Expression of a single gene encoding microbody NAD-malate dehydrogenase during glyoxysome and peroxisome development in cucumber

Abstract

A full-length cDNA clone encoding microbody NAD(+)-dependent malate dehydrogenase (MDH) of cucumber has been isolated. The deduced amino acid sequence is 97% identical to glyoxysomal MDH (gMDH) of watermelon, including the amino terminal putative transit peptide. The cucumber genome contains only a single copy of this gene. Expression of this mdh gene increases dramatically in cotyledons during the few days immediately following seed imbibition, in parallel with genes encoding isocitrate lyase (ICL) and malate synthase (MS), two glyoxylate cycle enzymes. The level of MDH, ICL and MS mRNAs then declines, but then MDH mRNA increases again together with that of peroxisomal NAD(+)-dependent hydroxypyruvate reductase (HPR). The mdh gene is also expressed during cotyledon senescence, together with hpr, icl and ms genes. These results indicate that a single gene encodes MDH which functions in both glyoxysomes and peroxisomes. In contrast to icl and ms genes, expression of the mdh gene is not activated by incubating detached green cotyledons in the dark, nor is it affected by exogenous sucrose in the incubation medium. The function of this microbody MDH and the regulation of its synthesis are discussed.

Natural variation in iron use efficiency and mineral remobilization in cucumber (Cucumis sativus)

“…One of the key features of leaf senescence is remobilization of nutrients. Cucumber cotyledons have previously been used as a model system for studying senescence processes (Becker et al 1978;Delorme et al 2000;Graham et al 1992;Kim and Smith 1994;McLaughlin and Smith 1995;Prakash et al 2001;Yamauchi et al 2002). Major nutrients such as lipids and total protein were shown to decrease over the first week of germination (Becker et al 1978).…”

Alfalfa malate dehydrogenase (MDH): molecular cloning and characterization of five different forms reveals a unique nodule‐enhanced MDH

“…Several MDH cDNA clones have been isolated and sequences compared from both plant (Cretin et al, 1988;Gietl, 1992;Guex et al, 1995;Kim and Smith, 1994;Metzler et al, 1989) and animal sources (Birktoft et al, 1982;Grant et al, 1986;Joh et al, 1987a;Joh et al, 1987b). The sequences of both the mouse and yeast c-and mMDH genes have been reported (Minard and McAlister-Henn, 1991;Setoyama et al, 1988;Takeshima et al, 1988;Thompson et al, 1988).…”

Protein Phosphatase 2A Holoenzyme Is Targeted to Peroxisomes by Piggybacking and Positively Affects Peroxisomal β-Oxidation

“…2I). To determine the identity of these structures, the peroxisomal marker glyoxysomal malate dehydrogenase (gMDH)-cyano fluorescent protein (CFP; Kim and Smith, 1994) was coexpressed with B9u::VYCE and A2::VYNE. The YFP fluorescence from BiFC interaction coincided with CFP fluorescence in the same structures (Fig.…”

“…The bombarded onion cells were incubated for 1 to 2 d in the dark at room temperature and then observed under the microscope. Peroxisomal markers used were gMDH-CFP that contains the PTS2 sequence of gMDH from cucumber (Cucumis sativus; Kim and Smith, 1994) and Red fluorescent protein-SKL (Matre et al, 2009). Microscopy was carried out on a Nikon TE-2000U inverted fluorescence microscope equipped with an Exfo X-Cite 120 fluorescence illumination system and filters for CFP (exciter, S436/10; and emitter, S470/30), YFP (exciter, HQ500/20; and emitter, S535/30), and a special red chlorophyll autofluorescence filter set (exciter, HQ630/39; and emitter, HQ680/40; Chroma Technology).…”