Methyl-Sensitive Amplification Polymorphism (MSAP) Analysis Provides Insights into the DNA Methylation Underlying Heterosis in Kenaf (Hibiscus Cannabinus L.) Drought Tolerance

Kenaf (Hibiscus cannabinus L.) is an industrial fiber crop with significant heterosis and tolerance to abiotic stresses. However, the mechanism underlying heterosis in kenaf under drought conditions is completely unknown. In this study, F1 hybrids were remarkably tolerant to drought stress. Through methylation-sensitive amplification polymorphism (MSAP) analysis, we highlighted that total DNA methylation level under drought decreased by 11.2% in F1 and increased by 29.7% and 13.1% in parents CP079 and CP071, respectively. Unlike parents, the hypomethylation rate was 38% higher than hypermethylation in F1, the overall change in methylation pattern was higher in F1 (1.6%) than parents (0.4%). Furthermore, 35 key DNA fragments showing different methylation patterns were analyzed and found that the cytosine methylation status of DnaJ, ERF5, ZIP2, and PATL3 revealed changes in DNA methylation that may affect their respective expression level. Subsequently, virus-induced gene silencing (VIGS) mediated knockdown of the DnaJ, significantly increased the sensitivity of kenaf seedlings to drought. Overall, this study provides an epigenetic mechanism that could be used to improve the breeding strategy in kenaf.