Effect of exogenous calcium pretreatment on the rapid induction kinetics and PQ pools of tomato seedlings under LNT.

<p>For Fig. 6A, the rapid induction kinetics upon onset of strong continuous illumination was investigated on the tomato leaves after dark adaptation for 20(Vt) were used to estimate I1-I2 and I2-P contribution and discuss about slow and fast PQ poll reduction. Vt is defined as the ratio of variable fluorescence to the maximal variable fluorescence F_V (Fm-Fo), i.e., Vt = (Ft-Fo)/(Fm-Fo), where Ft is the fluorescence at a given time. For Fig. 6B, the P700 signal was determined during a single turnover flashes (ST, 50 µs, PQ pool being oxidized) followed by multiple turnover flashes (MT, 50 ms, PQ pool is fully reduced) in the presence of far-red (FR) background light. The ratio of MT-area/ST-area is used to estimate the size of functional PQ pools. CK, the plant grown at optimal temperature, and used for control; CaCl₂+LNT, the plant pretreated with CaCl₂ and grown at low night temperature(LNT); H₂O+LNT, the plant pretreated with H₂O and grown at LNT; EGTA+LNT, the plant pretreated with EGTA and grown at LNT. Data are the means of four replicates with standard errors shown by vertical bars. *indicates significant difference (P≤0.05), and **indicates a highly significant difference (P≤0.01). Comparisons between the figures among all treatments under low night temperature are shown in parentheses.