Abstract
Two phototropins, PHOT1 and PHOT2, function as blue light photoreceptors. Here, we investigate the effect of phototropins on the leaf photomorphogenesis. The downward curling in the photo1phot2 leaves has been already reported. Hence, we measured the size of epidermal cells in the phot1phot2 mutant and found that the size decreased in the abaxial side, while it was normal in the adaxial side. Hence, the downward curling in the photo1phot2 leaves can be explained by asymmetrical growth of the epidermal cells. We also found that the phot1phot2 mutant showed elongation defect in palisade cells, suggesting that phototropin regulates the polar cell elongation in the palisade tissues. We then asked in which tissue of the leaves PHOT2 regulates the leaf flatness and the palisade cell elongation. One the basis of present results, roles of PHOT2 in different tissues to control the leaf morphogenesis will be discussed.
