Karrikin1 Enhances Drought Tolerance in Creeping Bentgrass in Association with Antioxidative Protection and Regulation of Stress-Responsive Gene Expression

Karrikins are active components of smoke that can promote seed germination and regulate seedling morphogenesis. However, the role karrikins as alleviators abiotic stress remains largely elusive. In this study, we examined whether exogenous application karrikin1 (KAR1) might improve drought tolerance in creeping bentgrass (Agrostis stolonifera cv. PennA4), investigated underlying mechanism. We found 100 nM KAR1 enhanced bentgrass, manifested by significant increases leaf relative water content, efficiency photosystem II, chlorophyll proline membrane stability, well significantly activities antioxidant enzymes. RT–PCR analysis indicated improved be related to upregulation expression karrikin-responsive genes (KAI2, MAX2 AFL1), transcription factors (ABF3, bHLH148, MYB13 DREB2A), defense (Cu/Zn-SOD, APX2, CAT1, POD2), downregulation chlorophyll-degradation (PPH Chl-PRX). These findings suggest may activating factors, enhancing accumulation capacity, suppressing senescence under prolonged stress.