Transcriptome-wide and expression analysis of the NAC gene family in pepino (Solanum muricatum) during drought stress

Shipeng Yang; Haodong Zhu; Liping Huang; Guangnan Zhang; Lihui Wang; Xiaoting Jiang; Qiwen Zhong

doi:10.7717/peerj.10966

Transcriptome-wide and expression analysis of the NAC gene family in pepino (Solanum muricatum) during drought stress

PeerJ. 2021 Mar 29:9:e10966. doi: 10.7717/peerj.10966. eCollection 2021.

Authors

Shipeng Yang^#¹, Haodong Zhu^#², Liping Huang¹, Guangnan Zhang¹, Lihui Wang¹, Xiaoting Jiang³, Qiwen Zhong¹

Affiliations

¹ Qinghai Key Laboratory of Vegetable Genetics and Physiology, Agriculture and Forestry Sciences Institute of Qinghai University, Qinghai University, Xining, P.R. China.
² Qinghai University, Xining, P.R. China.
³ Qinghai Higher Vocational & Technical Institute, Ledu, P.R. China, Xining, China.

^# Contributed equally.

Abstract

Solanum muricatum (Pepino) is an increasingly popular solanaceous crop and is tolerant of drought conditions. In this study, 71 NAC transcription factor family genes of S. muricatum were selected to provide a theoretical basis for subsequent in-depth study of their regulatory roles in the response to biological and abiotic stresses, and were subjected to whole-genome analysis. The NAC sequences obtained by transcriptome sequencing were subjected to bioinformatics prediction and analysis. Three concentration gradient drought stresses were applied to the plants, and the target gene sequences were analyzed by qPCR to determine their expression under drought stress. The results showed that the S. muricatum NAC family contains 71 genes, 47 of which have conserved domains. The protein sequence length, molecular weight, hydrophilicity, aliphatic index and isoelectric point of these transcription factors were predicted and analyzed. Phylogenetic analysis showed that the S. muricatum NAC gene family is divided into seven subfamilies. Some NAC genes of S. muricatum are closely related to the NAC genes of Solanaceae crops such as tomato, pepper and potato. The seedlings of S. muricatum were grown under different gradients of drought stress conditions and qPCR was used to analyze the NAC expression in roots, stems, leaves and flowers. The results showed that 13 genes did not respond to drought stress while 58 NAC genes of S. muricatum that responded to drought stress had obvious tissue expression specificity. The overall expression levels in the root were found to be high. The number of genes at extremely significant expression levels was very large, with significant polarization. Seven NAC genes with significant responses were selected to analyze their expression trend in the different drought stress gradients. It was found that genes with the same expression trend also had the same or part of the same conserved domain. Seven SmNACs that may play an important role in drought stress were selected for NAC amino acid sequence alignment of Solanaceae crops. Four had strong similarity to other Solanaceae NAC amino acid sequences, and SmNAC has high homology with the Solanum pennellii. The NAC transcription factor family genes of S. muricatum showed strong structural conservation. Under drought stress, the expression of NAC transcription factor family genes of S. muricatum changed significantly, which actively responded to and participated in the regulation process of drought stress, thereby laying foundations for subsequent in-depth research of the specific functions of NAC transcription factor family genes of S. muricatum.

Keywords: Drought stress; Gene expression; Gene regulation; NAC; Solanum muricatum.

Grants and funding

This research was supported by the Association of Qinghai Science and Technology (2019QHSKXRCTJ06), the Key Laboratory Project of Qinghai Science & Technology Department (2020-ZJ-Y02), and the Qinghai Agriculture and Forestry Science Innovation Fund (2020-NKY-02). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.