Ploidy Level Research Articles

Variations in Fruit Ploidy Level and Cell Size between Small- and Large-Fruited Olive Cultivars during Fruit Ontogeny.

Olive (Olea europaea L.) is one of the major oil fruit tree crops worldwide. However, the mechanisms underlying olive fruit growth remain poorly understood. Here, we examine questions regarding the interaction of endoreduplication, cell division, and cell expansion with olive fruit growth in relation to the final fruit size by measuring fruit diameter, pericarp thickness, cell area, and ploidy level during fruit ontogeny in three olive cultivars with different fruit sizes. The results demonstrate that differences in the fruit size are related to the maximum growth rate between olive cultivars during early fruit growth, about 50 days post-anthesis (DPA). Differences in fruit weight between olive cultivars were found from 35 DPA, while the distinctive fruit shape became detectable from 21 DPA, even though the increase in pericarp thickness became detectable from 7 DPA in the three cultivars. During early fruit growth, intense mitotic activity appeared during the first 21 DPA in the fruit, whereas the highest cell expansion rates occurred from 28 to 42 DPA during this phase, suggesting that olive fruit cell number is determined from 28 DPA in the three cultivars. Moreover, olive fruit of the large-fruited cultivars was enlarged due to relatively higher cell division and expansion rates compared with the small-fruited cultivar. The ploidy level of olive fruit pericarp between early and late growth was different, but similar among olive cultivars, revealing that ploidy levels are not associated with cell size, in terms of different 8C levels during olive fruit growth. In the three olive cultivars, the maximum endoreduplication level (8C) occurred just before strong cell expansion during early fruit growth in fruit pericarp, whereas the cell expansion during late fruit growth occurred without preceding endoreduplication. We conclude that the basis for fruit size differences between olive cultivars is determined mainly by different cell division and expansion rates during the early fruit growth phase. These data provide new findings on the contribution of fruit ploidy and cell size to fruit size in olive and ultimately on the control of olive fruit development.

MIKE: an ultrafast, assembly-, and alignment-free approach for phylogenetic tree construction.

Constructing a phylogenetic tree requires calculating the evolutionary distance between samples or species via large-scale resequencing data, a process that is both time-consuming and computationally demanding. Striking the right balance between accuracy and efficiency is a significant challenge. To address this, we introduce a new algorithm, MIKE (MinHash-based k-mer algorithm). This algorithm is designed for the swift calculation of the Jaccard coefficient directly from raw sequencing reads and enables the construction of phylogenetic trees based on the resultant Jaccard coefficient. Simulation results highlight the superior speed of MIKE compared to existing state-of-the-art methods. We used MIKE to reconstruct a phylogenetic tree, incorporating 238 yeast, 303 Zea, 141 Ficus, 67 Oryza, and 43 Saccharum spontaneum samples. MIKE demonstrated accurate performance across varying evolutionary scales, reproductive modes, and ploidy levels, proving itself as a powerful tool for phylogenetic tree construction. MIKE is publicly available on Github at https://github.com/Argonum-Clever2/mike.git.

Hybridization, polyploidization, and morphological convergence make dozens of taxa into one chaotic genetic pool: a phylogenomic case of the Ficus erecta species complex (Moraceae).

The Ficus erecta complex, characterized by its morphological diversity and frequent interspecific overlap, shares pollinating fig wasps among several species. This attribute, coupled with its intricate phylogenetic relationships, establishes it as an exemplary model for studying speciation and evolutionary patterns. Extensive researches involving RADseq (Restriction-site associated DNA sequencing), complete chloroplast genome data, and flow cytometry methods were conducted, focusing on phylogenomic analysis, genetic structure, and ploidy detection within the complex. Significantly, the findings exposed a pronounced nuclear-cytoplasmic conflict. This evidence, together with genetic structure analysis, confirmed that hybridization within the complex is a frequent occurrence. The ploidy detection revealed widespread polyploidy, with certain species exhibiting multiple ploidy levels, including 2×, 3×, and 4×. Of particular note, only five species (F. abelii, F. erecta, F. formosana, F. tannoensis and F. vaccinioides) in the complex were proved to be monophyletic. Species such as F. gasparriniana, F. pandurata, and F. stenophylla were found to encompass multiple phylogenetically distinct lineages. This discovery, along with morphological comparisons, suggests a significant underestimation of species diversity within the complex. This study also identified F. tannoensis as an allopolyploid species originating from F. vaccinioide and F. erecta. Considering the integration of morphological, molecular systematics, and cytological evidences, it is proposed that the scope of the F. erecta complex should be expanded to the entire subsect. Frutescentiae. This would redefine the complex as a continuously evolving group comprising at least 33 taxa, characterized by blurred species boundaries, frequent hybridization and polyploidization, and ambiguous genetic differentiation.

In vitro multiplication and phytochemical evaluation of Apios americana Medik for enhanced production of the staple food and tissues with versatile bioactivities

Apios americana Medik tissues, including tubers, flowers, leaves, and vines have both nutritional and therapeutic benefits. These tissues are extensively used in products like beverages and food supplements, driving an exponential increase in worldwide demand for the plant. However, conventional propagation of A. americana through seeds and tubers faces several challenges, including limited seed sets under manual pollination, resulting in reduced production. To overcome these challenges, micropropagation emerges as a promising solution. The current research study has developed an effective in vitro propagation strategy for A. americana using direct regeneration from apical segment explants. Full-strength Quoirin and Lepoivre (QL) medium, supplemented with vitamins and 2.0 mg/L benzylaminopurine (BAP), yielded the highest number of shoots (7.50 ± 0.06) per apical segment explant. QL medium fortified with 1.0 mg/L indole-3-butyric acid (IBA) demonstrated the highest root number (2.80 ± 0.30), length (85.80 ± 7.49 mm), and surface area (10.40 ± 0.82 cm2) in regenerated A. americana shoots. The survival rate of the regenerants in the ex vitro environment was 92.7% after acclimatization. In vitro-regenerated A. americana plants and mother plants exhibited similar ploidy level, chlorophyll content, photosynthetic rate, phytochemical composition, and antioxidant capacity, indicating similarity in their physiological and biochemical properties. This protocol offers a rapid and scalable method for generating high-quality, A. americana plant stocks with stable genome size/ploidy level, meeting the exponentially growing demand for plant tissues. Additionally, it holds potential applications in A. americana breeding and germplasm preservation.

Transcriptome analysis reveals polyploidy-related differential gene expression among diploid, triploid, and tetraploid Pacific oysters (Crassostrea gigas) based on growth-related phenotypes

Tetraploid oysters hold a significant position in the global oyster industry, particularly as core germplasm resources for the production of triploids. Triploids exhibit desirable characteristics such as reduced gonadal development, larger adult size, and superior flesh quality compared with diploids. However, tetraploids often face challenges of slow growth and chromosomal instability during the breeding process, and the mechanisms underlying the formation of these polyploid characteristics remain unclear. This study aimed to elucidate these mechanisms by constructing a polyploid oyster system and comparing the differences in growth-related phenotypes and gene expression among diploids, triploids, and tetraploids. We identified 1404 differentially expressed genes (DEGs) between diploids and triploids, 1814 DEGs between triploids and tetraploids, and 933 DEGs between diploids and tetraploids. Furthermore, we observed distinct gene expression patterns related to innate immunity response and biomineralization between different ploidy levels. Through trend analysis, we clustered genes with similar expression level changes across different ploidy levels and conducted gene ontology (GO) enrichment analysis on genes with different expression profiles. The results indicated that genes associated with the innate immunity response exhibited significantly upregulated expression with increasing ploidy, while genes related to biomineralization showed higher or lower expression levels in triploid oysters. As biomineralization is closely linked to oyster shell growth, this highlights the crucial role of genes associated with biomineralization in regulating the rapid shell growth observed in triploid oysters. Confronted with environmental challenges, tetraploid oysters may display a stronger innate immune response than diploids and triploids. Our study provides valuable resources for investigating the functional aspects of genes related to polyploid phenotype differences and offers new insights into the molecular mechanisms of existing issues in tetraploid oyster breeding.

Hybridization in the Subtribe Alopecurinae Dumort. (Poaceae) According to Molecular Phylogenetic Analysis: Different Ploidy Level Tells Different Origin of the Groups.

We performed next-generation sequencing of the 18S rDNA-ITS1-5.8S rDNA region along with traditional Sanger sequencing of rbcL, matK, ndhF, and ITS1-5.8S rDNA-ITS2 to clarify the hybridization pattern in the subtribe Alopecurinae and in the genus Alopecurus in particular. Our data support the hybrid origin of Alopecurus × brachystylus from hybridization between A. geniculatus (sect. Alopecurium) and A. pratensis (sect. Alopecurus). Moreover, in the rDNA of hybrid A. × brachystylus, only A. aequalis-like ribotypes from tetraploid A. geniculatus participated. Surprisingly, we found the traces of introgression of A. arundinaceus-like ribotypes not only in hybrid A. × marssonii (A. geniculatus × A. arundinaceus) but in A. aequalis s. str. as well. A high-polyploid group from the section Alopecurus, A. aggr. alpinus has undoubted hybrid origin: e. g., A. brachystachyus has rDNA from the sect. Alopecurium. Alopecurus alpinus, with its allies, is clearly distinct from other members of the sect. Alopecurus (especially by maternal line) and thus we can re-establish a previous opinion about the separate group to which A. alpinus belongs. Species from the section Colobachne (presumably Alpine grasses from Ancient Mediterranean region) probably hybridized with the A. alpinus group. Even A. myosuroides (sect. Pseudophalaris) that could be referred to the separate genus has ribotypes common with the species of the section Alopecurium (A. aequalis, A. geniculatus) in one of the accessions. Additionally, we found that the possible polyphyletic origin of the genus Limnas. Limnas stelleri is very close to Alopecurus magellanicus according to NGS data, while L. malyschevii is more or less distinct from other studied species of the genus Alopecurus.

Divergence of 10 satellite repeats in Artemisia (Asteraceae: Anthemideae) based on sequential fluorescence in situ hybridization analysis: evidence for species identification and evolution.

Artemisia is a large genus encompassing about 400 diverse species, many of which have considerable medicinal and ecological value. However, complex morphological information and variation in ploidy level and nuclear DNA content have presented challenges for evolution studies of this genus. Consequently, taxonomic inconsistencies within the genus persist, hindering the utilization of such large plant resources. Researchers have utilized satellite DNAs to aid in chromosome identification, species classification, and evolutionary studies due to their significant sequence and copy number variation between species and close relatives. In the present study, the RepeatExplorer2 pipeline was utilized to identify 10 satellite DNAs from three species (Artemisia annua, Artemisia vulgaris, Artemisia viridisquama), and fluorescence in situ hybridization confirmed their distribution on chromosomes in 24 species, including 19 Artemisia species with 5 outgroup species from Ajania and Chrysanthemum. Signals of satellite DNAs exhibited substantial differences between species. We obtained one genus-specific satellite from the sequences. Additionally, molecular cytogenetic maps were constructed for Artemisia vulgaris, Artemisia leucophylla, and Artemisia viridisquama. One species (Artemisia verbenacea) showed a FISH distribution pattern suggestive of an allotriploid origin. Heteromorphic FISH signals between homologous chromosomes in Artemisia plants were observed at a high level. Additionally, the relative relationships between species were discussed by comparing ideograms. The results of the present study provide new insights into the accurate identification and taxonomy of the Artemisia genus using molecular cytological methods.

Harnessing the potential of transverse thin cell layer culture for high-frequency micropropagation of Thai ginseng (Kaempferia parviflora Wall. Ex Baker)

In vitro plant propagation techniques play an important role in modern agriculture and horticulture, offering efficient methods for the accelerated multiplication of high-value plant species. Thin cell layer (TCL) culture technique has emerged as a promising approach for large-scale in vitro plantlets production. This study explores the potential of TCL culture as a cutting-edge strategy to enhance the efficiency of multiple shoots formation in Kaempferia parviflora. An attempt was also made to look into the synergistic effects of cytokinin and auxin [6-benzyladenine (BA) - indole-3-acetic acid (IAA)] during micropropagation. Shoot tip explants (from rhizome sprouts) were cultured onto Murashige and Skoog (MS) medium enriched with BA (2.0–8.0 mg/L) and IAA (0.2–0.8 mg/L) in combination where the highest shoot number (7.3 shoots/explant) and length (5.9 cm) was obtained in 8.0 mg/L BA and 0.8 mg/L IAA. Subsequently, the transverse thin cell layer (tTCL) culture system was successfully utilized whereby the shoot tip explants were individually sliced from tips at the meristem and cultured onto MS medium supplemented with BA (2.0–8.0 mg/L) and IAA (0.2–0.8 mg/L) in combination. The regenerated tTCLs exhibited the highest shoot multiplication (9.3 shoots/tTCL; 28 shoots/shoot tip) and length (5.3 cm) in 4.0 mg/L BA + 0.8 mg/L IAA, thus significantly increased number of plantlets were obtained from tTCL culture (953.0 plantlets) compared to shoot tip culture (527.7 plantlets) after six sub-culture cycles. The tTCL regenerants were successfully acclimatized (with 90% survival) and displayed active growth. Genetic fidelity assessment via inter-simple sequence repeats, conserved DNA-derived polymorphism, directed amplification of minisatellite-region DNA, and start codon targeted polymorphism marker systems suggested that a very low level (5.8%; 148 out of 2572 scorable bands) of polymorphism was detected whereas the ploidy level remained unchanged, confirmed by flow cytometry analysis. The implementation of tTCL culture, coupled with a controlled sub-culture regimen, holds significant potential for the efficient commercial-scale production of K. parviflora.

Phylogenomics and morphology of Celmisiinae (Asteraceae: Astereae): Taxonomic and evolutionary implications

The tribe Astereae (Asteraceae) includes 36 subtribes and 252 genera, and is distributed worldwide in temperate and tropical regions. One of the subtribes, Celmisiinae Saldivia, has been recently circumscribed to include six genera and ca. 160 species, and is restricted to eastern Australia, New Zealand, and New Guinea. The species show an impressive range of growth habit, from small herbs and ericoid subshrubs to medium-sized trees. They live in a wide range of habitats and are often dominant in subalpine and alpine vegetation. Despite the well-supported circumscription of Celmisiinae, uncertainties have remained about their internal relationships and classification at genus and species levels. This study exploited recent advances in high-throughput sequencing to build a robust multi-gene phylogeny for the subtribe Celmisiinae. The target enrichment Angiosperms353 bait set and the hybpiper-nf and paragone-nf pipelines were used to retrieve, infer, and assemble orthologous loci from 75 taxa representing all the main putative clades within the subtribe. Because of the diploidised ploidy level in Celmisiinae, as well as missing data in the assemblies, uncertainty remains surrounding the inference of orthology detection. However, based on a variety of gene-family sets, coalescent and concatenation-based phylogenetic reconstructions recovered similar topologies. Paralogy and missing data in the gene-families caused some problems, but the estimated phylogenies were well-supported and well-resolved. The phylogenomic evidence supported Celmisiinae and three main clades: the Pleurophyllum clade (Pleurophyllum, Macrolearia and Damnamenia), mostly in the New Zealand Subantarctic Islands, Celmisia of mainland New Zealand and Australia, and Shawia (including ‘Olearia pro parte’ and Pachystegia) of New Zealand, Australia and New Guinea. The results presented here add to the accumulating support for the Angiosperms353 bait set as an efficient method for documenting plant diversity.

LocoGSE, a sequence-based genome size estimator for plants.

Extensive research has focused on exploring the range of genome sizes in eukaryotes, with a particular emphasis on land plants, where significant variability has been observed. Accurate estimation of genome size is essential for various research purposes, but existing sequence-based methods have limitations, particularly for low-coverage datasets. In this study, we introduce LocoGSE, a novel genome size estimator designed specifically for low-coverage datasets generated by genome skimming approaches. LocoGSE relies on mapping the reads on single copy consensus proteins without the need for a reference genome assembly. We calibrated LocoGSE using 430 low-coverage Angiosperm genome skimming datasets and compared its performance against other estimators. Our results demonstrate that LocoGSE accurately predicts monoploid genome size even at very low depth of coverage (<1X) and on highly heterozygous samples. Additionally, LocoGSE provides stable estimates across individuals with varying ploidy levels. LocoGSE fills a gap in sequence-based plant genome size estimation by offering a user-friendly and reliable tool that does not rely on high coverage or reference assemblies. We anticipate that LocoGSE will facilitate plant genome size analysis and contribute to evolutionary and ecological studies in the field. Furthermore, at the cost of an initial calibration, LocoGSE can be used in other lineages.

Evidence of conservative range in mountain grasses during past climate change: Only contractions or local expansions possible

The ongoing biodiversity crisis associated with anthropogenic global warming has especially severe effects on mountain and cold-adapted species. The lesson from the postglacial period can provide examples for future predictions, but scenarios of the range shift of mountain species are not fully explored. Different stories could happen if a species achieved long-distance dispersal and reached lowland locations or if survived only in mountains, during the ice age. In the case of grasses, a key role in range dynamics is played also by polyploidy. Due to their enhanced genetic and physiological plasticity, polyploids are thought to be less likely to become extinct during global changes.The present study explores the postglacial range shifts in two Festuca species, which differ in range size (endemic vs widespread) and in ploidy level (diploid vs mixed-ploidy). We used phylogeography and distribution models to analyze changes in potential range during global warming. We achieved a sophisticated prediction by using modeling based on climate and edaphic factors.Our findings indicate a low level of gene flow between populations, irrespective of variation in distance, range size and ploidy. Slightly shorter genetic distances were observed between the tetraploid populations compared to the diploids. Our data indicates that diploids adapted to cold conditions were restricted to mountains during glaciations, while polyploids spread more widely during cold periods. Nevertheless, since the LGM it appears that all studied ranges have been rather conservative, with maybe some local contractions and expansions, especially in tetraploids. Moreover, tetraploids demonstrated the most stable potential range during climate warming.The studied cases are characterized by individual and complex range dynamics dependent on local conditions and cytotype behaviour. However, generally speaking, studied mountain species demonstrate a conservative range, which places them at risk of extinction during global warming due to the lack of effective means of escape.

Vascular system of rice leaves depending on ploidy level

The current paper has provided data on the study of the vascular system of flag leaves of rice plants grown in a greenhouse in the period 2022–2023. The objects of the study were 24 rice samples developed at the FSBSI “ARC “Donskoy” using the method of androgenesis and cell culture. The purpose of the work was to determine the degree of development of the vascular system of flag leaves of regenerated rice plants with different ploidy levels (1n, 2n, 4n). When studying the vascular system of plant leaves (the number and area of bundles), it was found that haploid plants had smaller vascular bundles compared to diand tetraploid samples. The average beam diameter had dimensions of 59.5, 69.3 and 75.3 µm, the area of one beam was 2815.6, 3827.2 and 4540.5 µm², respectively. In the leaves of rice samples, a larger number of small and large vascular bundles have been formed with increasing ploidy level. Their number was 36–44 in haploids, 40–52in diploids, 52–60 in tetraploids. The average number of bundles was 40.3, 46.6 and 55.2, respectively. The venation pattern was individual for each sample. Between single large bundles there are from one to seven small veins, most often 4–6 pieces. Thus, samples with different ploidy levels differ in the anatomical structure of the leaves, which ultimately affects their morphology and productivity.

Ploidy and fruit trait variation in oil-tea Camellia: Implications for ploidy breeding

Plant polyploidy often occurs in conjunction with higher yield and superior quality. Therefore, obtaining polyploid germplasms is a significant part of breeding. The oil-tea Camellia tree is an important native woody plant that produces high-quality edible oil and includes many species of Camellia with different ploidies. However, whether higher ploidy levels in oil-tea Camellia trees are related to better traits remains unclear. In this study, the ploidy levels of 30 different oil-tea Camellia strains in three different species in the Sect. Paracamellia were determined by flow cytometry and chromosome preparation, and the phenotypic characteristics and fatty acid compositions of the fruits were examined by field observations and laboratory analyses. The correlations between the ploidy level of oil-tea Camellia and the main traits of the fruit were investigated. Our results showed that 10 Camellia lanceoleosa strains were diploid, 10 Camellia meiocarpa strains were tetraploid and 10 Camellia oleifera strains were hexaploid. Hexaploid C. oleifera had larger fruit size and weight, more seeds per fruit, greater seed weight per fruit, higher oil content and greater yield per crown width than tetraploid C. meiocarpa and diploid C. lanceoleosa, but their fruit peel thickness and fresh seed rate were significantly lower, and these traits were significantly correlated with ploidy level. In addition, in terms of fatty acid composition, hexaploid C. oleifera had a higher oleic acid content than tetraploid C. meiocarpa and diploid C. lanceoleosa, but their linoleic acid, linolenic acid and arachidonic acid contents were lower. The contents of palmitic acid, stearic acid and total unsaturated fatty acids were not significantly correlated with ploidy level. In conclusion, certain correlations exist between the main characteristics of oil-tea Camellia fruit and the ploidy level, and increasing the ploidy level led to an increase in fruit yield with no effect on oil composition. The discovery of variations in the main characteristics of oil-tea Camellia fruit with different ploidies will facilitate germplasm innovation and lay a foundation for ploidy breeding and mechanistic research on fruit traits.

Morphological and habitat differentiation between diploids and tetraploids of a Drakensberg near‐endemic taxon, Rhodohypoxis baurii var. platypetala (Hypoxidaceae)

AbstractEnvironmental factors may shape the spatial distribution of ploidy levels. Here, we undertook a cytogeographical study of Rhodohypoxis baurii var. platypetala (Hypoxidaceae), a Drakensberg near‐endemic taxon. We addressed the following questions: (1) Are there mixed‐ploidy populations or is each population represented by a single ploidy level? (2) Is there a pattern in the environmental distribution of ploidy levels? (3) Are there specific environmental variables associated with each ploidy level locality? (4) Are plant traits similar or different within and among ploidy levels across populations that experience different environmental factors? We measured leaf and flower traits of individuals that were sampled for flow cytometry from 17 populations across the KwaZulu‐Natal and Free State provinces in South Africa. We extracted daily climate data for 13 variables and collected soil samples to evaluate pH and nutrient properties to characterize the sampled populations to test for relationships with ploidy level distributions. Twelve populations were found to contain only diploids, four populations contained only tetraploids, and only one population was ‘mixed ploidy’ (both diploid and triploid individuals present). There was an overlap in the altitudinal range of diploid and tetraploid populations, but diploids reached the highest altitudes recorded for the current study. We also found that R. baurii var. platypetala occurs in acidic soils and that tetraploids occurred in soils with marginally higher nitrogen and phosphorus than soils where diploids occur. Tetraploids generally occurred in warmer conditions, in drier soils, and possessed broader leaves and larger flowers than diploids. Our study suggests that soil factors and temperature at a small (within localities) spatial scale likely shape ploidy level distributions in the Drakensberg grasslands.

Cannabis Triploids Exhibit Reduced Fertility and Similar Growth and Flower Production Compared to Diploids

Cannabis (Cannabis sativa) grown for flowers containing cannabinoids requires all female plants, which are susceptible to seed set from exposure to pollen. Created triploids demonstrated reduced seed production compared with diploids in field and greenhouse studies in which plants were challenged with pollen from males. In the field, seed production as a percent of floral biomass ranged from 6.7% to 18.0% for triploids and from 52.6% to 57.1% for diploids. The photoperiod-insensitive triploid genotype ‘Purple Star’ × ‘Wilhelmina’ had 98.5% fewer filled (containing a developed embryo) seeds than the photoperiod-insensitive diploid genotype ‘Tsunami’ × ‘Wilhelmina’. In the greenhouse, triploid ‘Wife’ had 99.5% fewer filled seeds than diploid ‘Wife’. Plant growth and flower production were similar with eight triploid and seven diploid genotypes evaluated over three greenhouse studies. There were a few superior triploid and diploid genotypes; however, their performance was more likely attributable to the parental cultivar combination than ploidy level. The optimal cross direction for producing triploid seed in large quantities is tetraploid × diploid because the diploid × tetraploid cross exhibits triploid block caused by endosperm paternal excess. Colchicine-induced tetraploid parent plants should be tested over a prolonged period to eliminate cryptic chimeral mixoploids or tetraploid plants should be derived from seed produced by crossing two colchicine-induced putative tetraploid plants to ensure that seeds from tetraploid × diploid crosses will be triploid. The latter approach is necessary for photoperiod-insensitive cultivars because a prolonged period of ploidy testing is not possible for these plants. These findings indicate that triploid plants have significantly reduced fertility and are a suitable alternative to diploids in situations in which pollen exposure is possible.

High-density bin-based genetic map reveals a 530-kb chromosome segment derived from wild peanut contributing to late leaf spot resistance.

Twenty-eight QTLs for LLS disease resistance were identified using an amphidiploid constructed mapping population, a favorable 530-kb chromosome segment derived from wild species contributes to the LLS resistance. Late leaf spot (LLS) is one of the major foliar diseases of peanut, causing serious yield loss and affecting the quality of kernel and forage. Some wild Arachis species possess higher resistance to LLS as compared with cultivated peanut; however, ploidy level differences restrict utilization of wild species. In this study, a synthetic amphidiploid (Ipadur) of wild peanuts with high LLS resistance was used to cross with Tifrunner to construct TI population. In total, 200 recombinant inbred lines were collected for whole-genome resequencing. A high-density bin-based genetic linkage map was constructed, which includes 4,809 bin markers with an average inter-bin distance of 0.43cM. The recombination across cultivated and wild species was unevenly distributed, providing a novel recombination landscape for cultivated-wild Arachis species. Using phenotyping data collected across three environments, 28 QTLs for LLS disease resistance were identified, explaining 4.35-20.42% of phenotypic variation. The major QTL located on chromosome 14, qLLS14.1, could be consistently detected in 2021 Jiyang and 2022 Henan with 20.42% and 12.12% PVE, respectively. A favorable 530-kb chromosome segment derived from Ipadur was identified in the region of qLLS14.1, in which 23 disease resistance proteins were located and six of them showed significant sequence variations between Tifrunner and Ipadur. Allelic variation analysis indicating the 530-kb segment of wild species might contribute to the disease resistance of LLS. These associate genomic regions and candidate resistance genes are of great significance for peanut breeding programs for bringing durable resistance through pyramiding such multiple LLS resistance loci into peanut cultivars.

Polyploid goldback and silverback ferns (Pentagramma) occupy a wider, colder, and wetter bioclimatic niche than diploid counterparts.

The western North American fern genus Pentagramma (Pteridaceae) is characterized by complex patterns of ploidy variation, an understanding of which is critical to comprehending both the evolutionary processes within the genus and its current diversity. We undertook a cytogeographic study across the range of the genus, using a combination of chromosome counts and flow cytometry to infer ploidy level. Bioclimatic variables and elevation were used to compare niches. We found that diploids and tetraploids are common and widespread, and triploids are rare and sporadic; in contrast with genome size inferences in earlier studies, no hexaploids were found. Diploids and tetraploids show different geographic ranges: only tetraploids were found in the northernmost portion of the range (Washington, Oregon, and British Columbia) and only diploids were found in the Sierra Nevada of California. Diploid, triploid, and tetraploid cytotypes were found to co-occur in relatively few localities: in the southern (San Diego County, California) and desert Southwest (Arizona) parts of the range, and along the Pacific Coast of California. Tetraploids occupy a wider bioclimatic niche than diploids both within P. triangularis and at the genus-wide scale. It is unknown whether the wider niche of tetraploids is due to their expansion upon the diploid niche, if diploids have contracted their niche due to competition or changing abiotic conditions, or if this wider niche occupancy is due to multiple origins of tetraploids.

Exploring floral morphoanatomy and embryology in wild populations of Chrysolaena flexuosa (Vernonia, Asteraceae): a contribution to understanding its ornamental potential.

Chrysolaena flexuosa (Sims.) H. Rob. is a South American species in the tribe Vernonieae, with potential ornamental value: it has attractive inflorescences, is suitable for pot cultivation, and its cypselae are useful for dried flower arrangements. Apart from studies on the growth dynamics of this species under cultivation, chromosome number, DNA content, ploidy level, size, pollen viability, and the characterization of phenotypic and genetic variability, it is noteworthy that other aspects regarding the floral architecture, reproductive mode, and gametophyte formation of C. flexuosa have not yet been studied. For this reason, our study encompasses a floral morphoanatomical survey and a comprehensive assessment of gametophyte development in the species. As a result of this study, we report new floral morphotypes, confirming that the morphological variability of the species might be greater than speculated. The morphoanatomy of the androecium and gynoecium and the male and female gametophyte developmental characteristics are uniform in all the populations studied despite the different ploidy levels. Chrysolaena flexuosa has five tetrasporangiate stamens of the dicotyledonous type of development; all the populations studied displayed a unilocular inferior ovary with a single anatropous, unitegumented, and tenuinucellar ovule. Given that all the embryo sacs observed were of the Polygonum-type development regardless of the ploidy level, we infer that the populations analyzed are fertile and undergo sexual reproduction. Our results not only contribute further research in the field of breeding systems and propagation of this species, but also promote the successful introduction of C. flexuosa to the plant ornamental market.

Identifikasi Tingkat Ploidi Tanaman Pisang Menggunakan Flow Cytometer di Jawa Tengah

In Indonesia, banana plants are known to have high genetic diversity, both cultivated and wild bananas. Banana plants are naturally known to have several levels of ploidy, namely diploid, triploid, and tetraploid. This study aims to identify the level of ploidy in banana plants explored in Central Java. The research method used flow cytometer, which analyzes the size of the plant genome, thus providing an overview of the level of ploidy and genetic diversity in banana plant populations. The research samples were banana plant leaves from various exploration locations in Central Java. The identification results show that of the 30 banana plant leaf samples that were successfully analyzed, it is known that the largest number of samples from banana plants that have triploid ploidy level (2n = 3x), namely 15 numbers, diploid ploidy level (2n = 2x) as many as 14 numbers, and found 1 cultivated banana with tetraploid ploidy level (2n = 4x). The results of ploidy level identification can provide guidance for researchers and plant breeders in selecting the right genotype for the development of superior varieties.

Genome Size in the Arenaria ciliata Species Complex (Caryophyllaceae), with Special Focus on Northern Europe and the Arctic.

The main aim of the present study has been the completion of genome size data for the diverse arctic-alpine A. ciliata species complex, with special focus on the unexplored arctic taxon A. pseudofrigida, the north-European A. norvegica, and A. gothica from Gotland (Sweden). Altogether, 46 individuals of these three Nordic taxa have been sampled from seven different regions and their genome size estimated using flow cytometry. Three other alpine taxa in the A. ciliata complex (A. multicaulis, A. ciliata subsp. ciliata, and A. ciliata subsp. bernensis) were also collected and analyzed for standardization purposes, comprising 20 individuals from six regions. A mean 2c value of 1.65 pg of DNA was recorded for A. pseudofrigida, 2.80 pg for A. norvegica, and 4.14 pg for A. gothica, as against the reconfirmed 2c value of 1.63 pg DNA for the type taxon A. ciliata subsp. ciliata. Our results presenting the first estimations of genome sizes for the newly sampled taxa, corroborate ploidy levels described in the available literature, with A. pseudofrigida being tetraploid (2n = 4x = 40), A. norvegica possessing predominantly 2n = 8x = 80, and A. gothica with 2n = 10x = 100. The present study also reconfirms genome size and ploidy level estimations published previously for the alpine members of this species complex. Reflecting a likely complex recent biogeographic history, the A. ciliata species group comprises a polyploid arctic-alpine species complex characterized by reticulate evolution, polyploidizations and hybridizations, probably associated with rapid latitudinal and altitudinal migrations in the Pleistocene-Holocene period.