Data Sheet 1_Foliar folic acid application enhances nitrogen assimilation and improves quality-related metabolites accumulation in Dendrobium officinale.docx

Here, we profiled folate derivatives across tissues and stem developmental stages of Dendrobium officinale and evaluated how foliar nutrient treatments affect folate accumulation and nitrogen metabolism. Folate profiling revealed distinct tissue-specific patterns: leaves were the major sink for total and reduced folates, whereas flowers preferentially accumulated formylated folates.

Foliar application of balanced nutrient solutions, particularly Huaduoduo No. 1, markedly increased total folate levels. In vitro enzyme assays showed that folates, especially 5-formyltetrahydrofolate (5-F-THF), enhanced nitrate reductase (NR) and nitrite reductase (NiR) activities, with a stronger effect on NiR. Consistent with these findings, foliar application of folic acid (FA; 15 mg L^-1) increased NR and NiR activities in planta, accompanied by higher nitrate and lower nitrite levels.