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Plastid movement in statocytes of the arg1 ( altered response to gravity ) mutant
Author(s) -
Shiva Kumar Neela,
Stevens Martin Henry H.,
Kiss John Z.
Publication year - 2008
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.95.2.177
Subject(s) - gravitropism , biology , amyloplast , plastid , arabidopsis thaliana , botany , microbiology and biotechnology , arabidopsis , mutant , chloroplast , genetics , gene
The ability of a plant to respond to gravity is crucial for growth and development throughout the life cycle. A key player in the cellular mechanisms of gravitropism is ARG1 ( a ltered r esponse to g ravity), a DnaJ‐like protein that associates with components of the vesicular trafficking pathway and carries a C‐terminal domain with similarities to cytoskeleton‐associated proteins. The arg1–2 mutant of Arabidopsis thaliana has reduced and delayed gravitropism in roots, shoots, and inflorescence stems when grown in the light or dark. We performed light microscopic studies of plastid movement in the gravity‐perceiving statocytes (endodermal cells) of hypocotyls of arg1–2 and WT light‐grown seedlings following reorientation to better characterize the role of ARG1 in gravitropism. Cryofixation/freeze substitution procedures were used because they provide a reliable indication of rapid cellular events within the statocytes. Our results suggest that ARG1 affects gravitropism by reducing plastid movement/sedimentation, a process known to be essential for early phases of signaling cascades in the statocytes.