WVD2 and WDL1 modulate helical organ growth and anisotropic cell expansion in Arabidopsis.
Wild-type Arabidopsis roots develop a wavy pattern of growth on tilted agar surfaces. For many Arabidopsis ecotypes, roots also grow askew on such surfaces, typically slanting to the right of the gravity vector. We identified a mutant, wvd2-1, that displays suppressed root waving and leftward root slanting under these conditions. These phenotypes arise from transcriptional activation of the novel WAVE-DAMPENED2 (WVD2) gene by the cauliflower mosaic virus 35S promoter in mutant plants. Seedlings overexpressing WVD2 exhibit constitutive right-handed helical growth in both roots and etiolated hypocotyls, whereas the petioles of WVD2-overexpressing rosette leaves exhibit left-handed twisting. Moreover, the anisotropic expansion of cells is impaired, resulting in the formation of shorter and stockier organs. In roots, the phenotype is accompanied by a change in the arrangement of cortical microtubules within peripheral cap cells and cells at the basal end of the elongation zone. WVD2 transcripts are detectable by reverse transcriptase-polymerase chain reaction in multiple organs of wild-type plants. Its predicted gene product contains a conserved region named "KLEEK," which is found only in plant proteins. The Arabidopsis genome possesses seven other genes predicted to encode KLEEK-containing products. Overexpression of one of these genes, WVD2-LIKE 1, which encodes a protein with regions of similarity to WVD2 extending beyond the KLEEK domain, results in phenotypes that are highly similar to wvd2-1. Silencing of WVD2 and its paralogs results in enhanced root skewing in the wild-type direction. Our observations suggest that at least two members of this gene family may modulate both rotational polarity and anisotropic cell expansion during organ growth.
Yuen
Christen Y L
CY
Laboratory of Genetics, University of Wisconsin, 445 Henry Mall, Madison, Wisconsin 53706, USA.
Pearlman
Rebecca S
RS
Silo-Suh
Laura
L
Hilson
Pierre
P
Carroll
Kathleen L
KL
Masson
Patrick H
PH
D000595:Amino Acid Sequence; D016880:Anisotropy; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002455:Cell Division / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D018546:Hypocotyl / Q000235:genetics / Q000254:growth & development; D008870:Microtubules / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D029681:Arabidopsis Proteins; C474075:WDL1 protein, Arabidopsis; C474074:WVD2 protein, Arabidopsis