Profilin plays a role in cell elongation, cell shape maintenance, and flowering in Arabidopsis.
Profilin (PFN) is an ubiquitous, low-M(r), actin-binding protein involved in the organization of the cytoskeleton of eukaryotes including higher plants. PFNs are encoded by a multigene family in Arabidopsis. We have analyzed in vivo functions of Arabidopsis PFN by generating transgenic plants carrying a 35S-PFN-1 or 35S-antisense PFN-1 transgene. Etiolated seedlings underexpressing PFN (PFN-U) displayed an overall dwarf phenotype with short hypocotyls whose lengths were 20% to 25% that of wild type (WT) at low temperatures. Light-grown PFN-U plants were smaller in stature and flowered early. Compared with equivalent cells in WT, most cells in PFN-U hypocotyls and roots were shorter, but more isodiametric, and microscopic observations of etiolated PFN-U hypocotyls revealed a rough epidermal surface. In contrast, light-grown seedlings overexpressing PFN had longer roots and root hair although etiolated seedlings overexpressing PFN were either the same size or slightly longer than WT seedlings. Transgenic seedlings harboring a PFN-1-GUS transgene directed expression in root and root hair and in a ring of cells at the elongating zone of the root tip. As the seedlings matured PFN-1-GUS was mainly expressed in the vascular bundles of cotyledons and leaves. Our results show that Arabidopsis PFNs play a role in cell elongation, cell shape maintenance, polarized growth of root hair, and unexpectedly, in determination of flowering time.
Ramachandran
S
S
Laboratory of Plant Cell Biology, Institute of Molecular Agrobiology, National University of Singapore, 1 Research Link, Singapore 117604.
Christensen
H E
HE
Ishimaru
Y
Y
Dong
C H
CH
Chao-Ming
W
W
Cleary
A L
AL
Chua
N H
NH
D000199:Actins / Q000378:metabolism; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins; D003285:Contractile Proteins; D018506:Gene Expression Regulation, Plant; D018546:Hypocotyl / Q000235:genetics / Q000254:growth & development; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008855:Microscopy, Electron, Scanning; D010641:Phenotype; D063245:Plant Development; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D010944:Plants / Q000235:genetics / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D051304:Profilins; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014018:Tissue Distribution
D000199:Actins; D029681:Arabidopsis Proteins; D003285:Contractile Proteins; D008840:Microfilament Proteins; C495746:PRF1 protein, Arabidopsis; D051304:Profilins; D018749:RNA, Plant