Effects of exogenous H2O2 combined with vermicompost initiation on physiology and transcriptome of seedless watermelon seeds at low tem-perature

LI Canpeng; FANG Ke; XIONG Cheng; ZHOU Yan; XIANG Zuoqin; DAI Sihui; HE Changzheng

doi:10.16861/j.cnki.zggc.2024.0684

Abstract：To enhance the germination performance of seedless watermelon(Heima Wangzi)under low-temperature conditions,seeds were subjected to hydrogen peroxide(H2O2)priming using concentrations of 1％,3％,5％,7％,9％,11％,13％,and 15％for 2 hours,followed by vermiculite treatment.A parallel control group was primed with distilled water for 2 hours preceding vermiculite exposure.Germination responses were assessed under controlled low-temperature stress at 15 ℃.The results demonstrated that both germination rate and germination potential initially increased and subse-quently decreased with rising hydrogen peroxide concentrations,peaking at 91％and 80％,respectively,under the 9％hydrogen peroxide treatment.These values were significantly higher than those of the control group.The activities of antioxidant enzymes,including peroxidase,superoxide dismutase,and catalase,exhibited trends similar to germination rates,with significant increases of 152.5％,157.6％,and 73.4％,respectively,compared to the control.Although malondi-aldehyde content initially peaked after vermiculite priming,it gradually declined with increasing hydrogen peroxide con-centrations.Transcriptome sequencing of seeds treated with 9％hydrogen peroxide and the control group revealed 1468 differentially expressed genes.GO analysis highlighted significant enrichment in functions related to translation,cytoplas-mic large ribosomal subunits,and ribosome structure.KEGG analysis further indicated prominent enrichment in pathways such as phenylpropanoid biosynthesis and flavonoid biosynthesis.Notably,hydrogen peroxide priming up-regulated key enzyme genes and transcription factors in the phenylpropanoid biosynthesis pathway,enhancing signal transduction and secondary metabolite synthesis,thereby improving seed adaptability and stress resistance.In conclusion,hydrogen perox-ide priming combined with vermiculite treatment effectively enhances the low-temperature germination capacity of water-melon seeds.This approach offers a practical strategy for early spring watermelon cultivation to mitigate cold stress.