Reference "Maize rbcS promoter activity depends on sequence elements not found in dicot rbcS promoters"

Reference ID

7329

Title

Maize rbcS promoter activity depends on sequence elements not found in dicot rbcS promoters

Source

The Plant cell, 1991, vol. 3, pp. 997-1012

Authors (2)

Schaffner-A-R

Sheen-J

Abstract

Although the molecular mechanisms of dicot photosynthetic gene regulation have
been pursued actively, comparable studies of monocot regulation have been slow
to come forth. We show here that monocot (maize and wheat) but not dicot (pea,
tobacco, and Arabidopsis) ribulose-1,5-bisphosphate carboxylase small subunit
(rbcS) gene promoters are active in maize mesophyll protoplasts. The
evolutionarily conserved GT and G boxes of dicot rbcS promoters are not
essential for light-responsive expression in monocot leaf cells. Instead, at
least six constitutive and light-sensitive regulatory elements are likely
important for maize rbcS expression. Synergism between upstream and downstream
promoter elements is required. Whereas in dicots, light triggers coupled leaf
development and photosynthetic gene expression, in monocots, light regulation of
rbcS is uncoupled from leaf development. Light regulation of maize rbcS may be
divided into direct and indirect contributions mediated by different regulatory
elements. Because wheat and maize rbcS promoters show sequence homologies and
similar expression patterns in monocot and dicot leaf cells, it appears likely
that monocots share conserved regulatory elements irrespective of whether they
utilize the C3 or C4 pathway for carbon fixation.