JIA-2018-09

Journal of Integrative Agriculture 2018, 17(9): 2007–2014 RESEARCH ARTICLE Available online at www.sciencedirect.com ScienceDirect Isolation and characterization of the secondary wall-related SND1 gene in hawthorn CHEN Ke-qin 1 , GUO Yun-na 2 , SONG Meng-ru 2 , DAI Hong-yan 2 , ZHANG Zhi-hong 1 1 Group of Molecular Biology of Fruit Trees, College of Horticulture, Shenyang Agricultural University, Shenyang 110866, P.R.China 2 Group of Fruit Germplasm Evaluation & Utilization, College of Horticulture, Shenyang Agricultural University, Shenyang 110866, P.R.China Abstract Secondary wall-associated NAC domain protein1 (SND1) is a key regulator directly regulating the expression levels of MYB46 and MYB83 in the regulation network for secondary wall synthesis, especially in plant fibres. In this study, a SND1 gene was isolated from hawthorn ( Crataegus pinnatifida ) and named as CpSND1 because it has a conservative N-terminal DNA- binding domain withAtSND1. Arabidopsis plants overexpressing CpSND1 had similar phenotypes as plants overexpressing AtSND1 , including inhibited growth, upward-curling leaves, sepal dysplasia and sterility. In addition, overexpressing CpSND1 in Arabidopsis also induced the expression of downstream genes, including lignin, cellulose and xylan biosynthesis genes as well as MYB genes. Our results provided functional information of CpSND1 for future genetic engineering in hawthorn. Keywords: hawthorn, transcription factor, SND1, secondary cell wall, transcriptional regulation level, and most of the regulation theory comes from the model herbaceous plant Arabidopsis thaliana . NAC (NAM- ATAF1/2-CUC2) and MYB act as the key master switches that control secondary cell wall deposition; these proteins also regulate a battery of downstream transcription factors (TFs) and secondary cell wall biosynthesis genes (Taylor- Teeples et al . 2015). NAC proteins are plant-specific TFs and have been shown to function in plant development processes and abiotic and/or biotic stress responses. The NAC domain was named from the first letters of the Petunia NAM and Arabidopsis ATAF1/2 and CUC2 proteins (Aida et al . 1997). In Arabidopsis , there are two types of NAC TFs acting as on-off switches that take part in regulating secondary wall formation in vascular cells and fibre cells. The first type of NAC TFs (Vascular-related NAC-domain) VND6 and VND7 contribute to both secondary wall biosynthesis and programmed cell death of the vessels in both root and shoot tissues (Kubo et al . 2005; Yamaguchi et al . 2008). Received 12 September, 2017 Accepted 30 September, 2017 Correspondence DAI Hong-yan, E-mail: daihy1970@163.com ; ZHANG Zhi-hong, E-mail: zhang_sau@163.com © 2018 CAAS. Publishing services by Elsevier B.V. All rights reserved. doi: 10.1016/S2095-3119(17)61791-X 1. Introduction Secondary cell walls are largely composed of three main polymers: cellulose, hemicellulose, and lignin. These polymers are produced in sclerenchyma cells and are normally required to enable vascular plants not only to build strong xylem conduits for the transport of water and minerals but also to attain strong mechanical support for the plant body (Raven et al . 1999). The formation of the secondary cell wall is mainly regulated at the transcriptional