Salinity stress impacts flavonoid biosynthesis in a variety-dependent manner in spinach (Spinacia oleracea)

Authors: CHANDRAMOULI, SURAJ - Rice University; Dzakovich, Michael

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/23/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Climate change is causing increasing salinity in agricultural regions, which negatively impacts crop growth and nutritional value. Spinach, a widely consumed leafy green with significant health benefits, is somewhat resistant to salinity stress, but the effects of salt on its beneficial flavonoids—compounds that have antioxidative, anti-inflammatory, and anti-cancer properties—are not well understood. This lack of knowledge is a critical gap, as understanding how salinity affects flavonoid production is essential for managing spinach growth in changing environmental conditions and ensuring its nutritional quality. This study provides one of the first detailed analyses of how salinity stress impacts flavonoid biosynthesis in spinach. Using hydroponic systems, three commercially available spinach varieties (Flamingo F1, Auroch F1, and Sunangel F1) were exposed to varying levels of salinity. The research measured flavonoid content and plant growth, identifying how different spinach varieties responded to salt stress. The findings reveal that salinity stress significantly reduces flavonoid levels in some spinach varieties, with a 24.3% decrease observed in Auroch F1 under high salinity. At the same time, the dry matter content of spinach increased, suggesting an adaptive mechanism to salt stress. These results contribute valuable insights into the role of genetic factors in determining how spinach responds to salinity. This study lays the foundation for future research into managing spinach production under changing climate conditions and optimizing the health benefits of spinach and other crops in saline environments.

Technical Abstract: One effect of climate change is an increasing prevalence of salinity stress in key agricultural production regions. Spinach, one of the most consumed leafy greens in the United States and a frequent ingredient in baby food, is relatively resistant to salinity stress. There are mixed reports in the literature suggesting that the unique flavonoids produced by spinach may be altered by salinity stress. However, the impacts of salinity stress on the regulation of spinach flavonoid biosynthesis are poorly defined. Spinach flavonoids exhibit antioxidative, anti-inflammatory, and anti-carcinogenic properties in vitro. Understanding how salinity stress affects spinach flavonoid biosynthesis is critical for defining controlled environment strategies to manipulate this crop and anticipate how climate change might impact the nutritional value of other crops. Three commercially available spinach accessions (Flamingo F1, Auroch F1, and Sunangel F1) were cultivated using deep-water culture hydroponics in a randomized complete block design over a single growing period. Plants were grown in control solution (Hoagland’s No. 1; 2.1 dS/cm) or one of three salinity treatments (Hoagland’s No.1 adjusted to 4.2, 6.4, or 9.3 dS/cm). Treatments were applied for 14 days, beginning 24 days after planting. Fresh and dry matter accumulation was determined and samples were analyzed for 39 species of flavonoids using liquid chromatography tandem mass spectrometry (LC-MS/MS). Flavonoid biosynthesis in certain varieties of spinach responds negatively to salinity stress. For example, total content decreased by 24.3% in Auroch F1 grown in high salinity relative to control. Additionally, dry matter content increased with salinity level across all varieties (9.03% to 10.62%), suggesting a common mechanism of adaptation. Spinach fresh weight did not exhibit a significant response to salinity stress. Genetic factors associated with each variety appeared to be the primary determinant of flavonoid composition and response to salinity. These data represent one of the first attempts to comprehensively quantify spinach and determine the impact of salinity stress on their biosynthesis. Characterized germplasm can be used to test future hypotheses about the impact of environmental manipulation on the health-beneficial properties of spinach. Additional replications of this study are needed to more robustly define spinach’s biochemical adaptations to salinity.