Effects of Light Fluence and Wavelength on Expression of the Gene Encoding Cucumber Hydroxypyruvate Reductase

Abstract

ble HPR mRNA are regulated both developmentally and by white light (Hondred et al., 1987).We then isolated cDNA and genomic clones for a cucumber gene encoding HPR and showed that expression of the H~~ gene is li*ted to photosynthe~c organs and is regulated developmentally and by white light (Greenler et al., 1989; Hpr mRNA is Observed in etiolated cucumber cotyledons to 5 d after germh=hm (Greenler et al., 1989

Nitric Oxide Signaling During Senescence and Programmed Cell Death in Leaves

“…Apart from a delay in senescence, these plants therefore develop normally (Gan and Amasino, 1995). In cotyledons of curcurbits the synthesis of HPR is induced by cytokinin (Chen and Leisner, 1985;Andersen et al, 1996) and light (Bertoni and Becker, 1993), and the activity of HPR decreases during senescence (De Bellis and Nishimura, 1991).…”

Expression of the Cucumber Hydroxypyruvate Reductase Gene Is Down-Regulated by Elevated CO2

“…An irradiation period of 4 h was shown to be both necessary and sufficient for maximal Hpr mRNA accumulation (Bertoni and Becker, 1993). Shorter irradiations cause Hpr mRNA to accumulate to a level that is directly proportional to the length of the irradiation period, but not to the fluence rate.…”

“…After Hpr mRNA is depleted during dark adaptation of light-grown cucumber seedlings, the pre-dark H p r mRNA level is restored either by a 24-h white-light irradiation (Greenler and Becker, 1990) or by a 4-h irradiation followed by 16 to 20 h of darkness (Bertoni and Becker, 1993). …”

“…After two molecules of phosphoglycolate are converted to CO, and hydroxypyruvate, HPR reduces hydroxypyruvate to glycerate, which is phosphorylated and returns to the Calvin cycle for continued CO, fixation. Overall, the glycolate pathway salvages roughly 75% of the fixed carbon diverted from the Calvin cycle due to Rubisco activity.Hpr mRNA accumulation in cucumber is strongly stimulated by white light (Hondred et al, 1987;Greenler and Becker, 1990;Bertoni and Becker, 1993) and requires the presence of functional chloroplasts (Schwartz et al, …”

“…Hpr mRNA accumulation in cucumber is strongly stimulated by white light (Hondred et al, 1987;Greenler and Becker, 1990;Bertoni and Becker, 1993) and requires the presence of functional chloroplasts (Schwartz et al, …”