Search Results (53)

The undertaking of distant hybridization holds paramount significance for the innovation of tea germplasm resources and the cultivation of superior, specialized tea varieties. However, challenges manifest during the process of tea plant distant hybridization breeding, with reproductive barriers impeding the successful acquisition of hybrid progeny; the precise stages at which these barriers occur remain unclear. In this study, utilizing Camellia sinensis cv. Jinxuan as the maternal parent, as well as C. gymnogyna Chang and C. sinensis cv. Yinghong No.9 as the paternal parents, interspecific distant hybridization (DH) and intraspecific hybridization (IH) were conducted. The investigation involved the observation of pollen germination and pollen tube behavior on the stigma, the scrutiny of the developmental dynamics of the ovary post-hybridization, and the examination of the stages and reasons for reproductive disorders during tea tree distant hybridization. The findings indicate that both IH and DH exhibit pre-fertilization barriers. The pre-embryonic development of hybrids obtained from DH is normal, but there is a significant fruit drop during the stage of fruit development. The germination rate of mature seeds obtained from DH is low, and there are pronounced post-fertilization disorders, which are the primary reasons for the difficulty in achieving successful tea plant distant hybridization. An analysis of the genetic variation in phenotypes and chemical components in the progeny after distant hybridization revealed widespread variation and rich genetic diversity. The identification of progeny with a high amino acid and caffeine content holds promise for future production and breeding, providing valuable theoretical references for the selection of parents in the creation of low-caffeine-content tea germplasm resources. Full article

Leaves are the most ubiquitous plant organs, whose macrostructures exhibit close correlations with environmental factors while simultaneously reflecting inherent genetic and evolutionary patterns. These characteristics render them highly significant for plant taxonomy, ecology, and related disciplines. Therefore, this study presents the first comprehensive evaluation of Malus leaf macrostructures for infraspecific classification. By establishing a trait-screening system, we conducted a numerical taxonomic analysis of leaf phenotypic variation across 73 Malus germplasm (34 species and 39 cultivars). Through ancestor-inclined distribution characteristic analysis, we investigated phylogenetic relationships at both the genus level and infraspecific ranks within Malus. A total of 21 leaf phenotypic traits were selected from 50 candidate traits based on the following criteria: high diversity, abundance, and evenness (D ≥ 0.50, H ≥ 0.80, and E ≥ 0.60); significant intraspecific uniformity and interspecific distinctness ($\overline{CV}$ ≤ 10% and $CV$ ≥ 15%). Notably, the selected traits with low intraspecific variability ($\overline{CV}$ ≤ 10%) exhibit environmental robustness, likely reflecting low phenotypic plasticity of these specific traits under varying conditions. This stability enhances their taxonomic utility. It was found that the highest ancestor-inclined distribution probability reached 90% for 10 traceable cultivars, demonstrating reliable breeding lines. Based on morphological evidence, there was a highly significant correlation between the evolutionary orders of (Sect. Docyniopsis → Sect. Sorbomalus → Sect. Malus) and group/sub-groups (B₁ → B₂ → A). This study demonstrates that phenotypic variation in leaf macrostructures can effectively explore the affinities among Malus germplasm, exhibiting taxonomic significance at the infraspecific level, thereby providing references for variety selection. However, hybrid offspring may exhibit mixed parental characteristics, leading to blurred species boundaries. And convergent evolution may create false homologies, potentially misleading morphology-based taxonomic inferences. The inferred taxonomic relationships present certain limitations that warrant further investigation. Full article

Pummelo (Citrus maxima) is an ancestral species that has given rise to several major citrus varieties, such as sweet orange (C. x aurantium var. sinensis) and grapefruit (C. x aurantium var. paradisi). This species is also cultivated and its fruit consumed, particularly in Asia. Over the course of evolution, the allogamous reproduction of pummelos and the absence of asexual multiplication have contributed to its diversification. To assess its phenotypic diversity and the chemical composition of leaf and peel essential oils, genetic analysis using DNA markers is an essential prerequisite to ensure the identity and if varieties belong to this species. Fifty-eight accessions classified as grapefruits or pummelos were analyzed using 42 SSRs, 4 Indels, and 36 SNP markers. Based on the allelic composition of these markers, 20 cultivars were detected belonging to pummelos, 18 cultivars to grapefruits, and 11 were interspecific hybrids. The grapefruit inter-cultivar SSR diversity is null. The genetic origin of five interspecific hybrids is elucidated. The level of phenotypic diversity and of essential oil composition corroborate the modes of diversification, with high levels for those resulting from crosses and very low levels for the group of grapefruit mutants. Only the characteristics of breeding selection (pulp color, acidity and aspermia) are variable in grapefruits. In the composition of leaf essential oils (LEOs), nine profiles were detected in grapefruits based on variations in six compounds (neral, geranial, β-phellandrene, γ-terpinene, (E)-β-ocimene, and β-pinene). The seven interspecific hybrids involving pummelo as one parent show particular LEO profiles but without specific compounds, with the exception of p-cymenene which is present only in Wheeny. The diversity of peel essential oils in pummelos is lower, but variations in γ-terpinene, β-pinene, limonene, and myrcene make it possible to define seven profiles. With genetic verification the chemical and phenotypic diversity of the two species, pummelo and grapefruit, revealed in this study can be used as a reference for behavior in a specific environment. Full article

Studying fruit genetic trends, heterosis, and growth traits in pear hybrid progeny provides the foundation for variety breeding. The aim of this research is to reveal the trait performance of the hybrid progeny of Chinese white pear and Western pear and provide a theoretical basis for other breeders to predict the trait performance of their hybrid progeny when selecting Eastern pear and Western pear as parents. Our research team constructed a ‘Yuluxiang’ × ‘Xianghongli’ interspecific hybrid population in 2015, and in 2023, we conducted a two-year investigation of 16 traits in 140 hybrid progeny, including 11 fruit traits and 5 growth traits, and analyzed and compared the genetic variation and heterosis of traits, as well as the correlation between various traits. The results showed that the hybrid progeny was widely segregated for single fruit weight (FW), soluble solid (SS) content, and titratable acid (TA) content and conformed to a normal distribution, with quantitative genetic traits under polygenic control. The highest two-year coefficients of variation for TA were 54.42% in 2023 and 39.17% in 2024. A genetic trend of decreasing FW was observed, which was greatly influenced by the male sex. The ratio of soft soluble flesh to crispy flesh was 1:1, and the gene controlling this trait may be a quality trait controlled by a single gene. The traits that showed transgressive heterosis for two years included fruit longitudinal diameter (FLoD), fruit shape index (FSI), and TA, and those that showed negative heterosis included FW, SS, leaf longitudinal diameter (LLoD), and leaf lateral diameter (LLaD). Correlation analysis indicated that the progeny of crosses in this combination, which had red fruit skin, may also present red early flowering color (EFC) and young leaf color (YLC), reddish brown annual branch color (ABC), and lower FSI, fruit stalk length (FSL), LLaD, and TA. Thus, at the seedling stage, individuals with red-colored fruit may be screened by observing the color of young leaves and young stems and the lateral diameter of the leaves. Principal component analysis showed that among the 16 traits included in six principal components, peel color (PC), FLoD, 2024SS, fruit tape (FT), and FSI were the main factors causing differences in fruit phenotypes. This study systematically elucidated the genetic trends of agronomic traits in pears and will provide a theoretical basis for the selection of parents and early selection of hybrid progeny in pear hybrid breeding. Full article

Paeonia ludlowii is a threatened and valuable germplasm in the cultivated tree peony gene pool, with distinctive traits such as tall stature, pure yellow flowers, and scarlet foliage in autumn. However, the crossability barrier limits gene transfer from P. ludlowii to cultivated tree peony. Therefore, our study investigated the reasons for the lack of crossability between P. ludlowii and Paeonia ostii ‘Fengdan’. Distant cross pollination (DH) resulted in the formation of many calloses at the ends of the pollen tubes, which grew non-polar, twisted, entangled, and often stopped in the style. Pollen tubes elongated the fastest in self-pollination (CK), and pollen tubes elongated faster and fewer pollen tube abnormalities were observed in stigmas treated with KCl solution before pollination (KH) than in DH. During pollen–pistil interactions, the absence of stigma exudates, high levels of H₂O₂, O₂⁻, MDA, ^•OH, ABA, and MeJA, and lower levels of BR and GA₃ may negatively affect pollen germination and pollen tube elongation in the pistil of P. ostii ‘Fengdan’. Pollen tubes in CK and KH penetrated the ovule into the embryo sac at 24 h after pollination, whereas only a few pollen tubes in DH penetrated the ovule at 36 h after pollination. Pre-embryo abnormalities and the inhibition of free nuclear endosperm division resulted in embryo abortion in most of the fruits of DH and many fruits of KH, which occurred between 10 and 20 days after pollination, whereas embryos in CK developed well. Early embryo abortion and endosperm abortion in most of the fruits of DH and KH led to seed abortion. Seed abortion in KH and DH was mainly due to an insufficient supply of auxins and gibberellins and lower content of soluble protein and soluble sugars. The cross failure between P. ludlowii and P. ostii ‘Fengdan’ is mostly caused by a pre-fertilization barrier. KH treatment can effectively promote pollen tube growth and facilitate normal development of hybrid embryos. These findings provide new insights into overcoming the interspecific hybridization barrier between cultivated tree peony varieties and wild species. Full article

Interspecific hybridization serves as a crucial strategy for innovating sugarcane germplasms. Currently, nearly all modern sugarcane varieties that incorporate genetic material are derived from Saccharum spontaneum. The number of chromosomes in S. spontaneum ranges from 40 to 128, contributing significantly to the diversity of its genetic resources. However, the genetic mechanisms driving chromosome number variation in S. spontaneum remain to be fully elucidated. Here, oligonucleotide fluorescence in situ hybridization (Oligo-FISH) was conducted to identify individual chromosomes and explore chromosome transmission during the intraspecific hybridization of S. spontaneum. The results indicate that from the progenies generated from S. spontaneum Yunnan2017-22 (2n = 8x = 64) and Yunnan82-1 (2n = 8x = 64) emerged two distinct karyotypes, 2n = 12x = 96 (A1) and 2n = 8x = 64 (A2, A33-1, A18). This implies that the chromosome inheritances were 2n + n and n + n in the progenies. However, self-pollinated samples of A1 (2n = 12x = 96) produced normal offspring C1 (2n = 94) and C2 (2n = 96). The 2n + n inheritance pattern did not continue. In another cross, the progenies derived from S. spontaneum Yunnan2017-41 (2n = 8x = 64) and Yunnan8 (2n = 10x = 80) carried a karyotype of 2n = 9x = 72, with n + n inheritance mode. These findings highlight the existence of two chromosome inheritance modes, 2n + n and n + n, in the context of the intraspecific hybridization of S. spontaneum. Additionally, hybridization between different ploidy S. spontaneum was also accompanied by chromosomal translocations (A1, A2, A18, A18) and loss (A2, A33-1, AA-4, and C2) that further resulted in the complexity of the S. spontaneum genome. Together, these findings highlight diverse chromosome inheritance in S. spontaneum hybridization, and provide a theoretical foundation for the further utilization of S. spontaneum germplasm in sugarcane breeding. Full article

Nightlily (Hemerocallis citrina Baroni) is an important vegetable with edible floral organs. It possesses considerable economic value due to its edibility, ornamental, and medicinal properties. However, the genetic linkage map construction and quantitative trait locus (QTL) mapping of nightlily have not been performed. This study used two varieties ‘Dongzhuanghuanghua’ and ‘Chonglihua’ of nightlily as cross parents to establish an intraspecific hybridization population of 120 F₁ progenies. The ‘Datonghuanghua’ (female) variety of nightlily and ‘Lullaby Baby’ (male) variety of daylily were selected to construct an interspecific hybridization population of 55 F₁ progenies. A total of 965 expressed sequence tag–simple sequence repeats (EST-SSRs), along with 20 SSR markers from various sources, were used for genetic mapping. Among these markers, CT/TC (9.24%) of the dinucleotide and GGA/GAG/AGG (4.67%) of the trinucleotide repeat motifs were most abundant. In the intraspecific hybridization genetic map, a total of 124 markers were resolved into 11 linkage groups, with a total map length of 1535.07 cM and an average interval of 12.38 cM. Similarly, the interspecific hybridization map contained 11 linkage groups but with 164 markers, a total map length of 2517.06 cM, and an average interval of 15.35 cM. The two constructed maps had 48 identical markers and demonstrated good collinearity. The collinearity analysis showed that 161 markers hit the genomic sequence of the published H. citrina genome, indicating that the two constructed genetic maps had high accuracy. Phenotypic data were investigated over two consecutive years (2018 and 2019) for flower bud fresh weight, dry weight, and bud length in two hybridization populations. A total of nine QTLs associated with flower bud-related traits were identified, among which those located on linkage group 8 of the intraspecific genetic map and linkage group 4 of the interspecific genetic map showed good stability. All nine QTLs had LOD values of not less than 4 and PVE values of not less than 15% over two years. This is the first report about the intra- and interspecific genetic map construction and QTL mapping of the flower bud-related traits in nightlily based on a genetic map. The results promote marker-assisted breeding and offer insights into the mechanisms underlying important traits of the genus Hemerocallis. Full article

More than ten species of the Actinidia Lindl. genus bear edible fruits rich in biologically active compounds, which are essential and beneficial for human health. The most popular cultivars today are the large-fruited Actinidia species, A. deliciosa and A. chinensis, commonly known as kiwi. However, small-fruited kiwi cultivars are gaining prominence due to their high nutritional value, superior cold resistance, and suitability for temperate climates. In Russia, these are represented by Far Eastern species: A. arguta, A. kolomikta, and A. polygama. Despite increasing consumer interest, Russian Actinidia cultivars remain little studied, with fragmented genetic data available for breeding purposes. Our objective was to analyze the Actinidia collection at the Federal Horticultural Center for Breeding, Agrotechnology, and Nursery and the N.V. Tsitsin Main Botanical Garden (MBG RAS, Moscow), which includes samples from four species, A. kolomikta, A. arguta, A. polygama, A. purpurea, interspecific hybrids, and derived varieties, using RAD sequencing. We assessed the genetic variability of all species, identified population groups within A. kolomikta and A. arguta based on origin, determined ploidy levels across the collection, and identified a set of SNP markers associated with valuable agronomic traits. Full article

In this study, 53 pear genotypes were evaluated, including 19 Asian varieties, 7 botanical species and 13 new interspecific hybrids. The ploidy level and nuclear DNA content were determined by flow cytometry. In addition, the morphological traits and their possible correlations with the genome size were analyzed. One triploid genotype was found. The Asian varieties had a lower average genome size (553.4 Mbp) than the European varieties (564.1 Mbp). The average nuclear DNA content was 1.14 pg/2C for the diploid genotypes and 1.77 pg/2C DNA for the triploids. The Asian varieties had significantly larger leaves than the European ones. Pyrus calleryana had the smallest flowers and P. Caucasica the largest, but the varieties showed no significant differences in flower size. The pollen grain size ranged from 37.7 to 59.0 μm. However, there were no significant correlations between the genotype groups or genome sizes. The Asian cultivars had, on average, smaller stomata (28.4 μm) than the European cultivars (31.6 μm). The largest stomata size was measured for the triploid genotypes (37.9 μm). There was a positive correlation between the genome size and stomatal length and a negative correlation between the genome size and leaf length, leaf width and flower diameter. Full article

This study focused on the phenology of Coffea arabica var. Esperanza L4A5, an F1 interspecific hybrid obtained by crossing commercial varieties with wild genotypes from Ethiopia and Sudan. Most phenological studies on C. arabica have been conducted in traditional high-altitude regions, leaving a gap in the understanding of its behavior in non-traditional areas such as the Caribbean region of Costa Rica. To establish a baseline on the phenological behavior of the Esperanza L4A5 hybrid in this region, we conducted a four-year study examining the effects of different agroforestry associations: (1) Albizia saman; (2) Hymenaea courbaril and Erythrina poeppigiana; (3) Anacardium excelsum and Erythrina poeppigiana; and coffee plots under full sun. Additionally, the phenology of the coffee plants was evaluated under differentiated fertilizations (physical, chemical, and without fertilization), considering meteorological factors such as temperature, humidity, and rainfall. The observed variables included the development of floral nodes, pre-anthesis, anthesis, and fruiting stages. To analyze the relationships between environmental factors, tree cover, fertilization, and the phenological stages, we employed multiple linear regression (MLR), which revealed that both tree cover and physical and chemical fertilizations had significant effects on the presence of developed floral nodes and, consequently, on fruit production. Furthermore, the random forest (RF) model was applied to capture complex interactions between variables and to rank the importance of meteorological factors, tree cover, and fertilization practices. These analyses demonstrated that the Esperanza L4A5 hybrid exhibited viable phenological development under the atypical conditions of the Caribbean region of Costa Rica, suggesting its potential to adapt and thrive in non-traditional coffee-growing areas. Full article

Banana breeding consists of obtaining diploid, triploid, and tetraploid intra- and interspecific hybrids by conventional breeding methods with the objective of aggregating characteristics of agronomic and commercial interest. Given the narrow genetic base of bananas, Embrapa’s Banana Genetic Breeding Program (BGBP) aims at crosses between improved diploids (ID) (ID × ID) and between improved diploids (ID) and commercial triploids (ID × CTP) and tetraploids (ID × CTT), in order to increase the genetic base and variability in bananas regarding agronomic traits of interest and resistance to main biotic and abiotic factors. These improved diploids are resistant to main fungal diseases such as yellow (YSD) and black Sigatoka (BSD) disease and Fusarium wilt (race 1 and subtropical race 4), the latter being one of the most devastating diseases in bananas. The genetic diversity between 22 improved diploids and seven commercial banana triploids was analyzed using DNA molecular markers. Five IRAP (Inter-Retrotransposon Amplified Polymorphism, 7 ISSR (Inter-Simple Sequence Repeats) and 12 SSR (Simple Sequence Repeat) markers were used. The genetic dissimilarity matrix was based on the Jaccard dissimilarity index; clusters were separated using the UPGMA (Unweighted Pair Group Method With Arithmetic Mean) method and cophenetic correlation of 0.8755. This study of the genetic diversity between improved diploids and commercial triploids, based on the genetic dissimilarity matrix, revealed that the most dissimilar diploids were DM23 and DM15 (74%) and DM16 and DM15 (74%). The smallest genetic distances between the improved diploids and commercial triploids were between TCGN25 and DM17 (50%) and TCN26 and DM17 (50%). The genetic distance matrix also revealed important genotypes to be used in crosses in order to maintain good characteristics in commercial triploids when crossed with improved diploids. The results of our study provide better breeding strategies for one of the largest banana-breeding programs worldwide focused on the development of banana varieties resistant to main biotic and abiotic factors. Full article

Pear (Pyrus spp.) is a major fruit crop in the Rosaceae family, and extensive efforts have been undertaken to develop elite varieties. With advances in genome sequencing technologies, single-nucleotide polymorphisms (SNPs) are commonly used as DNA markers in crop species. In this study, a large-scale discovery of SNPs was conducted using genotyping by sequencing in a collection of 48 cultivated pear accessions. A total of 256,538 confident SNPs were found on 17 chromosomes, and 288 SNPs were filtered based on polymorphic information content, heterozygosity rate, and genome distribution. This subset of SNPs was used to genotype an additional 144 accessions, consisting of P. pyrifolia (53), P. ussuriensis (27), P. bretschneideri (19), P. communis (26), interspecific hybrids (14), and others (5). The 232 SNPs with reliable polymorphisms revealed genetic variations between and within species in the 192 pear accessions. The Asian species (P. pyrifolia, P. ussuriensis, and P. bretschneideri) and interspecific hybrids were genetically differentiated from the European species (P. communis). Furthermore, the P. pyrifolia population showed higher genetic diversity relative to the other populations. The 232 SNPs and four subsets (192, 96, 48, and 24 SNPs) were assessed for variety identification. The 192 SNP subset identified 173 (90.1%) of 192 accessions, which was comparable to 175 (91.1%) from the 232 SNPs. The other three subsets showed 81.8% (24 SNPs) to 87.5% (96 SNPs) identification rates. The resulting SNPs will be a useful resource to investigate genetic variations and develop an efficient DNA barcoding system for variety identification in cultivated pears. Full article

Leaf rust (caused by Puccinia triticina Erikss., Pt) is a severe foliar disease of cultivated wheat worldwide. Severe development of the disease results in significant losses in seed yield and quality. Growing immune varieties is the most rational method for Pt control in terms of effectiveness and ecological safety. However, the gene pool of cultivated wheat is very narrow for seedling Pt effective resistance genes, which hampers breeding for this trait. One of the well-known methods to broaden genetic diversity for resistance is the introgression of highly effective genes from wild relatives into the genomes of cultivated wheat. The Aegilops L. species have been proven to be perfectly suited for this purpose. No gene for Pt resistance has been transferred to wheat from Aegilops biuncialis Vis. (Lorent’s goatgrass) up to now. Previously, we selected eight accessions of the species from the VIR (N.I. Vavilov All-Russian Institute of Plant Genetic Resources) genebank that showed a perfect level of resistance to leaf rust. In this research, we studied the genetic control of resistance using hybridological, phytopathological, and molecular analyses. According to the F₁–F₃ hybrid evaluation results, each accession possesses one dominant gene for Pt resistance, and genes in different accessions are allelic or very tightly linked. Phytopathological test clone analysis showed that this gene is not identical to Lr9, Lr19, Lr24, Lr39, and Lr47, which are effective against Pt populations in some areas of Russia. This conclusion was partially supported by the results of the identification of DNA markers specific to these genes in bread wheat. Thus, we identified one dominant gene (temporarily symbolized as LrBi1) for effective seedling Pt resistance; it is recommended for introgression to cultivated wheat via interspecific hybridization. Full article

The flowering period of rice significantly impacts variety adaptability and yield formation. Properly shortening the reproductive period of rice varieties can expand their ecological range without significant yield reduction. Targeted genome editing, like CRISPR/Cas9, is an ideal tool to fine-tune rice growth stages and boost yield synergistically. In this study, we developed a CRISPR/Cas9-mediated multiplex genome-editing vector containing five genes related to three traits, Hd2, Ghd7, and DTH8 (flowering-stage genes), along with the recessive rice blast resistance gene Pi21 and the aromatic gene BADH2. This vector was introduced into the high-quality japonica rice variety in Zhejiang province, Jiahe212 (JH212), resulting in 34 T₀ plants with various effective mutations. Among the 17 mutant T₁ lines, several displayed diverse flowering dates, but most exhibited undesirable agronomic traits. Notably, three homozygous mutant lines (JH-C15, JH-C18, and JH-C31) showed slightly earlier flowering dates without significant differences in yield-related traits compared to JH212. Through special Hyg and Cas marker selection of T₂ plants, we identified seven, six, and two fragrant glutinous plants devoid of transgenic components. These single plants will serve as sib lines of JH212 and potential resources for breeding applications, including maintenance lines for indica–japonica interspecific three-line hybrid rice. In summary, our research lays the foundation for the creation of short-growth-period CMS (cytoplasmic male sterility, CMS) lines, and also provides materials and a theoretical basis for indica–japonica interspecific hybrid rice breeding with wider adaptability. Full article

The kiwifruit, Actinidia genus, has emerged as a nutritionally rich and economically significant crop with a history rooted in China. This review paper examines the global journey of the kiwifruit, its genetic diversity, and the role of advanced breeding techniques in its cultivation and improvement. The expansion of kiwifruit cultivation from China to New Zealand, Italy, Chile and beyond, driven by the development of new cultivars and improved agricultural practices, is discussed, highlighting the fruit’s high content of vitamins C, E, and K. The genetic resources within the Actinidia genus are reviewed, with emphasis on the potential of this diversity in breeding programs. The review provides extensive coverage to the application of modern omics technologies, including genomics, transcriptomics, proteomics, and metabolomics, which have revolutionized the understanding of the biology of kiwifruit and facilitated targeted breeding efforts. It examines both conventional breeding methods and modern approaches, like marker-assisted selection, genomic selection, mutation breeding, and the potential of CRISPR-Cas9 technology for precise trait enhancement. Special attention is paid to interspecific hybridization and cisgenesis as strategies for incorporating beneficial traits and developing superior kiwifruit varieties. This comprehensive synthesis not only sheds light on the current state of kiwifruit research and breeding, but also outlines the future directions and challenges in the field, underscoring the importance of integrating traditional and omics-based approaches to meet the demands of a changing global climate and market preferences. Full article