High-throughput phenotyping to detect anthocyanins, chlorophylls, and carotenoids in red lettuce germplasm

Abstract

Some plant pigments are strong antioxidants and benefit human health. Given their low cost and popularity, biofortified lettuce cultivars can promote consumption of these compounds. In this study, we assessed anthocyanin, chlorophyll, and carotenoid content in 30 red lettuce genotypes, as well as the Soil Plant Analysis Development index (SPAD) and vegetation indices (CIG, CVI, GNDVI, and NDVI), using high-throughput phenotyping. We calculated vegetation indices by using images of the plant canopy obtained from a remotely piloted aircraft (RPA) together with a red, green, and near-infrared band camera. The SPAD index and leaf pigments were measured through traditional laboratory methods, which are costly and time-consuming. Genetic variability among the genotypes for leaf pigments was confirmed by the Scott-Knott test and UPGMA dendrogram. Anthocyanin was the pigment that most contributed to genetic diversity and highly correlated with CIG, CVI, and GNDVI. These indices also moderately correlated with chlorophylls and carotenoids. Genotypes with higher pigment content, especially anthocyanin, had higher indices. Therefore, the image-based plant phenotyping technique correlated with the traditional methodology and can provide an alternative for indirect selection of plants with high leaf pigment content, especially anthocyanin, in red lettuce.