Table 1

Primer sequences used in this study"

Fig. 1

Amplified product stripe of StHsfA3 (A) and its amino acid sequence (B) M: DNA 2000 marker; 1: amplified fragment of StHsfA3 in Fig. A; the motifs marked with red line are the four short peptide sequences containing tryptophan (W) in Fig. B."

Fig. 2

Structural analysis of StHsfA3 in potato A: secondary structure prediction; B: tertiary structure prediction; C: conservative domain prediction; D: signal peptide prediction."

Fig. 3

Hydrophobicity analysis (A) and transmembrane domain analysis (B) of StHsfA3 A: the curves above zero show that these amino acids are hydrophobic, and the higher score, the stronger the hydrophobicity; the curves below zero show that these amino acids are hydrophilic, and the lower score, the stronger the hydrophilicity. B: there is no transmembrane domain."

Fig. 4

Neighbor-joining phylogenetic tree of HsfA3s from 16 plant species The Neighbor-joining phylogenetic tree of HsfA3 amino acid sequences from 16 plant species was constructed by ClustalX 2.1 and MEGA 4.0, which was bootstrapped over 1000 cycles. Abbreviations for each species and database accession numbers are as follows: MdHsfA3: Malus domestica (XP_008391748.1); ZjHsfA3: Ziziphus jujube (XP_015898712.1); CsHsfA3: Citrus sinensis (XP_006481891.1); AtHsfA3: Arabidopsis thaliana (NP_195992.2); VrHsfA3: Vigna radiata var. radiate (XP_014511066.1); GmHsfA3: Glycine max (XP_003541445.1); PeHsfA3: Populus euphratica (XP_011016541.1); NtHsfA3: Nicotiana tabacum (XP_ 016473897.1); CaHsfA3: Capsicum annuum (XP_016542894.1); SlHsfA3: Solanum lycopersicum (NP_001234854.1); OsHsfA3: Oryza sativa Japonica Group (XP_015623061.1); ZmHsfA3: Zea mays (NP_001147968.1); SiHsfA3: Setaria italica (XP_004952622.1); BdHsfA3: Brachypodium distachyon (XP_003575055.1); HvHsfA3: Hordeum vulgare (AEB26588.1). "

Fig. 5

Vector construction of 35S::StHsfA3 (A), enzyme digestion identification of 35S::StHsfA3 vector (B), regeneration of transgenic potato (C), PCR identification of StHsfA3 overexpression transgenic plant lines (D), and qRT-PCR determination of StHsfA3 in WT and StHsfA3 overexpression transgenic plant lines (E) Schematic diagram of 35S::StHsfA3 vector with site of restriction enzymes in Fig. A. M: 1 kb plus DNA marker; P: pBA002-StHsfA3 plasmid; 1, 2: enzyme digestion identification of pBA002-StHsfA3 plasmid in Fig. B. a: preincubation in darkness; b: bud formation; c: selection of transgenic lines; d: plants in pot in Fig. C. M: DNA 2000 marker; WT: non-transgenic potato plant, used as a negative control; +: pBA002-StHsfA3 plasmid, used as a positive control; L1-L5: Transgenic lines in Fig. D. The expression levels of StHsfA3 were determined in different plants in Fig. E. **: significantly different at the 0.01 probability level. "

Fig. 6

RWC (A) and MDA (B) content in the leaves of non-transgenic plants and StHsfA3 overexpression transgenic plants under different temperature treatments WT: non-transgenic plants; L: StHsfA3 overexpression transgenic plant lines; RWC: relative water content; MDA: malondialdehyde; temperature treatments: 22℃ (optimal temperature) and 35℃ (heat stress) for eight hours. Values are means ± SE of three independent experiments with three replicates in each experiment. Bars with different lowercase letters are significantly different at P < 0.05 according to Duncan’s multiple range tests."

Fig. 7

Expression levels of StHsfA3 (A), StHsp26-CP (B), and StHsp70 (C) in the leaves of non-transgenic plants (WT) and transgenic plant lines (L) under different temperature treatments WT: non-transgenic plants; L: StHsfA3 overexpression transgenic plant lines; temperature treatments: 22℃ (optimal temperature) and 35℃ (heat stress) for two hours. Values are means ± SE of two experimental replicates with three biological replicates in each experiment. Bars with different lowercase letters are significantly different at P < 0.05 according to Duncan’s multiple range tests."

Fig. S1

cDNA sequence of potato HscfA3 and corresponding amino acid sequence"