Molecular cloning and characterization of an early light-inducible gene, BrELIP, from Brassica rapa, and its overexpression protects Arabidopsis

The gene encoding for the early light-induced protein (ELIP), which confers tolerance against photo-oxidative stress conditions in plants, was cloned from Chinese cabbage (Brassica rapa; BrELIP) and examined with regard to both its expression characteristics and its putative functions in photo-damage pathways. BrELIP evidences a high degree of similarity to Arabidopsis FLIP genes, and its expression is induced by intense light, cold, high temperatures and NaCl treatment, but not by wounding or paraquat exposure. The accumulation of BrELIP transcripts was induced under low-temperature conditions (below 4 degrees C) and was also increased by intense light, of 1,000 mu molm(-2) s(-1). In addition, the accumulation of BrELIP mRNA was induced via the induction of heat-shock conditions at temperatures in excess of 28 degrees C. BrELIP was also transiently expressed during the greening of the plants. The expression of the ELIP gene in two inbred lines of the Chinese cabbage plant, Chiifu and Kenshin, evidenced different light sensitivity characteristics, indicating that an inbred line, derived from a low- latitude origin, might have a lower degree of sensitivity to a high-light stress environment. BrELIP-overexpressing Arabidopsis plants evidenced resistance to high-light stress by protecting PSII against photoinactivation, via the facilitation of an efficient flow of light energy through photochemical pathways, as well as the efficient release of excess heat energy. Our findings indicated that BrELIP fulfills a photoprotective function in Arabidopsis plants during a variety of stress conditions.