DNA methylation and gene expression differences during alternative in vitro morphogenetic processes in eggplant (Solanum melongena L.)

In vitro-cultured cotyledon explants, of eggplant (Solanum melongena L.) are capable of producing somatic embryos or shoots, depending on which growth regulators are exogenously applied (auxins versus cytokinins). Rapidly growing suspension cultures were established to, model these alternative morphogenetic processes. Clear differences in DNA methylation and gene expression patterns could be detected when suspension cultures grown under different growth regulator regimes were compared by restriction fragment length polymorphism. (RFLP) or Differential Display analyses. Some of the random genomic clones showing methylation pattern differences, as well as some differentially expressed transcripts were analyzed in detail. One of the genomic clones, SMG56, proved to be the first identified 1-aminocyclopropane-1-carboxylate (ACC) synthase gene in eggplant. From 15 cloned Differential Display fragments two somatic embryogenesis (SME39, SME50), and one organogenesis (SME88) related transcripts were identified.