How does overproduction of antisense RNA in the chloroplast impact the growth and development of tobacco plants?

Two different antisense RNAs have been shown to have regulatory functions in cyanobacteria, suggesting that asRNA also may have served regulatory purposes in the pre-endosymbiotic chloroplast. The goal of this project was to determine the effects of an asRNA in the chloroplast by using tobacco plants engineered to overexpress an asRNA to the 5S ribosomal gene (AS5) in the chloroplast. The transgenic plants, AS5OX-1 and AS5OX-2, as well as a wild type control, were germinated on soil and transplanted to 8-gallon pots after two weeks. Plant height was measured daily to determine growth rate. After 40 days, the plants were harvested and phenotypic measurements made, including leaf and stem dimensions and chlorophyll count. The data collected showed that the transgenic plants were generally smaller than the wild type plants; they had significantly shorter and thinner stems, as well as smaller leaves. These results led us to conclude that overexpressing AS5 in the chloroplast of tobacco plants causes slower growth during the stem elongation phase.

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Two different antisense RNAs have been shown to have regulatory functions in cyanobacteria, suggesting that asRNA also may have served regulatory purposes in the pre-endosymbiotic chloroplast. The goal of this project was to determine the effects of an asRNA in the chloroplast by using tobacco plants engineered to overexpress an asRNA to the 5S ribosomal gene (AS5) in the chloroplast. The transgenic plants, AS5OX-1 and AS5OX-2, as well as a wild type control, were germinated on soil and transplanted to 8-gallon pots after two weeks. Plant height was measured daily to determine growth rate. After 40 days, the plants were harvested and phenotypic measurements made, including leaf and stem dimensions and chlorophyll count. The data collected showed that the transgenic plants were generally smaller than the wild type plants; they had significantly shorter and thinner stems, as well as smaller leaves. These results led us to conclude that overexpressing AS5 in the chloroplast of tobacco plants causes slower growth during the stem elongation phase.