Identification, characterization and functional analysis of AGAMOUS subfamily genes associated with floral organs and seed development in Marigold (Tagetes erecta)

Chunling Zhang,Wenjing Wang,Wenquan Qi,Yanhong He,Ludan Wei,Hang Li,Manzhu Bao,Zhe Cao

doi:10.1186/s12870-020-02644-5

Chunling Zhang, Wenjing Wang + Show 6 more

Open Access

https://doi.org/10.1186/s12870-020-02644-5

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Abstract

BackgroundAGAMOUS (AG) subfamily genes regulate the floral organs initiation and development, fruit and seed development. At present, there has been insufficient study of the function of AG subfamily genes in Asteraceae. Marigold (Tagetes erecta) belongs to Asteraceae family whose unique inflorescence structure makes it an important research target for understanding floral organ development in plants.ResultsFour AG subfamily genes of marigold were isolated and phylogenetically grouped into class C (TeAG1 and TeAG2) and class D (TeAGL11–1 and TeAGL11–2) genes. Expression profile analysis demonstrated that these four genes were highly expressed in reproductive organs of marigold. Subcellular localization analysis suggested that all these four proteins were located in the nucleus. Protein-protein interactions analysis indicated that class C proteins had a wider interaction manner than class D proteins. Function analysis of ectopic expression in Arabidopsis thaliana revealed that TeAG1 displayed a C function specifying the stamen identity and carpel identity, and that TeAGL11–1 exhibited a D function regulating seed development and petal development. In addition, overexpression of both TeAG1 and TeAGL11–1 leaded to curling rosette leaf and early flowering in Arabidopsis thaliana.ConclusionsThis study provides an insight into molecular mechanism of AG subfamily genes in Asteraceae species and technical support for improvement of several floral traits.

Highlights

AGAMOUS (AG) subfamily genes regulate the floral organs initiation and development, fruit and seed development
AGAMOUS subfamily genes To study the functions of AG subfamily genes in marigold, we amplified TeAG1 (991 bp), TeAG2 (837 bp), TeAGL11–1 (735 bp), and TeAGL11–2 (831 bp)
Previous studies demonstrated that AG subfamily genes originated from several paraphyletic lineages in flowering plants, most of which probably arose from multiple whole-genome duplication events (WGDs) in flowering plants during long-term evolutionary process [9,10,11,12]

Summary

Introduction

AGAMOUS (AG) subfamily genes regulate the floral organs initiation and development, fruit and seed development. Based on the genetic studies, a well-known ABCDE model is introduced to explain genetic regulation in floral organ determination. In this model, class A and E genes determine the sepals; class A, B, and E genes specify the petals; class B, C, and E genes regulate the stamens fate; class C and E genes control the carpel formation; and class D and E genes direct the ovule development [7, 8]. The AGAMOUS (AG) subfamily genes belonging to MADS-box classes C/D are involved in the regulation of floral organ, floral meristem, and fruit development. The AG lineage undergoes the second WGDs in core eudicots, resulting in two sub-clades of euAG and PLENA (PLE) [9, 10]

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