Contribution of biotechnology to persimmon breeding

Persimmon originated in China, spread soon to Japan, Korea and other Asian countries and became a very popular fruit. Its spread to Europe occurred in the XVII century and later it spread to all continents. Besides of being an interesting crop in all countries where is grown the progress in Breeding and Genetics has been lacked by its polyploidy nature. The first use of molecular markers was applied to diversity studies in which different types of markers were used as RAPDs, AFLPs and SSRs. One of the first targets on breeding is the lack of astringency in the fruit at the ripen stage named PCNA, this trait involved many efforts for targeting the region linked to the AST (astringent locus). A region tightly linked to this locus was identified and a multiplex PCR method based on primers developed from the region, allowed detecting recessive and dominant alleles. Results allowed use of MAS. Besides of molecular markers developed, the molecular mechanism involved in the non-astringency trait has been related to an alteration in proanthocyanidins (PAs) accumulation, in large cells named “tannin cells” and its development during the process of fruit development. MBW ternary complexes composed of MYB, MYC (bHLH) and WDR domain proteins, are involved in the transcriptional regulation of anthocyanin and proanthocyanidin (PA) biosynthesis pathways in several species. Orthologous of members of MBW complexes in persimmon have been identified and differences in its expression have been found between astringent and non-astringent phenotypes; suggesting that an MBW-like complex could be involved in PAs accumulation in persimmon fruit. Interaction among these MBW proteins and its involvement in regulating PA biosynthetic pathway has been demonstrated. Persimmon has a polygamous gynodioecious sexual system. Elucidation of genetic and molecular basis of sex expression in D. kaki leading to de development of molecular markers, is an important goal for avoiding the presence of seeds in parthenocarpic persimmon fruits. A diploid relative, Diospyros lotus was used for investigation of the sex expression into the genus. The model of inheritance, a small RNA acting as a sex determinant, was identified and molecular markers associated to sex expression developed. Currently, examples of MAS being applied in the breeding programs from Spain and Japan demonstrated the interest of the progress of molecular techniques in persimmon success.