Differential regulation of physiological responses and selenium accumulation in blueberry seedlings under selenium stress by melatonin and the strigolactone

Abstract

This study investigated the effects of exogenous melatonin (MT, 150 μ mol/L) and strigolactone analogue (GR24, 1 μmol/L) on the growth and selenium (Se) accumulation of ‘Farthing’ blueberry ( Vaccinium corymbosum L.) seedlings under Se stress (0.5 mg/L). Compared with the control group, Se treatment alone significantly inhibited the growth of blueberry seedlings, as evidenced by reductions in plant height, root length, biomass, and photosynthetic capacity. However, under Se stress, compared with Se treatment alone, MT or GR24 application significantly increased plant height, root length, biomass, and photosynthetic pigment contents, enhanced the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), and affected the contents of osmotic regulators (soluble protein, soluble sugar). In addition, MT and GR24 differentially regulated Se accumulation in the plant. Compared with Se treatment alone, MT treatment increased root Se content by 12.01% and shoot Se content by 15.38%; GR24 treatment increased root Se content by 30.01% and shoot Se content by 40.78%. Both MT and GR24 increased the Se translocation factor, with GR24 showing a significantly higher translocation factor than MT. In conclusion, both MT and GR24 effectively alleviated Se toxicity, improved stress tolerance, and differentially regulated Se accumulation and distribution in blueberries.