabidopsis leaf and sepal proximodistal growth is tuned by two phytohormones.Two class A AUXIN RESPONSE FACTORs(ARFs),ARF6 and ARF8,activate the transcription of DWARF4,which encodes a key brassinosteroid(BR)biosynthetic enzyme.At the cellular level,the phytohormones promote more directional cell expansion along the proximodistal axis,as well as final cell sizes.BRs promote the demethyl-esterification of cell wall pectins,leading to isotropic in-plane cell wall loosening.Notably,numerical simulation showed that isotropic cell wall loosening could lead to directional cell and organ growth along the proximodistal axis.Taken together,we show that auxin acts through biosynthesis of BRs to determine cell wall mechanics and directional cell growth to generate leaves of variable roundness.展开更多
基金supported by the National Natural Science Foundation of China(NSFC)grants 31825002 and 31861143021the Key Research Project of the Frontier Science of CAS grant ZDBS-LY-SM012,and the Strategic Priority Research Program of CAS grant XDA24020203.Y.W.acknowledges the National Key R&D Program of China grant 2019YFA0903902 and NSFC grant 31871245.F.D.was supported by a Young Scientists Fund of NSFC(grant 32000507).C.T.was supported by NSFC grants 31961133010 and 31970805the Youth Innovation Promotion Association of CAS(award 2017139).
文摘Leaf shape is highly variable within and among plant species,ranging from slender to oval shaped.This is largely determined by the proximodistal axis of growth.However,little is known about how proximal–distal growth is controlled to determine leaf shape.Here,we show that Arabidopsis leaf and sepal proximodistal growth is tuned by two phytohormones.Two class A AUXIN RESPONSE FACTORs(ARFs),ARF6 and ARF8,activate the transcription of DWARF4,which encodes a key brassinosteroid(BR)biosynthetic enzyme.At the cellular level,the phytohormones promote more directional cell expansion along the proximodistal axis,as well as final cell sizes.BRs promote the demethyl-esterification of cell wall pectins,leading to isotropic in-plane cell wall loosening.Notably,numerical simulation showed that isotropic cell wall loosening could lead to directional cell and organ growth along the proximodistal axis.Taken together,we show that auxin acts through biosynthesis of BRs to determine cell wall mechanics and directional cell growth to generate leaves of variable roundness.
