Consistent with what we observed in GO analysis, 65. www.selleckchem.com/products/XL184.html 3% of these genes belong to the first six functional groups, suggesting that the occurrence of endo sperm chalkiness in rice might be closely related to these functional and regulatory pathways. In addition, only three genes associated with photosynthesis were differentially expressed between Asominori and CSSL50 1, implying that photo synthesis efficiency may not play a significant role in the formation of chalkiness in rice. Enhanced sucrose and starch synthesis vs. disrupted cellulose, hemicellulose and pectin metabolism in CSSL50 1 Physio biochemical analysis of chalky rice endosperm indicated that the change in starch composition is a major difference between chalky and non chalky rice grains.

GO analysis also showed that genes associated with carbohydrate metabolism are significantly represented among the differentially expressed transcripts. As shown in Additional file 4, more than 50 genes are annotated to be associated with carbohydrate metabolism. Of particular interest were several key genes that are known to be directly involved in the synthesis of starch and cell wall related polysaccharides. A closer examination of these carbohydrate metabo lism genes revealed that the differentially expressed genes in CSSL50 1 were in favor of enhancing sucrose, amylose, and amylopectin synthesis. As shown in Figure 4, two genes, sucrose phosphatase and sucrose phosphate synthase that directly catalyze sucrose synthesis, are up regulated, whereas the enzyme b fruc tofuranosidase that catalyzes the hydrolysis of sucrose to glucose and fructose is down regulated.

The potentially accumulated sucrose, catalyzed by the rever sible enzymatic activity of sucrose synthase, may increase the concentration of UDP glucose, which can be converted into glucose 1 phos phate and subsequently converted into ADP glucose for starch synthesis. Microarray data also revealed several additional enzymes that are up regulated in CSSL50 1 for the accumulation of ADP glucose, up regulation of glucose 6 phosphate isomerase to promote fructose 6 phosphate to glucose 6 phosphate conversion, down regulation of UDP glucose 4 epimerase to reduce conversion Anacetrapib of UDP glucose to UDP galactose, up regulation of phosphoglycerate kinase and down regulation of phosphoglycerate mutase for the accumulation of 3 phosphoglycerate, an activator for ADP glucose pyrophosphorylase that converts glucose 1 phosphate to ADP glucose.