Gene expression in transgenic rice with corn pollen-specific promoter Zmg13
2007
Aldemita, R.R. (Hodges, T.K.), Philippine Rice Research Inst., Maligaya, Science City of Muñoz, Nueva Ecija 3119 (Philippines). Plant Breeding and Biotechnology Div. | Purdue Univ., West Lafayette, Indiana 47909 (USA). Dept. of Botany and Plant Pathology
A promoter fragment of the corn pollen-specific gene Zmg13 was evaluated for its control of gene expression in transgenic rice. Mature pollens of rice variety 'IR54' were bombarded with pCPPGUS containing the reporter GUS A controlled by a 5'fragment of the Zmg13 gene (starting from the -260 bp position), and they exhibited transient GUS activity. Protoplasts of the rice variety 'Radon' that were treated with pCPPGUS in the presence of polyethylene glycol (PEg) did not exhibit transient GUS activity. To determine the activity of promoter Zmg13 in transgenic rice 'Radon' protoplasts were co-transformed with pCPPGUS and p35S Bar B (containing the bar gene that confers resistance to phosphinothricin (PPT), the active ingredient in the herbicide (Basta) using PEG-mediated transformation. Transgenic plants resistant to Basta and showing GUS activity in the pollen were obtained after selection with 8 mg/L PPT at a selection efficiency of 86.6% and a co-transformation efficiency of 72%. GUS expression in the mature pollen was found to be influenced by the number of integration events and the physiological age of the pollen. Low gene copy integration events were found to yield GUS activity of about 50% of the mature pollen- the expected results based on the hemizygous condition of the Tsubo plants. Somatic tissues did not express 9US. The results indicated that the corn pollen promoter functions in rice and controls the expression of the GUS A gene in the expected developmental and tissue/cell-specific manner. This is the first report of a monocot pollen-specific promoter isolated from one species, corn, and expressed in another monocot, rice in a developmental and cell-specific manner.
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