everal enzyme encoding genes, e. g. PK, pyruvate dehy drogenase, and enolase, involved in pyruvate metabo lism, suggesting that O2 and O7 are, likely indirectly, implied in the regulation of this metabolite. Recent results, obtained by constitutive over expression Bortezomib buy of the maize TF Dof, a member of the Dof TFs unique to plants, in transgenic Arabi dopsis was directly associated with the PEPC gene expression, leading to a marked increase in acid con tents, and a reduction of glucose. In addition, trans genic expression in potato of a PEPC insensitive to feedback inhibition by malate resulted in a shift of C flux from soluble carbohydrates and starch to organic Inhibitors,Modulators,Libraries acids and amino acids, implying the ultimate link between C and N metabolism.
Thus, the Inhibitors,Modulators,Libraries o2 and o7 mutation may lead to an increased level of pyruvate by down regulating genes encoding enzymes involved in the pyruvate Inhibitors,Modulators,Libraries metabolism providing a link between C and N partitioning. A further outcome from our work concerns the down regulation observed in the o2o7 double endosperm mutant, in comparison to wild type, of genes encoding auxin binding proteins. The phytohormone auxin regu lates a wide variety of plant developmental programs through various regulatory mechanisms, including auxin binding proteins. For example, in maize the synthesis of a number of seed storage proteins has been shown to be subjected to regulation by phytohormones. Moreover, recent evidence indicates that a reduced accumulation of auxins in the maize defective endo sperm B18 mutant, due to down regulation of Pin formed1, a member of the PINFORM family of auxin efflux carriers, leads to a reduction in dry matter accu mulation in the seed.
Similarly, Inhibitors,Modulators,Libraries the cell wall inver tase deficient miniature1 mutant exhibits several pleitropic changes, including a reduction in kernel mass and a detrimental effect on auxin levels throughout ker nel development, indicating that developing seeds may modulate growth by altering tryptophan dependent auxin biosynthesis in response to sugar concentration. This has suggested a potential cross talk between sugar and auxin pathways. It is tempting to speculate, on the basis of the present and previous studies on the o2 and o7 mutants, indicating a reduction in kernel mass and an altered sugar metabolism, that a drastic imbalance of the sugar metabolism in the o2o7 endo sperm mutant may be the cause of the observed down regulation of enolase and auxin bindin protein gene expression.
However, further research on these ver satile signaling switches will be needed to clarify this point. A close examination of the expression patterns of genes involved in sugar and starch metabolism Cilengitide shows that both the o2 and o7 mutations create perturbations in the hexose sucrose metabolism. It has been reported that sugars, such as glucose and sucrose, can act as sig nals to trigger changes in the expression of a broad range of genes, including genes apply for it associated with C and N metabolism, signal transduction, and post transcr