Decoding the Temporal Accumulation Pattern of Anthocyanins From Dynamic Expression of Purple aleurone1 Gene in Blue- and Red-kernel Maize Breeding Lines.

Purple aleurone1 (Pr1) gene plays vital role in anthocyanin biosynthesis in maize kernel. Here, accumulation pattern of anthocyanins and expression of Pr1 gene were analyzed during three kernel developmental stages (KDS) viz., 15, 30, and 45 days after pollination (DAP) among three wild-type (Pr1Pr1) and three mutant (pr1pr1) maize inbreds. Inbreds with dominant Pr1 allele produced blue-kernel, while inbreds with recessive pr1 allele possessed red-kernel. Total anthocyanin (TA) ranged from 36.5 to 514.2 ppm. Across genotypes, TA during 15 DAP was 59.2 ppm, while it increased to 205.4 ppm and 357.6 ppm at 30 and 45 DAP, respectively. Cyanidin-3-glucoside (C3G), cyanidin 3-(6´´-malonylglucoside) (C3MG), cyanidin-3,5-diglucoside (C3DG), pelargonidin-3-glucoside (P3G) and peonidin-3-glucoside (Pn3G) were components of anthocyanins. Of these, C3G (60%) was the major anthocyanin in blue-kernel, followed by C3MG (15%), C3DG (10%), P3G (10%), and Pn3G (5%). In red-kernel inbreds, P3G (69%) was the predominant fraction, followed by Pn3G (8%), C3G (11%), C3DG (7%) and C3MG (5%). Across KDS, transcript levels of Pr1 were ~ 53-fold higher over recessive pr1. The highest expression of Pr1 was observed at 30 DAP, whereas the lowest expression was recorded at 15 DAP. Transcript levels of Pr1 were positively correlated with TA (r = 0.49), C3G (r = 0.67), C3MG (r = 0.74), C3DG (r = 0.29) and Pn3G (r = 0.32), while negative association was observed with P3G (r= -0.29). Information generated here provided insight into the regulation of anthocyanins in maize kernel. This study elucidates the temporal expression dynamics of Pr1 gene with accumulation of anthocyanins at different stages of kernel development in maize.