Terpenoids constitute the largest class of plant secondary metabolites, playing essential roles in plant defense and aroma formation. Zanthoxylum bungeanum Maxim., an economically important Rutaceae species, is renowned for its distinctive aromatic fruits with significant culinary and medicinal value. However, the molecular mechanisms underlying terpenoid biosynthesis, particularly terpene synthase (TPS) gene functions, remain poorly understood. This study conducted genome-wide identification and characterization of the TPS gene family in Z. bungeanum, identifying 70 ZbTPS genes classified into five subfamilies: TPS-a, TPS-b, TPS-c, TPS-e/f, and TPS-g. Phylogenetic analysis revealed TPS-a and TPS-b as the largest subfamilies, functioning primarily as sesquiterpene and monoterpene synthases, respectively. Chromosomal localization showed uneven distribution with clusters near chromosome ends, suggesting expansion through tandem duplication. Integrating expression profiling across six fruit developmental stages with GC-MS metabolite analysis revealed correlations between ZbTPS expression and terpenoid accumulation patterns. ZbTPS55 exhibited chloroplast localization and positive correlations with key monoterpene compounds including limonene, ocimene, and geraniol. Functional validation through heterologous overexpression in tobacco, transient transformation of Z. bungeanum callus, and VIGS-mediated silencing in Z. armatum confirmed ZbTPS55 as a rate-limiting enzyme in monoterpene biosynthesis. This work elucidates the genetic basis of flavor formation in Z. bungeanum and provides candidate genes for molecular breeding targeting improved aroma quality and stress resilience.

High crop yields require adequate nutrients, particularly nitrate (N) and phosphorus (P). Identifying regulators for efficient N-P utilization is critical in wheat. To explore N-P interactions, we analyze root transcriptomes under varying N-P supplies and identify TaTCP6 as a potential regulator. Nitrate-stimulated TaTCP6 directly triggers the expression of genes related to nitrogen utilization. TaTCP6 competes with TaSPX1/4 for the release of TaPHR2, and also interacts with TaPHR2 to enhance the transactivation capacity of downstream genes. Thus, through the dual roles of TaTCP6, the TCP6-SPX-PHR2 module activates the expression of phosphorus starvation response (PSR) genes. Inhibiting TaTCP6 reduces N and P absorption, negatively impacting yield, while overexpressing TaTCP6 increases grain yield. Notably, overexpression of TaSPX1 suppresses nitrogen utilization genes, especially under low phosphorus conditions. In conclusion, our findings highlight the role of TaTCP6 in coordinating N and P utilization and propose a strategy to reduce fertilizer inputs for sustainable agriculture.

Mutualistic symbioses between plants and microorganisms have served as a cornerstone for terrestrial ecosystem establishment since the colonization of land by plants ca. 470 million years ago (Ma). These mutualisms diversified in symbiont partners and ecological functions in response to dynamic environmental shifts, with root-based architectures emerging later as a key adaptive innovation. Phylogenomic analyses reveal a conserved common symbiotic signalling pathway (CSSP) through the mycorrhizal-actinorhizal-rhizobial (MAR) evolutionary trajectory, underscoring convergent evolutionary mechanisms that facilitated the repeated emergence of mutualistic root-microbe interactions. Despite this shared foundation, recent studies highlight lineage-specific adaptations in symbiont recognition, immune evasion, and nutrient exchange, reflecting divergent evolutionary pressures and ecological niches. For instance, actinorhizal symbioses, although understudied compared to legume-rhizobia systems, exhibit unique adaptations in host specificity and nitrogen-fixation efficiency, offering untapped potential for sustainable agriculture and reforestation. This review synthesizes information from different disciplines to elucidate the origin and diversification of root symbioses, emphasizing molecular innovations and ecological drivers that shaped their evolution. We further explore the role of environmental pressures, such as resource availability and climate change, in driving the adaptive diversification of these symbiotic relationships. By integrating evolutionary, molecular, and ecological perspectives, this work advances our understanding of root symbioses as dynamic systems shaped by both conserved mechanisms and context-dependent adaptations.

Cherries are one of the economically important fruit crops in the Rosaceae family,Prunus genus.As the first fruits of the spring season in the northern hemisphere,their attractive appearance,intensely desirable tastes,high nutrients content,and consumer-friendly size captivate consumers worldwide.In the past 30 years,although cherry geneticists and breeders have greatly progressed in understanding the genetic and molecular basis underlying fruit quality,adaptation to climate change,and biotic and abiotic stress resistance,the utilization of cherry genomic data in genetics and molecular breeding has remained limited to date.Here,we thoroughly investigated recent discoveries in constructing genetic linkage maps,identifying quantitative trait loci(QTLs),genome-wide association studies(GWAS),and validating functional genes of edible cherries based on available de novo genomes and genome resequencing data of edible cherries.We further comprehensively demonstrated the genetic architecture of the main agronomic traits of edible cherries by methodically integrating QTLs,GWAS loci,and functional genes into the identical reference genome with improved annotations.These collective endeavors will offer new perspectives on the availability of sequence data and the construction of an interspecific pangenome of edible cherries,ultimately guiding cherry breeding strategies and genetic improvement programs,and facilitating the exploration of similar traits and breeding innovations across Prunus species.

The partitioning and metabolism of carbohydrates and lignin in leaves are essential for numerous physiological functions, growth and development of plants. This study was aimed to characterize these processes in four leaf types (i.e., autumn-, summer-, spring- and current-year spring shoots) of two citrus hybrids (loose-skin mandarin cultivars OP (i.e., cultivars 'Orah' (OR) Citrus reticulata Blanco and 'Ponkan' (PO) Citrus reticulata Blanco and the sweet orange cultivars NT 'Newhall navel orange' (NO) Citrus sinensis (L.) Osbeck and 'Tarocco' (TA) Citrus sinensis (L.) Osbeck) differing in fruit maturation under field conditions. For this purpose, we analyzed the levels of foliar structural, non-structural carbohydrates and lignin and the expression of related genes. Our results showed that the contents of structural, non-structural carbohydrates and lignin measured in the two hybrids and its partitioning were mostly determined by differences in gene expression recorded in hybrids, cultivars and leaf type. Particularly, differences between leaf types were largely attributed to up- and down-regulation of the expression of genes of cellulose synthesis, lignin precursor synthesis, the Calvin cycle, glycolysis, the tricarbonic acid and starch synthesis and degradation pathways. These differences between leaf types required more complex transcriptional regulation than differences between hybrids and cultivars. The present results indicated that the two citrus hybrids studied differed in the expression of structural, non-structural carbohydrates and lignin-related genes. Future studies have to show if the differences observed in foliar partitioning and metabolism of carbohydrates and lignin are translated into partitioning and metabolism of carbohydrates and lignin in the roots.

Floral sex differentiation is a pivotal biological process with implications for species evolution and biodiversity. Zanthoxylum armatum, a economically important pseudo-dioecious species, exhibits remarkable sexual plasticity, including a rare female-to-male sex transition, yet the underlying regulatory mechanisms remain poorly understood. To decipher the mechanisms underlying this phenomenon, we conducted a high-resolution temporal analysis integrating transcriptomics and phytohormone profiling across seven critical floral developmental stages. Our results revealed that sexual fate is governed by a dynamic hormonal antagonism: male flower development is promoted by a surge of bioactive cytokinins (e.g., tZR, cZR) and gibberellins (e.g., GA1, GA9), while female fate is associated with auxin conjugation (e.g., IAA-Asp) and cytokinin inactivation. Concurrent transcriptomic analyses identified key transcription factors-including MADS-box, AP2/ERF, WRKY, and GRF families-that are differentially expressed between sexes and orchestrate organ identity and development. Furthermore, weighted gene co-expression network analysis (WGCNA) linked specific hormonal signatures to distinct genetic modules, and alternative splicing analysis uncovered post-transcriptional regulation of genes critical for meiosis and pollen function. Additionally, alternative splicing analysis uncovered a complex network of splicing events that contribute to the regulation of gene expression during flower development. This study provides a comprehensive regulatory framework for floral sex determination in Z. armatum, highlighting the intricate interplay between phytohormones and transcriptional networks. Our findings offer foundational insights into the mechanisms of sex determination in plants and pave the way for manipulating sexual expression to enhance yield stability in horticultural crops.

Efficient photosynthesis and economic water use are essential for citrus growth, development and fruit production. The present study was aimed to characterize these processes in current-year spring, autumn, summer and spring shoots of citrus hybrid OP with cultivars ‘Orah’ (OR) and ‘Ponkan’ (PO) and citrus hybrid NT with cultivars ‘Newhall navel orange’ (NO) and ‘Tarocco’ (TA). Cultivars NO and PO show mid-fruit ripening, and cultivars TA and OR late-fruit ripening under field conditions. To characterize photosynthesis and water use, CO2 and H2O gas exchange, water use efficiency and expression of related genes were analyzed. The CO2 and H2O gas exchange parameters measured were determined by hybrid, cultivar and leaf type. Genes involved in lipid and pectin catabolic processes, cell wall biogenesis and modification, carbohydrate and xyloglucan metabolism, cellulose biosynthesis and cell growth were significantly upregulated in current-year spring shoots compared to the other leaf types investigated. Expression of photosynthesis- and transpiration-related genes was significantly enhanced in leaves of late-ripening cultivar OR compared to the other cultivars. These results indicate that the two hybrids of the four citrus cultivars studied differ in the expression of photosynthesis- and transpiration-related genes, but these differences cannot be attributed to fruit maturation.

Symbiotic associations between plants and microorganisms are crucial to global biogeochemical cycling and ecosystem stability. Mycorrhizal fungi and nitrogen (N2)-fixing bacteria are recognized as the two main groups of microorganisms involved in such symbiotic interactions. They not only constitute the most wide-spread symbiotic microorganisms, but also ensure plants to acquire additional N resources directly from the atmosphere. Although plant-microbial interactions, for example, the performance of AM-plant and rhizobia-legume plant symbioses, have been well studied and reviewed in detail previously, still less information is known about these processes in actinorhizal symbioses. The present review is aimed to summarize current knowledge of the interaction of partners in actinorhizal root symbioses, in particular the signalling processes during establishment of BNF, and the specificity of and dependency on different symbiotic partners in this interactions, based on evolution and distribution in the plant and microbial kingdom. The features of nutrient transfer in these root symbiotic relationships and the significance of actinorhizal symbioses for the performance of plants under environmental stress are discussed and compared with AM and rhizobia-legume symbioses. In addition, research gaps in actinorhizal root symbioses research are identified and future research avenues are suggested.

Shuguimei is a new early-ripening Chinese cherry [Cerasus pseudocerasus (Lindl.) G. Don] cultivar bred by Sichuan Agricultural University. The cultivar was derived from a cross between Hongfei and Nanzaohong in 2016. Through artificial cross pollination, approximately 200 hybrid seedlings flowered in 2019. The hybrid seedling HN880 was initially selected as an excellent individual in 2020 for its superior performance and high quality. The field trials were conducted at three sites in Sichuan Province (including Chengdu city, Suining city and Xichang city) from 2020 to 2023. It was approved as a new Chinese cherry cultivar by the Sichuan Provincial Non-major Crop Cultivar Certification Committee in January 2025, and named as Shuguimei. The young trees exhibit vigorous growth with a semiopen posture. The branchlets are grayish-brown, and the mature leaves are green and oblong-ovate with a long tail tip and a round base. The inflorescence typically consists of corymbs with 3-6 flowers. The flower buds are reddish, and the petals are white with a pink margin. Each flower has five round petals, one pistil, and 35-45 stamens with orange-yellow anthers. The fruit is primarily elliptical, with orangered peel. Its flesh is light yellow, juicy, and rich in flavor. Fruit mass ranges from 4.5 to 5.6 g. The average longitudinal diameter is 1.95 cm, the transverse diameter 2.11 cm, with a fruit shape index around 0.93. The average pit mass is 0.29 g. The fruit stalk is medium in length, averaging 2.33 cm. The total soluble solid (TSS) content ranges from 14.5% to 16.9%, and the titratable acid (TA) content is about 0.42%, giving a TSS/TA ratio of about 37.33. Glucose and fructose are the main components of soluble sugars, with contents of 392.48 and 301.67 g·kg-1, respectively. Malic acid is the predominant organic acid, at 84.59 g·kg-1. The overall eating quality is excellent. In Chengdu, Sichuan Province, the fruit development period lasts about 48-52 days, maturing in early to mid-April, which is 5-7 days earlier than its male parent, Hongfei. The vegetative growth period is about 310 days. Shuguimei bears fruit earlier and has good yield potential, with a small yield in the second year after planting and substantial fruiting in the fourth to fifth year. The average yield can reach 8400-8700 kg·hm-2. Young trees bear more fruit on middle and long branches, while adult trees predominantly bear fruit on boundary branches, short branches, and medium to long branches. The cultivar shows strong growth potential, adaptability, and resistance to diseases. It is suitable for planting in areas with ecological conditions similar to those found in the plains and hills of Sichuan Province. Shuguimei is best suited for planting in sandy loam with good drainage and deep soil layers. Spacing recommended is (2.5-3) m × (3.5-4) m. It is suitable to adopt open-center or central leader system.

BACKGROUND:Chinese cherry [Cerasus pseudocerasus (Lindl.) G.Don], an economically important fruit species native to southwestern China, plays a key role in regional agriculture. Organic acid composition is crucial for determining organoleptic quality of Chinese cherry, yet the underlying regulatory mechanisms remain unclear. RESULTS:In this study, we analyzed organic acid composition in mature fruits from 34 Chinese cherry accessions and tracked dynamic changes throughout fruit development in two landraces with distinct acidity levels (high and low), via HPLC and transcriptomics. Malic acid is the predominant organic acid component, which accounted for 73.66% of total acids. The high-acid landrace exhibited very rapid malate accumulation and relatively fast degradation, while the low-acid landrace showed minor changes in malate levels throughout fruit development. A total of 7,698 DEGs were clustered into six clusters, with DEGs from three clusters being significantly enriched in the "pyruvate metabolism" and "TCA cycle" pathways. Key genes involved in malate biosynthesis (cMDH, PEPC2) and transport (ALMT4, VHP) were up-regulated in the high-acid landrace, while NADP-ME, a gene associated with malate degradation, was down-regulated. Co-expressed network analysis highlighted strong correlations between key structural genes and transcription factors (MYB, ARF, AP2, and bHLH). Notably, CpODORANT1like and CpARF2Blike were identified as potential regulators of acidity, modulating NADP-ME and PEPC2 expression, respectively. These candidate genes were validated through an integrated analysis of phenotypic data and expression pattern of 34 genotypes. CONCLUSIONS:Our results suggest that malate accumulation in Chinese cherry is regulated at both the metabolic and vacuolar storage levels. This study deepens our understanding of the mechanisms regulating fruit acidity in Chinese cherry, which could inform future breeding efforts aimed at improving fruit flavor.

Chinese cherry [Cerasus pseudocerasus (Lindl.) G.Don] (syn. Prunus pseudocerasus Lindl.) is an economically important fruiting cherry species with a diverse range of attractive colors, spanning from the lightest yellow to the darkest black purple. However, the MYB transcription factors involved in anthocyanin biosynthesis underlying fruit color variation in Chinese cherry remain unknown. In this study, we characterized the R2R3-MYB gene family of Chinese cherry by genome-wide identification and compared it with those of 10 Rosaceae relatives and Arabidopsis thaliana. A total of 1490 R2R3-MYBs were classified into 43 subfamilies, which included 29 subfamilies containing both Rosaceae MYBs and AtMYBs. One subfamily (S45) contained only Rosaceae MYBs, while three subfamilies (S12, S75, and S77) contained only AtMYBs. The variation in gene numbers within identical subfamilies among different species and the absence of certain subfamilies in some species indicated the species-specific expansion within MYB gene family in Chinese cherry and its relatives. Segmental and tandem duplication events primarily contributed to the expansion of Chinese cherry R2R3-CpMYBs. The duplicated gene pairs underwent purifying selection during evolution after duplication events. Phylogenetic relationships and transcript profiling revealed that CpMYB10 and CpMYB4 are involved in the regulation of anthocyanin biosynthesis in Chinese cherry fruits. Expression patterns, transient overexpression and VIGS results confirmed that CpMYB10 promotes anthocyanin accumulation in the fruit skin, while CpMYB4 acts as a repressor, inhibiting anthocyanin biosynthesis of Chinese cherry. This study provides a comprehensive and systematic analysis of R2R3-MYB gene family in Chinese cherry and Rosaceae relatives, and identifies two regulators, CpMYB10 and CpMYB4, involved in anthocyanin biosynthesis in Chinese cherry. These results help to develop and utilize the potential functions of anthocyanins in Chinese cherry.

Urea is the most frequently used nitrogen (N) fertilizer worldwide. However, the mechanisms in plants to cope with excess urea are largely unknown, especially for woody legumes that can meet their N demand by their own N2-fixation capacity. Here, we studied the immediate consequences of different amounts of urea application and exposure duration on photosynthesis, N metabolism, and the activity of antioxidative enzymes of Robinia pseudoacacia seedlings. For this purpose, seedlings were grown for 3 months under normal N availability with rhizobia inoculation and, subsequently, 50 mg N kg−1 was applied to the soil twice with urea as additional N source. Our results show that excess urea application significantly promoted photosynthesis, which increased by 80.3% and 84.7% compared with CK after the 1st and 2nd urea applications, respectively. The increase in photosynthesis translated into an increase in root and nodule biomass of 88.7% and 82.0%, respectively, while leaf biomass decreased by 4.8% after the first application of urea. The N content in leaves was 92.6% higher than in roots, but excess urea application increased the N content of protein and free amino acids in roots by 25.0%, and 43.3%, respectively. Apparently, enhanced root growth and N storage in the roots constitute mechanisms to prevent the negative consequences of excess N in the shoot upon urea application. Nitrate reductase (NR) activity of leaves and roots increased by 74.4% and 26.3%, respectively. Glutathione reductase (GR) activity in leaves and roots was enhanced by 337% and 34.0%, respectively, but then decreased rapidly to the initial level before fertilization. This result shows that not only N metabolism, but also antioxidative capacity was transiently promoted by excess urea application. Apparently, excess urea application initially poses oxidative stress to the plants that is immediately counteracted by enhanced scavenging of reactive oxygen species via enhanced GR activity.

Chinese cherry [Cerasus pseudocerasus (Lindl.) G.Don], native to China, is an economically important fruit crop with attractive colors and delicious flavors. However, the specific metabolites present in cherry fruits have remained unknown. Here, we firstly characterized 1439 metabolite components of Chinese cherry fruits, predominantly including amino acids, flavonoids, and phenolic acids. Moreover, we screened ten biomarkers of Chinese cherry accessions by ROC curve analysis. Among 250 flavonoids, 26 structurally unique anthocyanins collectively determined fruit color, with cyanidins playing a dominant role. Differences in accumulated metabolites between anthocyanin and proanthocyanidin pathways were likely responsible for the variation in fruit color, ranging from yellow to black purple. Meanwhile, we found limocitrin-7-O-glucoside, along with eight other compounds, as underlying contributors to bitter off-taste experienced in fruits. This study provides insights into the regulatory network of metabolites involved in color variation and bitterness formation and genetic improvement of Chinese cherry fruits.

Chinese cherry [Prunus. pseudocerasus Lindl., syn. Cerasus. pseudocerasus (Lindl.) G.Don], an economically important tetraploid fruit crop native to southwestern China, is celebrated as “the earliest fruit of spring”. Understanding the inheritance and heterosis of major agronomical traits is essential for advancing its breeding. In this study, we conducted a three-year observation and inheritance analysis of 32 economic traits in the reciprocal F1 populations (NH, n = 114; HN, n = 87) derived from Chinese cherry landraces “Nanzaohong” and “Hongfei”. The results revealed a broad segregation for all traits in F1 offspring. Fruit size exhibited an inheritance tendency toward smaller dimensions, with some individuals displaying extreme values (Fruit weight, HH = 3.90~12.15%) that highlighted the potential for selecting larger fruits. The hybrids showed a tendency for sweeter fruit flavor, with total soluble solids (RHm = 7.00~19.35%) and soluble sugar (RHm = 11.09% and 17.47%) exhibiting hybrid vigor, along with a decreasing tendency in titratable acid (RHm = −16.08~−1.05%). The flowering and fruiting phenology tended to occur earlier, with extremely early and late flowering lines offering the potential to extend the ornamental and harvesting periods. Fruit bitterness (H2 = 0.98 and 0.95) and fruit skin color (H2 = 0.93 and 0.89) displayed the highest heritability. Correlation analysis revealed strong internal correlations among trait categories, confirming the reliability of the data collection and analysis. Moreover, no significant differences were observed between the maternal and the paternal effect on the inheritance for agronomic traits attributes. This study systematically clarifies the inheritance trends of agronomic traits in Chinese cherry, providing a foundation for the rational selection of parental lines in breeding strategies and laying the groundwork for future molecular genetic research.

Mutualistic root symbioses, particularly those involving mycorrhizal fungi and nitrogen-fixing bacteria, are pivotal to ecosystem productivity and stability. Plant-soil feedbacks (PSFs) and climate serve as primary regulators of these symbiotic interactions, determining their establishment, maintenance, and diversity. PSFs, encompassing the complex interactions between plants and soil biota, modulate nutrient uptake and ultimately influence plant growth and development. Climate not only shapes the abundance, composition and performance of soil biota, but also directly impacts the distribution and response of plant symbioses to environmental shifts including rising temperatures and modified precipitation patterns. This review compiles recent advancements in the ecology and diversity of mycorrhizal and nitrogen-fixing associations, emphasizing the interaction between soil biota and climate, and their implications for ecosystem functions in the context of climate change. It also identifies key gaps in our understanding, such as the molecular mechanisms at play, the genetic variability involved, and the impact of global environmental changes on symbiotic networks. Addressing these questions is essential for a more profound comprehension of the complex plant-soil dynamics that sculpt terrestrial ecosystems.

Chinese cherry is an economically significant fruiting cherry species within Rosaceae family. Soluble sugar and organic acid are crucial factors affecting fruit flavor, while the genetic basis for these traits in Chinese cherry remains largely unknown. In this study, we determined sugar and acid components in 190 and 187 representative hybrids from an intraspecific cross of Chinese cherry over two consecutive years. Fructose and glucose were the major sugars in both progeny and parents, but their contents varied considerably between years. Fructose represented a higher proportion in progeny than in parents. Malic acid was the most predominant component, accounting for a relatively stable proportion (∼70%) for both years. The F1 population exhibited wide phenotypic variations, with coefficient of variation ranging from 6.57% to 108.63%. Regarding inheritance patterns, sugars tended towards smaller values, while malic acid exhibited significant transgressive heterosis. Sugars and acids were primarily governed by 2MG-AD or 2MG-EA model. Major gene heritability exceeded 88% for acids but much lower (12%∼75%) for sugars. These results suggest that acid contents might be controlled by two major genes, while sugars are mainly governed by polygenes. This study provides a theoretic basis for understanding genetic predisposition underlying sugar-acid fractions in Chinese cherry fruit.

>Common wheat is a staple food for 35%of the global population,therefore increasing wheat yield in an ever-changing environment is essential for food security in the present day (Peng et al., 2011).Root system is responsible for water and nutrient acquisition, thus crucial for competitive fitness and crop yield in challenging environments (Karlova et al., 2021; Liu et al., 2022). Over the past decades,extensive research has focused on identifying genes accountable for root growth and development in plants (Rogers and Benfey, 2015).

Fruit softening is a complex, genetically programmed and environmentally regulated process, which undergoes biochemical and physiological changes during fruit development. The molecular mechanisms that determine these changes in Chinese cherry [Cerasus peseudocerasus (Lindl.) G.Don] fruits are still unknown. In the present study, fruits of hard-fleshed ‘Hongfei’ and soft-fleshed ‘Pengzhoubai’ varieties of Chinese cherry were selected to illustrate the fruit softening at different developmental stages. We analyzed physiological characteristics and transcriptome profiles to identify key cell wall components and candidate genes related to fruit softening and construct the co-expression networks. The dynamic changes of cell wall components (cellulose, hemicellulose, pectin, and lignin), the degrading enzyme activities, and the microstructure were closely related to the fruit firmness during fruit softening. A total of 6,757 and 3,998 differentially expressed genes (DEGs) were screened between stages and varieties, respectively. Comprehensive functional enrichment analysis supported that cell wall metabolism and plant hormone signal transduction pathways were involved in fruit softening. The majority of structural genes were significantly increased with fruit ripening in both varieties, but mainly down-regulated in Hongfei fruits compared with Pengzhoubai, especially DEGs related to cellulose and hemicellulose metabolism. The expression levels of genes involving lignin biosynthesis were decreased with fruit ripening, while mainly up-regulated in Hongfei fruits at red stage. These obvious differences might delay the cell all degrading and loosening, and enhance the cell wall stiffing in Hongfei fruits, which maintained a higher level of fruit firmness than Pengzhoubai. Co-expressed network analysis showed that the key structural genes were correlated with plant hormone signal genes (such as abscisic acid, auxin, and jasmonic acid) and transcription factors (MADS, bHLH, MYB, ERF, NAC, and WRKY). The RNA-seq results were supported using RT-qPCR by 25 selected DEGs that involved in cell wall metabolism, hormone signal pathways and TF genes. These results provide important basis for the molecular mechanism of fruit softening in Chinese cherry.

Polyploidy is considered a driving force in plant evolution and diversification. Chinese cherry [Cerasus pseudocerasus (Lindl.) G.Don], an economically important fruit crop native to China, has evolved at the tetraploid level, with a few pentaploid and hexaploid populations. However, its auto- or allo-polyploid origin remains unclear. To address this issue, we analyzed the ploidy levels and rDNA chromosomal distribution in self- and open-pollinated seedling progenies of tetraploid and hexaploid Chinese cherry. Genomic in situ hybridization (GISH) analysis was conducted to reveal the genomic relationships between Chinese cherry and diploid relatives from the genus Cerasus. Both self- and open-pollinated progenies of tetraploid Chinese cherry exhibited tetraploids, pentaploids, and hexaploids, with tetraploids being the most predominant. In the seedling progenies of hexaploid Chinese cherry, the majority of hexaploids and a few pentaploids were observed. A small number of aneuploids were also observed in the seedling progenies. Chromosome 1, characterized by distinct length characteristics, could be considered the representative chromosome of Chinese cherry. The basic Chinese cherry genome carried two 5S rDNA signals with similar intensity, and polyploids had the expected multiples of this copy number. The 5S rDNA sites were located at the per-centromeric regions of the short arm on chromosomes 4 and 5. Three 45S rDNA sites were detected on chr. 3, 4 and 7 in the haploid complement of Chinese cherry. Tetraploids exhibited 12 signals, while pentaploids and hexaploids showed fewer numbers than expected multiples. Based on the GISH signals, Chinese cherry demonstrated relatively close relationships with C. campanulata and C. conradinae, while being distantly related to another fruiting cherry, C. avium. In combination with the above results, our findings suggested that Chinese cherry likely originated from autotetraploidy.

【Objective】The aim of this study was to pave the way for the construction of high-density genetic map and QTL (quantitative trait locus) analysis, so as to facilitate the parental selection and mating design in the breeding programs targeting for new varieties in Chinese cherry (Cerasus pseudocerasus (Lindl.) G.Don) by investigating and analyzing fruit traits of F1 progenies between Nanzaohong (NZH, early maturity, orange red) and Hongfei (HF, purple red, with good comprehensive characteristics).【Method】The heredity variation and inheritance tendency of 17 fruit quality traits in the F1 segregating populations (n=226) were investigated, which were derived from the reciprocal cross between NZH and HF These traits included fruit weight, longitudinal, transverse and lateral diameter, total soluble solids (TSS), soluble sugar (SS), titratable acid (TA), anthocyanin content, fruit shape index, fruit development period, and fruit stalk length, etc.【Result】The average fruit weight in offspring of both NZH × HF (4.30 g; range: 2.59-7.46 g) and HF × NZH (4.05 g; range: 2.45-6.48 g) was smaller than the mid-parent value (4.58 g). The TSS content (14.55% and 14.51%) was higher than those of two parents (12.97% and 11.36%), and the ratio of individuals with TSS content higher than high parent（HH）was 78.52% and 76.09%. The average TA content of individuals from the reciprocal cross was lower than the low parent (LL) (47.92% and 41.94%). Peel color segregated in the F1 progenies, with orange red, red, purple red and black purple being observed. Hybrids with red fruit color accounted for the largest proportion. The anthocyanin content is in the range of 3.12-112.51 and 1.80-79.94 mg/kg. The average fruit development period of NZH × HF progenies was two days shorter than that of HF × NZH progenies, which was mainly affected by the male parent. The fruit stalk length showed heterosis with HH values of 49.25% and 43.33%, respectively. The mixed major gene and polygene inheritance model method was evaluated for their fitness relating to these traits. Two major genes plus polygenes model was the optimal genetic model for 11 (out of 12) quantitative traits except for the fruit longitudinal diameter, which was controlled by one major gene plus polygenes.【Conclusion】The main fruit quality characteristics were quantitative traits controlled by polygenic loci. The inheritance trend of the fruit weight, longitudinal, transverse, lateral diameter, TA, and anthocyanin content tended to be decreased, while the TSS, SS content and fruit stalk length tended to be increased.