The Effect of Light on the Accumulation of Lipids in Rice Seeds

To investigate the effects of light on the accumulation of assimilate in rice seeds, ears were allowed to grow in darkness 10 d after their formation. The lipid content of rice bran on the 40th day increased by cultivation of ears in darkness whereas the dry weight and starch and sucrose contents of the rice seeds decreased. In the light, the triacylglyceride (TG) content of rice seeds was lowest on the 20th day but then increased continuously for the next 20 d, while the diacylglyceride (DG) content reached a maximum value on the 20th day. In darkness, in contrast, rice seeds showed a higher TG content, with a lower DG content and lower levels of other lipids on the 20th day compared with seeds exposed to light. These results suggest that the biosynthesis of starch and lipids in rice seeds is regulated by light.