讲座简介
Vascular plants have a long-distance transport system consisting of two tissue types, phloem and xylem. The cell lineages of the root vascular cylinder harboring phloem and xylem and the intervening procambial tissue originate from stem cells near the root tip. We and others have taken a combination of genetic and genomic approaches to understand how the specification of vascular cell lineages is determined at a molecular level. We have recently demonstrated that in Arabidopsis, cytokinin phytohormones negatively regulate protoxylem specification, a “default” identity. AHP6, an inhibitory pseudophosphotransfer protein, counteracts cytokinin signaling in a spatially specific manner, allowing protoxylem formation in this domain. On the other hand, APL, a MYB coiled-coil-type transcription factor has a dual role in promoting phloem differentiation and in repressing protoxylem differentiation. Recent progress in understanding the molecular control of vascular tissue specification by cytokinins and APL together with other regulatory pathways will be presented.
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