杨树ANT基因调控维管发育的分子机制

While vascular stem cells self-renew, they differentiate and develop into xylem cells including xylem vessels and fibers to increase the biomass of trees, and ultimately affect the yield and quality of wood.Vascular stem cells have the ability to differentiate on both sides. They develop into xylem cells in the centripetal direction and develop into phloem in the opposite direction. In a single cross section of the stem, vascularstem cells are composed of solely one cell layer circle, and their propagation area before differentiation is called the vascular cambium. The xylem cells adjacent to the stem cells are organizers of stem cells. High concentrations of auxin accumulated in the organizer cells determine the stem cell fate on one side, and activate the xylem fate identity genes HD-ZIP III genes on the other side. The activity of vascular stem cells is regulated by a small signal peptide-receptor-WOX network that similar to that of root and shoot apex stem cells. ANT family genes are specifically expressed in the vascular cambium, and their specific expression pattern suggests that they may be involved in regulating the vascular cambium development. We constructed poplar ANT loss-of-function mutants, poplar ANT RNAi transgenic poplars, and ANT overexpressed transgenic poplar. Compared with the wild type, ant mutants and ANT-RNAi suppressed transgenic poplars were taller and had more xylem vessels in their stems, while ANT overexpressed poplars were shorter and had fewer xylem vessel cells and areas. Further molecular biological studies revealed that the inhibitory effect of ANT on xylem vessels may beachieved by directly regulating HD-ZIP III family genes. This study may provide a new target gene for wood breeding.