Influence of Switchgrass TDIF-like Genes on Arabidopsis Vascular Development.

Dongdong Tian,Xueping Shi,Robert M Larkin,Zhe Zhang,Kebing Du,Jingwen Tang,Bo Zheng,Liwen Luo

doi:10.3389/fpls.2021.737219

Abstract

As a member of the CLAVATA3 (CLV3)/EMBRYO SURROUNDING REGION (CLE) family, the dodecapeptide tracheary element differentiation inhibitory factor (TDIF) has a major impact on vascular development in plants. However, the influence of polymorphisms in the TDIF peptide motif on activity remains poorly understood. The model plant, Arabidopsis provides a fast and effective tool for assaying the activity of TDIF homologs. Five TDIF homologs from a group of 93 CLE genes in switchgrass (Panicum virgatum), a perennial biomass crop, named PvTDIF-like (PvTDIFL) genes were studied. The expression levels of PvTDIFL1, PvTDIFL3MR3, and PvTDIFL3MR2 were relatively high and all of them were expressed at the highest levels in the rachis of switchgrass. The precursor proteins for PvTDIFL1, PvTDIFL3MR3, and PvTDIFL3MR2 contained one, three, and two TDIFL motifs, respectively. Treatments with exogenous PvTDIFL peptides increased the number of stele cells in the hypocotyls of Arabidopsis seedlings, with the exception of PvTDIFL_4p. Heterologous expression of PvTDIFL1 in Arabidopsis strongly inhibited plant growth, increased cell division in the vascular tissue of the hypocotyl, and disrupted the cellular organization of the hypocotyl. Although heterologous expression of PvTDIFL3MR3 and PvTDIFL3MR2 also affected plant growth and vascular development, PvTDIFL activity was not enhanced by the multiple TDIFL motifs encoded by PvTDIFL3MR3 and PvTDIFL3MR2. These data indicate that in general, PvTDIFLs are functionally similar to Arabidopsis TDIF but that the processing and activities of the PvTDIFL peptides are more complex.

Highlights

In plants, the CLAVATA3 (CLV3)/EMBRYO SURROUNDING REGION (CLE) gene family plays a vital role in cell division and cell differentiation by mediating intercellular communication (Fletcher et al, 1999; Fiers et al, 2005, 2007)
The five genes that were most similar to Arabidopsis tracheary element differentiation inhibitory factor (TDIF) were named PvTDIFL1, PvTDIFL2, PvTDIFL3MR3, PvTDIFL3MR2, and PvTDIFL4
Expression analysis showed that PvTDIFL genes were highly expressed in the rachis, which is rich in vascular tissue

Summary

Introduction

The CLAVATA3 (CLV3)/EMBRYO SURROUNDING REGION (CLE) gene family plays a vital role in cell division and cell differentiation by mediating intercellular communication (Fletcher et al, 1999; Fiers et al, 2005, 2007). In A. thaliana, at least 32 CLE genes have been identified (Ito et al, 2006; Kondo et al, 2006; Ohyama et al, 2009; Ogawa-Ohnishi et al, 2013). Based on their biological functions, the Arabidopsis CLE peptides were grouped into two major classes. The B-type/H-type CLE peptides, on the other hand, suppress xylem differentiation and promote vascular procambial cell division and include CLE41, CLE42, and CLE44 (Schoof et al, 2000; Ito et al, 2006; Whitford et al, 2008; Stahl et al, 2009; Hirakawa et al, 2010a,b)

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