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Hereditas(Beijing) ›› 2018, Vol. 40 ›› Issue (4): 327-338.doi: 10.16288/j.yczz.17-315

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MYB-like transcription factor SiMYB42 from foxtail millet (Setaria italica L.) enhances Arabidopsis tolerance to low-nitrogen stress

Qingqian Ding1,Xiaoting Wang1,2,Liqin Hu1,Xin Qi1,Linhao Ge1,Weiya XU1,Zhaoshi Xu1,Yongbin Zhou1,2,Guanqing Jia1,Xianmin Diao1,Donghong Min2,Youzhi Ma1,Ming Chen1()   

  1. 1. National Key Facility For Crop Gene Resource and Genetic Improvement, Key Laboratory of Biology and Genetic Improvement of Triticeae Crop, Ministry of Agriculture, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China
    2. State Key Laboratory of Arid Region Crop Adversity Biology, College of Agronomy, Northwest A＆F University, Yangling 712100, China
  • Received:2017-09-25 Revised:2018-01-02 Online:2018-04-20 Published:2018-03-12
  • Contact: Chen Ming E-mail:chenming02@caas.cn
  • Supported by:
    Supported by the National Majar Project for Developing New GM Crops(2016ZX08002005);the Innovation Project of Chinese Academy of Agricultural Sciences

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Abstract:

Myeloblastosis (MYB) transcription factors are one of the largest families of transcription factors in higher plants. They play an important role in plant development, defense response processes, and non-biological stresses, i.e., drought stress. Foxtail millet (Setaria italica L.), originated in China, is resistant to drought and low nutrition stresses and has been regarded as an ideal material for studying abiotic stress resistance in monocotyledon. In this study, we ran a transcription profile analysis of zheng 204 under low-nitrogen conditions and identified a MYB-like transcription factor SiMYB42, which was up-regulated under low-nitrogen stress. Phylogenetic tree analysis showed that SiMYB42 belongs to R2R3-MYB subfamily and has two MYB conserved domains. Expression pattern analysis showed that SiMYB42 was significantly up-regulated under various stress conditions, including low-nitrogen stress, high salt, drought and ABA conditions. The results of subcellular localization, quantitative real-time PCR and transcriptional activation analysis indicated that SiMYB42 protein localizes to the nucleus and cell membrane of plant cells, mainly expressed in the leaf or root of foxtail millet, and has transcription activation activity. Functional analysis showed that there was no significant difference between transgenic SiMYB42 Arabidopsis and wild-type (WT) Arabidopsis under normal conditions; however, under low-nitrogen condition, the root length, surface area and seedling fresh weight in transgenic SiMYB42 Arabidopsis, were significantly higher than their counterparts in WT. These results suggest that SiMYB42 transgenic plants exhibit higher tolerance to low-nitrogen stress. Expression levels of nitrate transporters genes NRT2.1, NRT2.4 and NRT2.5, which are the transcriptional targets of SiMYB42, were higher in transgenic SiMYB42 Arabidopsis plants than those in WT; the promoter regions of NRT2.1, NRT2.4 and NRT2.5 all have MYB binding sites. These results indicate that SiMYB42 might enhance foxtail millet tolerance to low-nitrogen condition through regulating the expression of nitrate transporter genes. This study reveals the possible functions of SiMYB42 in a low-nitrogen stress response pathway, and provides a foundation for further understanding the entire regulation network of foxtail millet in response to low-nitrogen stress.

Key words: foxtail millet (Setaria italica L.), MYB-like transcription factor, low-nitrogen stress, gene expression analysis, gene function analysis