AUTHOR=Song Min , Zhang Yanfeng , Jia Qingli , Huang Shuhua , An Ran , Chen Nana , Zhu Yantao , Mu Jianxin , Hu Shengwu 

TITLE=Systematic analysis of MADS-box gene family in the U’s triangle species and targeted mutagenesis of BnaAG homologs to explore its role in floral organ identity in Brassica napus

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2023

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1115513

DOI=10.3389/fpls.2022.1115513

ISSN=1664-462X

ABSTRACT=<p>MADS-box transcription factors play an important role in regulating floral organ development and participate in environmental responses. To date, the MADS-box gene family has been widely identified in <italic>Brassica rapa</italic> (<italic>B. rapa</italic>), <italic>Brassica oleracea</italic> (<italic>B. oleracea</italic>), and <italic>Brassica napus</italic> (<italic>B. napus</italic>); however, there are no analogous reports in <italic>Brassica nigra</italic> (<italic>B. nigra</italic>), <italic>Brassica juncea</italic> (<italic>B. juncea</italic>), and <italic>Brassica carinata</italic> (<italic>B. carinata</italic>). In this study, a whole-genome survey of the MADS-box gene family was performed for the first time in the triangle of U species, and a total of 1430 MADS-box genes were identified. Based on the phylogenetic relationship and classification of MADS-box genes in <italic>Arabidopsis thaliana</italic> (<italic>A. thaliana</italic>), 1430 MADS-box genes were categorized as M-type subfamily (627 genes), further divided into Mα, Mβ, Mγ, and Mδ subclades, and MIKC-type subfamily (803 genes), further classified into 35 subclades. Gene structure and conserved protein motifs of MIKC-type MADS-box exhibit diversity and specificity among different subclades. Comparative analysis of gene duplication events and syngenic gene pairs among different species indicated that polyploidy is beneficial for MIKC-type gene expansion. Analysis of transcriptome data within diverse tissues and stresses in <italic>B. napus</italic> showed tissue-specific expression of MIKC-type genes and a broad response to various abiotic stresses, particularly dehydration stress. In addition, four representative floral organ mutants (<italic>wtl</italic>, <italic>feml</italic>, <italic>aglf-2</italic>, and <italic>aglf-1</italic>) in the T0 generation were generated by editing four AGAMOUS (<italic>BnaAG</italic>) homoeologs in <italic>B. napus</italic> that enriched the floral organ variant phenotype. In brief, this study provides useful information for investigating the function of MADS-box genes and contributes to revealing the regulatory mechanisms of floral organ development in the genetic improvement of new varieties.</p>