Search Results (134)

This literature review systematizes current data on the development of triploid seedless hybrids in the Cucurbitaceae Juss family. The absence of seeds simplifies the consumption and industrial preparation of products from cucurbits. In addition, triploids showed larger plant habitus, field resistance to infections, extended shelf life, and higher fruit quality. Phenotypic differences in polyploids can stem from altered chromatin organization and gene regulation, as the nucleus must accommodate a doubled chromosome set. The triploid watermelon cultivation method developed in 1951 failed to gain traction among other crops in the gourd (Cucurbitaceae) family. The challenges of triploid seed production and use include the need for the development of tetraploid and diploid parental lines, as well as bypassing the problem of the low viability of tetraploid parent pollen and the issue of thick seed coats and underdeveloped embryos in triploids. The research findings presented in this review can be applied to the development of triploid seedless hybrids for other members of the Cucurbitaceae family. Full article

Triploid loquat (Eriobotrya japonica, 2n = 3x = 51) produces seedless fruit and holds significant breeding value. However, the scarcity of tetraploids hinders large-scale triploid propagation. Notably, spontaneous tetraploidization occurs in certain triploid progenies, offering a viable approach to enrich tetraploid germplasm. In this study, open-pollinated offspring (n = 385) from white-fleshed triploid cultivars ‘Wuhe Zaoyu’ and ‘Huayu Wuhe 1’, as well as lines Q16 and Q21, were analyzed using flow cytometry for ploidy identification and molecular markers for flesh color genotyping. Ploidy analysis of open-pollinated progeny from ‘Huayu Wuhe 1’, Q16 and Q21 revealed the presence of diploids, triploids, tetraploids and aneuploids, with tetraploids being the most abundant (36–68%). In ‘Huayu Wuhe 1’ progeny, polyploids exhibited greater leaf thickness and plant height than diploids and aneuploids. Molecular marker analysis revealed that among the 172 tetraploid progeny, two flesh color genotypes were identified: heterozygous red-fleshed (24%) and white-fleshed (76%). qPCR-based allele quantification revealed that the alleles of tetraploids with heterozygous red-fleshed genotypes were Aaaa or AAaa genotypes. These findings confirm that triploid progeny can serve as an effective source of tetraploids, supporting future breeding efforts for seedless triploids. The formation of these tetraploids is possibly through 2n gametes from either diploid or triploid plants. Full article

Hybridization and polyploidization are key evolutionary forces shaping fish biodiversity. But their interaction with environmental factors, such as temperature, remains poorly understood. This study examined how maternal genome composition and incubation water temperature influence the hatching success, ploidy structure, morphology and early growth of polyploid Cobitis larvae. Crosses were performed using triploid Cobitis females with three genomic compositions (EEN, EET and ETN), representing combinations of genomes from C. elongatoides (E), C. taenia (T) and C. tanaitica (N), and diploid C. taenia males as sperm donors. Fertilized eggs were incubated at 18 °C, 22 °C and 28 °C. Triploid and tetraploid offspring occurred in comparable proportions on average across all groups, but developmental abnormalities were significantly more observed in tetraploid larvae. Females with EET and ETN genomes achieved higher hatching success than those with the EEN genome. Temperature had a pronounced effect on developmental timing and success: hatching occurred earliest at 28 °C, but survival decreased and abnormalities were most frequent. These results highlight genome- and temperature-dependent trade-offs in early development of Cobitis hybrids, providing new insight into reproductive dynamics and the potential resilience of polyploid systems under climate warming. Full article

Triploids are typically formed through the fusion of a haploid gamete from a diploid organism and a diploid gamete from a tetraploid organism or through chromosome doubling in gametes by other means. To circumvent the multi-year flowering wait associated with tetraploid parents in conventional breeding, we developed a novel method for inducing triploid in birch through high-temperature treatment of female inflorescences. This approach integrates sexual hybridization with precise thermal treatment, with success hinging on the precise identification of the pollination window and the optimal treatment parameters. Our study systematically defines the optimal conditions for triploid production in birch via this high-temperature induction technique. The results demonstrate that the optimal period for stigma pollination was between day 5 to 6, immediately following the emergence of the stigma from the enclosing bracts. The most effective pollination was characterized by a bract dehiscence angle exceeding 60° on Day 15 after the pollination marks the phase of megaspore mother cell development. At this stage, the optimum treatment is either 40 °C for 2 h or alternately 42 °C for 1 h. These treatments result in the highest triploid induction rates of 33.82%, calculated with the total number of detected seedlings as the denominator. In addition, a logistic model was established between the ovary length-to-width ratio and the accumulated growing degree hours (GDH), providing a reliable quantitative indicator for determining the optimal timing of the high-temperature treatment. Compared with the conventional approach reliant on tetraploid parents, our method eliminates the lengthy phase of tetraploid induction and flowering wait (approximately 8 years), thereby reducing the triploid breeding cycle by about 6 years. The results substantiated the effectiveness of utilizing high temperatures to induce chromosome doubling in female gametes of birch species, providing a viable pathway for efficient polyploid breeding in this tree species. Full article

Global warming and soil salinization pose significant challenges to modern plant cultivation. Background/Objectives: Polyploidization of whole-genome duplication is an important evolutionary strategy, enhancing plant adaptation to environmental stress. This study investigates the impact of heat and salt stress on photosynthesis and proteomic changes in a polyploid series of Arabidopsis thaliana (diploid, triploid, and tetraploid). Methods: Two-month-old plants were exposed to heat stress (45 °C for 3 h) or salt stress (300 mM NaCl for 24 or 48 h). Stress effects were assessed via photosystem II maximum efficiency (F_v/F_m), the performance index (PI_ABS), and proline content. Proteomic responses were analyzed using 2D SDS-PAGE and mass spectrometry. Results: Our findings revealed that polyploid plants maintained higher photosynthetic performance than diploids under both heat and salt stress. While proline accumulation under heat stress was comparable across all ploidy levels, polyploids accumulated more proline under salt stress, indicating enhanced salinity tolerance. Proteomic analysis showed differential protein expression among diploid and polyploid plants in response to stress. Several differentially expressed proteins had functions involved in photosynthesis and stress response pathways. These findings confirm prior evidence of tetraploid Arabidopsis resilience to salinity and extend this observation to heat stress. Moreover, triploids also demonstrated increased stress tolerance, suggesting adaptive advantages of this intermediate ploidy level as well. Conclusions: Differential expression patterns among ploidy levels may reflect varied energy-saving strategies and alterations in protein structure and function. This work highlights the importance of polyploidy in improving plant stress resilience, offering insights for breeding stress-tolerant crops in a changing climate. Full article

Polyploids play significant roles in tea production due to their strong tolerance to adverse environmental conditions and their high levels of certain chemical components. Tetraploid can be used to produce more polyploid tea plants, but there have been only a handful of tetraploids found in tea plants. In spite of the extremely low probabilities, bud mutant selection is an effective way to obtain polyploid tree crops. In the present study, a Dashu tea, cytochimera, derived from a bud mutation was identified by using flow cytometry and chromosome observation. The morphology and photosynthetic characteristics of leaves were investigated briefly. Some chemical components were determined. Finally, the pollen viability and ploidy of progeny were detected. The results show that tetraploid cells account for 71.48 ± 3.88%–72.19 ± 2.80% of the leaf tissue in this cytochimera. Compared with the original diploid, the cytochimera exhibited broader, longer, and thicker leaves. Its net photosynthetic rate (high to 41.77 ± 0.38 μmol CO₂·m⁻²·s⁻¹) was higher than that of the original diploid (peak value 28.00 ± 2.29 μmol CO₂·m⁻²·s⁻¹) for most of the day when measured in September. Notably, the total content of 19 free amino acids in the tender spring shoots of cytochimera was 22.96 ± 0.58 mg/g, approximately twice of that of the diploid materials analyzed. The contents of 10 free amino acids, including theanine, were significantly higher than those in diploids, with some free amino acid contents reaching up to seven times those observed in diploids. In addition, the cytochimera produced larger pollen grains than the original diploid, although the in vitro germination rate was lower (14.63 ± 1.11%). Three open-pollinated progenies of cytochimera were identified as triploids. To sum up, cytochimera has larger and thicker leaves, a higher photosynthetic rate, and higher content of total free amino acids and some free amino acids, especially theanine, than the original diploid. Moreover, cytochimera has a certain level of fertility and can produce triploids. These findings suggest the potential for selecting polyploid tea plants from bud mutants and for developing new tea germplasms with enhanced amino acid contents. Full article

Cold stress poses a critical threat to fish survival by triggering metabolic dysfunction, oxidative damage, immune suppression, and apoptosis. However, hybrid polyploid fish triploid crucian carp (3nRCR, 3n = 150) demonstrate superior stress tolerance. In this study, we investigated the cold adaptation mechanisms in different ploidy cyprinid fishes: triploid crucian carp compared to its diploid improved red crucian carp (Carassius auratus red var., RCC, 2n = 100, ♀) and improved allotetraploid (4nAT, 4n = 200, ♂) progenitors. Under controlled cooling, 3nRCR lost equilibrium at a significantly lower temperature (3.2 °C) than RCC (4.0 °C) and 4nAT (4.5 °C), confirming its superior enhanced cold resistance. Histological examination revealed minimal tissue damage in 3nRCR, characterized by reduced gill inflammation and cellular apoptosis. Transcriptomics revealed triploid-specific molecular strategies: 3nRCR uniquely activated retinol metabolism and metabolic rewiring (arginine/proline metabolism, oxidative phosphorylation). Notably, in the immune-related NLR signaling pathway, both nlrp1 and nlrp3 (key inflammasome components) were significantly downregulated in 3nRCR (p < 0.01). In contrast, genes involved in endoplasmic reticulum (ER) stress response, including chop and nrf2, were markedly upregulated, indicating a reinforced cellular stress resolution mechanism absent in both RCC and 4nAT. Our results demonstrate that triploid cold adaptation is orchestrated through a balanced interaction among mitochondrial apoptosis, ER stress, and inflammasome pathways. These findings provide novel insights into hybrid polyploid adaptation mechanisms and targets for cold-resilient aquaculture breeding. Full article

For the Choerospondias axillaris (Roxb.) B.L.Burtt & A.W.Hill, a significant economic tree in the Anacardiaceae family with industrial, medicinal, and ecological value, the genome size remains unreported. Here, we optimized the flow cytometry-based method for ploidy analysis, finding that WPB lysis solution proved to be the most effective. Analysis of 58 C. axillaris accessions identified 47 diploids and 11 triploids. The average genome size of diploids was estimated at 450.36 Mb. Illumina sequencing of a diploid (No.22) generated 81.98 Gb of high-quality data (224.44X depth). K-mer analysis estimated the genome size at 365.25 Mb, with 0.91% genome heterozygosity, 34.17% GC content, and 47.74% repeated sequences, indicating high heterozygosity and duplication levels in the genome. Genome assembly may necessitate a combination of second- and third-generation sequencing technologies. Comparative analysis with the NT database revealed that C. axillaris exhibited the highest similarity to C. axillaris (3.01%) and Pistacia vera (2.5%). This study establishes a crucial theoretical framework for C. axillaris genome sequencing and molecular genetics. Full article

Plants vary in number of chromosomes (ploidy levels), which can influence morphological traits, including the size and density of stomata cells. Although biologists can detect these differences under a microscope, the process is often time-consuming and tedious. This study aims to automate the classification of blackcurrant (Ribes nigrum L.) ploidy levels—diploid, triploid, and tetraploid—by leveraging deep learning techniques. Convolutional Neural Networks and Vision Transformers are employed to perform microscopic image classification across two distinct blackcurrant datasets. Initial experiments demonstrate that these models can effectively classify ploidy levels when trained and tested on subsets derived from the same dataset. However, the primary challenge lies in proposing a model capable of yielding satisfactory classification results across different datasets ensuring robustness and generalization, which is a critical step toward developing a universal ploidy classification system. In this research, a variety of experiments is performed including application of augmentation technique. Model efficacy is evaluated with standard metrics and its interpretability is ensured through Gradient-weighted Class Activation Mapping visualizations. Finally, future research directions are outlined with application of other advanced state-of-the-art machine learning methods to further refine ploidy level prediction in botanical studies. Full article

Triploid breeding is a promising approach for developing seedless varieties, but the long juvenile phase of perennial fruit trees necessitates efficient early selection. In loquat (Eriobotrya japonica), a fruit crop with high demand for seedlessness, the relative contributions of hybridity, ploidy level, and parent-of-origin effects (POEs) to triploid seedling vigor remain elusive. To dissect these factors, we established a comprehensive experimental system comprising reciprocal diploid (2x), triploid (3x), and tetraploid (4x) hybrids from two genetically distinct cultivars. The ploidy, hybridity and genetic architecture of hybrid and parental groups were verified using flow cytometry, chromosome counting, newly developed InDel markers and genome-wide SNP analysis. Phenotypic evaluation of eight vigor-related traits revealed that plant height and soluble starch content were the most robust indicators of triploid heterosis in loquat. Notably, paternal-excess triploids [3x(p)] consistently outperformed all other groups. Quantitative analysis revealed POE as the main positive driver of triploid heterosis (+10.37% for plant height), far exceeding the negative impacts of hybridity (−12.75%) and ploidy level (−20.87%). These findings demonstrate that POE predominantly drives seedling vigor heterosis in triploid loquat. We propose a practical breeding strategy that combines prioritizing paternal-excess crosses with novel InDel markers for rapid verification of superior seedless progeny. Full article

A plant breeding program needs helpful markers, especially morphological ones, which can allow breeders to dispense with other markers, including cytological traits and flow cytometry. These markers can assist plant breeders in distinguishing diploid and tetraploid plants during the seedling stage. Therefore, the present study aimed to investigate and validate effective methodologies for the early identification of artificially induced polyploids in black cumin. Thus, we established an extensional program for black cumin breeding including producing seeds, active compounds, and flowers as ornamental plants. Field experiments on tetraploids and diploids were carried out to evaluate the morphological and yield traits of both plants. Also, some cytological studies and Gas Chromatography (GC) analysis were conducted to achieve these goals. The results showed the possibility of realizing diploid and tetraploid plants in early growing black seeds in the field (mainly after the first cotyledon leaves). This crucial outcome can support plant breeders in identifying polyploidy during the seedling stage without referring to biochemical markers, flow cytometry, and cytological traits. All morphological and yield-related traits were superior in diploid plants compared to tetraploids. The results showed that diploid and tetraploid plants exhibited plant heights of 116 cm and 95 cm, numbers of secondary branches of 112 and 22, numbers of flowers of 111.7 and 24.75, and shoot fresh weights of 610 g and 147.5 g, respectively. Furthermore, the number of seeds per capsule, seed yield per plant, and oil percentage in diploids were 97.5 seeds, 24 g, and 22.94%, compared with 35.25 seeds, 4.62 g, and 17.76% in tetraploids, respectively. This work used the cotyledon leaf shape as a morphological marker to distinguish the tetraploid and diploid plants, as diploids are typically taller with pointed cotyledons, whereas tetraploids are shorter with rounded cotyledon tips. This study will create great opportunities for plant breeders to save time and costs during their programs. Further studies on such suggested black cumin breeding programs are needed on diploids, triploids, and tetraploids. Full article

Ploidy level exerts profound influences on the phenotypic and physiological traits of Crassostrea gigas. Compared to diploids, triploids exhibit desirable characteristics such as sterility, a faster growth rate, and improved meat quality. In contrast, tetraploids often suffer from slow growth, yet the mechanisms underlying these polyploid-associated traits remain unclear. This study aimed to elucidate these mechanisms by comparing differences in growth-related phenotypes and gene expression among diploid, triploid, and tetraploid oysters. We identified 1533 differentially expressed genes (DEGs) between diploids and triploids, 946 DEGs between triploids and tetraploids, and 1326 DEGs between diploids and tetraploids. Through trend analysis, we clustered genes with similar expression changes across ploidy levels and conducted functional enrichment analysis on these gene clusters. The results revealed that genes associated with the innate immune response were significantly up-regulated in tetraploids, whereas genes related to biomineralization and metabolism were markedly up-regulated in triploids. These findings suggest that tetraploid oysters may mount a stronger innate immune response compared to diploids and triploids, while triploids demonstrate superior growth performance. This study provides valuable resources for investigating the functional aspects of genes related to polyploid phenotype differences. Full article

Duckweeds are aquatic plants with a worldwide distribution that can thrive under very contrasting ambient conditions due to their diversity and high phenotypic plasticity. In this study, we analyzed and compared the responses of four clones (i.e., distinct accessions) of Lemna gibba to two different light intensities. The clones represented different geographical origins and, in addition to two diploid cytotypes, included one tetraploid mutant and a triploid interspecific hybrid. We hypothesized that clonal origin had an effect on light acclimation. We studied growth, morphological (frond size and shape, mass-to-area ratio), and photosynthetic (pigment composition, chlorophyll fluorescence induction) traits of these clones to test whether light acclimation was a conserved process or whether clone-specific strategies could be found. We also analyzed frond-level photosynthetic adjustment during ontogenesis to track how light acclimation evolved in developing fronds. Our results confirmed that even clones of the same duckweed species and a hybrid of closely related species followed partially different strategies in acclimation to ambient conditions. This acclimation involved various morphological, physiological, and biochemical adjustments but happened in a very short time window at the early life stage when young, still-developing fronds could flexibly achieve an optimized phenotype. In addition to explaining the worldwide success of duckweeds in colonizing very contrasting habitats, our results also highlight the importance of approaching duckweed responses at the frond level, where the actual acclimation takes place. Full article

Although previous studies have investigated the reproductive (performance and mode) and lifespan traits of parthenogenetic Artemia, ploidy level has not been considered. Four parthenogenetic Artemia lineages, i.e., diploid, triploid, tetraploid, and pentaploid, were examined to determine the role of ploidy level under osmotic stress conditions (50, 100, and 150 ppt). Although the reproductive mode of the pentaploid lineage is unaffected by changes in salinity, it is entirely switched to oviparity in the diploid lineage at 50 ppt and in the tetraploid lineage at 100 ppt. Moreover, tetraploid reproduction is completely inhibited at 50 ppt. Although oviparity has been proposed as an adaptive strategy enhancing Artemia fitness at high salinities, the exclusive oviparous reproduction observed in the diploid parthenogenetic lineage at 50 ppt suggests that low salinity may also act as an environmental stressor, driving oviparity to ensure the next generation. On the basis of lifespan data, the tetraploid lineage presents greater euryhalinity than other ploidy levels do, whereas the pentaploid lineage is more stenohaline. Additionally, discriminant function analysis revealed that diploid and tetraploid lineages display heterogeneous reproductive/lifespan patterns across salinities, whereas triploid and pentaploid lineages exhibit homogeneous patterns within their respective groups. Our findings challenge the prevailing view that the ploidy level of parthenogenetic Artemia is correlated with tolerance to critical hypersaline conditions. In conclusion, we propose that the life history of parthenogenetic Artemia is influenced not only by ploidy level but also by the multifactorial integration of environmental conditions (particularly salinity and temperature) and local intra-variation/adaptation within isolated habitats. Full article

Grass carp is an economically important cultured species in China. Triploid embryo production is widely applied in aquaculture to achieve reproductive sterility, improve somatic growth, and reduce ecological risks associated with uncontrolled breeding. In this study, a simple cold shock method for inducing triploid grass carp was developed. The triploid induction rate of 71.73 ± 5.00% was achieved by applying a cold treatment at 4 °C for 12 min, starting 2 min after artificial fertilization. Flow cytometry and karyotype analysis revealed that triploid individuals exhibited a 1.5-fold increase in DNA content compared to diploid counterparts, with a chromosomal composition of 3n = 72 (33m + 36sm + 3st). Additionally, embryonic transcriptome analysis demonstrated that, in the cold shock-induced embryos, genes associated with abnormal mesoderm and dorsal–ventral axis formation, zygotic genome activation (ZGA), and anti-apoptosis were downregulated, whereas pro-apoptotic genes were upregulated, which may contribute to the higher abnormal mortality observed during embryonic development. Overall, this study demonstrates optimized conditions for inducing triploidy in grass carp via cold shock and provides insights into the transcriptomic changes that take place in cold shock-induced embryos, which could inform future grass carp genetic breeding programs. Full article