Abstract
Zinc finger-homeodomain (ZF-HD) transcription factors play an important role in the regulation of plant growth and development, as well as the regulation of stress responses. Studies on the ZF-HD family genes have been conducted in many plants, however, the characteristics of this family in apple (Malus domestica) fruit remains to be poorly understood. In this study, we identified nineteen ZF-HD family genes in apple at the whole-genome scale, which were unevenly located on ten chromosomes. These MdZF-HD genes were phylogenetically divided into two subfamilies: zinc finger-homeodomain (ZHD) and MINI ZINC FINGER (MIF), and the ZHD subfamily was further classified into five groups (ZHDI–ZHDV). Analysis of the gene structures showed that most MdZF-HD genes lack introns. Gene expression analysis indicated that nine selected MdZF-HD genes were differentially responsive to 1-MCP (1-methylcyclopropene) treatment during the postharvest storage of “Qinguan” apple fruit. Moreover, the transcripts of six genes were further validated in “Golden Delicious” apple fruit, and five genes (MdZHD1/2/6/10/11) were significantly repressed and one gene (MdZHD7) was slightly induced by ethylene treatment. These results indicated that these six MdZF-HD genes may involve in the regulation of ethylene induced ripening process of postharvest apple fruit. These findings provide new clues for further functional investigation of ZF-HD genes, such as their roles in the regulation of fruit ripening.
Highlights
Varieties of regulatory proteins manipulate a series of developmental processes in plants
Nineteen Zinc finger-homeodomain (ZF-HD) family candidate genes were obtained by using the NCBI conserved domain database CDD and smart website for double verification of the conserved structure of the protein, and the genes were named MdZHD1-MdZHD15 and MdMIF1-MdMIF4 based on the chromosome location information (Table 1)
The results indicated that except for the acidic proteins (MdZHD5/11/12/15), the other MdZF-HD proteins were basic proteins
Summary
Varieties of regulatory proteins manipulate a series of developmental processes in plants. Transcription factors (TFs) have been shown to play important roles in regulating the different biological processes of plant growth, flowering, fruiting, and fruit ripening (Mitsuda and OhmeTakagi, 2009). Zinc finger-homeodomain (ZF-HD), a plant specific transcription factor family, has attracted increasing attention due to its role in regulating plant growth and development as well as in response to a variety of biotic and abiotic stresses (Agarwal and Jha, 2010; Zhang et al, 2015; Khatun et al, 2017). The ZF-HD gene family can be divided into zinc finger-homeodomain (ZHD) and MINI ZINC FINGER (MIF) subfamilies (Vision et al, 2000; Schoof et al, 2004).
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