Panel A: Total carotenoids abundance, measured by PDA at absorbance 448 nm shows significant decreases in total carotenoid content in Δnos compared to wild type nos Drad (unpaired t-test). Panel B: Absorbance at 470 nm, further confirms a significant decrease in carotenoid abundance in Δnos Drad (*p<0.05, **p<0.01, ***p<0.001). Error bars represent mean ion counts +/− standard deviation of the means. Panel A1: LC-resolved carotenoid profile of wild type (black trace) and Δnos (red trace) Drad, measured by PDA at absorbance 470 nm. A reverse phase C18 column and gradient elution was performed for resolution of carotenoids, as described in Methods. Panel B1/B2: Extracted ion chromatographs (EIC) for deoxydeinoxanthin (m/z 567.414, [M + H]+) indicate that deoxydeinoxanthin is the major carotenoid species in wild type and is significantly depleted in Δnos Drad. Panel C1/C2: EIC for deinoxanthin (m/z 583.409, [M + H]+) shows that deinoxanthin is the predominant species in Δnos Drad.