Fig. 4. Thermotolerance and heat shock transcripts are controlled by TWA1.
a, Acquired thermotolerance depends on TPL/TPR-type corepressors and on JAM TFs with loss of thermotolerance conferred by TWA1 expression (TWA1(oe) lines) in jam1 jam2 jam3 (jam) plants. TWA1 was expressed under the viral 35S promoter in twa1-2 plants. tpr signifies the tpl tpr2 tpr4 genotype. Photographs were taken 1 day after heat stress (150 min, 45 °C) or without heat stress. Scale bar, 1 cm. b, The basal thermotolerance of 5-day-old seedlings. Root growth analysis as in Fig. 1b but without priming. c, Ion leakage of 3-week-old plantlets that were exposed to 37 °C for 24 h or kept at 22 °C. Ion leakage was expressed relative to maximum leakage by boiling. Data are mean ± s.d. n = 12 from three repetitions. Scale bar, 1 cm. d, Improved thermotolerance of TWA1(oe) lines without trade-offs in growth or changes in apparent photosynthetic parameters (Extended Data Fig. 9d,e). Photograph of plants grown for 38 days under short-day conditions at 22 °C and thermal images in false colours. Scale bars, 3 cm. e, Temperature- and TWA1-dependent induction of the HSFA2 promoter driving LUC expression in leaf protoplasts of different lines. Analysis was performed as in Fig. 3a. Expression of AlTWA1 and SaTWA1 in twa1-2 plants. Data are mean ± s.d. n = 3 per datapoint. f, Transcript changes in 5-day-old WT and twa1 seedlings grown at 20 °C and exposed to 37 °C for up to 20 min. The transcript level at t = 0 was set to 1. Data are mean ± s.d. n = 3, 10 seedlings per n. Statistical analysis details for b,c,e are provided as Source Data.