Post-Translational Stabilization of ELIPs and Regulation of other Light Stress Genes under Prolonged Light and Cold Stress in Barley

Abstract

In nature light and temperature stress occur very often in combination. When high light and temperature were applied together this treatment led to an increase in the expression of Early Light Inducible Proteins (ELIPs) together with other light stress proteins. To study in more detail the expression of light stress proteins at low temperatures barley plants were grown for several days under various light intensities (100, 500, 1000 and 1500 μE m-2 s-1) and temperatures (5-25°C). It was observed that in plants grown at high light intensities and low temperatures the amount of ELIP protein increased considerably above the levels that could be obtained by a short term (2-8 h) high light experiment at 25°C. The highest protein levels were reached at the lowest temperature coupled to high light intensities (500 to 1500 μE m-2 s-1). In the latter case, the protein levels were almost at the maximal level already in the morning, while at the lowest light intensity the ELIP protein accumulates during the light phase. It appeared that the ELIP accumulation was primarily the result of a restored capacity of protein synthesis at low temperatures but also of a reduced degradation of ELIPs during the night phase. At 25°C the ELIPs were almost completely decomposed during the dark period.