Lipidomics Analysis Reveals the Effect of Light Intensity on Lipid Metabolism and Leaf Color in Light-Sensitive Albino Tea Plant (Camellia Sinensis cv. Baijiguan)

Background: Camellia sinensis cv. Baijiguan is a light-sensitive albino tea germplasm. Under light stress, the development of thylakoid membrane structure is not complete, leading to the white color of leaves. Previous studies have shown that the change of lipid can cause the change of thylakoid membrane structure. However, there is no study on the effect of lipid on the leaf color of light-sensitive albino tea germplasm. Thus, we hypothesized that the changes of lipid composition in Baijiguan could affect the leaf color. Results: : In order to understand the mechanisms of its light sensitivity, Baijiguan and Rougui were grown under three different conditions: normal light, shading, shading followed by the resuming of light. The total lipids were isolated from the second leaf， 156 lipid species were identified and analyzed by lipidomics. We found that under normal light condition，the newly-developed leaves showed the yellow color with incomplete development of thylakoid membrane, the defense enzyme activity was maintained at a high level, accelerated degradation of chlorophyll. The ratio of MGDG to DGDG of Baijiguan was lower than that of Rougui which kept normal green leaf color. The shading treatment, reduced the content of MGDG and DGDG; meanwhile chlorophyll accumulated, and the thylakoid membrane formed, the leaves turned into green color. When shade-treated leaves were reexposed to light, the MGDG to DGDG ratio increased significantly, the lipid content decreased significantly, and the albinism emerged again. Conclusion: Our data demonstrated that the effect of light intensity on Baijiguan leaf color was realized by changing the lipid content and components in the leaves, and offered a new insight about the mechanisms of its leaf albinism.