Effectiveness of Molecular Markers for Detecting the Non-astringent Trait of Chinese Persimmon and a Trial to Identify the Gene Conferring Chinese PCNA Trait in ‘Luo Tian Tian Shi'

The hexaploid persimmons (Diospyros kaki. Thumb; 2n=6x=90) are classified into four types depending on its nature of astringency-loss of the fruit. Among these four types, pollination-constant and non-astringent (PCNA) is most desirable for fresh consumption since it stably loses their astringency on the tree.  The trait of natural astringency-loss in Japanese PCNA cultivars is recessive, while that in a Chinese PCNA cultivar, Luo Tian Tian Shi, is dominant.  The locus controlling the trait of natural astringency-loss is different between Japanese and Chinese PCNA cultivars. Until now, we constructed seven molecular markers (RO-1 to RO-7) to detect Chinese PCNA trait by AFLP analysis using segregated F₁ offspring of  ‘Luo Tian Tian Shi’ x Japanese PCNA ‘Okugosho’, and the most preferable marker was RO-6. However, we do not analyze efficiency of this marker (RO-6) to F₁ offspring from different combinations of paternal parent.  So, we have investigated the efficiency of this marker to 74 or 109 F₁ individuals from  ‘Luo Tian Tian Shi’ x Japanese PCA ‘Iwasedo’ or ‘Yotsumizo’, respectively.  Consequently, we confirmed a good fitness of this marker, in which all PCNA individuals of 30 among L-I offspring (‘Luo Tian Tian Shi’ x ‘Iwasedo’) and 54 individuals of 55 PCNA individuals in L-Y offspring (‘Luo Tian Tian Shi’ x ‘Yotsumizo’) had this marker.  In addition, to identify the gene (CPCNA) conferring Chinese PCNA trait using BAC library of D. lotus, a close diploid relative of D. kaki, we have initiated the trial to confirm whether the linearity exists in genome of D. lotus for the molecular markers detected in ‘Luo Tian Tian Shi’.  Since CPCNA locus seemed to exist between RO-6 and RO-5 markers in ‘Luo Tian Tian Shi’ due to our previous experiment, we screened several clones using the sequences of each marker and obtained several clones of BAC library of D. lotus.  And then, we detected SNPs in the end sequences of clones obtained from RO-5 and RO-6 marker, both of which only exist in female plant of dioecious D. lotus.  Currently, we are analyzing F₁ generation derived from the cross between male and female plant of D. lotus for examining the linearity of the markers in D. lotus.