In order to provide theoretical guidance for the genetic improvement of fruit quality and selection of superior persimmon clones by cross-breeding, the genetic variation of the important phenotypic and quality traits of the fruit of the F₁ persimmon progenies was studied.

The genetic diversity of 36 F₁ hybrid plants of ‘Fuyu’ × ‘Akagaki’ was analyzed by measuring 4 phenotypic indexes and 8 fruit quality indexes, and statistical methods such as person correlation analysis, principal component analysis and cluster analysis were used to analyze the correlation among the traits and the discretization among the individual plants of the F₁ persimmon.

(1) The variation coefficients of 12 traits of the F₁ progenies of persimmon hybridization ranged from 10.80%-165.97%, among which the variation coefficient of soluble tannins was 165.97%. The variation coefficient of the horizontal diameter of fruits was 10.80%. (2) Among the 66 pairs of correlations generated by the 12 traits, 9 correlation pairs reached an extremely significant level (P < 0.01) and 9 pairs reached a significant level (P < 0.05). The insoluble tannin content was significantly positively correlated with the total tannin content and it showed an extremely significantly negative correlation with the content of soluble proteins. There was a significantly positive correlation between the total tannin content and the total polyphenol content. (3) The 12 traits were reduced to 4 principal components by the principal component analysis, and the cumulative contribution rate was 73.42. Through the systematic clustering analysis, 36 individual plants of the F₁ generation were divided into 4 groups, including group I, Ⅱ, Ⅲ and Ⅳ. The clustering results fully reflected the characteristics of each group. (4) Through the data screen, the superior individuals of ZJ346, ZJ49 and ZJ40 were selected for different applications.

The genetic diversity of the 12 fruit traits of the F₁persimmon progenies is rich. Compared with the small variation of the phenotypic traits, the variation of important indicators of fruit intrinsic quality is more abundant.

Cloning, bioinformatics and expression analysis of UGDH gene family members in Broussonetia kazinoki×Broussonetia papyifera.

The UGDH gene sequences were obtained by using the transcriptome data of B. kazinoki×B. papyifera., named BpUGDH1, BpUGDH2 and BpUGDH4, respectively. The primers were designed to clone the UGDH gene family members of the hybrid B. papyrifera (BpUGDH3 has been cloned in the previous study). Bioinformatics analysis was performed using ExPASy, MHMMServerv2.0, Swiss-ModelL, SOPMA, MEGA11.0 and other software. The gene expression differences of different organs and tissues were analyzed by qRT-PCR.

The full-length sequences of BpUGDH1, BpUGDH2, BpUGDH3 and BpUGDH4 were 1 895, 927, 1 658 and 481 bp, respectively, encoding 480, 249, 480 and 131 amino acids. BpUGDH2 was a hydrophobic protein, and the rest was a hydrophilic protein. BpUGDH gene did not contain signal peptide. There is no transmembrane domain, and the proteins all had a conserved domain of the PLNO2353 superfamily. Multiple sequence alignment showed that the similarity between BpUGDH1, BpUGDH2, BpUGDH3 and BpUGDH4 protein sequences was 68.39%. The phylogenetic tree BpUGDH1 was clustered with soybean UGDH2. BpUGDH2 was closely related to soybean UGDH4, and BpUGDH2 and BpUGDH4 were clustered together. BpUGDH4 was closely related to rice UGDH1, rice UGDH2 and maize UGDH2. BpUGDH3 had a close relationship with Arabidopsis. Protein secondary structure analysis showed that BpUGDH1, BpUGDH2 and BpUGD4 were dominated by alpha helix and random coil, while BpUGDH3 was dominated by random coil, accounting for 39.79%. The results of qRT-PCR showed that the expression of BpUGDH1 was the highest in leaves. The expression of BpUGDH2 was the highest in root. The expression level of BpUGDH3 was the highest in the stem, and the expression level of BpUGDH4 was the highest in the stem.

In this study, the UGDH1, UGDH2 and UGDH4 genes of hybrid B. papyrifera were cloned and analyzed by bioinformatics with the UGDH3 gene of hybrid B. papyrifera. It laid a theoretical foundation for the study of the regulation of hemicellulose and pectin content and the interaction between them.

The genetic relationship and genetic diversity of the main cultivars of Beijing jujube were analyzed by fluorescent SSR molecular markers, and the DNA molecular identity card of jujube varieties was constructed, which laid a foundation for the breeding, production and utilization of new jujube varieties.

A total of 103 jujube germplasm materials were collected, and the SSR fluorescent marker primers were screened. The molecular weight and alleles of the amplified bands were analyzed by multiple fluorescence capillary electrophoresis, and the corresponding amplified bands were obtained. Each jujube germplasm material was marked and the DNA molecular identity of the test samples was constructed.

Based on SSR molecular marker technology,19 pairs of SSR primers were screened for genetic diversity analysis of 103 jujube varieties, and 7 pairs of core gene combinations were screened to construct DNA molecular identity cards. The results showed that a total of 156 alleles were detected in 103 jujube cultivars by 19 pairs of primers after SSR-PCR amplification, with an average of 8.211 alleles per pair of primers. The effective alleles(Ne) ranged from 1.263 to 12.568, with an average of 3.467. Shannon's information index (I) ranged from 0.547 to 2.664, with an average of 1.351. The polymorphism information content (PIC) ranged from 0.32 to 0.917, with an average value of 0.603. The observed heterozygosity (Ho) and expected heterozygosity (He) ranged from 0.208 to 0.920 and 0.133 to 0.990, respectively. The average values of Ho and He were 0.639 and 0.637, showing a high heterozygosity. The genetic similarity coefficient was 0.85-0.98, and it was divided into two categories when the similarity coefficient was 0.85.

In summary, the genetic background of Jingzao 31, Jingzao 311, Mayazao and Yazao in Beijing is relatively narrow, the genetic similarity is high, and the gene exchange between different strains is less. The genetic relationship of Jingzao 60, Langjiayuanzao, Beijing Fengmiguan, Beijing paopaozao, Jingzao 28 and other jujubes is far away, and the genetic diversity is rich. The results provided an important basis for the identification of jujube varieties and the cultivation of new varieties.