Green light and nitrogen: Optimizing antioxidant production in lettuce for extraterrestrial survival

Astronauts on lunar and Martian surfaces face increased health risks due to lack of Earth's protective atmosphere and magnetosphere, including higher cancer and DNA damage risks from cosmic radiation and solar wind. Antioxidant intake, sourced mainly from fresh produce, is crucial for countering these threats. Our research addressed the challenge of producing high-antioxidant vegetables in situ for Bioregenerative Life Support Systems (BLSS), focusing on optimizing growth conditions for lettuce varieties to enhance ascorbic acid synthesis.It aimed to boost ascorbic acid metabolism in lettuce by manipulating green light intensity and nitrogen levels. We tested 'youmaicai' and 'rapid' lettuce under varying green light (10 %, 20 %, 30 %) and nitrogen (2.5, 10.5, 18.5 mmol/L) conditions, assessing ascorbic acid content, total production of ascorbic acid, AsA-GSH cycle enzyme activities, and gene expression. We found optimal conditions for each variety: 10 % light and 2.5-10.5 mmol/L nitrogen for 'youmaicai', and 30 % light and 10.5-18.5 mmol/L nitrogen for 'rapid'. This research not only contributes to the understanding of how green light and nitrogen supply can be optimized to boost the nutritional quality of lettuce but also offers practical strategies for improving crop yield and quality in controlled environments.By tailoring light and nutrient conditions, it is possible to significantly enhance the vitamin C content and overall growth efficiency of plants, which has important implications for sustainable food production both on Earth and in extraterrestrial settings.