EXPRESSION OF EARLY LIGHT-INDUCIBLE PROTEINS IN FLAG LEAVES OF FIELD-CROWN BARLEY

Early light-inducible protein (ELIP) mRNA and protein levels were anal yzed during maturation and senescence of barley (Hordeum vulgare L.) f lag leaves under field conditions. The data clearly demonstrate that E LIP mRNA levels are related to the sunlight intensity before sample co llection. Levels of mRNAs encoding both low and high molecular mass EL IPs fluctuate in parallel. Changes in mRNA levels are accompanied by c orresponding changes in protein levels except for days when average te mperatures are high. Comparison of flag leaves at different stages of development in spring and winter barley varieties suggests that light- stress-regulated ELIP gene expression is independent of the developmen tal stage of the leaves. Although chlorophyll content, photosystem II (PSII) efficiency, and 32-kD herbicide-binding protein of PSII levels decrease drastically after the onset of senescence, ELIP mRNA and prot ein still accumulate to high levels on bright days.