Expression of a-amylase genes during cereal grain germination and seedling growth is regulated negatively by sugar in embryos and positively by gibberellin (GA) in endosperm through the sugar response complex (SRC) and the GA response complex (GARC), respectively. We analyzed two a-amylase promoters, aAmy3 containing only SRC and aAmy8 containing overlapped SRC and GARC. aAmy3 was sugar-sensitive but GA-nonresponsive in both rice (Oryza sativa) embryos and endosperms, whereas aAmy8 was sugar-sensitive in embryos and GA-responsive in endosperms. Mutation of the GA response element (GARE) in the aAmy8 promoter impaired its GA response but enhanced sugar sensitivity, and insertion of GARE in the aAmy3 promoter rendered it GA-responsive but sugar-insensitive in endosperms. Expression of the GAREinteracting transcription factor MYBGA was induced by GA in endosperms, correlating with the endosperm-specific aAmy8 GA response. aAmy8 became sugar-sensitive in MYBGA knockout mutant endosperms, suggesting that the MYBGA-GARE interaction overrides the sugar sensitivity of aAmy8. In embryos overexpressing MYBGA, aAmy8 became sugar-insensitive, indicating that MYBGA affects sugar repression. a-Amylase promoters active in endosperms contain GARE, whereas those active in embryos may or may not contain GARE, confirming that the GARE and GA-induced MYBGA interaction prevents sugar feedback repression of endosperm a-amylase genes. We demonstrate that the MYBGA-GARE interaction affects sugar feedback control in balanced energy production during seedling growth and provide insight into the control mechanisms of tissue-specific regulation of a-amylase expression by sugar and GA signaling interference.

Abiotic stresses affect crop plants and cause decreases in plant quality and productivity. Plants can overcome environmental stresses by activating molecular networks, including signal transduction, stress perception, metabolite production and expressions of specific stress-related genes. Recent research suggests that chemical priming is a promising field in crop stress management because plants can be primed by chemical agents to increase their tolerance to various environmental stresses. We present a concept to meet this objective and protect plants through priming of existing defense mechanisms avoiding manipulation of the genome. In addition, recent developments in plant molecular biology include the discovery of genes related to stress tolerance, including functional genes for protecting cells and regulatory genes for regulating stress responses. Therefore, enhancing abiotic stress tolerance using a transgenic approach to transfer these genes into plant genomes has attracted more investigations. Both chemical priming agents and genetic engineering can enhance regulatory and functional genes in plants and increase stress tolerance of plants. This review summarizes the latest findings of chemical priming agents and major achievements in molecular approaches that can potentially enhance the abiotic stress tolerance of plants.

Mammalian intestinal fatty acid-binding protein (I-FABP) is a small cytosolic protein and is thought to play a crucial role of intracellular fatty acid trafficking and metabolism in gut. To establish an in vivo system for investigating its tissue-specific regulation during zebrafish intestinal development, we isolated 5'-flanking sequences of the zebrafish L-FABP gene and used a transgenic strategy to generate gut-specific transgenic zebrafish with green/red fluorescent intestine. The 4.5-kb 5'-flanking sequence of zebrafish I-FABP gene was sufficient to direct fluorescent expression in intestinal tube, first observed in 3 dpf embryos and then continuously to the adult stage. This pattern of transgenic expression is consistent with the expression pattern of the endogenous gene. In all five transgenic lines 45-52% of the F2 inheritance rates were consistent with the ratio of Mendelian segregation. These fish can also provide a valuable resource of labeled adult intestinal cells for in vivo or in vitro studies. Finally, it is possible to establish an in vivo system using these fish for screening genes required for gut development. genesis 38:26-31, 2004.

The objective of this study was to evaluate the influence of sugar composition on the sensory attributes of seven baked sweet potatoes. The sugar composition was analyzed using high performance liquid chromatography. Results showed that the total sugar content of baked sweet potatoes increased significantly because of the formation of maltose. The maltose content dramatically increased after baking, and became the major sugar component of baked sweet potatoes. On the other hand, baked sweet potatoes were evaluated on a 7-point hedonic scale for sensory analysis. Overall acceptability results showed that the panelists preferred baked CYY95-26 and TNG66 over the other baked varieties. Because the correlation between overall acceptability and sweetness was the highest (r00.69, p<0.01), sweetness was determined as the most important factor determining the overall acceptability of baked sweet potatoes. Although sugar composition changed on baking, the overall acceptability of baked sweet potatoes was highly associated with the sucrose content.

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