Plant Physiol, January 2002, Vol. 128, pp. 140-149
Differential Regulation of Transcripts Encoding Cytosolic
NADP-Malic Enzyme in C3 and C4
Flaveria Species1
Lien B.
Lai,2
S. Lorraine
Tausta, and
Timothy M.
Nelson*
Department of Molecular, Cellular and Developmental Biology, Yale
University, New Haven, Connecticut 06520-8104
A cytosolic NADP-malic enzyme (CYTME) has been described
previously in several plants, all C3 species. CYTME is
distinct from the chloroplastic NADP-malic enzyme (CHLME) that
is highly active in C4 species. We show that at least one
CytMe gene is present in all Flaveria
spp., including C3, C4, and
C3-C4 intermediate types. Based on the
CytMe expression patterns in Flaveria
pringlei (C3) and Flaveria trinervia
(C4), we suggest CYTME has several distinct roles,
including the supplying of NADPH for cytosolic metabolism, the
supporting of wound response or repair, and the balancing of cellular
pH in illuminated leaves. These three roles are likely correlated with
CytMe mRNAs of apparent sizes 2.0, 2.2, and 2.4 kb,
respectively, which differ in the length of the 5' untranslated
regions. Various regulatory mechanisms involving RNA processing and
translational efficiency are discussed.
1
This work was supported by the Department of
Energy (grant no. DE-FG02-91ER20038 to T.M.N.).
2
Present address: Department of Plant Biology, The Ohio
State University, Columbus, OH 43210-1293.
*
Corresponding author; e-mail timothy.nelson{at}yale.edu; fax
203-432-5632.
© 2002 American Society of Plant Physiologists
