Polyploid Plants Research Articles

Regulatory controls of duplicated gene expression during fiber development in allotetraploid cotton

Polyploidy complicates transcriptional regulation and increases phenotypic diversity in organisms. The dynamics of genetic regulation of gene expression between coresident subgenomes in polyploids remains to be understood. Here we document the genetic regulation of fiber development in allotetraploid cotton Gossypium hirsutum by sequencing 376 genomes and 2,215 time-series transcriptomes. We characterize 1,258 genes comprising 36 genetic modules that control staged fiber development and uncover genetic components governing their partitioned expression relative to subgenomic duplicated genes (homoeologs). Only about 30% of fiber quality-related homoeologs show phenotypically favorable allele aggregation in cultivars, highlighting the potential for subgenome additivity in fiber improvement. We envision a genome-enabled breeding strategy, with particular attention to 48 favorable alleles related to fiber phenotypes that have been subjected to purifying selection during domestication. Our work delineates the dynamics of gene regulation during fiber development and highlights the potential of subgenomic coordination underpinning phenotypes in polyploid plants.

Chronosequence of invasion reveals minimal losses of population genomic diversity, niche expansion, and trait divergence in the polyploid, leafy spurge.

Rapid evolution may play an important role in the range expansion of invasive species and modify forecasts of invasion, which are the backbone of land management strategies. However, losses of genetic variation associated with colonization bottlenecks may constrain trait and niche divergence at leading range edges, thereby impacting management decisions that anticipate future range expansion. The spatial and temporal scales over which adaptation contributes to invasion dynamics remain unresolved. We leveraged detailed records of the ~130-year invasion history of the invasive polyploid plant, leafy spurge (Euphorbia virgata), across ~500 km in Minnesota, U.S.A. We examined the consequences of range expansion for population genomic diversity, niche breadth, and the evolution of germination behavior. Using genotyping-by-sequencing, we found some population structure in the range core, where introduction occurred, but panmixia among all other populations. Range expansion was accompanied by only modest losses in sequence diversity, with small, isolated populations at the leading edge harboring similar levels of diversity to those in the range core. The climatic niche expanded during most of the range expansion, and the niche of the range core was largely non-overlapping with the invasion front. Ecological niche models indicated that mean temperature of the warmest quarter was the strongest determinant of habitat suitability and that populations at the leading edge had the lowest habitat suitability. Guided by these findings, we tested for rapid evolution in germination behavior over the time course of range expansion using a common garden experiment and temperature manipulations. Germination behavior diverged from the early to late phases of the invasion, with populations from later phases having higher dormancy at lower temperatures. Our results suggest that trait evolution may have contributed to niche expansion during invasion and that distribution models, which inform future management planning, may underestimate invasion potential without accounting for evolution.

High-quality Gossypium hirsutum and Gossypium barbadense genome assemblies reveal the landscape and evolution of centromeres

Centromere positioning and organization are crucial for genome evolution; however, research on centromere biology is largely influenced by the quality of available genome assemblies. Here, we combined Oxford Nanopore and Pacific Biosciences technologies to de novo assemble two high-quality reference genomes for Gossypium hirsutum (TM-1) and Gossypium barbadense (3-79). Compared with previously published reference genomes, our assemblies show substantial improvements, with the contig N50 improved by 4.6-fold and 5.6-fold, respectively, and thus represent the most complete cotton genomes to date. These high-quality reference genomes enable us to characterize 14 and 5 complete centromeric regions for G. hirsutum and G. barbadense, respectively. Our data revealed that the centromeres of allotetraploid cotton are occupied by members of the centromeric repeat for maize (CRM) and Tekay long terminal repeat families, and the CRM family reshapes the centromere structure of the At subgenome after polyploidization. These two intertwined families have driven the convergent evolution of centromeres between the two subgenomes, ensuring centromere function and genome stability. In addition, the repositioning and high sequence divergence of centromeres between G. hirsutum and G. barbadense have contributed to speciation and centromere diversity. This study sheds light on centromere evolution in a significant crop and provides an alternative approach for exploring the evolution of polyploid plants.

Artificial Polyploid Plant Induction of Local North Sumatra Garlic (Allium sativum L.) with Oryzalin Treatment in M1 Generation

Artificial Polyploid Plant Induction of Local North Sumatra Garlic (Allium sativum L.) with Oryzalin Treatment in M1 Generation

Differences in pathogen resistance between diploid and polyploid plants: a systematic review and meta‐analysis

Polyploidy, the state of having more than two full sets of chromosomes, has been hypothesized to provide several evolutionary advantages to flowering plants including increased ability to resist pathogens and parasites. However, studies comparing pathogen resistance in conspecific and congeneric diploids and polyploids have produced mixed results. While the supposed relationship between polyploidy and pathogen resistance has been commented on in several narrative reviews, it has never been subjected to a systematic meta‐analysis. We examined the effect of polyploidy on pathogen resistance by synthesizing 214 effect sizes from 128 studies. We find that, overall, there is no consistent effect of polyploidy on pathogen resistance. Subgroup analyses suggest that polyploids perform significantly better than diploids only in resisting hemibiotrophic pathogens, and autopolyploids tend show greater resistance than allopolyploids. This is surprising given the fact that polyploids possess extra allele copies of R‐gene alleles that provide resistance to biotrophic pathogens, and this pattern may indicate that signaling cascades needed to elicit hypersensitive responses are disrupted by polyploidy. Disruption is supported by the observation that, across all pathogens, autopolyploids show significantly greater resistance compared to diploids, whereas allopolyploids do not. This is corroborated by the observation that synthetic autopolyploids perform significantly better than their allopolyploid and established counterparts. Regarding pathogen type, diploids show greater resistance than polyploids to pathogens that are fungi or nematodes. Analyses of publication bias indicate little to no bias, and analyses of heterogeneity indicate that phylogeny explains almost none of the observed heterogeneity. These results underscore the importance of not only systematic review but also the strong degree to which the effects of polyploidy depend on ecological context.

Interploidy Introgression Shaped Adaptation during the Origin and Domestication History of Brassica napus.

Polyploidy is recurrent across the tree of life and known as an evolutionary driving force in plant diversification and crop domestication. How polyploid plants adapt to various habitats has been a fundamental question that remained largely unanswered. Brassica napus is a major crop cultivated worldwide, resulting from allopolyploidy between unknown accessions of diploid B. rapa and B. oleracea. Here, we used whole-genome resequencing data of accessions representing the majority of morphotypes and ecotypes from the species B. rapa, B. oleracea, and B. napus to investigate the role of polyploidy during domestication. To do so, we first reconstructed the phylogenetic history of B. napus, which supported the hypothesis that the emergence of B. napus derived from the hybridization of European turnip of B. rapa and wild B. oleracea. These analyses also showed that morphotypes of swede and Siberian kale (used as vegetable and fodder) were domesticated before rapeseed (oil crop). We next observed that frequent interploidy introgressions from sympatric diploids were prominent throughout the domestication history of B. napus. Introgressed genomic regions were shown to increase the overall genetic diversity and tend to be localized in regions of high recombination. We detected numerous candidate adaptive introgressed regions and found evidence that some of the genes in these regions contributed to phenotypic diversification and adaptation of different morphotypes. Overall, our results shed light on the origin and domestication of B. napus and demonstrate interploidy introgression as an important mechanism that fuels rapid diversification in polyploid species.

Colchicine Effect of Mitosis Root Tip by Banana Kepok Yellow (Musa paradisiaca L.) Polyploid Explants

Colchicine can inhibit spindle formation so that doubled chromosomes fail to separate during anaphase cytologically to induce mutations that produce polyploid plants. Yellow kepok banana is a triploid banana. The supply of yellow kepok bananas is hampered by conventional cultivation methods and the limited availability of quality seeds. This study aims to determine the effect of adding colchicine compound to tissue culture media on the mitotic index, chromosome number, and chromosomal abnormalities in yellow kepok bananas and the formation of polyploid plantlets. This study was included in the experimental study by conducting mitotic preparation and observing morphology after the test sample was induced by colchicine. The results of the research that has been done show that the addition of the compound colchicine to the tissue culture medium of yellow kepok banana causes a decrease in the mitotic index, an increase in the number of chromosomes, the presence of chromosomal abnormalities, the formation of polyploid plantlets, and an increase in the number of roots, but there is a reduction in root length.

Asynapsis and meiotic restitution in tomato male meiosis induced by heat stress.

Susceptibility of the reproductive system to temperature fluctuations is a recurrent problem for crop production under a changing climate. The damage is complex as multiple processes in male and female gamete formation are affected, but in general, particularly pollen production is impaired. Here, the impact of short periods of elevated temperature on male meiosis of tomato (Solanum lycopersicon L.) is reported. Meiocytes in early stage flower buds exposed to heat stress (>35°C) exhibit impaired homolog synapsis resulting in partial to complete omission of chiasmata formation. In the absence of chiasmata, univalents segregate randomly developing unbalanced tetrads and polyads resulting in aneuploid spores. However, most heat-stressed meiotic buds primarily contain balanced dyads, indicating a propensity to execute meiotic restitution. With most meiocytes exhibiting a complete loss of chiasma formation and concomitantly showing a mitotic-like division, heat stress triggers first division restitution resulting in clonal spores. These findings corroborate with the plasticity of male meiosis under heat and establish a natural route for the induction of sexual polyploidization in plants and the engineering of clonal seed.

Nano-Strainer: A workflow for the identification of single-copy nuclear loci for plant systematic studies, using target capture kits and Oxford Nanopore long reads.

In modern plant systematics, target enrichment enables simultaneous analysis of hundreds of genes. However, when dealing with reticulate or polyploidization histories, few markers may suffice, but often are required to be single-copy, a condition that is not necessarily met with commercial capture kits. Also, large genome sizes can render target capture ineffective, so that amplicon sequencing would be preferable; however, knowledge about suitable loci is often missing. Here, we present a comprehensive workflow for the identification of putative single-copy nuclear markers in a genus of interest, by mining a small dataset from target capture using a few representative taxa. The proposed pipeline assesses sequence variability contained in the data from targeted loci and assigns reads to their respective genes, via a combined BLAST/clustering procedure. Cluster consensus sequences are then examined based on four pre-defined criteria presumably indicative for absence of paralogy. This is done by calculating four specialized indices; loci are ranked according to their performance in these indices, and top-scoring loci are considered putatively single- or low copy. The approach can be applied to any probe set. As it relies on long reads, the present contribution also provides template workflows for processing Nanopore-based target capture data. Obtained markers are further tested and then entered into amplicon sequencing. For the detection of possibly remaining paralogy in these data, which might occur in groups with rampant paralogy, we also employ the long-read assembly tool canu. In diploid representatives of the young Compositae genus Leucanthemum, characterized by high levels of polyploidy, our approach resulted in successful amplification of 13 loci. Modifications to remove traces of paralogy were made in seven of these. A species tree from the markers correctly reproduced main relationships in the genus, however, at low resolution. The presented workflow has the potential to valuably support phylogenetic research, for example in polyploid plant groups.

Research Progress of Chromosome Doubling and 2n Gametes of Ornamental Plants

Polyploid plants, an important source for the selection of ornamental plants for their advantages of faster growth, higher yields, and stronger adaptability to an adverse environment, play an essential role in the development of economic plants for agricultural stress. The methodology has been improved to decrease blindness and increase the efficiency of ornamental plants’ polyploid breeding in the long term. The progress of research on ornamental plants related to natural polyploidy, chromosome doubling, the 2n gametes pathway, and plant ploidy identification are reviewed in this paper. The main routes in polyploid breeding are chromosome doubling and sexual hybridization. Screening of suitable induction methods and plant material should be enhanced in chromosome doubling to improve induction efficiency. Regarding polyploid breeding, the utilization and research on 2n gametes produced by natural conditions or artificial induction should be strengthened to shorten the breeding years. Therefore, further research should strengthen the combination of chromosome doubling and sexual hybridization to improve breeding efficiency and strengthen the research and application of polyploid plants. This thesis review provides some reference value for polyploid breeding in ornamental plants.

Chromosome translocation affects multiple phenotypes, causes genome-wide dysregulation of gene expression, and remodels metabolome in hexaploid wheat.

Chromosomal rearrangements (CRs) may occur in newly formed polyploids due to compromised meiotic fidelity. Moreover, CRs can be more readily tolerated in polyploids allowing their longer-term retention and hence potential spreading/fixation within a lineage. The direct functional consequences of CRs in plant polyploids remain unexplored. Here, we identified a heterozygous individual from a synthetic allohexaploid wheat in which the terminal parts of the long-arms of chromosomes 2D (approximately 193 Mb) and 4A (approximately 167 Mb) were reciprocally translocated. Five homogeneous translocation lines including both unbalanced and balanced types were developed by selfing fertilization of the founder mutant (RT [2DL; 4AL]-ter/1, reciprocal translocation). We investigated impacts of these translocations on phenotype, genome-wide gene expression and metabolome. We find that, compared with sibling wild-type, CRs in the form of both unbalanced and balanced translocations induced substantial changes of gene expression primarily via trans-regulation in the nascent allopolyploid wheat. The CRs also manifested clear phenotypic and metabolic consequences. In particular, the genetically balanced, stable reciprocal translocations lines showed immediate enhanced reproductive fitness relative to wild type. Our results underscore the profound impact of CRs on gene expression in nascent allopolyploids with wide-ranging phenotypic and metabolic consequences, suggesting CRs are an important source of genetic variation that can be exploited for crop breeding.

Differentiation of rhizosphere fungal assemblages by host ploidy level in mixed‐ploidy Larrea tridentata populations

Polyploidy – whole genome duplication – is common in plants. Studies over the last several decades have documented numerous mixed‐ploidy populations. Whether arising via recurrent whole genome duplication events within a population, or from secondary contact, the persistence of mixed populations is possible by niche differentiation. Specifically, one mechanism facilitating ploidy co‐occurrence is microbially‐mediated niche differentiation (MMND), wherein cytotypes occupy different niches via interactions with different sets of microbes. Inherently cryptic, MMND is underexplored in polyploid plant populations. Here, we search for evidence of MMND in creosotebush Larrea tridentata, a dominant desert shrub of the southwestern US and northern Mexico. We sequenced root‐associated fungal taxa in soils of diploid, autotetraploid, and autohexaploid plants growing in two naturally‐occurring mixed‐cytotype populations. Within populations, we found substantial fungal assemblage overlap across host plant cytotypes. However, using indicator species analysis, we identified some fungi that are differentiated by host plant cytotype, satisfying a necessarycondition for MMND. Future study is needed to determine the degree of niche differentiation conferred, if any, and whether the identified fungi play a role in the long‐term persistence of multiple cytotypes within populations.

HANGES IN A NUMBER OF CHARACTERISTICS OF COMMON DANDELION (TARAXACUM OFFICINALE WIGG) DURING INVASION INTO ANTROPOGENICALLY DISTURBED AREAS OF THE HIGHLANDS

Chromosome count, plant height, number of inflorescences per plant, number of seeds per inflorescence, seed weight, germination and germination energy of plant seeds growing at altitudes of 200, 600, 1300, 2050, 2700 and 3050 m above sea level (Central Caucasus) were studied. The studies were conducted in 2013, 2014 and 2018 at the same sampling points. Chromosome counts were determined by cytogenetic method. In the T. officinale species, high ploid individuals predominate in populations when invading anthropogenically disturbed territories of the highlands. Polyploid plants are larger in size compared to their low ploid predecessors, but in high-altitude, selection is aimed at preserving smaller phenotypes. The increase in seed mass characteristic of polyploid plants was supported by natural selection and in conditions of highlands. Germination and germination energy did not change with the increase of altitude.

Genetic Mapping, Candidate Gene Identification and Marker Validation for Host Plant Resistance to the Race 4 of Fusarium oxysporum f. sp. cubense Using Musa acuminata ssp. malaccensis.

Fusarium wilt of banana is a devastating disease that has decimated banana production worldwide. Host resistance to Fusarium oxysporum f. sp. Cubense (Foc), the causal agent of this disease, is genetically dissected in this study using two Musa acuminata ssp. Malaccensis segregating populations, segregating for Foc Tropical (TR4) and Subtropical (STR4) race 4 resistance. Marker loci and trait association using 11 SNP-based PCR markers allowed the candidate region to be delimited to a 12.9 cM genetic interval corresponding to a 959 kb region on chromosome 3 of 'DH-Pahang' reference assembly v4. Within this region, there was a cluster of pattern recognition receptors, namely leucine-rich repeat ectodomain containing receptor-like protein kinases, cysteine-rich cell-wall-associated protein kinases, and leaf rust 10 disease-resistance locus receptor-like proteins, positioned in an interspersed arrangement. Their transcript levels were rapidly upregulated in the resistant progenies but not in the susceptible F2 progenies at the onset of infection. This suggests that one or several of these genes may control resistance at this locus. To confirm the segregation of single-gene resistance, we generated an inter-cross between the resistant parent 'Ma850' and a susceptible line 'Ma848', to show that the STR4 resistance co-segregated with marker '28820' at this locus. Finally, an informative SNP marker 29730 allowed the locus-specific resistance to be assessed in a collection of diploid and polyploid banana plants. Of the 60 lines screened, 22 lines were predicted to carry resistance at this locus, including lines known to be TR4-resistant, such as 'Pahang', 'SH-3362', 'SH-3217', 'Ma-ITC0250', and 'DH-Pahang/CIRAD 930'. Additional screening in the International Institute for Tropical Agriculture's collection suggests that the dominant allele is common among the elite 'Matooke' NARITA hybrids, as well as in other triploid or tetraploid hybrids derived from East African highland bananas. Fine mapping and candidate gene identification will allow characterization of molecular mechanisms underlying the TR4 resistance. The markers developed in this study can now aid the marker-assisted selection of TR4 resistance in breeding programs around the world.

Cytosine base editors (CBEs) for inducing targeted DNA base editing in Nicotiana benthamiana

BackgroundThe base editors can introduce point mutations accurately without causing double-stranded DNA breaks or requiring donor DNA templates. Previously, cytosine base editors (CBEs) containing different deaminases are reported for precise and accurate base editing in plants. However, the knowledge of CBEs in polyploid plants is inadequate and needs further exploration.ResultsIn the present study, we constructed three polycistronic tRNA-gRNA expression cassettes CBEs containing A3A, A3A (Y130F), and rAPOBEC1(R33A) to compare their base editing efficiency in allotetraploid N. benthamiana (n = 4x). We used 14 target sites to compare their editing efficiency using transient transformation in tobacco plants. The sanger sequencing and deep sequencing results showed that A3A-CBE was the most efficient base editor. In addition, the results showed that A3A-CBE provided most comprehensive editing window (C1 ~ C17 could be edited) and had a better editing efficiency under the base background of TC. The target sites (T2 and T6) analysis in transformed N. benthamiana showed that only A3A-CBE can have C-to-T editing events and the editing efficiency of T2 was higher than T6. Additionally, no off-target events were found in transformed N. benthamiana.ConclusionsAll in all, we conclude that A3A-CBE is the most suitable vector for specific C to T conversion in N. benthamiana. Current findings will provide valuable insights into selecting an appropriate base editor for breeding polyploid plants.

Polyploidy affects responses to Nickel in Ni-hyperaccumulating plants: Evidence from the model species Odontarrhena bertolonii (Brassicaceae)

Compared with their diploid progenitors, polyploid plants often display enhanced vigor and adaptive ability to extreme conditions. Previous studies investigated polyploid fitness under various forms of environmental stress, but whether the whole-genome duplication can affect growth, accumulation ability and tolerance levels to trace metals in metal-accumulating species remains obscure. We investigated this topic using an experimental approach and Odontarrhena bertolonii as model system. This obligate serpentine endemic includes diploid and tetraploid accessions with allopatric distribution in Tuscany and Liguria. Three diploid (2 n = 2x = 16) and three natural autotetraploid (2 n = 4x = 32) accessions were compared for growth, leaf traits, photosynthetic parameters and metal accumulation after cultivation on natural serpentine soil and in Ni-containing hydroponic solutions. In soil cultivation, shoot Ni concentration was similar in diploid and tetraploid plants, but the metal content per plant was significantly higher in polyploids because of their higher biomass production. The latter was mainly due to the production of larger leaves, coupled to a lower specific leaf area, which pointed to a better adaptation of the tetraploids to serpentine soil. In hydroponics, all the accessions showed an hormetic-like Ni effect, with stimulation of growth and photosynthesis in the low-dose zone. The data fitting to the hormetic model displayed significant differences in some parameters, with the tetraploid plants showing higher maximal length of roots and shoots and higher requirement of both external and internal Ni concentrations for optimal growth, in respect to diploid plants. On the other hand, Ni tolerance to both external and internal metal concentrations was similar in the plants of the two ploidy levels. Our results suggest that whole-genome duplication can affect the potential for growth and Ni-hyperaccumulation in obligate Ni-accumulator plants like O. bertolonii. This points to the opportunity of selecting polyploid instead of diploid accessions for environmental restoration and metal cropping practices, when the candidate species includes both chromosome races.

Optimal protocol for in vitro polyploid induction of Cymbidium aloifolium (L.) Sw

BackgroundCymbidium aloifolium is a popular ornamental flower in Thailand with both economic and medical values. Polyploid induction techniques are used to improve plant quality. This study identified polyploidy levels of C. aloifolium induction by colchicine. Protocorms of C. aloifolium were treated on solid New Dogashima Medium (NDM) with various concentrations of colchicine (0, 0.01, 0.02, 0.03, 0.04 and 0.05% w/v) for 2, 4 and 8 weeks.ResultsColchicine effectively induced plant polyploidy. Tetraploid plants were found after treatment with 0.03% and 0.04% colchicine for 8 weeks, while at increased concentration and duration, survival, response and growth performance decreased. Tetraploid plants showed the lowest growth performance but highest size of stomatal and epidermal cells. Growth performance and leaf surface anatomy data were analyzed by Pearson’s correlation and PCA. Results showed that stomatal and epidermal cell sizes had strongly negative correlations with other variables, while HCA revealed that stomatal and epidermal cell sizes of tetraploid plantlets were larger but stomatal and epidermal cell densities decreased when compared with the diploids.ConclusionColchicine at suitable concentrations and duration produced polyploid plants with alteration of morphological and anatomical traits. This study provides potential information to support orchid quality production as ornamental plants and a source of pharmaceutical raw materials.

EVALUATING THE CORRELATION OF PLOIDY LEVEL, LEAF SIZE, STOMATA CHARACTERISTICS AND TUBER WEIGHT IN Dioscorea spp. POPULATIONS FROM JALISCO, MÉXICO

<p><strong>Background. </strong>“Camote de cerro” (<em>Dioscorea </em>spp.) is a plant of great importance in West rural areas of Mexico as food source and alternative medicine. <em>Dioscorea</em> is an important crop around the world for its carbohydrate contribution to diets. Yams are polyploid plants, and species with modifications at ploidy level also present changes in leaf size and stomata characteristics. These variations can favor resistance to adverse conditions. <strong>Objective.</strong> In the present study, evaluation and correlation of ploidy levels, leaf size, stomata characteristics and tuber weight were carried out for <em>Dioscorea </em><em>remotiflora</em> Kunth and <em>Dioscorea sparsiflora </em>Hemsley<em> </em>in accessions obtained from 11 localities in México. <strong>Methodology.</strong> Chromosome counting was carried out in root meristems<em>. </em>Measuring and counting stomata were carried out. Productivity rate (PR) was calculated dividing harvested tuber weight over seed tuber weight, for each experimental unit. Leaves width and length were measured<em>.</em> <strong>Results.</strong> Show that variation is higher among different localities than among specimens from the same locality. Significant differences were observed for, ploidy levels (P), stomata dimensions and number of chloroplasts in stomata. Differences in chloroplast numbers present in occlusive cells were also significant for different species. <strong>Implications.</strong> Ploidy level showed a relation with chloroplasts numbers in stomata and stomata width. Leaf size presented a relation with stomata dimensions, and leaf width showed a relation with tuber weight. <strong>Conclusions.</strong> These observations allowed us to determine that there are variation among populations; stomata width and chloroplast number in a population can help to determine ploidy levels, and leaf width is a response variable that allows to predict tuber weight.</p>

Growth, physiology, and stomatal parameters of plant polyploids grown under ice age, present-day, and future CO2 concentrations.

Polyploidy plays an important role in plant evolution, but knowledge of its eco-physiological consequences, such as of the putatively enlarged stomata of polyploid plants, remains limited. Enlarged stomata should disadvantage polyploids at low CO2 concentrations (namely during the Quaternary glacial periods) because larger stomata are viewed as less effective at CO2 uptake. We observed the growth, physiology, and epidermal cell features of 15 diploids and their polyploid relatives cultivated under glacial, present-day, and potential future atmospheric CO2 concentrations (200, 400, and 800 ppm respectively). We demonstrated some well-known polyploidy effects, such as faster growth and larger leaves, seeds, stomata, and other epidermal cells. The stomata of polyploids, however, tended to be more elongated than those of diploids, and contrary to common belief, they had no negative effect on the CO2 uptake capacity of polyploids. Moreover, polyploids grew comparatively better than diploids even at low, glacial CO2 concentrations. Higher polyploids with large genomes also showed increased operational stomatal conductance and consequently, a lower water-use efficiency. Our results point to a possible decrease in growth superiority of polyploids over diploids in a current and future high CO2 climatic scenarios, as well as the possible water and/or nutrient dependency of higher polyploids.

Neopolyploidy causes increased nutrient requirements and a shift in plant growth strategy in Heuchera cylindrica.

Functional traits fall along a continuum from resource-conservative to acquisitive and are powerful predictors of the ecological settings necessary for a species to persist and establish. As a consequence, a major problem that functional trait analysis could address is understanding the ecological contexts necessary for the persistence of polyploid plants, because early generation polyploids, or "neopolyploids", are at a high extinction risk. Since neopolyploidy could increase nutrient limitation, growth strategies should shift to accommodate the increased need for resources, but this prediction is untested. To address this gap, we compared the functional trait responses of diploids, synthetic neotetraploids, and naturally occurring tetraploids of Heuchera cylindrica, an herbaceous perennial plant, to nutrient manipulations in a greenhouse experiment. We found strong support for the hypothesis that neotetraploidy increases nutrient requirements, as evidenced by reduced productivity and increased tissue concentrations of nitrogen and phosphorus in neotetraploids. We also found that repeated formation of independent origins of neotetraploidy led to differing responses to nutrient supply, but neotetraploidy generally shifted functional traits to be more resource-acquisitive and inefficient. Taken together, our results suggest that shifts in functional trait responses may constrain the ability of neopolyploids to establish in nutrient-poor habitats. This article is protected by copyright. All rights reserved.