Gene dosage effect of WEE1 on growth and morphogenesis from arabidopsis hypocotyl explants.
OBJECTIVE
How plant cell-cycle genes interface with development is unclear. Preliminary evidence from our laboratory suggested that over-expression of the cell cycle checkpoint gene, WEE1, repressed growth and development. Here the hypothesis is tested that the level of WEE1 has a dosage effect on growth and development in Arabidospis thaliana. To do this, a comparison was made of the development of gain- and loss-of-function WEE1 arabidopsis lines both in vivo and in vitro.


METHODS
Hypocotyl explants from an over-expressing Arath;WEE1 line (WEE1(oe)), two T-DNA insertion lines (wee1-1 and wee1-4) and wild type (WT) were cultured on two-way combinations of kinetin and naphthyl acetic acid. Root growth and meristematic cell size were also examined.


RESULTS
Quantitative data indicated a repressive effect in WEE1(oe) and a significant increase in morphogenetic capacity in the two T-DNA insertion lines compared with WT. Compared with WT, WEE1(oe) seedlings exhibited a slower cell-doubling time in the root apical meristem and a shortened primary root, with fewer laterals, whereas there were no consistent differences in the insertion lines compared with WT. However, significantly fewer adventitious roots were recorded for WEE1(oe) and significantly more for the insertion mutant wee1-1. Compared with WT there was a significant increase in meristem cell size in WEE1(oe) for all three ground tissues but for wee1-1 only cortical cell size was reduced.


CONCLUSIONS
There is a gene dosage effect of WEE1 on morphogenesis from hypocotyls both in vitro and in vivo.
School of Biosciences, Cardiff University, Park Place, UK.
Natasha
N
Spadafora
Lara
L
Perrotta
Jeroen
J
Nieuwland
Diego
D
Albani
M Beatrice
MB
Bitonti
Robert J
RJ
Herbert
John H
JH
Doonan
Angela M
AM
Marchbank
Ilario
I
Siciliano
Anne
A
Lentz Grønlund
Dennis
D
Francis
Hilary J
HJ
Rogers
D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002452:Cell Count; D002453:Cell Cycle / Q000235:genetics*; D048429:Cell Size; D018628:Gene Dosage; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D018546:Hypocotyl / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D007701:Kinetin / Q000494:pharmacology; D018519:Meristem / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D016254:Mutagenesis, Insertional; D009284:Naphthols / Q000494:pharmacology; D010641:Phenotype; D019441:Plant Epidermis / Q000166:cytology / Q000235:genetics / Q000254:growth & development; D010937:Plant Growth Regulators / Q000494:pharmacology; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D013997:Time Factors; D046509:Tissue Culture Techniques
D029681:Arabidopsis Proteins; D009284:Naphthols; D010937:Plant Growth Regulators; C005366:naphthyl acetate; D017346:Protein Serine-Threonine Kinases; C514674:WEE1 protein, Arabidopsis; D007701:Kinetin