Genome-wide identification of the soybean cytokinin oxidase/dehydrogenase gene family and its diverse roles in response to multiple abiotic stress

Yanli Du; Zhaoning Zhang; Yanhua Gu; Weijia Li; Weiyu Wang; Xiankai Yuan; Yuxian Zhang; Ming Yuan; Jidao Du; Qiang Zhao

doi:10.3389/fpls.2023.1163219

Genome-wide identification of the soybean cytokinin oxidase/dehydrogenase gene family and its diverse roles in response to multiple abiotic stress

Front Plant Sci. 2023 Apr 17:14:1163219. doi: 10.3389/fpls.2023.1163219. eCollection 2023.

Authors

Yanli Du^{1

2}, Zhaoning Zhang¹, Yanhua Gu¹, Weijia Li¹, Weiyu Wang¹, Xiankai Yuan¹, Yuxian Zhang^{2

3}, Ming Yuan⁴, Jidao Du^{1

2

5}, Qiang Zhao^{3

5}

Affiliations

¹ Agricultural College, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang, China.
² National Cereals Technology Engineering Research Center, Daqing, Heilongjiang, China.
³ Heilongjiang Bayi Agricultural University, Key Laboratory of Ministry of Agriculture and Rural Affairs of Soybean Mechanized Production, Daqing, Heilongjiang, China.
⁴ Qiqihar Branch of Heilongjiang Academy of Agricultural Sciences, Qiqihar, Heilongjiang, China.
⁵ Research Center of Saline and Alkali Land Improvement Engineering Technology in Heilongjiang Province, Daqing, Heilongjiang, China.

Abstract

Cytokinin oxidase/dehydrogenase (CKX) irreversibly degrades cytokinin, regulates growth and development, and helps plants to respond to environmental stress. Although the CKX gene has been well characterized in various plants, its role in soybean remains elusive. Therefore, in this study, the evolutionary relationship, chromosomal location, gene structure, motifs, cis-regulatory elements, collinearity, and gene expression patterns of GmCKXs were analyzed using RNA-seq, quantitative real-time PCR (qRT-PCR), and bioinformatics. We identified 18 GmCKX genes from the soybean genome and grouped them into five clades, each comprising members with similar gene structures and motifs. Cis-acting elements involved in hormones, resistance, and physiological metabolism were detected in the promoter regions of GmCKXs. Synteny analysis indicated that segmental duplication events contributed to the expansion of the soybean CKX family. The expression profiling of the GmCKXs genes using qRT-PCR showed tissue-specific expression patterns. The RNA-seq analysis also indicated that GmCKXs play an important role in response to salt and drought stresses at the seedling stage. The responses of the genes to salt, drought, synthetic cytokinin 6-benzyl aminopurine (6-BA), and the auxin indole-3-acetic acid (IAA) at the germination stage were further evaluated by qRT-PCR. Specifically, the GmCKX14 gene was downregulated in the roots and the radicles at the germination stage. The hormones 6-BA and IAA repressed the expression levels of GmCKX1, GmCKX6, and GmCKX9 genes but upregulated the expression levels of GmCKX10 and GmCKX18 genes. The three abiotic stresses also decreased the zeatin content in soybean radicle but enhanced the activity of the CKX enzymes. Conversely, the 6-BA and IAA treatments enhanced the CKX enzymes' activity but reduced the zeatin content in the radicles. This study, therefore, provides a reference for the functional analysis of GmCKXs in soybean in response to abiotic stresses.

Keywords: CKX gene family; abiotic stress; expression analysis; growth and development; soybean.

Grants and funding

This work was supported by the National Key Research and Development Program (2021YFD1201603-3), the Heilongjiang Bayi Agricultural University Support Program for San Zong (ZRCQC202102 and ZRCQC202201), the Talent Introduction Project of Heilongjiang Bayi Agricultural University (XYB202006), the Postdoctoral General Project of Heilongjiang Province (LBH-Z21196), and the Innovative Research Project for Graduate Students of Heilongjiang Bayi Agricultural Reclamation University (YJSCX2022-Y01).