Abstract
Epidermal and most of mesophyll tissues in leaves are derived from clonally distinct layers of shoot apical meristem called L1 and L2, respectively. Cell proliferations in these tissues are non-cell-autonomously integrated, yet the mechanism is largely unknown. ANGUSTIFOLIA3 (AN3) acts as a positive regulator for cell proliferation in leaves. Cell proliferation is defective both in epidermal and mesophyll tissues in an3 while AN3 mRNA is detected in the mesophyll but hardly detectable in the epidermal tissue. These facts suggest that an inter-cell-layer communication for cell proliferation is mediated by AN3 or its downstream pathway.
Here, we constructed plants expressing AN3-GFP specifically in L1- or L2-layer under the control of PDF1 or CLV1 promoter in the an3-4 background, respectively. Then, we analyzed their leaf phenotypes. As a result, leaf size and shape were restored similar to wild type. Cell proliferation was also fully rescued in epidermal and mesophyll tissues. Interestingly, we observed GFP signal not only in mesophyll but also epidermal tissues of an3-4/pCLV1::AN3-GFP, indicating that inter-cell-layer coordination of cell proliferation is mediated by AN3 iteself.
