在经典植物模型拟南芥中对植物根发育所做的一项研究发现，一种微RNA（miRNA165/6）与细胞间的通信有关，并且是根细胞命运的一个决定因子。
将水和溶质从根向茎输送的木质部微管的模式形成，被发现取决于一个新颖的双向信号作用通道，该通道涉及一个转录因子在一个方向上、microRNA在另一个方向上的细胞到细胞间的运动。这个转录因子为SHORT ROOT，是在维管柱中产生的，它进入内皮中，在那里与SCARECROW一起激发微RNA MIR165a 和166b，后者又回到维管细胞中，降解它们的目标、编码“Class III homeodomain-leucine zipper”转录因子的信使RNA。
这个调控通道中由在演化上保守的转录因子和miRNA组成的一个级联的参与表明，它也许是对陆地生长条件的一种演化适应。 （生物谷Bioon.com）
生物谷推荐原文出处：
Nature doi:10.1038/nature08977
Cell signalling by microRNA165/6 directs gene dose-dependent root cell fate
Annelie Carlsbecker1,2,8, Ji-Young Lee3,4,8, Christina J. Roberts2, Jan Dettmer1, Satu Lehesranta1, Jing Zhou3,4, Ove Lindgren1,5, Miguel A. Moreno-Risueno6, Anne Vatén1, Siripong Thitamadee1, Ana Campilho1, Jose Sebastian3, John L. Bowman7, Yk? Helariutta1,8 & Philip N. Benfey6,8
Institute of Biotechnology/Department of Biosciences, University of Helsinki, FIN-00014, Finland
Department of Physiological Botany, Evolutionary Biology Center, Uppsala University, Norbyv?gen 18D, SE-752 36 Uppsala, Sweden
Boyce Thompson Institute for Plant Research, Tower Road, Ithaca, New York 14853, USA
Graduate Field of Plant Biology, Cornell University, Ithaca, New York 14853, USA
Institute of Technology, University of Tartu, Tartu 50411, Estonia
Biology Department and IGSP Center for Systems Biology, Duke University, Durham, North Carolina 27708, USA
School of Biological Sciences, Monash
A key question in developmental biology is how cells exchange positional information for proper patterning during organ development. In plant roots the radial tissue organization is highly conserved with a central vascular cylinder in which two water conducting cell types, protoxylem and metaxylem, are patterned centripetally. We show that this patterning occurs through crosstalk between the vascular cylinder and the surrounding endodermis mediated by cell-to-cell movement of a transcription factor in one direction and microRNAs in the other. SHORT ROOT, produced in the vascular cylinder, moves into the endodermis to activate SCARECROW. Together these transcription factors activate MIR165a and MIR166b. Endodermally produced microRNA165/6 then acts to degrade its target mRNAs encoding class III homeodomain-leucine zipper transcription factors in the endodermis and stele periphery. The resulting differential distribution of target mRNA in the vascular cylinder determines xylem cell types in a dosage-dependent manner.
