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Gene dosage effect of WEE1 on growth and morphogenesis from arabidopsis hypocotyl explants

Spadafora, Natasha, Perrotta, Lara, Nieuwland, Jeroen, Albani, Diego, Bitonti, M. Beatrice, Herbert, Robert J., Doonan, John H., Marchbank, Angela M., Siciliano, Ilario, Lentz Grønlund, Anne, Francis, Dennis, Rogers, Hilary J.
Annals of botany 2012 v.110 no.8 pp. 1631-1639
acetic acid, adventitious roots, apical meristems, cell cycle, dose response, explants, gene dosage, gene overexpression, genes, hypocotyls, kinetin, morphogenesis, mutants, root growth, seedlings, transfer DNA
Background and Aims 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. Key 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 .