Bridging the gap between amyloplasts and directional auxin transport in plant gravitropism
Moritaka Nakamura1, Takeshi Nishimura2, Miyo Terao Morita2
1Division of Plant Environmental Responses, National Institute for Basic Biology, Okazaki, 444-8585, Japan.
Abstract:
Gravitropism is the directional control of plant organ growth in response to gravity. Specialized gravity-sensing cells contain amyloplasts that can change their position according to the direction of gravity. Gravity signaling, which is elicited by the relocation of amyloplasts, is a key process that redirects auxin transport from gravity-sensing cells to the lower flank of gravity-responsive organs. Despite the long history of research on plant gravitropism, a molecular detail of gravity signaling remained unexplained. Recent studies have characterized the Arabidopsis LAZY1 family genes to be key factors of gravity signaling. Furthermore, studies regarding Arabidopsis AGCVIII kinases have demonstrated the requirement of auxin transporter PIN-FORMED3 (PIN3) phosphorylation in plant gravitropism.
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