Arabidopsis T-DNA insertional lines for CDC25 are hypersensitive to hydroxyurea but not to zeocin or salt stress.
OBJECTIVE
In yeasts and animals, cyclin-dependent kinases are key regulators of cell cycle progression and are negatively and positively regulated by WEE1 kinase and CDC25 phosphatase, respectively. In higher plants a full-length orthologue of CDC25 has not been isolated but a shorter gene with homology only to the C-terminal catalytic domain is present. The Arabidopis thaliana;CDC25 can act as a phosphatase in vitro. Since in arabidopsis, WEE1 plays an important role in the DNA damage/DNA replication checkpoints, the role of Arath;CDC25 in conditions that induce these checkpoints or induce abiotic stress was tested. Methods arath;cdc25 T-DNA insertion lines, Arath;CDC25 over-expressing lines and wild type were challenged with hydroxyurea (HU) and zeocin, substances that stall DNA replication and damage DNA, respectively, together with an abiotic stressor, NaCl. A molecular and phenotypic assessment was made of all genotypes Key


RESULTS
There was a null phenotypic response to perturbation of Arath;CDC25 expression under control conditions. However, compared with wild type, the arath;cdc25 T-DNA insertion lines were hypersensitive to HU, whereas the Arath;CDC25 over-expressing lines were relatively insensitive. In particular, the over-expressing lines consistently outgrew the T-DNA insertion lines and wild type when challenged with HU. All genotypes were equally sensitive to zeocin and NaCl.


CONCLUSIONS
Arath;CDC25 plays a role in overcoming stress imposed by HU, an agent know to induce the DNA replication checkpoint in arabidopsis. However, it could not enhance tolerance to either a zeocin treatment, known to induce DNA damage, or salinity stress.
Spadafora
Natasha D
ND
School of Biosciences, Cardiff University, Main College, Cardiff, UK.
Doonan
John H
JH
Herbert
Robert J
RJ
Bitonti
M Beatrice
MB
Wallace
Emily
E
Rogers
Hilary J
HJ
Francis
Dennis
D
D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001761:Bleomycin / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000235:genetics*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005838:Genotype; D006918:Hydroxyurea / Q000494:pharmacology*; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D016254:Mutagenesis, Insertional / Q000187:drug effects / Q000235:genetics*; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological / Q000187:drug effects; D020687:cdc25 Phosphatases / Q000235:genetics / Q000378:metabolism*
D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D009097:Multienzyme Complexes; D012333:RNA, Messenger; C036483:T-DNA; D001761:Bleomycin; C105427:Zeocin; D012965:Sodium Chloride; D010088:Oxidoreductases; C510678:arsenate reductase 2, Arabidopsis; D020687:cdc25 Phosphatases; D006918:Hydroxyurea