ied, 36. 7% exhibited significant homology with sequences deposited in public databases and could be unequivocally associated with known biological processes. A complete list of differen tial gene expression detected in the mutant endosperms, for the various functional classes as described above, in comparison with wild type, is CHIR99021 available in Additional file 1, Table S1, while a selection of the most interesting up and down regulated genes is given in Table 3. Amino acid metabolism Several ESTs homologous to enzymes involved in amino acid synthesis were differentially expressed in the o2, o7, and o2o7 endosperms. In particular, ESTs homologous to phosphoglycerate dehydrogenase, cysteine synthase, methionine synthase, S adenosylmethionine synthetase, and a methyl transferase, all enzymes involved in the Ser, Gly, Cys, and Met pathways were negatively affected in the o2 endosperm.

However, neither of these showed a significantly altered expression level in the o7 and o2o7 endosperms. Finally, the Ile, Val and Leu pathways were affected in all three lines. ESTs homologous to acetolactate synthase and ketolacid reductoisomerase, and involved in the biosynthesis of these amino acids were significantly reduced in expression in all three backgrounds, while leucine dehydrogenase was significantly different from wt only in the o7 endosperm. ESTs homologous to enzymes involved in tryptophan synthesis were affected in o2 endosperm. Tryptophan synthase homologues showed a significant reduction of expression in o2 endosperms, while anthra nilate phosphoribosyl transferase and anthranilate synthase homologous ESTs were found to be differentially expressed in all three mutant backgrounds.

The former showed a significant reduction of its expression level, while the latter appeared up regulated by 50%. Carbon metabolism and redox processes Maize is an autotrophic organism that only needs minerals, light, water and air to synthesize organic com pounds to grow, however, endosperm is a heterotrophic organ. A large proportion of its proteins support pri mary metabolic processes and synthesis of more or less complex molecules such as nucleotides, amino acids, carbohydrates, lipids and secondary compounds. Accordingly, alterations in the expression levels of sev eral genes encoding enzymes involved in these processes are expected in this study.

A large set of ESTs exhibiting differential expression amongst the lines analyzed showed sequence homology with enzymes involved in C metabolism, including the trichloroacetic cycle and glycolysis. In particular, seven ESTs homologous to TCA cycle related enzymes were identified all of which were down AV-951 regulated. Four of Sunitinib FLT3 the ESTs were down regulated only in the o2 endo sperm. These are related with oxaloacetate to citrate, isocitrate to 2 oxo gluta rate and 2 oxo glutarate to 3 carboxy 1 hydroxypropyl ThPP and S succinyl dihydrolipoamide inter conversions. The remaining ESTs, which could be associated with succinate to fumarate, m