Functional characterization of Lilium lancifolium cold-responsive Zinc Finger Homeodomain (ZFHD) gene in abscisic acid and osmotic stress tolerance

Yubing Yong; Yue Zhang; Yingmin Lyu

doi:10.7717/peerj.11508

Functional characterization of Lilium lancifolium cold-responsive Zinc Finger Homeodomain (ZFHD) gene in abscisic acid and osmotic stress tolerance

PeerJ. 2021 May 25:9:e11508. doi: 10.7717/peerj.11508. eCollection 2021.

Authors

Yubing Yong^{1

2}, Yue Zhang¹, Yingmin Lyu¹

Affiliations

¹ Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, China National Engineering Research Center for Floriculture, Beijing Laboratory of Urban and Rural Ecological Environment, College of Landscape Architecture, Beijing Forestory University, Beijing, Haidian, China.
² College of Landscape Architecture, Central South University of Forestry and Technology, Changsha, Hunan, China.

Abstract

Background: We have previously performed an analysis of the cold-responsive transcriptome in the mature leaves of tiger lily (Lilium lancifolium) by gene co-expression network identification. The results has revealed that a ZFHD gene, notated as encoding zinc finger homeodomain protein, may play an essential regulating role in tiger lily response to cold stress.

Methods: A further investigation of the ZFHD gene (termed as LlZFHD4) responding to osmotic stresses, including cold, salt, water stresses, and abscisic acid (ABA) was performed in this study. Based on the transcriptome sequences, the coding region and 5' promoter region of LlZFHD4 were cloned from mature tiger lily leaves. Stress response analysis was performed under continuous 4 °C, NaCl, PEG, and ABA treatments. Functional characterization of LlZFHD4 was conducted in transgenic Arabidopsis, tobacco, and yeast.

Results: LlZFHD4 encodes a nuclear-localized protein consisting of 180 amino acids. The N-terminal region of LlZFHD4 has transcriptional activation activity in yeast. The 4 °C, NaCl, PEG, and ABA treatments induced the expression of LlZFHD4. Several stress- or hormone-responsive cis-acting regulatory elements (T-Box, BoxI. and ARF) and binding sites of transcription factors (MYC, DRE and W-box) were found in the core promoter region (789 bp) of LlZFHD4. Also, the GUS gene driven by LlZFHD4 promoter was up-regulated by cold, NaCl, water stresses, and ABA in Arabidopsis. Overexpression of LlZFHD4 improved cold and drought tolerance in transgenic Arabidopsis; higher survival rate and better osmotic adjustment capacity were observed in LlZFHD4 transgenic plants compared to wild type (WT) plants under 4 °C and PEG conditions. However, LlZFHD4 transgenic plants were less tolerant to salinity and more hypersensitive to ABA compared to WT plants. The transcript levels of stress- and ABA-responsive genes were much more up-regulated in LlZFHD4 transgenic Arabidopsis than WT. These results indicate LlZFHD4 is involved in ABA signaling pathway and plays a crucial role in regulating the response of tiger lily to cold, salt and water stresses.

Keywords: Abscisic acid (ABA); Lily; Osmotic stress; Zinc finger homeodomain (ZFHD) protein.

Grants and funding

This research was supported by China National Key Research & Development Project (grant no. 2019YFD1000400) and China National Natural Science Foundation (grant nos. 31672190, 31872138, 31071815, 31272204). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.