Variation of DNA Cytosine Methylation Patterns among Parent Lines and Reciprocal Hybrids in Hot Pepper

Abstract

DNA methylation plays an important role for regulation of gene expression in plants. Heterosis has been widely explored in Capsicum breeding to improve yield and quality, but the genetic and molecular mechanism underlying the phenomenon remains elusive. In present study, the genomic cytosine methylation of two Capsicum genotypes (the purple and green cotyledon hot pepper) and their reciprocal hybrids were analyzed using the methylation sensitive amplified polymorphism (MSAP). Results showed that the levels of DNA methylation in F_{1 D85×D34} (67.0%) was higher, but F_{1 D34×D85} (64.36%) was slightly lower, than the mid-parent value (MPV, 64.83%). Moreover, the characteristics of DNA methylation status were significant different among the reciprocal hybrids and their parental lines. Four classes of MSAP patterns, A, B, C and D, were identified. In pattern B, the de-methylation ratio, the proportion of de-methylated loci in the total polymorphic methylation loci, was 36.2% and 41.0% in F_{1 D85×D34} and F_{1 D34×D85.} The hyper-methylation ratio (pattern C), the proportion of hyper-methylation loci in the total polymorphism methylation loci, was 51.1% and 41.6% in F_{1 D85×D34} and F_{1 D34×D85.} This study has demonstrated that in Capsicum heterosis involves adjustment of DNA methylation, especially changes in DNA methylation patterns.