Phytochemical and agronomic characterization of high-flavonoid lettuce lines grown under field conditions

Authors: CHO, EUNJIN - Rutgers University; GURDON, CSANAD - Rutgers University; Zhao, Rebecca; PENG, HUI - University Of Florida; POULEY, ALEXANDER - Rutgers University; RASKIN, ILYA - Rutgers University; Simko, Ivan

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/18/2023
Publication Date: 10/22/2023
Citation: Cho, E., Gurdon, C., Zhao, R.B., Peng, H., Pouley, A., Raskin, I., Simko, I. 2023. Phytochemical and agronomic characterization of high-flavonoid lettuce lines grown under field conditions. Plants. 12(19). Article 3467. https://doi.org/10.3390/plants12193467.
DOI: https://doi.org/10.3390/plants12193467

Interpretive Summary: Consumption of fruit and vegetable flavonoids has a beneficial effect on human health. Eight lettuce mutant lines accumulating high levels of flavonoids and their precursors (cyanidin, quercetin, kaempferol, or naringenin) were recently developed, however their performance was tested only under controlled environment conditions. Mutant lines together with seven control accessions were therefore assessed for their accumulation of flavonoids, biomass production, content of pigments, resistance to diseases, postharvest quality, and mineral elements compositions in field conditions. All mutant lines consistently accumulated high levels of flavonoids, confirming that these mutant lines produce high levels of beneficial phytochemicals under field conditions. Fresh weight of mutant lines at harvest was comparable to commercial leaf cultivars, except for the naringenin accumulating mutant. All but one flavonoid hyperaccumulating mutant lines can be considered for field cultivation.

Technical Abstract: Flavonoids are antioxidant phytochemicals that confer a beneficial effect on human health. We have previously developed and characterized eight lettuce (Latuca sativa L.) lines that accumulated high levels of diverse flavonoids and their precursors in controlled environment conditions. Three Rutgers Scarlet lettuce (RSL) lines selected in tissue culture for deep red color (RSL-NAR, RSL-NBR, RSL-NFR) accumulate anthocyanins and quercetin, three lines identified in a chemically mutagenized red lettuce population accumulate kaempferol (KfoA and KfoB) or naringenin chalcone (Nco), and two lines that were spontaneous green mutants derived from the red line RSL-NAR (GSL, GSL-DG) accumulate quercetin. These eight lines were field grown in the Salinas Valley of California for four years together with the seven control accessions of varying colors (light green, dark green, red, and dark red). At market maturity, a substantial variation in plant composition was observed, but the three RSL lines consistently accumulated high levels of cyanidin, GSL and GSL-DG accumulated the highest levels of quercetin, KfoA and KfoB accumulated kaempferol, and Nco amassed naringenin chalcone, confirming that these mutant lines produce high levels of beneficial phytochemicals under field conditions. Mutant lines and control accessions were also assessed for their biomass production (plant weight, height, and width), overall content of pigments (leaf chlorophyll and anthocyanins), resistance to diseases (downy mildew, lettuce drop, and Impatiens necrotic spot virus), postharvest quality of processed tissue (deterioration and enzymatic discoloration), and composition of 23 mineral elements. All but one mutant line had a fresh plant weight at harvest comparable to commercial leaf cultivars; only Nco plants were significantly smaller. Therefore, except Nco, the new, flavonoid hyperaccumulating lines can be considered for field cultivation.