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- Author or Editor: Carole L. Bassett x
- Journal of the American Society for Horticultural Science x
Levels of the large subunit (LSU) of rubisco (ribulose 1,5 bisphosphate carboxylase/oxygenase) were measured in vegetative and floral organs of `Violet' Japanese morning glory (Ipomoea [Pharbitis] nil Roth). Identification of the LSU in polypeptides separated by two-dimensional gel electrophoresis allowed estimation of the relative abundance of this polypeptide in the organs examined. Further quantitation was achieved by immunoblotting protein extracts either alone or in combination with various amounts of extracts from other organs. The amount of LSU decreased in the order leaves > cotyledons > sepals > corollas > androecium, gynoecium. The relative abundance of LSU in sepals (74%) compared to photosynthetically competent organs [leaves (100%) and cotyledons (81%)] suggests that sepals may be photosynthetically competent in supporting development of the other floral organs.
Reflective films are used in orchard management to improve fruit coloration. Numerous physiological studies on the effects of application of these films have been conducted, including variation of angles of light incidence and reflection, spectral determination of reflected light, and effects on photosynthesis and pigment development. At present there have been no studies on the effects of these treatments on gene expression, particularly with regard to genetic factors controlling light perception and genes targeted by specific regulators. We sampled a fully developed leaf from apple (Malus ×domestica) branches of mature trees in 2 consecutive years. The grass between the tree rows was left untreated, sprayed with a formulation of a reflective particle film (RPF), or covered with a single layer of an aluminized plastic film (APF). Leaves at the same branch position were sampled between 1000 and 1200 hr on sunny days. Nine different gene transcripts associated with light perception, sorbitol transport, and actin (control) were measured by semiquantitative reverse transcription–polymerase chain reaction and five by quantitative reverse transcription–polymerase chain reaction. Transcript abundance of most genes was unaffected by treatment or slightly enhanced by RPF. These results are consistent with earlier observations indicating that application of this film stimulated carbon partitioning to the fruit likely through the reduced red/far-red ratio of reflected light. In contrast, the level of several gene transcripts, including MdPif3, MdPhyB, and MdSot3, was reduced by application of the APF. Only one gene, MdElip1A/B, was significantly and dramatically elevated by APF.
In response to environmental cues plants undergo changes in gene expression that result in the up- or down-regulation of specific genes. To identify genes in peach [Prunus persica (L.) Batsch.] trees whose transcript levels are specifically affected by low temperature (LT) or short day photoperiod (SD), we have created suppression subtractive hybridization (SSH) libraries from bark tissues sampled from trees kept at 5 °C and 25 °C under short day (SD) photoperiod or exposed to a night break (NB) interruption during the dark period of the SD cycle to simulate a long day (LD) photoperiod. Sequences expressed in forward and reverse subtractions using various subtracted combinations of temperature and photoperiod treatments were cloned, sequenced, and identified by BLAST and ClustalW analysis. Low temperature treatment resulted in the up-regulation of a number of cold-responsive and stress-related genes and suppression of genes involved in “housekeeping” functions (e.g., cell division and photosynthesis). Some stress-related genes not observed to be up-regulated under LT were increased in response to SD photoperiod treatments. Comparison of the patterns of expression as a consequence of different temperature and photoperiod treatments allowed us to determine the qualitative contribution of each treatment to the regulation of specific genes.