Study of Sexual-Linked Genes (OGI and MeGI) on the Performance of Androecious Persimmons (Diospyros kaki Thunb.)

It is reported that the production of floral sexual phenotype in hexaploid monoecious persimmon (Diospyros kaki) is closely related to a pseudogene called OGI, and a short interspersed nuclear element (SINE)-like insertion (named Kali) in the OGI promoter leads to the gene silence. As a result, DNA methylation level of MeGI promoter determines the development of male or female flowers. However, the molecular mechanism in androecious D. kaki, which only bear male flowers, remains elusive. Here, real-time quantitative polymerase chain reaction (RT-qPCR), molecular cloning, and bisulfite PCR sequencing technique were carried out using 87 materials, including 56 androecious resources, 15 monoecious, and 16 gynoecious cultivars, to investigate the performance of OGI and MeGI on the specific androecious type of D. kaki in China. In conclusion, the Kali insertion was exactly located in the OGI promoter region, and the OGI gene and the Kali sequence were existing and conserved in androecious D. kaki. Meanwhile, we also demonstrated that the MeGI gene was widespread in our investigated samples. Ultimately, our result convincingly provided evidence that the low expression of OGI is probably ascribed to the presence of Kali displaying strong methylation in the OGI promoter, and low expression of MeGI, as well as high DNA methylation level, in the promoter was closely connected with the production of male flowers; this result was consistent with the monoecious persimmon model. Our findings provide predominant genetic aspects for investigation into androecious D. kaki, and future perfecting the sex-determining mechanisms in persimmon.

Automated summary

The production of male or female flowers in hexaploid monoecious persimmon is determined by the DNA methylation level of MeGI promoter, and the presence of Kali insertion in the OGI promoter leads to gene silence. The molecular mechanisms in androecious D. kaki were investigated using RT-qPCR, molecular cloning, and bisulfite PCR sequencing, revealing that low expression of OGI and MeGI, as well as high DNA methylation level, are associated with the production of male flowers. These findings provide important genetic insights for studying androecious D. kaki and improving the sex-determining mechanisms in persimmon.