Reference "Tissue-specific light-regulated expression directed by the promoter of a C4 gene, maize pyruvate,orthophosphate dikinase, in a C3 plant, rice"

Reference ID

5356

Title

Tissue-specific light-regulated expression directed by the promoter of a C4 gene, maize pyruvate,orthophosphate dikinase, in a C3 plant, rice

Source

Proceedings of the National Academy of Sciences of the United States of America, 1993, vol. 90, pp. 9586-9590

Authors (4)

Matsuoka-M	Tada-Y
Fujimura-T	Kano-Murakami-Y

Abstract

Pyruvate,orthophosphate dikinase (PPDK; EC 2.7.9.1) activity is abundant in
leaves of C4 plants, while it is difficult to detect in leaves of C3 plants.
Recent studies have indicated that C3 plants have a gene encoding PPDK, with a
structure similar to that of PPDK in C4 plants. However, low expression makes
PPDK detection difficult in C3 plants. This finding suggests that high PPDK
expression in C4 plants is due to regulatory mechanisms which are not operative
in C3 plants. We have introduced a chimeric gene consisting of the gene encoding
beta-glucuronidase (GUS; EC 3.2.1.31) controlled by the PPDK promoter from a C4
plant, maize, into a C3 cereal, rice. The chimeric gene was exclusively
expressed in photosynthetic organs, leaf blades and sheaths, and not in roots or
stems. Histochemical analysis of GUS activity demonstrated high expression of
the chimeric gene in photosynthetic organs, localized in mesophyll cells, and no
or very low activity in other cells. GUS expression was also regulated by light
in that it was low in etiolated leaves and was enhanced by illumination. These
observations indicate that the mechanisms responsible for cell-specific and light-
inducible regulation of PPDK observed in C4 plants are also present in C3
plants. We directly tested whether rice has DNA-binding protein(s) which
interact with a previously identified cis-acting element of the C4-type gene.
Gel retardation assays indicate the presence in rice of a protein which binds
this element and is similar to a maize nuclear protein which binds PPDK in
maize. Taken together, these results indicate that the regulatory system which
controls PPDK expression in maize is not unique to C4 plants.