Effects of exogenous strigolactones on growth and physiological characteristics of two Primulina species under drought stress.

Abstract

To investigate the role of strigolactones (SLs) in alleviating the impacts of drought stress on Primulina, we examined the effects of drought and exogenous SLs analogue GR24 (20 μmol·L^-1) on the growth of two Primulina species, P. hiemalis and P. longii, with PEG-6000 (PEG-6000=20%) to simulate drought stress. The results showed that spraying GR24 effectively alleviated the wilting and yellowing degree of leaves in both species, and effectively promoted root growth. Root vitality and total length of new roots of P. hiemalis was significantly increased by 12.1% and 26.2%, respectively. Leaf photosynthetic capacity was improved, which effectively alleviated the inhibitory effect of drought on photosynthesis. The total chlorophyll content, intercellular CO₂ concentration, and net photosynthetic rate of leaves of P. hiemalis were significantly increased by 5.9%, 1.5%, and 27.5%, respectively, while the intercellular CO₂ concentration of P. longii was significantly increased by 2.5%. The activity of antioxidant enzyme was significantly increased in the leaves and roots of both species, among which the activities of superoxide dismutase, peroxidase, and catalase in the leaves and the activities of superoxide dismutase and catalase in the roots of P. hiemalis and P. longii were significantly increased by 50.3%, 22.3%, 31.2%, 67.7%, 12.5%, and 51.2%, 29.0%, 11.1%, 27.6%, 18.2%, respectively. The degree of peroxidation was effectively reduced, and the content of malondialdehyde in leaves of P. hiemalis and P. longii was significantly reduced by 10.0% and 16.6%, respectively. In all, drought stress significantly inhibited the growth of Primulina, and the external application of SLs could significantly alleviate the damage of drought stress on Primulina plants.