Discovery of a millennial androecious germplasm and its potential in persimmon (Diospyros kaki Thunb.) breeding

Persimmon (Diospyros kaki Thunb.) can produce unisexual (male and female) and bisexual (hermaphrodite) flowers, showing relatively complex sexuality at the species level. In China, there are more than 1000 persimmon germplasms, but most are gynoecious cultivars that bear female flowers only. To date, few germplasms have been reported to generate male flowers, until seven androecious persimmons were recently found in the Dabieshan Mountains at the juncture of Hubei, Anhui and Henan Provinces in central China. Here, we report a new androecious germplasm located in Jiangxi Province that was cultivated by the first generation of the Luo family in the Song Dynasty nearly for a thousand years ago. Up to now, the millennial androecious germplasm has continuously borne only male flowers and the seeding plant still has a strong growth vigor. Investigation of the leaf and pollen morphology showed that this androecious germplasm is similar to 'Male 2' (androecious, discovered in Dabieshan Mountains) but different from two Japanese cultivars ('faishuu' and 'Zenjimaru'). Polymerase chain reaction (PCR) detection of the sex-linked marker DlSx-AF4S verified that the millennial androecious germplasm carries this sex-linked marker. Moreover, the RO2 marker, linked Chinese pollination constant non-astringent (C-PCNA) locus, was also present in the millennial androecious germplasm. Additionally, the genetic relationships between SSR markers showed that the millennial androecious germplasm is related to Dabieshan's androecious genotypes and some persimmon cultivars of Chinese origin. Collectively, our results revealed that the ancient androecious persimmon found in Jiangxi Province is distinguished from previously reported androecious germplasms and has the potential to serve as a breeding resource for selecting sex-linked PCNA persimmons in the future.