Effect of 5-azaC on the growth, flowering time and sexual phenotype of spinach

Spinach (Spinacia oleracea L.) is a diploid dioecious plant with a pair of homomorphic sex chromosomes X and Y. Plant DNA methylation, a known process for genome epigenetic modification, regulates gene expression in plants. To explore the effects of DNA methylation on spinach growth and sexual development, spinach seeds were treated with the demethylating reagent 5-azaC. The resulting phenotypes were then investigated, including germination percentage, root length, plant height, flowering time, and sexual phenotype. Results showed that 5-azaC at a low concentration (30 A mu M) only slightly influenced spinach development but promoted seed germination. The germination percentage, root length, and plant height negatively correlated with 5-azaC at 100-1000 A mu M. The flowering time significantly reduced at all four treatments with 5-azaC. In addition, 5-azaC influenced the sexual phenotype of spinach and remarkably increased the percentage of monoecious individuals. These results may suggest that vegetative and reproductive growth are both epigenetically regulated by DNA methylation.