Genome-Wide Identification of WRKY Transcription Factors in Chinese jujube (Ziziphus jujuba Mill.) and Their Involvement in Fruit Developing, Ripening, and Abiotic Stress.

Xin Chen,Ruihong Chen,Yanfeng Wang,Jian Huang,Cuiyun Wu

doi:10.3390/genes10050360

Abstract

Chinese jujube (Ziziphus jujuba Mill.) is an economically important fruit crop in China and mainly cultivated on land with high salinity and drought conditions in northern China. WRKY transcription factors (TFs) are involved in plant development and in responses to multiple abiotic stresses. In this study, we identified 61 and 52 putative ZjWRKY TFs in ‘Junzao’ and ‘Dongzao’ at the genome-wide level. Tissue expression profiling showed that 7 genes were constitutively expressed at high level in all tissues of ‘Junzao’. Transcriptome analysis revealed that 39 ZjWRKY genes were expressed during ‘Junzao’ jujube fruit ripening. Among these genes, the transcript abundance of 19 genes were differentially expressed between ‘Junzao’ and ‘Qingjiansuanzao’ fruit. In addition, RT-qPCR analyses revealed that 30, 14, and 18 ZjWRKY genes responded to drought, NaCl, and ABA treatments, respectively. Taken together, ZjWRKY genes expression dynamics during jujube fruit development, ripening, and their differences between jujube and wild jujube would provide insights into their possible roles regulating fruit ripening. In addition, those ZjWRKY genes responded strongly to drought and salt stress, which provide candidate ZjWRKY genes for facilitating tolerance breeding.

Highlights

Chinese jujube (Ziziphus jujuba Mill.) is a dominant fruit crops in China that is mainly cultivated in the middle and lower reaches of the Yellow River, a semi-arid region
We identified and compared 61 and 52 ZjWRKY transcription factors (TFs) from two famous jujube cultivars, i.e., ‘Junzao’ and ‘Dongzao’, respectively
Transcriptome analysis showed that 39 ZjWRKY genes expressed during ‘Junzao’ fruit ripening, among which 19 ZjWRKY genes were differentially expressed between ‘Junzao’ and ‘Qingjiansuanzao’, indicating their possible roles regulating sugar accumulation and acid metabolism

Summary

Introduction

Chinese jujube (Ziziphus jujuba Mill.) is a dominant fruit crops in China that is mainly cultivated in the middle and lower reaches of the Yellow River, a semi-arid region. 21st century, the center of jujube cultivation has shifted to arid regions in Northwest China, especially the Xinjiang Autonomous Region [1]. In this region, the jujube cultivation area covered 473,000 ha, accounting for 30% of the total jujube cultivation area in China in 2013, and the corresponding yield was. 2.22 million tons, accounting for 51% of the total production of dried jujube in China [2].

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