Defining the limits of flowers: the challenge of distinguishing between the evolutionary products of simple versus compound strobili

Rudall, Paula J.; Bateman, Richard M.

doi:10.1098/rstb.2009.0234

Cited by 47 publications

(25 citation statements)

References 80 publications

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“…8) and Chaw et al (1997) inferred from cpITS and 18S ribosomal DNA sequences, respectively, the former did not sample any cupressophytes and both used NJ methods. Ginkgo and cycads share a number of morphologic traits, such as haustorial pollen tubes (Friedman 1993), multiflagellated sperms (Brenner et al 2003), simple strobili (Rudall and Bateman 2010), and some specific patterns during embryo development (Wang et al 2011). The present chloroplast phylogenomics provides additional evidence that supports a sisterhood relationship between ginkgo and cycads.…”

Section: Discussionmentioning

confidence: 99%

Chloroplast Phylogenomics Indicates that Ginkgo biloba Is Sister to Cycads

Wu¹,

Chaw²,

Huang³

2013

Genome Biology and Evolution

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Molecular phylogenetic studies have not yet reached a consensus on the placement of Ginkgoales, which is represented by the only living species, Ginkgo biloba (common name: ginkgo). At least six discrepant placements of ginkgo have been proposed. This study aimed to use the chloroplast phylogenomic approach to examine possible factors that lead to such disagreeing placements. We found the sequence types used in the analyses as the most critical factor in the conflicting placements of ginkgo. In addition, the placement of ginkgo varied in the trees inferred from nucleotide (NU) sequences, which notably depended on breadth of taxon sampling, tree-building methods, codon positions, positions of Gnetopsida (common name: gnetophytes), and including or excluding gnetophytes in data sets. In contrast, the trees inferred from amino acid (AA) sequences congruently supported the monophyly of a ginkgo and Cycadales (common name: cycads) clade, regardless of which factors were examined. Our site-stripping analysis further revealed that the high substitution saturation of NU sequences mainly derived from the third codon positions and contributed to the variable placements of ginkgo. In summary, the factors we surveyed did not affect results inferred from analyses of AA sequences. Congruent topologies in our AA trees give more confidence in supporting the ginkgo–cycad sister-group hypothesis.

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Section: Discussionmentioning

confidence: 99%

Chloroplast Phylogenomics Indicates that Ginkgo biloba Is Sister to Cycads

Wu¹,

Chaw²,

Huang³

2013

Genome Biology and Evolution

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“…One of the most important developmental changes in the evolutionary origin of the flower was the combination of male and female reproductive organs onto a single axis (Frohlich & Parker, 2000;Baum & Hileman, 2006;Theissen & Melzer, 2007;Rudall & Bateman, 2010). However, the origin of bisexuality in the angiosperms remains enigmatic (Bateman et al, 2006;Frohlich & Chase, 2007;Doyle, 2008;Mathews & Kramer, 2012).…”

Section: Introductionmentioning

confidence: 99%

A link between LEAFY and B‐gene homologues in Welwitschia mirabilis sheds light on ancestral mechanisms prefiguring floral development

et al. 2017

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Flowering plants evolved from an unidentified gymnosperm ancestor. Comparison of the mechanisms controlling development in angiosperm flowers and gymnosperm cones may help to elucidate the mysterious origin of the flower. We combined gene expression studies with protein behaviour characterization in Welwitschia mirabilis to test whether the known regulatory links between LEAFY and its MADS-box gene targets, central to flower development, might also contribute to gymnosperm reproductive development. We found that WelLFY, one of two LEAFY-like genes in Welwitschia, could be an upstream regulator of the MADS-box genes APETALA3/PISTILLATA-like (B-genes). We demonstrated that, even though their DNA-binding domains are extremely similar, WelLFY and its paralogue WelNDLY exhibit distinct DNA-binding specificities, and that, unlike WelNDLY, WelLFY shares with its angiosperm orthologue the capacity to bind promoters of Welwitschia B-genes. Finally, we identified several cis-elements mediating these interactions in Welwitschia and obtained evidence that the link between LFY homologues and B-genes is also conserved in two other gymnosperms, Pinus and Picea. Although functional approaches to investigate cone development in gymnosperms are limited, our state-of-the-art biophysical techniques, coupled with expression studies, provide evidence that crucial links, central to the control of floral development, may already have existed before the appearance of flowers.

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“…Aggregations of the structures bearing ovules or pollen sacs are very common among seed plants, and flowerlike reproductive structures occur in several groups of nonangiosperm seed plants (for example, Bennettitales, Gnetales). Also, in some angiosperms, including several lineages near the base of the angiosperm phylogeny (for example, Hydatellaceae and certain Chloranthaceae), a discrete flower is difficult to define 28 . In theory, plant fossils that can be assigned convincingly to a clade of extant angiosperms, or to the stem group of such a clade, are unproblematic.…”

Section: Nature Plantsmentioning

confidence: 99%

Palaeobotanical redux: revisiting the age of the angiosperms

et al. 2017

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M ore than half a century ago, two pivotal reviews 1,2 showed that while the fossil history of angiosperms "is extra ordinarily and increasingly well documented in postEarly Cretaceous sediments…no bona fide angiosperm remains, either megafossil or microfossil, have yet been described from rocks older than Early Cretaceous" 1 . Here, we revisit this conclusion and assess the extent to which the situation has changed, given a substantial increase in the quantity and quality of palaeobotanical data and an increasing number of reports of angiosperms from older rocks.Since the key reviews of the 1960s, great progress has been made in understanding the major patterns in the angiosperm fossil record [3][4][5] . There have also been significant advances in understand ing evolutionary relationships within the angiosperm clade-espe cially in using DNA sequences from living plants to reconstruct phylogenetic patterns 6 . Widely accepted hypotheses indicate that more than 99% of angiosperm species occur in three major clades (eudicots, monocots, (eu)magnoliids), which are embed ded in a paraphyletic assemblage of other early diverging lineages that includes Amborellales, Austrobaileyales, Ceratophyllales, Chloranthales and Nymphaeales [6][7][8] . More controversial are esti mates of the age of the most recent common ancestor of extant angiosperms based on molecular clock techniques, and hypotheses of the phylogenetic position of angiosperms in relation to other seed plant lineages. As molecular clock estimates are most often calibrated using palaeontological data, and because the closest rela tives to angiosperms are almost certainly extinct groups, fossils are integral to progress in both of these areas.Building on important advances made during the 1970s preserved as compressions or impressions from Early Cretaceous strata [11][12][13] . Taken together, these discoveries and their sequence of appearance in the fossil record are broadly consistent with the patterns of relation ships established among extant angiosperms using molecular data, and the associated patterns of character evo lution. All of the reproductive structures recognized so far from Early Cretaceous sediments are either extinct forms, apparently with no close relatives among living angiosperms, or are related to Austrobaileyales, Chloranthales, Nymphaeales, various groups of eumagnoliids, or early branches of eudicots or monocots (Fig. 1, for references see refs 10 and 14). Preservation of fine structural details in some of these Early Cretaceous fossils further confirms their inferred relation ship with extant lineages that are hypothesized to have diverged at an early stage in angiosperm diversification based on molecular phylogenetics 15 . The improved angiosperm fossil record from the Cretaceous has facilitated the calibration of molecular clock age estimates for various angiosperm clades and for the age of angiosperms as a whole [16][17][18][19][20][21] . While current techniques remain susceptible to prob lems resulting from significantly different ...

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Defining the limits of flowers: the challenge of distinguishing between the evolutionary products of simple versus compound strobili

Cited by 47 publications

References 80 publications

Chloroplast Phylogenomics Indicates that Ginkgo biloba Is Sister to Cycads

Chloroplast Phylogenomics Indicates that Ginkgo biloba Is Sister to Cycads

A link between LEAFY and B‐gene homologues in Welwitschia mirabilis sheds light on ancestral mechanisms prefiguring floral development

Palaeobotanical redux: revisiting the age of the angiosperms

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