Figure 3.

Accumulation of Photosynthetic Pigments Is Altered in k1 k3 under Light Stress.

(A) Chlorophyll (top panel) and carotenoid (bottom panel) levels were measured in mature leaf tissue by absorption spectroscopy prior to transfer to 5× light stress and after 3, 5, and 7 d of light stress. Error bars indicate the sd of three biological replicates. Significant genotypic effects were identified by Student’s t test and are indicated with one, two, or three asterisks (corresponding to P value < 0.05, P value < 0.01, or P value < 0.001, respectively). FW, fresh weight; wt, the wild type.

(B) Induction of the xanthophyll cycle and xanthophyll pool size in response to 5× light stress was measured using HPLC with a photodiode array detector. Xanthophyll deepoxidation (top panel) is measured as (Z+0.5A)/(Z+A+V), where Z is zeaxanthin, A is antheraxanthin, and V is violaxanthin. The xanthophyll pool size (bottom panel) is the total of Z, A, and V on a dry weight basis. Error bars indicate the sd of three biological replicates. Significant genotypic effects were identified by Student’s t test and are indicated with one, two, or three asterisks (corresponding to P value < 0.05, P value < 0.01, or P value < 0.001, respectively). DW, dry weight.