Relationship between ploidy variation of citrus calli and competence for somatic embryogenesis.

This study focuses on the relationship between the genetic variation of calli and the competence for somatic embryogenesis in citrus. The DNA content of 35 citrus calli of different genotypes was measured three times by flow cytometry during a period of four years. The results showed that 71.4 % of the genotypes had a progressive increase of varied cells, while those of Page tangelo, Shamouti sweet orange, Russ navel orange and Cleopatra decreased; significant difference in the variation degree (percentages) existed among genotypes. Studies carried out on the induction of somatic embryogenesis revealed that 9 out of the 35 genotypes had still kept the competence of somatic embryogenesis, and the rest 26 had lost the competence. Correlation analysis indicated that there was no significant relationship between the variation degree and the embryogenesis competence r = -0.10 (P < 0.01), neither for the relationship between the subculture duration and the regeneration capacity.