Confocal image showing PIN1-GFP expression in the apical meristem cells of a tomato plant shoot. SAIKO YOSHIDA
S. Yoshida et al., “Stem cell activation by light guides plant organogenesis,” Genes Dev, 25:1439-50, 2011. Free 1000 Evaluation
For 150 years it was assumed that an unknown internal stimulus drove leaf genesis. But Saiko Yoshida and colleagues in the lab of Cris Kuhlemeier at the University of Bern have now determined that even though the location where new leaf development occurs—stem cells at the tip of a plant shoot—is shrouded by a dense covering of leaves, enough light can penetrate to activate growth hormones.
The authors looked at two hormones—cytokinin and auxin—known to react to environmental stimuli. Cytokinin promotes cell division, while auxin is responsible for leaf formation.
When researchers grew tomato plants in the dark, new leaf production ceased even when sugar was ...
