Strigolactone analog (rac-GR24) enhances chilling tolerance in mung bean seedlings

Abstract

Phytohormones, such as strigolactones, can ameliorate abiotic stress by regulating and augmenting physiological processes tailored towards stress tolerance. We investigated the physiological and biochemical responses of mung bean [Vigna radiata (L.) R. Wilczek] seedlings to treatments with different doses (0, 1, and 10 μM) of rac-GR24, a synthetic strigolactone analog, and subjected them to chilling stress. The results show that GR24 inhibited the chilling-induced decrease in photosystem II quantum efficiencies and yield while also limiting superoxide anion and H2O2 accumulation in the seedlings. Additionally, GR24 significantly lowered lipid peroxidation levels, although total antioxidant capacities were not significantly affected while radical scavenging activity and phenolic contents were diminished. Chilling-induced dehydration and disruption of water status were ameliorated by GR24 treatment via increased proline content, by 1 μM GR24 concentration, and soluble sugar accumulation. The activities of lipoxygenase and phenylpropanoid pathway enzymes (phenylalanine ammonia-lyase and tyrosine ammonia-lyase) were significantly increased by 10 μM GR24 treatment in mung bean seedlings under chilling stress. Our findings provide direct evidence for strigolactone-mediated enhancement of chilling tolerance in mung bean seedlings.