Professor Virginia State University Petersburg, Virginia
Body of Abstract: Starch is a major nutrient in the human diet and being considered key for bio-ethanol production. Starch is produced during photosynthesis by plants. Increasing starch production will help to provide foods for human consumption and animal feedstock, as well as for potential bioenergy production. Previously, we successfully cloned a homolog gene, DRM2, from Purslane and overexpressed PoDRM2 in the Arabidopsis. Comparing the growth of wild-type Columbia and homozygous PoDRM2 transgenic lines, the plant size of PoDRM2 lines was significantly larger than that of Columbia, and fresh biomass per plant increased almost 90%, suggesting a potential high efficiency in photosynthesis. We further investigated starch synthesis/accumulation in leaves. iodine staining showed that PoDRM2 transgenic Arabidopsis lines accumulated significantly more starch than did the control under both dark and light conditions. Total carbohydrates accumulated in leaves of transgenic lines more than doubled of wildtype. Furthermore, PoDRM2 lines contained more chlorophyll than the control. These results indicate that PoDRM2 functions as a key regulator of starch accumulation. PoDRM2 encodes a methyltransferase, and genome-wide bisulfite sequencing identified >2,500 genes with altered methylation status. 55 out of 61 genes on the photosynthesis pathway were altered. Our results suggest that DNA methylation plays an important role in plants regulating starch accumulation and photosynthesis.