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BMC Plant Biology 2011
Identification of differentially expressed genes associated with semigamy in Pima cotton (Gossypium barbadense L.) through comparative microarray analysisAbstract: The comparative analysis between isogenic 57-4 and Pima S-1 identified 284 genes in anthers and 1,864 genes in ovules as being differentially expressed in the semigametic genotype 57-4. Based on gene functions, 127 differentially expressed genes were common to both semigametic anthers and ovules, with 115 being consistently differentially expressed in both tissues. Nine of those genes were selected for qRT-PCR analysis, seven of which were confirmed. Furthermore, several well characterized metabolic pathways including glycolysis/gluconeogenesis, carbon fixation in photosynthetic organisms, sesquiterpenoid biosynthesis, and the biosynthesis of and response to plant hormones were shown to be affected by differentially expressed genes in the semigametic tissues.As the first report using microarray analysis, several important metabolic pathways affected by differentially expressed genes in the semigametic cotton genotype have been identified and described in detail. While these genes are unlikely to be the semigamy gene itself, the effects associated with expression changes in those genes do mimic phenotypic traits observed in semigametic plants. A more in-depth analysis of semigamy is necessary to understand its expression and regulation at the genetic and molecular level.Semigamy is a naturally occurring mutation that conditions atypical reproductive behavior in plants. It has been described in 13 plant species including Rudbeckia spp., Zephyranthes spp., Cooperia pedunculata, Coix aquatica, Gossypium barbadense, and most recently Theobroma cacao [1-6]. During semigamy, the sperm and egg cells undergo syngamy or cellular fusion, but forgo karyogamy, the fusion of the sperm and egg nuclei. In most semigametic plant species, the male nucleus and its derivatives are sequestered following syngamy and do not contribute to the genetic makeup of the zygote [3,4]. However, in G. barbadense and T. cacao, both of which are members of the plant family Malvaceae, the mode of semi
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