Characterization of cotton ARF factors and the role of GhARF2b in fiber development

Xiufang Zhang,Yugao Zhang,Zhiwen Chen,Chaochen Huang,Junfeng Cao,Zishou Zheng,Lingjian Wang,Xiaoxia Shangguan,Xia Liu

doi:10.1186/s12864-021-07504-6

Abstract

BackgroundCotton fiber is a model system for studying plant cell development. At present, the functions of many transcription factors in cotton fiber development have been elucidated, however, the roles of auxin response factor (ARF) genes in cotton fiber development need be further explored.ResultsHere, we identify auxin response factor (ARF) genes in three cotton species: the tetraploid upland cotton G. hirsutum, which has 73 ARF genes, and its putative extent parental diploids G. arboreum and G. raimondii, which have 36 and 35 ARFs, respectively. Ka and Ks analyses revealed that in G. hirsutum ARF genes have undergone asymmetric evolution in the two subgenomes. The cotton ARFs can be classified into four phylogenetic clades and are actively expressed in young tissues. We demonstrate that GhARF2b, a homolog of the Arabidopsis AtARF2, was preferentially expressed in developing ovules and fibers. Overexpression of GhARF2b by a fiber specific promoter inhibited fiber cell elongation but promoted initiation and, conversely, its downregulation by RNAi resulted in fewer but longer fiber. We show that GhARF2b directly interacts with GhHOX3 and represses the transcriptional activity of GhHOX3 on target genes.ConclusionOur results uncover an important role of the ARF factor in modulating cotton fiber development at the early stage.

Highlights

Cotton fiber is a model system for studying plant cell development
The 36 G. arboreum Auxin response factors (ARFs) genes were designated GaARF1–GaARF20, and the 73 G. hirsutum ARF genes in A- and D-subgenomes were designated as GhARF1A/D–GhARF21A/D (Table 1)
Phylogenetic analysis of Gossypium ARF proteins To illustrate the evolutionary relationships among the cotton ARFs, a phylogenetic tree was constructed using the protein sequences of 144 cotton ARFs, which were clustered into four clades (I–IV)

Summary

Introduction

The functions of many transcription factors in cotton fiber development have been elucidated, the roles of auxin response factor (ARF) genes in cotton fiber development need be further explored. Fiber development can be divided into four overlapping stages: The study of cotton fiber development regulation provides valuable knowledge to understanding plant cell growth and cell wall biosynthesis, and candidate genes for cotton molecular breeding [4]. Among recent progresses are the characterizations of transcription factors which regulate the major events of cotton fiber development, such as MYBs and HD-ZIP IVs involved in cotton fiber initiation and elongation, as well as a number of other types of factors. The picture of the regulation network of cotton fiber is far from complete

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Conclusion