The role of IpSAG12 in regulating florescence and senescence of cut Itoh peony flowers

Abstract

Senescence-associated genes (SAGs) play a crucial role in regulating organ senescence in plant growth and development. However, their specific role in the florescence and senescence processes of cut peony flowers, particularly Itoh peonies, remains largely unclear. This study employed transcriptome analysis to investigate the expression patterns of IpSAG genes during the florescence and senescence of cut Itoh peony flowers in vases. Additionally, the function of IpSAG12 was examined using virus-induced gene silencing (VIGS) via vacuum infiltration to elucidate its role. The findings revealed that the opening and senescence of cut Itoh peonies in vases progress through three stages: early opening, middle transition, and later senescence. Notably, ethylene release followed a specific pattern, increasing sharply at the onset of flowering, then declining quickly during the early opening stage, displaying an ethylene-climacteric trait. Furthermore, the expression of the senescence-associated gene IpSAG12 was minimal during the opening and transition stages but significantly increased by 27.5 times during the senescence stage. Silencing IpSAG12 using VIGS extended the vase life of cut flowers by approximately 12 hours. This intervention resulted in a reduced electrolyte leakage rate, lower malondialdehyde (MDA) content, decreased ethylene release rate, reduced activity of 1-aminocyclopropane-1-carboxylic acid oxidase 1 (ACO1), and lower expression of IpACS1 and IpACO1 compared to the TRV control group. Conversely, the soluble protein content significantly increased in petals of the TRV-IpSAG12 group. Collectively, these findings suggest that IpSAG12 is a critical target gene in the ethylene signaling pathway that governs petal senescence in Itoh peonies.