Strigolactone and salicylic acid regulate the expression of multiple stress-related genes and enhance the drought resistance of cherry rootstocks

Abstract

Drought is one of the most significant abiotic stress factors, which disrupts plant growth and development and restricts cherry (Cerasus spp.) production. Exploring effective methods to enhance the tolerance of cherry rootstocks to drought stress is a top urgency for scions to thrive. Strigolactones (SLs) and salicylic acid (SA) have been demonstrated to participate in various biotic and abiotic stresses. In current study, the effects of SLs and SA on cherry rootstocks under drought stress were investigated. The net photosynthetic rate, the maximum quantum yield of photosystem II, and the relative water content of the rac-GR24 and SA pretreatment groups were all higher under drought stress compared with well-watered group, but the antioxidant enzyme activities were lower, indicating that they greatly increased drought resistance. RNA-Seq analysis of leaf samples treated with drought stress (T1), drought stress along with 1 mM SA (T2), 1 μM rac-GR24 (T3), and 5 μM rac-GR24 (T4) pretreatments revealed that 837, 755, 586 and 489 differentially expressed genes (DEGs), respectively. Transcriptome analysis suggested that many of DEGs were ABA-related genes (PavNCED, and PavPP2C51), stress-related transcription factors (PavWRKY, and PavMYB), antioxidant enzyme genes (PavGST and PavPOD), and osmotic adjustment genes (PavUGTs, PavSUSs, and PavSPS1). In our study, PavDBP2D, PavABCG15-like, PavPUP9, PavLOG1-like, and PavENT8 were significantly activated by drought treatment, and rac-GR24 or SA pretreatment decreased these genes expression levels under the drought stress condition. Overall, our findings will provide a basic understanding of drought tolerance in cherry rootstocks modulated by SA and SLs, as well as new insights into regulatory mechanisms of drought tolerance in woody plants.