Cell fate specification in Arabidopsis roots requires coordinative action of lineage

Cell fate specification in Arabidopsis roots requires coordinative action of lineage 1 instruction and positional reprogramming 2 3 Qiaozhi Yu, Pengxue Li, Nengsong Liang, Hong Wang, Meizhi Xu, Shuang Wu 4 1. College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China 5 2. Haixia Institute of Science and Technology, Horticultural Plant Biology and Metabolomics 6 Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China 7 3. Corresponding Authors: [email protected] 8 9 Abstract 10 Tissue organization and pattern formation within a multicellular organism relies on 11 coordinated cell division and cell fate determination. In animals cell fates are mainly 12 determined by a cell lineage dependent mechanism, whereas in plants positional 13 information is thought to be the primary determinant of cell fates (Scheres, 2001; 14 Kidner et al., 2000; Kim et al., 2005; Scheres et al., 2002). However, our 15 understanding of cell fate regulation in plants mostly relies on the histological and 16 anatomical studies on Arabidopsis roots which contain a single layer of each cell type 17 in non-vascular tissues (Scheres et al., 1994; Dolan et al., 1993; Rost, 2011). Here we 18 investigate the dynamic cell fate acquisition in modified Arabidopsis roots with 19 additional cell layers which are artificially generated by the mis-expression of 20 SHORT-ROOT (SHR). We found that cell fate determination in Arabidopsis roots is a 21 dimorphic cascade with lineage inheritance dominant in the early stage of pattern 22 formation. The inherited cell identity can subsequently be removed or modified by 23 positional information. The instruction of cell fate conversion is not a fast read-out 24 during root development. The final identity of a cell type is determined by the 25 synergistic contribution from multiple layers of regulation, including symplastic 26 communication across tissues. Our findings underline the collaborative inputs during 27 cell fate instruction. 28 29