Jujube (Ziziphus jujuba Mill.) is a fruit tree that is gaining increasing importance in drought-affected regions worldwide. The fruit size is an important quantitative agronomic trait that affects not only the fruit yield and attractiveness but also consumer preference. Genetic enhancement of fruit appearance is a fundamental goal of jujube breeding programs. The genetic control of jujube fruit size traits is highly quantitative, and development of high-density genetic maps can facilitate fine mapping of quantitative trait loci (QTLs) and gene identification. However, studies regarding the construction of high-density molecular linkage maps and identification of quantitative trait loci (QTLs) targeting fruit size in jujube are limited. In this study, we performed whole-genome resequencing of the jujube cultivars “JMS2” and “Xing16” and their 165 F₁ progenies to identify genome-wide single-nucleotide polymorphism (SNP) markers and constructed a high-density bin map of jujube that can be used to assist in the selection of multiple traits in jujube breeding. This analysis yielded a total of 116,312 SNPs and a genetic bin map of 2398 bin markers spanning 1074.33 cM with an average adjacent interval of 0.45 cM. A quantitative genetic analysis identified 15 QTLs related to fruit size and the observed phenotypic variation associated with a single QTL ranged from 9.5 to 13.3%. Through the screening of overlapping and stable QTL regions, we identified 113 candidate genes related to fruit size. These genes were ascertained to be involved in cell division, cell wall metabolism, synthesis of phytohormones (ABA, IAA, and auxin), and encoding of enzymes and transcription factors. These candidate genomic regions will facilitate marker-assisted breeding of fruits with different sizes and shapes and lay a foundation for future breeding and manipulation of fruit size and shape in jujube.

Peach is an economically important fruit tree crop worldwide. The external color of the fruit governs the peach price, especially in fruits with different degrees of blush. Molecular marker-assisted breeding has become a necessary part of modern breeding practices, increasing their efficiency. Although the key related genes responsible for peel coloration have been found in peach, corresponding molecular markers have not been widely used in peach breeding. The development of molecular markers for peach peel color needs to be advanced and implemented in practice. This study aimed to explore the variation related to peach skin color and to develop molecular markers linked to these variants that can be used in breeding. By analyzing the expression of anthocyanin synthesis-related and regulatory genes, we confirmed that MYB10.1 is a key gene controlling skin color. We further identified that 5243 bp insertion and 483 bp deletion in the MYB10.1 promoter was highly associated with peach skin color phenotypes. In addition, we identified one transposon insertion mutation at the −2706 bp position of the MYB10.1 promoter associated with the non-red fruit skin trait and developed a molecular marker for validation. The insertion size amplified from the ‘ShiYuBaiTao’ genome DNA was approximately 3.5 kb. However, it explained a lower percentage of the non-red skin phenotype variance in peach, at 36.1%, compared to MYB10.1-2/MYB10.1-2 in this study. Based on these results, we propose that MYB10.1-2/MYB10.1-2 should not only be the only non-red skin genotype assessed but should also be combined with other molecular makers to increase the prediction accuracy of peach skin color.

A superior cultivar of dried jujube in China is ‘Huizao’ (HZ) jujube. Nonetheless, detailed evaluations of the texture quality of HZ fruit have been the subject of few studies. Texture is a significant indicator of the sensory and processed quality of a fruit. Here, we differentiate and characterize the texture quality of HZ fruit from the four primary producing regions in southern Xinjiang, as well as develop a system for assessing the texture quality of HZ fruit. Correlation investigation indicated strong relationships between the springiness, chewiness, cohesiveness, gumminess, and hardness of HZ fruit. Furthermore, according to the factor molecules, the texture quality of HZ fruit in the four production areas was evaluated as Bazhou (1.24) > Hotan (0.773) > Kashi (−0.577) > Aksu (−0.852). RDA analysis of six texture quality parameters and 24 climate conditions identified higher mean temperature (TEM) and lower relative humidity (RHU) as the primary factors contributing to the improved texture quality of HZ fruit in Xinjiang. This study identified the variations in the texture of HZ fruit in the four primary producing regions of Southern Xinjiang. The HZ fruit in Hotan and Bazhou exhibit superior springiness and stickiness, while the fruit in Aksu and Kashi exhibit greater hardness. The texture of HZ fruit is significantly influenced by springiness, hardness, and adhesiveness, and a comprehensive evaluation model has been established through this research. This will provide a theoretical foundation for optimizing the dominant producing areas and regional production of HZ varieties in Xinjiang.

A superior variant of dried jujube in China is ‘Huizao’ (HZ) jujube. Nonetheless, detailed evaluations of the texture quality of HZ fruits have been the subject of few studies. Texture is a significant indicator of the sensory and processed quality of a fruit. Here, we differentiate and characterize the texture quality of HZ fruits from the four primary producing regions in southern Xinjiang, as well as develop a system for assessing the texture quality of HZ fruits. Furthermore, five texture indices of HZ fruits from 109 plantations were exhaustively evaluated utilizing principal component analysis, Pearson correlation analysis, and hierarchical clustering analysis. Consequently, by the 10th, 30th, 70th, and 90th percentiles, each index was classified into five grades—lower, medium, high, and higher. Correlation investigation indicated strong relationships between the springiness, chewiness, cohesiveness, gumminess, and hardness of HZ fruits. Springiness, hardness, and adhesiveness are essential indicators that influence the texture of HZ fruits. We used clustering analysis to separate the six texture indices into three major categories (hard factor, stick-elastic factor, and adhesive factor), with indices representing hardness, springiness, and adhesiveness, respectively. Furthermore, according to the factor molecules, the texture quality of HZ fruits in the four production areas was evaluated as Bazhou (1.24) > Hotan (0.773) > Kashi (-0.577) > Aksu (-0.852). RDA analysis of six texture quality parameters and 24 climate conditions identified higher mean temperature (TEM) and lower relative humidity (RHU) as the primary factors contributing to the improved texture quality of HZ fruits in Xinjiang. This study identified the texture quality characteristics of HZ fruits in four major producing areas of Southern Xinjiang, and it offered a theoretical foundation for optimizing the dominant producing areas and regional production of HZ varieties in Xinjiang.