Considering the fact that a great part (more than 90%) of edible oil consumed in Iran is imported, increasing the domestic oil seed production is necessary to reduce this dependence. Among oil plants, rapeseed (Brassica napus) is most suitable and breeding on this plant is necessary for quality and quantity of its oil. Due to the fact that classical plant breeding methods are time consuming, expensive and incases impossible, therefore the new methods of biotechnology and genetic engineering are inevitably used in place of classical methods. In transferring useful genes to plants, the most important part of each gene is the promoter. The purpose of this research was to investigate the precise activities of promoter using the GUS reporter gene. For optimum results, CaMV 35S (Cauliflower mosaic virus) could be used as a suitable promoter regarding gene expression, and to control other genes. To achieve this, in a separate project of the GUS reporter gene (?-glucuronidase) behind cauliflower mosaic virus promoter had been coloned and introduced to rapeseed. The seeds of 7 transformed rapeseed plants (T0) with this gene as well as the control seeds (non-transformed) were planted in greenhouse. Total soluble protein content was extracted from the leaves at 4 different stages of growth (Rosette, Young Green, Mature Green and Senescence leaves), protein concentrations being spectrophotometrically measured. The amounts of chlorophyll a, b and carotenoid were determined according to the absorbance rates of extracts at 470, 646, 663 nm, the data were collected, and statistically analyzed. The results showed no significant difference between transgenic plants and control in terms of protein, chlorophyll and their carotenoid contents. In different stages of plant growth, variable amount of pigments were observed and in mature green stage these pigments reached their apex level. Besides the study of the quantity of chlorophyll, carotenoid and protein, the protein patterns were studied too using SDS-PAGE method. The results showed no new recognizable band in either transgenic or control plants at any stage. With regard to the results, when comparing chlorophyll, carotenoid and protein (quantitatively and qualitatively), one can conclude that transfer of GUS gene downstream of CaMV 35S promoter to rapeseed can not cause significant changes in the amount of either pigments or total soluble protein. Thus it’s suitable to use promoter CaMV 35S upstream of useful genes for transferring genes to rapeseed.
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