FIGURE 1.

Effects of 2 or 8 mM glutamate (Glu) + 2 mM MgCl₂ pre-treatments on Mg-Proto IX and chlorophyll (Chl) synthesis at room temperature (A) and leaf temperature after the subsequent cold stress (B). After the pretreatments with Glu and MgCl₂ for 48 h at the room temperature, cold stress was performed at 4 ± 1°C for additional 72 h. Levels of Chl precursors ALA, Proto IX, and Mg-Proto IX in 21-day wild-type Arabidopsis seedlings were determined (A). F.W., fresh weight. Error bars show standard deviations (n = 3). Arabidopsis leaf temperature was visualized by a FLIR T620 thermal-imaging camera. Average leaf temperatures based on the leaf area are shown below corresponding thermal images (B). Multiple comparisons using the least significant difference (LSD) method, uppercase letters represent a significant level of 0.05. With the same letter are not significantly different between the treatments.