Ectopic overexpression of an Arabidopsis monothiol glutaredoxin AtGRXS17 affects floral development and improves response to heat stress in chrysanthemum (Chrysanthemum morifolium Ramat.)

Chrysanthemum is one of the most economically valuable ornamental plants worldwide. However, the high temperature is a hindrance to chrysanthemum cultivation, causing delayed flowering, poor quality of ray florets, and reduced shelf life. Here, we report that ectopic overexpression of an Arabidopsis monothiol glutaredoxin AtGRXS17 in chrysanthemum improved response to heat stress, 35/25 °C (day/night temperatures) and 45/25 °C following 35/25 °C, in terms of flowering time and ray floret quality, respectively. Under heat stress conditions, AtGRXS17-overexpressing (AtGRXS17-OE) chrysanthemum plants had reduced H₂O₂ production, lower oxidative damage of cellular membranes, and greater photosynthetic ability compared to wild-type controls. Ectopic overexpression of AtGRXS17 promoted faster flower bud formation, resulting in earlier flowering, and prevented heat stress-caused loss of ray florets shape and wilting compared to wild-type controls. The findings demonstrate an approach to enhance quality flower production in a valuable ornamental crop.