In another embodiment of the present invention, the host plant or cell is further modified to tame the Calvin cycle so that the host can directly produce liquid fuel ethanol instead of synthesizing starch, celluloses, and lignocelluloses that are often inefficient and hard for the biorefinery industry to use. According to the present invention, inactivation of starch-synthesis activity is achieved by suppressing the expression of any of the key enzymes, such as, starch synthase, glucose-1-phosphate (G-1-P) adenylyltransferase, phosphoglucomutase, and hexose-phosphate-isomerase of the starch-synthesis pathway which connects with the Calvin cycle (Fig. 4c).

Introduction of a genetically transmittable factor that can inhibit the starch-syn­thesis activity that is in competition with designer ethanol-production pathway(s) for the Calvin-cycle products can further enhance photosynthetic ethanol produc­tion. In a specific embodiment, a genetically encoded-able inhibitor (Fig. 6c) to the competitive starch-synthesis pathway is an interfering RNA (iRNA) molecule that specifically inhibits the synthesis of a starch-synthesis-pathway enzyme, for exam­ple, starch synthase, glucose-1-phosphate (G-1-P) adenylyltransferase, phosphoglu­comutase, and/or hexose-phosphate-isomerase. Figure 6d-f depicts examples of a designer iRNA gene. The DNA sequences encoding starch-synthase iRNA, glucose-

1- phosphate (G-1-P) adenylyltransferase iRNA, a phosphoglucomutase iRNA and/ or a G-P-isomerase iRNA, respectively, can be designed and synthesized based on RNA interference techniques known to those skilled in the art [ 11]. Generally speaking, an interfering RNA (iRNA) molecule is anti-sense but complementary to a normal mRNA of a particular protein (gene) so that such iRNA molecule can specifically bind with the normal mRNA of the particular gene, thus inhibiting (blocking) the translation of the gene-specific mRNA to protein [12, 13].