Arabidopsis thaliana as a model organism from a biochemical perspective and The use of early light-induced proteins as a light stress marker

Sammanfattning: In the photosynthetic process higher plants, green algae and cyanobacteria convert light energy from the sun into carbohydrates, products essential to maintain life on earth. Even though sunlight is an essential condition for life it can also cause damage to plants. In order to cope with excess light plants have evolved several protective strategies including the accumulation of light stress proteins Elips (early light-induced protein). To facilitate studies on photosynthetic behaviour we developed a hydroponic cultivation system for Arabidopsis thaliana. The new cultivation method produces large amounts of plant material sufficient for e.g. biochemical studies. Using biochemical techniques originally developed for other model plants, Arabidopsis showed to be well suited not only for genetic but also for biochemical studies. Investigations of Elip expression in both Arabidopsis and pea plants demonstrate that Elips protective role is developmentally regulated. In general, Elip protein levels decrease with plant age in contrast to its transcript levels that accumulate in senescent plants. Other factors like low temperature and the content of protective pigments such as carotenoids and anthocyanins influence the Elip expression in leaves. Studies on Elip1 and Elip2 in Arabidopsis reveal that these two proteins are differently expressed in the thylakoid membrane. Therefore these data suggest that Elip1 and Elip2 might have different physiological roles under light stress conditions.