Over-expression of the cell cycle checkpoint gene, WEE1, may repress growth and development. Spadafora et al. culture explants of Arabidopsis thaliana from an over-expressing Arath;WEE1 line (WEE1oe), two T-DNA insertion lines (wee1-1 and wee1-4) and wild type (WT) on two-way combinations of kinetin and naphthyl acetic acid and examine root growth and meristematic cell size. They find indications of a repressive effectin WEE1oe and a significant increase in morphogenetic capacity in the two T-DNA insertion lines compared with WT. Relative to WT, WEE1oe seedlings exhibit a slower cell-doubling time in the root apical meristem and a shortened primary root, with fewer laterals; however, significantly fewer adventitious roots are recorded for WEE1oe and significantly more for the insertion mutant wee1-1. They conclude that there is a gene-dosage effect of WEE1 on morphogenesis from hypocotyls both in vitro and in vivo.
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