Systemic Endopolyploidy in Development of Spinach (Spinacia oleracea L.)

Occurrence of endopolyploid cells in somatic tissues of spinach (Spinacea oleracea L.) was investigated by flow cytometry. Endopolyploidy was not present in embryos during imbibition of seeds. Rapid endopolyploidization occurred in seedlings during germination. Spinach appears to become endopolyploid by repeated rounds of replication of its entire genome. Spinach contained cells with six ploidy levels that correspond to 2C, 4C, 8C, 16C, 32C and 64C, where C is the haploid nuclear genome complement. The endopolyploid nuclei fall into clear ploidy series (2C, 4C, 8C, 16C...). Therefore, the process of endopolyploidy corresponds to endoreduplication.The patterns of endopolyploidy was characteristic of tissue type and developmental stage. However, endopolyploidy was not observed in apical meristematic tissues. Endopolyploidization may give rise to genetic plasticity in spinach.