Low temperature increases the abundance of early light-inducible transcript under light stress conditions

Green pea plants respond to light stress by expression of a nuclear ELIP (early light-inducible protein) gene. Here we report that the accumulation of ELIP transcript in pea plants during light stress is enhanced by low temperature treatment. The enhanced level of ELIP transcript during combined light and cold stress was found to be due to an increased stability of ELIP messenger RNA under these conditions. This transcript is translatable in vitro. In vivo, however, the amount of accumulated protein in the thylakoids declines with the decrease in the temperature because the translational activity is strongly reduced already at 10 degrees C. Plants exposed to light stress at temperatures that do not allow accumulation of ELIP transcript respond by induction of ELIP mRNA and protein during recovery at low light intensity and ambient temperature. The amount of protein that accumulates as a result of this "memory effect" is, however, much lower than that which accumulates as a result of direct light stress. The memory of a perceived light stress persists in plants stored at low temperature for at least 3 h, and the stress response can be released after an increase in temperature. Prolonged cold treatment, however, has a negative effect on the translatability of the ELIP transcript that accumulates during recovery.