<i>amiRNA-BCB</i> plants are tolerant to freezing treatment.

<p><b>(A)</b> Freezing treatment of 3-week-old <i>amiRNA-BCB</i> transgenic plants (#4–9 and #9–2) and wild-type (WT) plants at the indicated temperature below freezing under long-day photoperiod with cold acclimation. The pictures were taken 7 days after treatments. <b>(B)</b> Quantification of survival of the plants in <b>(A)</b>. Error bars are standard deviation (<i>n</i> = 80–100), (*, <i>P</i> < 0.05, <i>t</i>-test). <b>(C)</b> Leakage of electrolytes in <i>amiRNA-BCB</i> transgenic plants and WT plants treated at indicated temperature below freezing. Error bars are standard deviation (<i>n</i> = 8). (*, <i>P</i> < 0.05, <i>t</i>-test). <b>(D)</b> Quantitative determination of lignin content from whole rosettes of three-week-old WT and <i>amiRNA-BCB</i> transgenic plants grown in soil with (<i>Grey</i>) or without (<i>Black</i>) cold treatment (4°C for 7 days). Twelve independent experiments were performed and the data are expressed as mean ± S.E. Means with the same letter are not significantly different at <i>P</i> < 0.05 by One Way ANOVA analysis.