mRNA accumulation and promoter activity of the gene coding for a hydroxyproline-rich glycoprotein in Oryza sativa

The accumulation of the mRNA corresponding to the gene coding for a hydroxyproline-rich glycoprotein has been studies in rice. The patterns of gene expression obtained are similar to those observed in maize in regions rich in dividing cells such as the meristematic zones of roots. However, the gene does not seem to be induced by wounding as it is the case in maize. This effect is correlated with the absence of sequences present in the promoter of the maize gene and that have been described as responsible for ethylene induction on other plant systems. Instead, the promoter has a sequence that corresponds to abscisic acid-responsive elements and, in fact, HRGP mRNA levels can be two-fold increased in rice leaves by ABA. The genes coding for homologous proteins in two cereal species such as maize and rice appear, therefore, to have distinct mechanisms of gene regulation.