Identification and functional characterization of the AGO1 ortholog in maize.

Dongdong Xu,Yunbi Xu,Wen‐Xue Li,Chuanxiao Xie,Hailong Yang,Cheng Zou

doi:10.1111/jipb.12467

Dongdong Xu, Yunbi Xu + Show 4 more

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https://doi.org/10.1111/jipb.12467

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Abstract

Eukaryotic Argonaute proteins play primary roles in miRNA and siRNA pathways that are essential for numerous developmental and biological processes. However, the functional roles of the four ZmAGO1 genes have not yet been characterized in maize (Zea mays L.). In the present study, ZmAGO1a was identified from four putative ZmAGO1 genes for further characterization. Complementation of the Arabidopsis ago1‐27 mutant with ZmAGO1a indicated that constitutive overexpression of ZmAGO1a could restore the smaller rosette, serrated leaves, later flowering and maturation, lower seed set, and darker green leaves at late stages of the mutant to the wild‐type phenotype. The expression profiles of ZmAGO1a under five different abiotic stresses indicated that ZmAGO1a shares expression patterns similar to those of Argonaute genes in rice, Arabidopsis, and wheat. Further, variation in ZmAGO1a alleles among diverse maize germplasm that resulted in several amino acid changes revealed genetic diversity at this locus. The present data suggest that ZmAGO1a might be an important AGO1 ortholog in maize. The results presented provide further insight into the function of ZmAGO1a.

Highlights

Argonaute (AGO) proteins are key mediators of all small-RNAguided gene-silencing processes involving % 21–26 nt short RNAs that are cleaved from double-stranded or partially double-stranded RNAs by the RNase III enzyme Dicer (Baulcombe 2004; Meister 2013)
These include the AGO proteins that bind to miRNAs and siRNAs, the PIWI proteins that bind to piRNAs, and the proteins that bind to secondary siRNAs that have only been described in C. elegans (Yigit et al 2006)
Based on the existing functional annotations, four OsAGO1 genes from rice, one AtAGO1 gene from Arabidopsis, and one TaAGO1 gene from wheat were chosen for analysis of their phylogenetic relationships with the four predicted putative ZmAGO1 genes

Summary

Introduction

Argonaute (AGO) proteins are key mediators of all small-RNAguided gene-silencing processes involving % 21–26 nt short RNAs (sRNAs) that are cleaved from double-stranded or partially double-stranded RNAs by the RNase III enzyme Dicer (Baulcombe 2004; Meister 2013). As key components of the RNA-induced silencing complex (RISC), Argonaute proteins guide sRNAs to specific targets through sequence complementarity, leading to cleavage of target mRNA sequences, translational repression, or chromatin modification (Baumberger and Baulcombe 2005). Through their crucial roles in the regulation of eukaryotic gene expression, AGO proteins broadly participate in numerous biological processes, including developmental timing, cell differentiation, cell proliferation, cell death, metabolic control, immunity, transposon silencing, alternative splicing, and DNA repair, among other processes (Wei et al 2012). As for crop plants, a total of 19 Argonaute genes in rice (Oryza sativa) and 15 in tomato (Solanum lycopersicum) have been

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