Highlights

• Glutamic acid pretreatment has an ameliorative effect on reduced photosynthetic efficiency in tomato leaves under chilling stress conditions.

• The decrease of Pn value cannot be attributed to stomatal limitations.

• Expression of cold-induced CBF genes in tomato was suppressed by glutamic acid pretreatment under chilling stress conditions.

• Increased level of MDA by chilling stress is attenuated by glutamic acid pretreatment.

Abstract

Low temperature stress negatively affects both the growth and development of plants through damage to photosynthetic components and the inhibition activity of antioxidant enzymes. Glutamic acid has recently been demonstrated to protect plants from various abiotic stresses such as cold, salt, osmosis and nitrogen deficiency. However, little molecular information explaining the effect of glutamic acid treatment on the growth of tomato plants under low temperature stress has been presented. Here, we report that glutamic acid (2.5 mM) applied to tomato plants prior to low temperature treatment caused increased photosynthetic efficiency together with enhanced content and/or activity of antioxidant enzymes, which could alleviate oxidative damage. Expression level of genes encoding antioxidant enzymes and C-repeat binding factors (CBFs), which are major transcription factors in cold-inducible gene expression was also altered in glutamic acid pretreated tomato plants compared to the control under low temperature stress conditions. Taken together, these results indicate that glutamic acid pretreatment is able to, at least partially, suppress the adverse effects of low temperature stress on the growth of tomato plants.