Figure legends
Figure 1. Sowing depth significantly affects both tomato seed germination and hypocotyl elongation. (A) Morphology of 10-day tomato cultivar ‘Heinz 1706’ seedlings after seeds were sown at different depth of soil. Dotted lines crossing the pots indicated the positions of seeds. Scale bar, 1cm. (B) Percentage of tomato seedlings emerged from soil. (C) Germination rate of tomato seeds at day 5 after sowing. (D) Morphology of 7-day tomato seedlings after sown at 4 cm depth of soil. Data are presented by means ± SE. Different letters indicate statistical significance (p < 0.05) determined by LSD Test in DPS Software.
Figure 2. Interactions between SlUVI4 and SlCCS52 proteins. (A) Yeast-two hybrid assay. Serial dilutions of yeast cells containing SlUVI4 fused with the activation domain (AD) and SlCCS52 fused with the DNA binding domain (BD) were plated on amino acid deficient yeast growth medium. (B) Confocal microscopy images from BiFC assay in onion epidermal cells. SlUVI4:YFPN together with SlCCS52A1:YFPC or SlCCS52A2:YFPC were transiently expressed in onion epidermal cells. Images were taken at 48 h after incubation. Green signals are from YFP. Scale bar, 50 μm.
Figure 3. Gene expression of SlUVI4 and SlCCS52s in different tissues and hypocotyls at different growth stages. The transcript abundance of SlUVI4 (A), SlCCS52A1 (B),SlCCS52A2 (C) and SlCCS52B (D) in different tissues of tomato cultivar ‘Heinz 1706’ and hypocotyls at day 1, 3, 5 and 7 after seed germination (1d, 3d, 5d, 7d) were analyzed by quantitative reverse transcription polymerase chain reaction (qRT-PCR). SlCBL1(Calcineurin B-like protein, Solyc12g015870) transcript abundance was used for data normalization. The transcript abundance of each gene in the root was used for all comparisons to calculate the relative expression. Data shown are means ± SE calculated from three independent experiments. Letters on the top of each column indicate statistically significant differences (p < 0.05) determined by LSD test in DPS software.
Figure 4. Different lights have distinct impacts on hypocotyl elongation and gene expression of SlUVI4 and SlCCS52s . Tomato seedlings of cultivar ‘Heinz 1706’ were grown on MS medium under red light (A-D) and blue light (E-H) conditions. (A, E) Morphology of tomato seedlings. (B, F) Hypocotyl length. (C, G) Diameter in the middle of hypocotyl. Data represents means ± SE (n > 15). Different letters indicate statistical significance (p < 0.05) determined by LSD test in DPS Software. (D, H) Nuclear DNA distribution in hypocotyls. Data are presented by means ± SD. EI values are on the top of columns. (I) qRT-PCR analysis of SlUVI4 , SlCCS52B ,SlCCS52A1 and SlCCS52A2 in hypocotyls using SlCBL1as a reference gene. Data shown are means ± SE calculated from three independent experiments.
Figure 5. MS salts and sugar enhance hypocotyl elongation through the promotion of SlUVI4 and SlCCS52B transcription. Tomato seedlings were grown on non-MS agar (NMS, A-D), MS agar (MS, E-H) and MS agar with sugar (MSS, I-L) for 1, 3, 5, and 7 days after seeds were sown. (A, E, I) Morphology of tomato seedlings. (B, F, J) Hypocotyl length. (C, G, K) Diameter in the middle of hypocotyl. Data represents means ± SE. Different letters indicate statistical significance (p < 0.05) determined by LSD test in DPS Software. (D, H, L) Nuclear DNA ploidy distribution in hypocotyls. Data represents means ± SD. The number on the top of each column indicates EI. (M) qRT-PCR analysis of SlUVI4 ,SlCCS52B , SlCCS52A1 , and SlCCS52A2 in hypocotyls using SlCBL1 as a reference gene. Data shown are means ± SE calculated from three independent experiments. Letters on the top of each column indicate statistically significant differences (p< 0.05) determined by LSD test in DPS software.
Figure 6. Heat enhances hypocotyl elongation through the transcriptional modulationSlUVI4 and SlCCS52 genes. (A) Morphology of day seedlings grown on NMS and MS agar plates at 25°C and 33°C. (B) Hypocotyl length. (C) Diameter in the middle of hypocotyl. (D) Nuclear DNA ploidy distribution in hypocotyls. (E) qRT-PCR analysis of SlUVI4 ,SlCCS52B , SlCCS52A1 and SlCCS52A2 in hypocotyls using SlCBL1 as a reference gene. The transcript abundance of each gene at 25°C was used to calculate the relative expression. Data shown are means ± SE calculated from three independent experiments. The asterisk on the top of column indicates statistically significant differences (p < 0.05) determined by studentt -test.
Figure 7. Auxin promotes the hypocotyl elongation via the transcriptional modulation of SlUVI4 and SlCCS52 genes. (A) Morphology of tomato cultivar ‘Heinz 1706’ seedlings after 0.1 nM IAA treatment for 7 days. (B) Hypocotyl length. (C) Diameter in the middle of hypocotyl. (D) Nuclear DNA ploidy distribution in hypocotyls. (E) qRT-PCR analysis of SlUVI4 and SlCCS52s in hypocotyls using SlCBL1 as a reference gene. Data shown are means ± SE calculated from two independent experiments. The asterisk on the top of column indicates statistically significant differences (p< 0.05) determined by student t -test.
Figure 8. Salt stress inhibits hypocotyl elongation through the transcriptional modulation of SlUVI4 and SlCCS52 genes. (A) Morphology of tomato cultivar ‘Heinz 1706’ seedlings after 150 mM NaCl treatment for 7 days. (B) Hypocotyl length. (C) Diameter in the middle of hypocotyl. (D) Nuclear DNA ploidy distribution in hypocotyls. (E) qRT-PCR analysis of SlUVI4 and SlCCS52B in hypocotyls using SlCBL1 as a reference gene. Data shown are means ± SE calculated from three independent experiments. The asterisk on the top of column indicates statistically significant differences (p< 0.05) determined by student t -test.
Figure 9. Ethylene affects the hypocotyl elongation via the transcriptional modulation of SlUVI4 and SlCCS52 genes. (A) Morphology of tomato cultivar ‘Heinz 1706’ seedlings after 10μM ACC treatment for 7 days. (B) Hypocotyl length. (C) Diameter in the middle of hypocotyl. (D) Nuclear DNA ploidy distribution in hypocotyls. (E) qRT-PCR analysis of SlUVI4and SlCCS52B in hypocotyls using SlCBL1 as a reference gene. Data shown are means ± SE calculated from three independent experiments. The asterisk on the top of column indicates statistically significant differences (p < 0.05) determined by student t -test.
Figure 10. Deletion mutants of SlUVI4 exhibit defective hypocotyl elongation. (A) Morphology of 7-day seedlings grown on MS medium. (B) Hypocotyl length. (C) Diameter in the middle of hypocotyl. Data represents means ± SE (n > 19). Different letters indicate statistical significance (p < 0.05) determined by LSD test in DPS Software. (D) Nuclear DNA ploidy distribution in hypocotyls. Data are presented by means ± SD. EI values are on the top of columns.
Figure 11. Overexpression of SlCCS52B suppresses hypocotyl elongation. (A) Morphology of 6-day seedlings grown on 1/2 MS medium under 10μmol m−2 s−1 light. (B) Hypocotyl length. Data represents means ± SE (n > 50). Different letters indicate statistical significance (p< 0.05) determined by LSD test in DPS Software. (c) Nuclear DNA ploidy distribution in hypocotyls. Data are presented by means ± SD. EI values are on the top of columns.