Search Results (279)

The genus Passiflora includes species important for fruit production, ornamental value, and breeding programs. Conventional methods, such as seed propagation and vegetative cuttings, face challenges like genetic heterogeneity, pathogen transmission, and long juvenile phases, limiting large-scale cultivation and breeding efficiency. In vitro culture technologies are essential for clonal propagation, germplasm conservation, and improving Passiflora species using biotechnology. This review critically evaluates current progress in micropropagation and regeneration systems in Passiflora spp. and examines the prospects of haploid and doubled haploid technologies as future breeding tools. Unlike previous reviews, which primarily focus on summarizing tissue culture protocols, this study integrates regeneration biology, developmental constraints, and emerging biotechnological approaches to provide a broader framework for research. Additionally, this review offers a comparative analysis of various regeneration systems across Passiflora species and highlights the challenges of genotype-dependent methods. By synthesizing recent advancements in haploid technology, it provides new insights into the potential for accelerating breeding programs in Passiflora, a field where robust protocols are still lacking. Full article

Grain quality in bread wheat is a complex trait determined by multiple genetic factors and their interaction with environmental conditions. This study investigated the genetic architecture of key grain quality traits in the Avalon × Cadenza double haploid (DH) population under contrasting climatic conditions in Kazakhstan. A set of 101 spring-type DH lines was evaluated over three years in three major wheat-growing regions of Kazakhstan, representing northern, central, and southern environments. Grain yield and nine grain quality traits were assessed, including amylose content (Amc, %), test weight per liter (TWL, g/L), grain protein content (GPC, %), gliadin content (Gli, %), glutenin content (Glu, %), grain hardness (GH, %), grain vitreousness (GV, %), falling number (FN, s), and sedimentation value determined in a 2% acetic acid solution (SV, mL). The objectives were to characterize phenotypic variation, examine trait relationships, and identify major and environmentally stable quantitative trait loci (QTLs) controlling grain quality. QTL mapping identified 89 QTLs associated with the nine studied traits, including 82 major QTLs explaining more than 10% of phenotypic variation and 16 stable QTLs detected in two or more environments. The largest numbers of QTLs were found for GPC, SV, and TWL. Stable QTLs were distributed across all three wheat genomes, with important regions detected on chromosomes 1A, 1B, 2D, 4A, 4D, 5A, 6A, and 7D. Several stable QTLs co-localized with genomic regions previously associated with grain quality and developmental regulation, including loci near Wx-B1, Rht-D1, and Ppd-D1, suggesting biologically meaningful links among gluten composition, starch biosynthesis, plant development, and grain physical properties. These results improve understanding of the genetic control of wheat grain quality across diverse environments in Kazakhstan and provide promising targets for marker-assisted selection to combine improved end-use quality with wide environmental adaptation. Full article

Haploid and doubled haploid (DH) technologies are important tools for accelerated wheat (Triticum aestivum L.) breeding, enabling the rapid production of fully homozygous lines and increasing the efficiency of genetic analysis of complex traits. This review presents a comprehensive analysis of the main approaches to producing haploid and DH wheat plants, with particular emphasis on androgenesis-mediated and chromosome elimination methods, including wheat-maize hybridisation. The biological basis of androgenesis is discussed in relation to stress-induced microspore reprogramming; however, the primary focus is on the methodological factors determining the efficiency of DH production, including the donor plant genotype, microspore development stage, pretreatment conditions, composition of the induction and regeneration media, and chromosome doubling. However, its widespread application remains limited by pronounced genotypic dependence, low responsiveness of many commercial varieties, albinism, and a lack of universally effective protocols. In contrast, distant hybridisation systems, particularly wheat-maize hybridisation, are generally characterised by greater reproducibility and less genotypic dependence, although they remain labour-intensive and require precise embryo rescue and chromosome doubling procedures. Overall, further progress in producing DH in wheat will be associated with the optimisation of protocols for difficult-to-respond genotypes and the integration of classical haploidisation systems with omics approaches, genomic selection, and genome-editing. Full article

Goji, a plant unique to China, is recognized for its dual use as both a food and a medicine and is rich in various nutrients. However, long-term asexual propagation often leads to cultivar degeneration and viral accumulation, which severely impact its yield, quality, and disease resistance. Homozygous seeds can stably produce offspring with uniform traits. Haploid breeding technology, which involves doubling the chromosomes of haploid plants to obtain homozygous diploids, can significantly accelerate the breeding process. The DMP (Domain of Unknown Function 679 Membrane Protein) family is a plant-specific family of membrane proteins involved in various biological functions, including physiological processes, reproductive development, and senescence. Concurrently, loss-of-function of the DMP gene impedes the proper integration of the paternal genome following fertilization. Consequently, the embryo develops with exclusively maternal chromosomes, a mechanism that underlies the induction of haploids. In this study, we conducted a genome-wide identification of the DMP gene family in goji, analyzing the physicochemical properties, chromosomal locations, cis-acting elements, phylogenetic relationships, sequence characteristics, expression patterns, and subcellular localization of its members. The objective was to identify DMP genes capable of inducing haploid production in goji berry for future breeding applications. The results revealed a total of 11 DMP family members in the goji berry genome, distributed across seven chromosomes. The proteins encoded by these members contain 136 to 237 amino acids, with molecular weights ranging from 15,267.96 to 26,141.01 Da and isoelectric points (pI) ranging from 5.14 to 9.32. The LbDMPs were found to contain numerous cis-acting elements that play roles in plant responses to abiotic stresses and various phytohormones. Notably, LbDMP1 and LbDMP11, which contain the typical DUF679 domain, are predominantly expressed in pollen, suggesting their involvement in the reproductive process of goji berry. They were therefore identified as candidate genes for haploid induction. Subcellular localization analysis demonstrated that LbDMP1 is localized to the plasma membrane, while LbDMP11 is localized to membrane systems such as the endoplasmic reticulum. This research provides a fundamental basis for further exploration of the functional roles of the DMP gene family in goji berry and offers valuable genetic resources for haploid induction in its breeding programs. Full article

Unpollinated ovary culture is an effective approach for generating haploid and doubled haploid lines, but its application in Chinese chive (Allium tuberosum) breeding has been constrained by strong genotype dependence and low regeneration efficiency. This study evaluated an efficient gynogenesis induction system and analyzed transcriptomic changes associated with embryogenesis. Among 20 evaluated genotypes, the commercial cultivar ‘21-CJ46’ showed the strongest response. The optimized induction conditions utilized ovaries collected 1 day before anthesis, cultured on Murashige and Skoog medium supplemented with 90 g/L sucrose, 1.0 mg/L 6-BA, and 0.2 mg/L 2,4-D at 25 °C. Under this system, ‘21-CJ46’ achieved a maximum embryo induction rate of 86.67%. Flow cytometry and chromosome counting indicated frequent spontaneous chromosome doubling, with regenerants mainly distributed as diploids and tetraploids. RNA-seq analysis comparing pre-induction (0 d) and 14 d ovaries showed extensive transcriptional reprogramming, including significant enrichment of phenylpropanoid biosynthesis, plant–pathogen interaction, and plant hormone signal transduction pathways. Differential expression analysis demonstrated that key embryogenesis regulators, such as BBM2, WUSCHEL9, LEC, PLT2, and ABI3, were regulated at 14 d. These results provide an induction protocol and molecular indications relevant to accelerating Chinese chive breeding. Full article

Double-haploid (DH) technology is a well-established method for speeding up the development of inbred lines in breeding programs. The major loci qhir1 and qhir8 are widely used in marker-assisted selection (MAS) to increase the haploid induction rate (HIR) in maize. However, previous studies have shown that HIR can be unstable within populations, even in the presence of these two loci. To identify novel loci associated with HIR, we performed QTL-seq analysis on 337 S₂ haploid inducers (qhir1+/qhir8+) derived from crossing K8 with BHI306. The population exhibited HIR ranging from 0% to 31.16%. We sequence-bulked DNA from 30 extremely high-HIR lines (15.72–31.16%) and 30 extremely low-HIR lines (0–3.84%), identifying candidate intervals on chromosomes 2 (qHI2), 3 (qHI3), 6 (qHI6), and 8 (qHI8). Based on the QTL-seq results, 147 high-confidence SNPs/InDels (R² > 0.3) led to the analysis of 58 genes across three QTLs. We retrieved ten missense mutation SNPs from three genes (GRMZM2G359746 (qHI2), AC198725.4 (qHI3), and GRMZM2G091276 (qHI8)), which are located on chromosomes 2, 3, and 8. Regression analysis of these SNPs showed an R² range of 0.27 to 0.72. The two most highly associated SNPs were located in exon 2 of GRMZM2G359746 (qHI2) and in exon 5 of GRMZM2G091276 (qHI8), respectively. Marker–trait association analysis revealed that lines carrying favorable alleles at both loci, together with qhir1+ and qhir8+, exhibited significantly higher average HIR (12.77%) compared to those with unfavorable alleles (6.66%). These findings provide valuable markers for enhancing maternal haploid inducer breeding programs in maize. Full article

Drought stress is a major limiting factor for canola production in arid and semi-arid regions, particularly during seed germination, seedling and flowering stages. In this study, we evaluated drought responses of doubled haploid (DH) lines derived from interspecific hybrids of B. napus × B. rapa and their parental cultivars under simulated (PEG-6000) and soil-based drought conditions. Drought stress significantly reduced germination, growth, and physiological performance in all genotypes; however, DH lines consistently exhibited superior tolerance. Under PEG-induced osmotic stress, DH lines maintained higher germination rates, root elongation, and relative water content compared with parental genotypes. During seedling and flowering stages drought, DH lines showed lower accumulation of hydrogen peroxide and malondialdehyde, alongside markedly higher antioxidant enzyme activities (CAT and POD) and improved photosynthetic efficiency (Fv/Fm). Gene expression analysis revealed strong induction of drought-responsive genes, including WRKY28, MYB, LTP, WSP, metallothionein, and protein kinase family genes, particularly in DH lines at prolonged stress exposure. Multivariate analyses (PCA and correlation) confirmed a close association between enhanced antioxidant capacity, transcriptional activation, and drought tolerance traits. Overall, our results demonstrate that homozygous doubled haploid lines derived from distant hybridization between B. napus and B. rapa exhibit enhanced drought tolerance at both early and reproductive stages. These genotypes represent valuable genetic resources for breeding drought-tolerance canola cultivars. Full article

Efficient in vitro regeneration remains a major constraint in the genetic transformation, genome editing, and molecular breeding of wheat (Triticum aestivum L.), largely due to strong genotype-dependent recalcitrance and limited activation of developmental programs required for somatic embryogenesis. Plant regeneration relies on extensive transcriptional reprogramming and epigenetic remodeling orchestrated by morphogenic regulators that modulate meristem identity, as well as cellular pluri- and totipotency. In this review, we synthesize current molecular knowledge on key transcription factors (BBM, WUS/WUS2, GRF-GIF, WOX, LAX1, SERK, WIND1/ERF115) and signaling peptides (CLE/CLV-WUS module, phytosulfokine/PSK) that regulate embryogenic competence in monocot cereals, with emphasis on their orthologs and functional relevance in wheat. We highlight how controlled expression of these morphogenic genes, promoter engineering, and transient or excisable induction systems can significantly enhance regeneration capacity, reduce chimerism in CRISPR-Cas-edited plants, and facilitate genotype-independent transformation. We also discuss epigenetic and metabolic constraints underlying wheat recalcitrance and their potential modulation to improve culture responsiveness. By integrating evidence from wheat, rice, maize, and barley, we outline conserved gene-regulatory networks that reinitiate totipotency and propose strategies to accelerate doubled haploid production and speed-breeding pipelines. Collectively, morphogenic factors emerge as central molecular tools for overcoming regeneration bottlenecks and enabling next-generation wheat improvement. The objective of this review is to synthesize and critically evaluate current molecular knowledge on morphogenic regulators controlling in vitro regeneration in wheat (Triticum aestivum L.), with particular emphasis on their roles in genetic transformation and genome editing. Full article

Tetraploid non-apomictic citrus genotypes are key female parents for 4x × 2x hybridizations aimed at producing seedless triploid hybrids. However, the extent to which different tetraploidization methods affect genome integrity remains insufficiently characterized at a genome-wide scale. In this study, genotyping-by-sequencing (GBS) was used to evaluate marker-based genomic stability in ten tetraploid plants of ‘Clemenules’, ‘Fina’, and ‘Marisol’ clementines obtained via colchicine treatment, in vitro adventitious organogenesis, or somatic cybridization. Diploid parental plants, two haploid plants of ‘Clemenules’ and ‘Fina’ clementines, and one doubled haploid plant of ‘Clemenules’ clementine were included, being the haploid and double haploid essential to resolve allelic phases. After quality filtering, 3333 SNP (Single Nucleotide Polymorphism) markers distributed across the nine citrus chromosomes were identified and used to compare allele dosage patterns along the genome. Across all GBS-covered regions, no major marker-based genomic gains or losses were detected in any tetraploid plant. These results indicate that, at the resolution provided by GBS, all three tetraploidization methods largely preserve chromosome structure, supporting their suitability for citrus triploid breeding programs based on 4x × 2x sexual hybridizations. Full article

Heading date (HD) is a key adaptive trait determining wheat regional suitability, yield stability, and resilience to environmental stresses. We dissected the genetic architecture of heading date (HD) by phenotyping a doubled haploid (DH) population (178 lines, CASL7AS × ZNL12) across five environments and constructing a high-density genetic map with the wheat 55K SNP array. A total of 38 QTLs associated with HD were identified on 12 chromosomes, among which 10 were consistently detected across multiple environments. Two major stable loci, QHD.ZAFU.2B and QHD.ZAFU.4A, explained substantial phenotypic variation and were considered key regulators of heading time. Candidate gene analysis revealed Ppd-B1 (TraesCSU02G196100) as the causal gene for QHD.ZAFU.2B. Within QHD.ZAFU.4A, a zinc finger RNA-binding protein gene (TraesCS4A02G394400) exhibiting strong flag-leaf expression at the heading stage was identified as the most promising candidate. Notably, most favorable alleles were derived from ZNL12, highlighting its potential for breeding applications aimed at manipulating heading time. These results provide valuable genomic resources and molecular targets for marker-assisted selection aimed at optimizing flowering time and improving wheat adaptation. Full article

Cabbage (Brassica oleracea L. var. capitata) is an important leafy vegetable crop, and the development of homozygous parental lines is essential for F₁ hybrid breeding. Isolated microspore culture (IMC) provides a rapid approach for producing haploid and doubled haploid (DH) lines. However, its efficiency in cabbage remains highly dependent on genotype, donor plant growth conditions, and culture conditions. This study aimed to optimize key factors affecting microspore embryogenesis and plant regeneration in a Korean green cabbage (‘SJ-Ca 13’) and to evaluate the ploidy and genetic characteristics of regenerated plants. Microspore yield and embryogenesis were strongly influenced by flower bud size. Bud size of 4.0 ± 0.5 mm yielded the highest number of microspores (4.17 × 10⁴ per bud) and exclusively produced microspore-derived embryos (2.33 embryos per Petri dish), whereas smaller or larger buds failed to induce embryogenesis. Heat shock treatment at 32.5 °C was essential for embryogenesis, with 24 or 48 h of treatment inducing embryo formation, while prolonged exposure (72 h) completely inhibited embryogenesis. Efficient shoot regeneration was achieved when microspore-derived embryos were cultured on semi-solid MS medium with reduced salt strength (1/3×) and higher agar concentration (1.0%), resulting in the highest shoot regeneration rate. Ploidy test revealed that 50% of regenerated plants were spontaneous doubled haploids. SSR analysis using 26 markers detected no genetic polymorphism among regenerated plants. Overall, this study establishes an efficient IMC and regeneration system for cabbage and demonstrates its potential for rapid DH line production to support cabbage breeding programs. Full article

Conventional rice breeding predominantly relies on hybridization techniques, with hybrid progenies typically requiring 8 to 10 generations of selfing to achieve genetically stable homozygous lines. In contrast, haploid breeding enables the derivation of stable doubled haploid (DH) lines from hybrid progeny in just one generation, substantially shortening the breeding cycle. Haploid breeding comprises two core steps: haploid induction and chromosome doubling, with efficient haploid induction being pivotal to the success of this technology. Currently, anther culture, due to its relatively mature and stable protocol, has become the primary method for obtaining haploids in rice haploid breeding. This review systematically summarizes the research progress in rice anther culture, focusing on the fundamental steps and applications of haploid breeding, the developmental history of anther culture, factors influencing anther culture efficiency and their underlying genetic mechanisms, current challenges and potential countermeasures, and future prospects for rice anther culture technology. Full article

Embryo spots on potato seed enhance the efficiency of doubled haploid screening by facilitating selection. While the spots are known to involve anthocyanin accumulation, their genetic regulation remains unclear. Here, loci and genes regulating spot formation were investigated. An F₁ population was generated by crossing the haploid inducer IVP101 (embryo-spotted male parent) with the diploid inbred line Y8 (non-spotted female parent). Subsequent BSA-seq of the extreme F₁ pools mapped a locus to chromosome 10 (49.96–54.31 Mb). QTL mapping via a high-density genetic map of the F₂ segregating population (derived from F₁ selfing) identified four QTLs (on chromosomes 2, 5, 10, 11). These included the QTLs qSP10-1 (explaining 23.85% of phenotypic variance) and qSP11-1 (18.23%). qSP11-1 overlapped with the reported P locus encoding flavonoid 3′,5′-hydroxylase (F3′5′H), whereas qSP10-1 confirmed the BSA-seq results. Integration of the BSA-seq and QTL mapping results narrowed the target gene locus to a 384.6 kb interval at the end of chromosome 10. Transcriptome sequencing of spotted vs. non-spotted F₁ seed, together with gene expression profiling in the qSP10-1 interval, identified five differentially expressed candidate genes. These findings clarify the genetic basis of potato embryo spot formation and provide a reference for breeding and further research. Full article

Gynogenesis offers a promising route for doubled haploid (DH) production in Cucurbita, yet efficient protocols remain scarce. This study established a reproducible ovary culture system for Cucurbita pepo and evaluated zeatin riboside (ZR) as an alternative cytokinin. Ovaries collected at anthesis and one day before were cultured to screen nine media with different cytokinin–auxin combinations. Subsequently, four optimized ZR-based formulations were evaluated. Both floral stages showed morphogenic activity, but embryo formation occurred almost exclusively in pre-anthesis ovaries. Among ZR treatments, E6.1 (1 mg·L⁻¹ ZR + 3 mg·L⁻¹ NAA, 30 g·L⁻¹ sucrose) achieved the highest embryogenic output (approximately 97 embryos per 100 explants), while high-sucrose media (120 g·L⁻¹) induced abundant swollen ovules but poor conversion, suggesting that excessive osmotic pressure promotes morphogenesis but hampers embryogenic transition. In total, 415 embryos were obtained, and 52 regenerants were analyzed by flow cytometry, confirming haploid, diploid, and mixoploid plants and evidencing spontaneous chromosome doubling during in vitro development. A categorical A–D scoring system enabled early prediction of embryogenic potential. This represents the first successful application of ZR in cucurbit gynogenesis and highlights its value as a biologically compatible cytokinin for DH production. The findings open new avenues for testing ZR-based formulations in other Cucurbita species under different auxin and sucrose regimes. 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