Methylation-sensitive amplification polymorphism analysis reveals the DNA methylation dynamics during capitulum development in Chrysanthemum lavandulifolium

Chrysanthemum lavandulifolium (Fischer ex Trautv.) Makino is a diploid plant belonging to the Asteraceae family, with typical capitula composed of female ray florets and bisexual disc florets. The differentiation and development of these two types of florets have long been important research focuses; however, the potential epigenetic mechanisms governing these processes have not been elucidated. In the present study, methylation-sensitive amplification polymorphism method was used to trace the dynamic changes of DNA methylation during capitulum development in C. lavandulifolium. DNA methylation patterns and levels were detected in the whole capitula during seven developmental stages, and the obtained results revealed that DNA demethylation was dominant during this process. In addition, DNA methylation patterns and levels showed significant differences between ray and disc florets. Moreover, the expression patterns of candidate genes potentially involved in the development processes of two types of florets were analyzed by real-time quantitative reverse transcription polymerase chain reaction, and correlation analysis indicated that the expression levels of ClPI, ClAG2, ClSEP1, ClCYC2c, ClCYC2d, and ClCYC2e were highly correlated with DNA methylation levels. These results indicate that DNA methylation may be involved in the differentiation and development of ray and disc florets. This study provides epigenetic insights into the capitulum development in C. lavandulifolium.

DNA methylation in lowbush blueberry (Vaccinium angustifolium Ait.) propagated by softwood cutting and tissue culture

Plant DNA methylation is one of the frequent epigenetic variations induced by tissue culture. Global DNA methylation was evaluated in lowbush blueberry (Vaccinium angustifolium Ait.) wild clone QB9C and cultivar Fundy propagated by conventional softwood cutting (SC) and tissue culture (TC) using the methylation-sensitive amplification polymorphism (MSAP) technique. In all, 106 and 107 DNA fragments were amplified using 16 selective primer combinations in SC plants of QB9C and Fundy, respectively. In micropropagated QB9C and Fundy plants, there were 105 and 109 amplified fragments, respectively. Overall, 25% of restriction sites were methylated at the cytosine nucleotide in QB9C plants propagated by SC compared with 19% in Fundy. In contrast, a total of 29% and 20% of restriction sites were methylated at cytosine in micropropagated QB9C and Fundy plants, respectively. Tissue culture plants demonstrated higher methylation events than SC plants in both genotypes. Previously, methylation polymorphism has been detected in TC plants but not in SC counterparts. Different patterns of DNA methylation and polymorphism in the plants propagated in in vitro and in vivo conditions suggest the possibility of involvement of these fragments in the processes of regulating plant growth and development under prevailing growth conditions.