American Journal of Botany最新文献_第6页

The immediate metabolomic effects of whole-genome duplication in the greater duckweed, Spirodela polyrhiza 大浮萍全基因组复制对代谢组的直接影响

IF 2.4 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2024-08-01 DOI: 10.1002/ajb2.16383

Tian Wu, Quinten Bafort, Frederik Mortier, Fabricio Almeida-Silva, Annelore Natran, Yves Van de Peer

Premise

In plants, whole-genome duplication (WGD) is a common mutation with profound evolutionary potential. Given the costs associated with a superfluous genome copy, polyploid establishment is enigmatic. However, in the right environment, immediate phenotypic changes following WGD can facilitate establishment. Metabolite abundances are the direct output of the cell's regulatory network and determine much of the impact of environmental and genetic change on the phenotype. While it is well known that an increase in the bulk amount of genetic material can increase cell size, the impact of gene dosage multiplication on the metabolome remains largely unknown.

Methods

We used untargeted metabolomics on four genetically distinct diploid-neoautotetraploid pairs of the greater duckweed, Spirodela polyrhiza, to investigate how WGD affects metabolite abundances per cell and per biomass.

Results

Autopolyploidy increased metabolite levels per cell, but the response of individual metabolites varied considerably. However, the impact on metabolite level per biomass was restricted because the increased cell size reduced the metabolite concentration per cell. Nevertheless, we detected both quantitative and qualitative effects of WGD on the metabolome. Many effects were strain-specific, but some were shared by all four strains.

Conclusions

The nature and impact of metabolic changes after WGD depended strongly on the genotype. Dosage effects have the potential to alter the plant metabolome qualitatively and quantitatively, but were largely balanced out by the reduction in metabolite concentration due to an increase in cell size in this species.

前言：在植物中，全基因组复制（WGD）是一种常见的突变，具有深远的进化潜力。鉴于多余基因组拷贝的相关成本，多倍体的建立是一个谜。然而，在适当的环境中，WGD 后的直接表型变化可以促进多倍体的建立。代谢物丰度是细胞调控网络的直接输出，决定了环境和基因变化对表型的大部分影响。众所周知，遗传物质总量的增加可使细胞体积增大，但基因剂量倍增对代谢组的影响在很大程度上仍不为人所知：方法：我们在大浮萍（Spirodela polyrhiza）的四对基因不同的二倍体-自交四倍体上使用非靶向代谢组学，研究WGD如何影响每个细胞和每个生物量的代谢物丰度：结果：自多倍体增加了每个细胞的代谢物含量，但单个代谢物的反应差异很大。然而，对单位生物量代谢物含量的影响受到了限制，因为细胞体积的增大降低了单位细胞的代谢物浓度。尽管如此，我们还是检测到了 WGD 对代谢组的定量和定性影响。许多影响是菌株特有的，但有些影响是所有四个菌株共有的：结论：WGD 后代谢变化的性质和影响在很大程度上取决于基因型。剂量效应有可能从质量和数量上改变植物的代谢组，但由于该物种细胞体积增大而导致代谢物浓度降低，这在很大程度上抵消了剂量效应。

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引用次数: 0

Lineage diversification and rampant hybridization among subspecies explain taxonomic confusion in the endemic Hawaiian fern Polypodium pellucidum 亚种间的品系多样化和猖獗杂交解释了夏威夷特有蕨类植物Polypodium pellucidum分类混乱的原因。

IF 2.4 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2024-07-30 DOI: 10.1002/ajb2.16379

Jonas I. Mendez-Reneau, Joseph L. Richards, Julia Hobbie, Emily Bollich, Nicholas J. Kooyers, Erin M. Sigel

Premise

Polypodium pellucidum, a fern endemic to the Hawaiian Islands, encompasses five ecologically and morphologically variable subspecies, suggesting a complex history involving both rapid divergence and rampant hybridization.

Methods

We employed a large target-capture data set to investigate the evolution of genetic, morphological, and ecological variation in P. pellucidum. With a broad sampling across five Hawaiian Islands, we deciphered the evolutionary history of P. pellucidum, identified nonhybrid lineages and intraspecific hybrids, and inferred the relative influence of geography and ecology on their distributions.

Results

Polypodium pellucidum is monophyletic, dispersing to the Hawaiian archipelago 11.53–7.77 Ma and diversifying into extant clades between 5.66 and 4.73 Ma. We identified four nonhybrid clades with unique morphologies, ecological niches, and distributions. Additionally, we elucidated several intraspecific hybrid combinations and evidence for undiscovered or extinct “ghost” lineages contributing to extant hybrid populations.

Conclusions

We provide a foundation for revising the taxonomy of P. pellucidum to account for cryptic lineages and intraspecific hybrids. Geologic succession of the Hawaiian Islands through cycles of volcanism, vegetative succession, and erosion has determined the available habitats and distribution of ecologically specific, divergent clades within P. pellucidum. Intraspecific hybrids have likely arisen due to ecological and or geological transitions, often persisting after the local extinction of their progenitors. This research contributes to our understanding of the evolution of Hawai'i's diverse fern flora and illuminated cryptic taxa to allow better-informed conservation efforts.

前提：夏威夷群岛特有的蕨类植物Polypodium pellucidum包括五个生态和形态多变的亚种，这表明其历史非常复杂，既有快速的分化，也有猖獗的杂交：方法：我们使用了一个大型目标捕获数据集来研究 P. pellucidum 的遗传、形态和生态变异的演变。通过对夏威夷五个岛屿的广泛取样，我们破译了P. pellucidum的进化史，确定了非杂交品系和种内杂交种，并推断了地理和生态对其分布的相对影响：结果：Polypodium pellucidum 是单系的，于 11.53-7.77 Ma 分散到夏威夷群岛，并在 5.66-4.73 Ma 之间分化成现存的支系。我们发现了四个具有独特形态、生态位和分布的非杂交支系。此外，我们还阐明了几种种内杂交组合，以及未被发现或已灭绝的 "幽灵 "种系对现存杂交种群做出贡献的证据：结论：我们为修订P. pellucidum的分类学提供了一个基础，以解释隐蔽的品系和种内杂交。夏威夷群岛的地质演替经历了火山爆发、植被演替和侵蚀等周期，这决定了P. pellucidum的可利用栖息地和生态特异性分化支系的分布。种内杂交种很可能是由于生态和地质转变而产生的，往往在其祖先灭绝后仍在当地存在。这项研究有助于我们了解夏威夷多种蕨类植物群的进化过程，并揭示了隐蔽类群，从而更好地开展保护工作。

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引用次数: 0

Species-tree topology impacts the inference of ancient whole-genome duplications across the angiosperm phylogeny 物种树拓扑结构影响整个被子植物系统发育过程中古老的全基因组复制的推断。

IF 2.4 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2024-07-22 DOI: 10.1002/ajb2.16378

Michael T. W. McKibben, Geoffrey Finch, Michael S. Barker

Premise

The history of angiosperms is marked by repeated rounds of ancient whole-genome duplications (WGDs). Here we used state-of-the-art methods to provide an up-to-date view of the distribution of WGDs in the history of angiosperms that considers both uncertainty introduced by different WGD inference methods and different underlying species-tree hypotheses.

Methods

We used the distribution synonymous divergences (K_s) of paralogs and orthologs from transcriptomic and genomic data to infer and place WGDs across two hypothesized angiosperm phylogenies. We further tested these WGD hypotheses with syntenic inferences and Bayesian models of duplicate gene gain and loss.

Results

The predicted number of WGDs in the history of angiosperms (~170) based on the current taxon sampling is largely similar across different inference methods, but varies in the precise placement of WGDs on the phylogeny. K_s-based methods often yield alternative hypothesized WGD placements due to variation in substitution rates among lineages. Phylogenetic models of duplicate gene gain and loss are more robust to topological variation. However, errors in species-tree inference can still produce spurious WGD hypotheses, regardless of method used.

Conclusions

Here we showed that different WGD inference methods largely agree on an average of 3.5 WGD in the history of individual angiosperm species. However, the precise placement of WGDs on the phylogeny is subject to the WGD inference method and tree topology. As researchers continue to test hypotheses regarding the impacts ancient WGDs have on angiosperm evolution, it is important to consider the uncertainty of the phylogeny as well as WGD inference methods.

前言：被子植物的历史以反复发生古老的全基因组重复（WGD）为标志。在此，我们使用最先进的方法提供了被子植物历史上 WGDs 分布的最新观点，该观点考虑了不同 WGD 推断方法和不同基本物种树假说所带来的不确定性：方法：我们利用转录组和基因组数据中旁系和直系同义差异（Ks）的分布来推断WGD，并将其置于两个假定的被子植物系统发生中。我们还利用同源推断和贝叶斯重复基因增减模型进一步检验了这些WGD假说：结果：根据目前的分类群取样，被子植物历史上 WGD 的预测数量（约 170 个）在不同的推断方法中基本相似，但在 WGD 在系统发育上的精确位置上存在差异。基于 Ks 的方法往往会由于世系间替代率的差异而产生不同的 WGD 假设位置。重复基因增减的系统发生学模型对拓扑结构的变化更为稳健。然而，无论使用哪种方法，物种树推断中的错误仍会产生虚假的 WGD 假设：在这里，我们发现不同的WGD推断方法在被子植物个体历史中平均3.5个WGD上基本一致。然而，WGD 在系统发育中的精确位置取决于 WGD 推断方法和树的拓扑结构。在研究人员继续检验古代WGD对被子植物进化影响的假设时，必须考虑到系统发育的不确定性以及WGD推断方法。

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引用次数: 0

Estimates of late Early Cretaceous atmospheric CO2 from Mongolia based on stomatal and isotopic analysis of Pseudotorellia 基于气孔和同位素分析的蒙古早白垩世晚期大气二氧化碳估算。

IF 2.4 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2024-07-17 DOI: 10.1002/ajb2.16376

Xiaoqing Zhang, Dana L. Royer, Gongle Shi, Niiden Ichinnorov, Patrick S. Herendeen, Peter R. Crane, Fabiany Herrera

Premise

The Aptian–Albian (121.4–100.5 Ma) was a greenhouse period with global temperatures estimated as 10–15°C warmer than pre-industrial conditions, so it is surprising that the most reliable CO₂ estimates from this time are <1400 ppm. This low CO₂ during a warm period implies a very high Earth-system sensitivity in the range of 6 to 9°C per CO₂ doubling between the Aptian-Albian and today.

Methods

We applied a well-vetted paleo-CO₂ proxy based on leaf gas-exchange principles (Franks model) to two Pseudotorellia species from three stratigraphically similar samples at the Tevshiin Govi lignite mine in central Mongolia (~119.7–100.5 Ma).

Results

Our median estimated CO₂ concentration from the three respective samples was 2132, 2405, and 2770 ppm. The primary reason for the high estimated CO₂ but with relatively large uncertainties is the very low stomatal density in both species, where small variations propagate to large changes in estimated CO₂. Indeed, we found that at least 15 leaves are required before the aggregate estimated CO₂ approaches that of the full data set.

Conclusions

Our three CO₂ estimates all exceeded 2000 ppm, translating to an Earth-system sensitivity (~3–5°C/CO₂ doubling) that is more in keeping with the current understanding of the long-term climate system. Because of our large sample size, the directly measured inputs did not contribute much to the overall uncertainty in estimated CO₂; instead, the inferred inputs were responsible for most of the overall uncertainty and thus should be scrutinized for their value choices.

前提：始新世-阿尔卑斯时期（121.4-100.5Ma）是一个温室时期，全球气温估计比工业化前温度高10-15°C，因此，令人惊讶的是，这个时期最可靠的二氧化碳估算值是2，这意味着从始新世-阿尔卑斯时期到今天，每二氧化碳增加一倍，地球系统的敏感性就会提高6-9°C：我们根据叶片气体交换原理（弗兰克斯模型），对蒙古中部特夫希因戈维褐煤矿（约 119.7-100.5 Ma）三个地层相似样本中的两个假蕨类植物物种应用了一个经过充分验证的古二氧化碳替代物：我们从三个样本中估算出的二氧化碳浓度中值分别为 2132、2405 和 2770 ppm。估计二氧化碳浓度较高但不确定性相对较大的主要原因是这两个物种的气孔密度都很低，微小的变化会导致估计二氧化碳浓度的大幅变化。事实上，我们发现至少需要 15 片叶子，估计的二氧化碳总量才能接近完整数据集的二氧化碳总量：我们的三个二氧化碳估算值都超过了 2000 ppm，这意味着地球系统敏感度（约 3-5°C/CO2 双倍）更符合当前对长期气候系统的理解。由于我们的样本量大，直接测量的输入量对二氧化碳估算值的总体不确定性影响不大；相反，推断的输入量造成了总体不确定性的大部分，因此应仔细审查其数值选择。

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引用次数: 0

Are plant traits drivers of endophytic communities in seasonally flooded tropical forests? 植物性状是季节性洪涝热带森林中内生菌群落的驱动力吗？

IF 2.4 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2024-07-16 DOI: 10.1002/ajb2.16366

Marion Boisseaux, Valérie Troispoux, Alice Bordes, Jocelyn Cazal, Saint-Omer Cazal, Sabrina Coste, Clément Stahl, Heidy Schimann

Premise: In the Amazon basin, seasonally flooded (SF) forests offer varying water constraints, providing an excellent way to investigate the role of habitat selection on microbial communities within plants. However, variations in the microbial community among host plants cannot solely be attributed to environmental factors, and how plant traits contribute to microbial assemblages remains an open question.

Methods: We described leaf- and root-associated microbial communities using ITS2 and 16 S high-throughput sequencing and investigated the stochastic-deterministic balance shaping these community assemblies using two null models. Plant ecophysiological functioning was evaluated by focusing on 10 leaf and root traits in 72 seedlings, belonging to seven tropical SF tree species in French Guiana. We then analyzed how root and leaf traits drove the assembly of endophytic communities.

Results: While both stochastic and deterministic processes governed the endophyte assembly in the leaves and roots, stochasticity prevailed. Discrepancies were found between fungi and bacteria, highlighting that these microorganisms have distinct ecological strategies within plants. Traits, especially leaf traits, host species and spatial predictors better explained diversity than composition, but they were modest predictors overall.

Conclusions: This study widens our knowledge about tree species in SF forests, a habitat sensitive to climate change, through the combined analyses of their associated microbial communities with functional traits. We emphasize the need to investigate other plant traits to better disentangle the drivers of the relationship between seedlings and their associated microbiomes, ultimately enhancing their adaptive capacities to climate change.

前言：在亚马逊盆地，季节性洪水（SF）森林提供了不同的水分限制，为研究生境选择对植物内微生物群落的作用提供了极好的方法。然而，寄主植物之间微生物群落的变化不能完全归因于环境因素，植物特征如何影响微生物群落仍是一个未决问题：方法：我们利用 ITS2 和 16 S 高通量测序技术描述了与叶和根相关的微生物群落，并利用两种无效模型研究了形成这些群落组合的随机-确定性平衡。我们对法属圭亚那的 7 种热带 SF 树种的 72 株幼苗的 10 个叶片和根部特征进行了评估，从而确定了植物的生态生理功能。然后，我们分析了根和叶片性状如何驱动内生群落的形成：结果：虽然叶片和根部的内生菌群落分布受随机过程和确定过程的影响，但随机过程占主导地位。真菌和细菌之间存在差异，这表明这些微生物在植物体内有不同的生态策略。性状（尤其是叶片性状）、寄主物种和空间预测因子比组成更好地解释了多样性，但总体而言，它们的预测效果一般：这项研究通过对自生森林（对气候变化敏感的栖息地）中的相关微生物群落的功能特征进行综合分析，拓宽了我们对自生森林树种的认识。我们强调有必要研究其他植物性状，以更好地厘清树苗与其相关微生物群落之间关系的驱动因素，最终提高它们对气候变化的适应能力。

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引用次数: 0

Cretaceous and Paleocene fossils reveal an extinct higher clade within Cornales, the dogwood order 白垩纪和古新世的化石揭示了山茱萸目中一个已经灭绝的更高支系。

IF 2.4 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2024-07-15 DOI: 10.1002/ajb2.16372

Austin T. Nguyen, Brian A. Atkinson

Premise

Characterization and phylogenetic integration of fossil angiosperms with uncertain affinities is relatively limited, which may obscure the diversity of extinct higher taxa in the flowering plant tree of life. The order Cornales contains a diversity of extinct taxa with uncertain familial affinities that make it an ideal group for studying turnover in angiosperms. Here, we describe a new extinct genus of Cornales unassignable to an extant family and conduct a series of phylogenetic analyses to reconstruct relationships of fossils across the order.

Methods

Two permineralized endocarps were collected from the Cedar District Formation (Campanian, 82–80 Ma) of Sucia Island, State of Washington, United States. Fossils were sectioned with the cellulose acetate peel technique and incorporated into a morphological dataset. To assess the utility of this dataset to accurately place taxa in their respective clades, we used a series of phylogenetic pseudofossilization analyses. We then conducted a total-evidence analysis and a scaffold-based approach to determine relationships of fossils.

Results

Based on their unique combination of characters, the fossils represent a new genus, Fenestracarpa washingtonensis gen. nov. et sp. nov. Pseudofossilization analyses indicate that our morphological dataset can be used to accurately recover taxa at the major clade to family level, generally with moderate to high support. The total-evidence and scaffold-based analyses recovered Fenestracarpa and other fossil genera in an entirely extinct clade within Cornales.

Conclusions

Our findings increase the reported diversity of extinct Cornales and indicate that the order's initial radiation likely included the divergence of an extinct higher clade that endured the end-Cretaceous Mass extinction but perished during the Cenozoic.

前提：对具有不确定亲缘关系的被子植物化石的特征描述和系统发育整合相对有限，这可能会掩盖开花植物生命树中已灭绝的高等类群的多样性。被子植物门（Cornales）包含多种亲缘关系不确定的已灭绝类群，是研究被子植物更替的理想类群。在这里，我们描述了一个无法归属于现生科的新的已灭绝科属，并进行了一系列系统发育分析，以重建整个目中化石的关系：从美国华盛顿州苏西亚岛的雪松区地层（钟乳期，82-80 Ma）采集了两块过矿化的内生化石。化石采用醋酸纤维素剥离技术进行切片，并纳入形态数据集。为了评估该数据集在将类群准确归入各自支系方面的效用，我们使用了一系列系统发育假化石分析。然后，我们进行了总证据分析和基于支架的方法来确定化石之间的关系：结果：基于其独特的特征组合，这些化石代表了一个新属--Fenestracarpa washingtonensis gen.假化石分析表明，我们的形态学数据集可用于准确恢复从大支系到科一级的类群，一般具有中等到较高的支持率。总证据分析和基于支架的分析将 Fenestracarpa 属和其他化石属归入 Cornales 中一个完全灭绝的支系：我们的发现增加了已灭绝的 Cornales 的多样性，并表明该目最初的辐射可能包括一个已灭绝的较高支系的分化，该支系经历了白垩纪末的大灭绝，但在新生代灭绝。

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引用次数: 0

Salt tolerance in a neotropical orchid in the absence of local adaptation to salt spray 一种新热带兰花在当地不适应盐雾的情况下的耐盐性。

IF 2.4 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2024-07-15 DOI: 10.1002/ajb2.16373

Thales M. de Lima, Simone F. Silva, Rafael V. Ribeiro, Julia Sánchez-Vilas, Fabio Pinheiro

Premise

Salt tolerance has rarely been investigated regionally in the neotropics and even more rarely in Orchidaceae, one of the largest families. Therefore, investigating local adaptation to salt spray and its physiological basis in Epidendrum fulgens, a neotropical orchid species, brings important new insights.

Methods

We assessed the degree of salt tolerance in E. fulgens by testing whether coastal populations are more tolerant to salt, which could point to local adaptation. To understand the physiological basis of such salt tolerance, we exposed wild-collected individuals to salt spray for 60 days, then measured leaf expansion, osmotic potential, sodium leaf concentration, chlorophyll leaf index, chlorophyll fluorescence, relative growth rate, and pressure–volume curves.

Results

There is no local adaptation to salt spray since both inland and coastal plants have a high tolerance to salt stress. This tolerance is explained by the ability to tolerate high concentrations of salt in leaf tissues, which is related to the high succulence displayed by this species.

Conclusions

We showed an unprecedented salt tolerance level for an orchid species, highlighting our limited knowledge of that trait beyond the traditional studied groups. Another interesting finding is that salt tolerance in E. fulgens is linked to succulence, is widespread, and is not the result of local adaptation. We suggest that E. fulgens and its allied species could be an interesting group to explore the evolution of important traits related to tolerance to salt stress, like succulence.

前言：在新热带地区很少对耐盐性进行区域性研究，在兰科（兰属植物中最大的科之一）更是如此。因此，研究新热带兰科植物富贵竹（Epidendrum fulgens）对盐雾的局部适应性及其生理基础将带来重要的新发现：方法：我们通过测试沿海种群是否更耐盐碱来评估富贵竹的耐盐碱程度。为了了解这种耐盐性的生理基础，我们将野生采集的个体暴露在盐雾中 60 天，然后测量叶片扩展、渗透电位、钠叶浓度、叶绿素叶指数、叶绿素荧光、相对生长率和压力-体积曲线：结果：由于内陆和沿海植物对盐胁迫都有很强的耐受性，因此当地对盐雾没有适应性。这种耐受性的原因是叶片组织能够耐受高浓度的盐分，这与该物种表现出的高肉质性有关：结论：我们发现兰花物种具有前所未有的耐盐性，这凸显了我们在传统研究群体之外对这一特性的有限了解。另一个有趣的发现是，富贵草的耐盐性与多汁性有关，而且分布广泛，并非当地适应的结果。我们认为，富贵草及其同属物种可能是一个有趣的群体，可用于探索与耐盐胁迫相关的重要性状（如多汁性）的进化。

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引用次数: 0

Effects of anther-stigma position on cross-pollination efficiency in a hermaphroditic plant 花药柱头位置对两性植物异花授粉效率的影响。

IF 2.4 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2024-07-15 DOI: 10.1002/ajb2.16377

Matias C. Baranzelli, Manuel Ochoa-Sánchez, Sergio E. Ramos, Fernanda Baena-Díaz, Paula Sosenski, Karina Boege, Cesar A. Domínguez, Juan Fornoni

Premise

Evolution of cross-pollination efficiency depends on the genetic variation of flower traits, the pollen vector, and flower trait matching between pollen donors and recipients. Trait matching has been almost unexplored among nonheterostylous species, and we examined whether the match of anther length in pollen donors and stigma length in pollen recipients influences the efficiency of cross-pollination. To explore potential constraints for evolutionary response, we also quantified genetic variation and covariation among sepal length, petal length and width, stamen length, style length, and herkogamy.

Methods

We created 58 experimental arrays of Turnera velutina that varied in the extent of mismatch in the position of anthers and stigmas between single-flowered plants. Genetic variation and correlations among flower traits were estimated under greenhouse conditions.

Results

Style length, but not herkogamy, influenced the efficiency of cross-pollination. Plants with stamen length that matched the style length of other plants were more efficient pollen donors, whereas those with the style protruding above the stamens of other plants were more efficient pollen recipients. Significant broad-sense heritability (0.22 > h_B² < 0.42) and moderate genetic correlations (0.33 > r < 0.85) among floral traits were detected.

Conclusions

Our results demonstrated that anther-stigma mismatch between flowers contributed to variation in the efficiency of cross-pollination. The genetic correlations between stamen length and other floral traits suggests that any change in cross-pollination efficiency would be driven by changes in style rather than in stamen length.

前提：异花传粉效率的进化取决于花朵性状的遗传变异、花粉载体以及花粉供体和受体之间花朵性状的匹配。我们研究了花粉供体中花药长度与受体中柱头长度的匹配是否会影响异花授粉的效率。为了探索进化反应的潜在限制因素，我们还量化了萼片长度、花瓣长度和宽度、雄蕊长度、花柱长度和异花授粉之间的遗传变异和协变：方法：我们创建了58个Turnera velutina实验阵列，这些阵列在单花植株之间的花药和柱头位置错配程度各不相同。在温室条件下对花朵性状的遗传变异和相关性进行了估计：结果：花柱长度影响异花授粉的效率，而非雌雄同株异花授粉。雄蕊长度与其他植株的花柱长度一致的植株是更有效的花粉供体，而花柱突出于其他植株雄蕊之上的植株是更有效的花粉受体。显著的广义遗传力（0.22 > hB 2 r 结论：我们的研究结果表明，花朵之间的花药-柱头不匹配导致了异花授粉效率的差异。雄蕊长度与其他花性状之间的遗传相关性表明，异花授粉效率的任何变化都是由花柱的变化而不是雄蕊长度的变化引起的。

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引用次数: 0

The timing of visits by large and small bees differentially affects pollination success in Mimulus ringens 大蜜蜂和小蜜蜂来访的时间不同会影响环斑绣线菊的授粉成功率。

IF 2.4 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2024-07-14 DOI: 10.1002/ajb2.16375

Randall J. Mitchell, Dana Starvaggi, Victor Fitzgerald, Jeffrey D. Karron

Premise

Cross-fertilization in most flowering plants is facilitated by mobile animals that transport pollen while foraging for floral rewards. The contributions of different visitors can vary widely, depending on the amount of pollen transferred during a single visit and on the frequency and timing of the visits of each pollinator taxon.

Methods

We used three approaches to measure the pollination value of bees that visit Mimulus ringens: pollinator interviews, field population observations, and caging studies.

Results

The single-visit effectiveness of small bees (primarily Halictidae) was only half that of larger bees (primarily Bombus) for pollen delivery and removal. In five field populations, we found substantial temporal and spatial variation in visitation and pollination. In most sites big bees were active before 08:00 hours, and by 10:00–11:00 hours, stigmas were usually fully pollinated and closed, and little pollen remained in anthers. Small bees seldom visited before 10:00 hours. Excluding big bees from plants confirmed that pollination is reduced and delayed in this ecological context.

Conclusions

Big bees are the primary pollinators of M. ringens, accounting for at least 75% of seed production. Not only are they more effective per visit, in most situations they also visit before small bees become active. Although small bees are not usually important pollinators of M. ringens, they have the potential to partially replace them as a “fail-safe” pollinator in contexts where big bees are not abundant. In a world where pollinator abundance is declining, such backup pollinators may be important for maintaining plant reproduction.

前言：大多数开花植物的异花授粉都是由移动动物在觅花时运输花粉促成的。不同访花者的贡献可能相差很大，这取决于单次访花的花粉量以及每种授粉类群的访花频率和时间：方法：我们采用了三种方法来衡量蜜蜂访问环斑含羞草的授粉价值：授粉者访谈、野外种群观察和笼养研究：结果：小型蜜蜂（主要是半翅目蜜蜂）的单次花粉传递和清除效率仅为大型蜜蜂（主要是蜂科蜜蜂）的一半。在五个野外种群中，我们发现访问和授粉的时间和空间差异很大。在大多数地点，大蜜蜂在 8:00 之前就开始活动，到 10:00-11:00 时，柱头通常已完全授粉并闭合，花药中的花粉所剩无几。小蜜蜂很少在 10:00 点之前来访。从植物中排除大蜜蜂证实，在这种生态环境下，授粉会减少和延迟：结论：大蜜蜂是M. ringens的主要传粉者，至少占种子产量的75%。大蜜蜂不仅每次访问更有效，而且在大多数情况下，它们还会在小蜜蜂开始活跃之前访问。虽然小蜜蜂通常不是林蛙的重要授粉者，但在大蜜蜂数量不足的情况下，它们有可能部分取代大蜜蜂，成为 "万无一失 "的授粉者。在授粉者数量日益减少的今天，这种后备授粉者对于维持植物的繁殖可能非常重要。

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引用次数: 0

Striking genetic homogeneity in the widespread South American bracken 广泛分布的南美洲蕨类植物具有惊人的遗传同质性。

IF 2.4 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2024-07-12 DOI: 10.1002/ajb2.16374

Agustina Yañez, Sylvia P. Kinosian, M. Mónica Ponce, Diego G. Gutierrez, Pedro B. Schwartsburd, Michael Sundue, Paul G. Wolf

Premise

Bracken (Pteridium, Dennstaedtiaceae) is a cosmopolitan genus of aggressive disturbance colonizers that are toxic to agricultural livestock. The taxonomy of Pteridium has been treated in multiple schemes, ranging from one to six species worldwide, with numerous subspecies and varieties. Recent work has focused on the worldwide distribution and systematics of the bracken fern, but South America has been poorly represented. We present the first continent-wide sampling and analysis of Pteridium esculentum, a Southern Hemisphere diploid species.

Methods

Within South America, P. esculentum has several morphotypes, distinguished into subspecies by variation in indument and lamina architecture. We used double digest restriction site-associated DNA sequencing (ddRADSeq) to assess the phylogenetic relationships of P. esculentum subspecies.

Results

We found a striking genetic homogeneity in the species, being able to support only two morphotypes from molecular data: P. e. arachnoideum and P. e. campestre. We had high confidence for shallow and deep phylogenetic relationships, but less support for relationships among crown groups.

Conclusions

We describe an east-west geographic pattern that would explain the relationships between populations; and, in contrast to previous studies, we detected differences with P. esculentum from Australia. These results will lay the foundations for studying variations in this species' behavior as a weed, as well as its impact on the production of agricultural livestock in South America.

前提：蕨类植物（Pteridium，Dennstaedtiaceae）是一种世界性的侵扰性定植属植物，对农业牲畜有毒。蕨类植物的分类有多种方案，在世界范围内有 1 到 6 种，还有许多亚种和变种。最近的研究主要集中在蕨类植物的全球分布和系统学方面，但对南美洲的研究很少。我们首次对南半球二倍体蕨类植物 Pteridium esculentum 进行了全大陆范围的取样和分析：在南美洲，P. esculentum 有多个形态型，根据毛被和叶片结构的变化分为亚种。我们使用双消化限制性位点相关 DNA 测序（ddRADSeq）来评估 P. esculentum 亚种的系统发育关系：结果：我们发现该物种具有显著的遗传同质性，分子数据只能支持两种形态：P. e. arachnoideum 和 P. e. campestre。我们对浅层和深层的系统发育关系有很高的信心，但对冠群间关系的支持度较低：结论：我们描述了一种东西向的地理模式，这种模式可以解释种群之间的关系；与之前的研究不同，我们发现了与来自澳大利亚的 P. esculentum 的差异。这些结果将为研究该物种作为杂草的行为变化及其对南美洲农业牲畜生产的影响奠定基础。

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引用次数: 0