Conesa A, Gotz S, Garcia-Gomez JM, Terol J, Talon M, Robles M (2005) Blast2GO: a universal tool for annotation, visualization and analysis in functional genomics research. Bioinformatics 21:3674–3676. https://doi.org/10.1093/bioinformatics/bti610 A nuclear‐localized HSP70 confers thermoprotective activity and drought‐stress tolerance on plants. Biotechnol. Lett. 31, 597–606. [ PubMed] [ Google Scholar] Herman DJ, Knowles LO, Knowles NR. Heat stress affects carbohydrate metabolism during cold-induced sweetening of potato ( Solanum tuberosum L.). Planta. 2017;245(3):563–82. Li YF, Wang YX, Tang YH, Kakani VG, Mahalingam R (2013) Transcriptome analysis of heat stress response in switchgrass ( Panicum virgatum L.). BMC Plant Biol 13:153–164. https://doi.org/10.1186/1471-2229-13-153 Ouyang Y, Chen J, Xie W, Wang L, Zhang Q. Comprehensive sequence and expression profile analysis of hsp20 gene family in rice. Plant Mol Biol. 2009;70(3):341–57.

Most of the StHsp20 genes (61.7%) were grouped into a nucleocytoplasmic subfamily, which was also illustrated in Arabidopsis, pepper and tomato [ 23, 26, 27]. Among these subfamilies, CI was the largest subfamily, containing 18 StHsp20 genes. Based on these results, we inferred that, because proteins are mainly synthesized in the cytoplasm, this could be the primary place for Hsp20 proteins to interact with denatured proteins, preventing inappropriate aggregation and degradation. Furthermore, the Hsp20 genes in the same subfamily from different species were more similar than those of the same species but belonging to various subfamilies. The finding indicated that synteny might exist in Arabidopsis, Populus, rice and soybean Hsp20 proteins, and that Hsp20 subfamilies diversified before the divergence within these species. The expression patterns of Hsp20 genes in different tissues have been described in many species, such as Arabidopsis, rice, pepper and tomato [ 24, 26, 27, 35]. There is no uniform gene expression pattern for plant Hsp20 genes. According to the RNA-seq data of potato, several StHsp20 genes such as StHsp20-22 and StHsp20-41, exhibited incongruous expression patterns in various tissues, indicating that different StHsp20 proteins may have diverse functions. Three genes, StHsp20-18, StHsp20-26 and StHsp20-30, were highly and indiscriminately expressed in all of the investigated tissues under normal condition. Similar with several Hsp20 genes in soybean, the three StHsp20s showed specific housekeeping expression activity [ 25]. Lescot M, Déhais P, Thijs G, Marchal K, Moreau Y, Yves VDP, Pieree R, Stephane R. Plantcare, a database of plant cis-acting regulatory elements and a portal to tools for in silico analysis of promoter sequences. Nucleic Acids Res. 2002;30(1):325–7. Evaluation of parents and selection for heat tolerance in the early generations of a potato ( Solanum tuberosum L.) breeding program. Theor. Appl. Genet. 82, 130–136. [ PubMed] [ Google Scholar] Potato is the third most important food crop in the world after rice and wheat. More than a billion people worldwide eat potato, and global crop production exceeds 300 MT per annum. Yet, this crop is particularly vulnerable to increased temperature, which is considered to be the most important uncontrollable factor affecting growth and yield (Levy and Veilleux, 2007). Potato ( Solanum tuberosum L.) originated in the Andes of South America from regions with cool temperatures, and most cultivated germplasm is highly sensitive to elevated temperature. For most commercial cultivars, yield is optimal at average daytime temperatures in the 14–22°C range, above which yield falls off sharply (Van Dam etal., 1996).

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Auffray C, Hood L (2012) Editorial: systems biology and personalized medicine—the future is now. Biotechnol J 7(8):938–939. https://doi.org/10.1002/biot.201200242 Qain J, Chen J, Liu YF, Yang LL, Li WP, Zhang LM. Overexpression of Arabidopsis HsfA1a enhances diverse stress tolerance by promoting stress-induced HSP expression. Genet Mol Res. 2014; 13(1):1233–1243. doi: 10.4238/2014.February.27.8. [ PubMed] [ CrossRef] [ Google Scholar] Effect of temperature on carbohydrate metabolism in potato plants. J. Exp. Bot. 42, 619–625. [ Google Scholar] Yan J, Yu L, Xuan J, Lu Y, Lu S, Zhu W (2016) De novo transcriptome sequencing and gene expression profiling of spinach ( Spinacia oleracea L.) leaves under heat stress. Sci Rep 6:19473. https://doi.org/10.1038/srep19473

Sarkar NK, Kim YK, Grover A. Rice sHsp genes: genomic organization and expression profiling under stress and development. BMC Genomics. 2009;10(1):393.Hu B, Jin J, Guo AY, He Z, Luo J, Gao G. GSDS 2.0: an upgraded gene feature visualization server. Bioinformatics. 2015;31(8):1296–7. The current study identified 48 StHsp20 genes, and analyzed their structure, chromosomal location, phylogeny, gene duplication, stress-related cis-elements and expression patterns in different tissues and abiotic stresses. The study provides comprehensive information on the StHsp20 gene family and will aid in understanding the functional divergence of Hsp20 genes in potato. A/T‐rich sequences act as quantitative enhancers of gene expression in transgenic tobacco and potato plants. Plant Mol. Biol. 37, 885–896. [ PMC free article] [ PubMed] [ Google Scholar] Ren X, Vorst O, Fiers M, Stiekema WJ, Nap J. In plants, highly expressed genes are the least compact. Trends Genet. 2006;22(10):528–32. Momčilović I, Pantelić D, Zdravković-Korać S, Oljača J, Rudić J, Fu J. (2016). Heat-induced accumulation of protein synthesis elongation factor 1a implies an important role in heat tolerance in potato. Planta. 2016;244(3):671–9.