PROMOTER TISSUE-SPECIFIC ACTIVITY AND ETHYLENE CONTROL OF THE GENE CODING FOR THE MAIZE HYDROXYPROLINE-RICH GLYCOPROTEIN IN MAIZE CELLS TRANSFORMED BY PARTICLE BOMBARDMENT

The translational construct, containing 719 bp of promoter and 5'-untr anslated region and the first 16 bp of coding region, of the maize gen e Hrgp gp encoding a hydroxyproline-rich glycoprotein fused to a glucu ronidase reporter cassette, has been tested for activity in different maize tissues by microprojectile bombardment. The promoter has been fo und to be very active in the tissues of the plant, such as meristems o r young shoots, with high cell wall formation activity where a high ex pression has also been shown for the endogenous gene. The promoter was also shown to be very active in cell types with a protection role suc h as in pericarp or styles and in cell types where the reinforcement o f the cell wall is needed, as styles, auricles and cortical cells in t he root tip. The promoter activity is developmentally regulated in the endosperm, being highest simultaneously with active cell division at the early-mid stages of development. In the presence of ethylene, the promoter shows an increased activity in accordance with the increment of mRNA accumulation observed in the plant upon ethylene treatment. It is concluded that the promoter fragment starting at -719 bp (numberin g related to the ATG) of the Hrgp gp gene keeps the essential cis-DNA elements necessary for spatial, temporal and hormonal gene expression in maize. (C) 1997 Elsevier Science Ireland Ltd.