ANALYSIS OF THE DIURNAL EXPRESSION PATTERNS OF THE TOMATO CHLOROPHYLL alb BINDING PROTEIN GENES. INFLUENCE OF LIGHT and CHARACTERIZATION OF THE GENE FAMILY *

Steady-state mRNA levels of the chlorophyll alb binding ( cab ) proteins oscillate substantially during a diurnal cycle in tomato leaves. This accumulation pattern is also observed in complete darkness, supporting the hypothesis that the expression of cab genes is at least partially regulated by an endogenous rhythm (“biological clock”). The amplitude of the cab mRNA accumulation is dependent on the duration of illumination and the circadian phase in which light was applied to the tomato plants. These results at the molecular level correlate well with the photoperiodic phenomenon. The characterization of the expression pattern of individual members of the cab gene family was attempted. Distinct primer extension products were detected using specific oligonucleotides homologous to the cab 1, cab 4, cab 5 and cab 8 genes. Based on this analysis the transcription start sites of these genes were determined to be between position -70 and -9 upstream of the ATG codon. During the diurnal cycle the cab 1 and cab 4 genes exhibit the same expression pattern; no transcripts detected at 3 and 6 a.m., maximum mRNA levels were measured at noon and decreasing levels in the afternoon.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74852/1/j.1751-1097.1990.tb01752.x.pd

Induction of leaf senescence in Arabidopsis thaliana by long days through a light-dosage effect

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74662/1/j.1399-3054.1996.tb00463.x.pd

Photomodulation of stem extension in light-grown plants: evidence for two reactions

Internode elongation was measured in plants of Phaseolus vulgaris and Glycine max grown under 8 h photoperiods at 25 W m−2 in white fluorescent light, followed by light-extensions varying in quality, irradiance and duration. Two distinct responses to light were observed under these conditions. A reduction in PFR/P increased elongation, but elongation was also modified by a second reaction in which internode length increased with increase in the duration and irradiance of the day-extension. This light-promoted response occurred in both red and blue light. In the PFR-inhibition response, light acted directly on the expanding internode. The light-promoted response, in contrast, required irradiation of the leaf. The response to a short end-of-day exposure to far-red light progressively diminished as successive internodes expanded under the treatment, whereas the light-promoted response increased. The two processes appeared to interact and, in the later-expanding internodes, the effect of a reduction in PFR was greater under long day-extensions with mixed red and far-red light than in the end-of-day treatments