Angiosperms have become the dominant terrestrial plant group by diversifying for ~145 million years into a broad range of environments. During the course of evolution, numerous morphological ...innovations arose, often preceded by whole genome duplications (WGD). The mustard family (Brassicaceae), a successful angiosperm clade with ~4000 species, has been diversifying into many evolutionary lineages for more than 30 million years. Here we develop a species inventory, analyze morphological variation, and present a maternal, plastome-based genus-level phylogeny. We show that increased morphological disparity, despite an apparent absence of clade-specific morphological innovations, is found in tribes with WGDs or diversification rate shifts. Both are important processes in Brassicaceae, resulting in an overall high net diversification rate. Character states show frequent and independent gain and loss, and form varying combinations. Therefore, Brassicaceae pave the way to concepts of phylogenetic genome-wide association studies to analyze the evolution of morphological form and function.
Seeds carry complex microbial communities, which may exert beneficial or deleterious effects on plant growth and plant health. To date, the composition of microbial communities associated with seeds ...has been explored mainly through culture-based diversity studies and therefore remains largely unknown. In this work, we analyzed the structures of the seed microbiotas of different plants from the family Brassicaceae and their dynamics during germination and emergence through sequencing of three molecular markers: the ITS1 region of the fungal internal transcribed spacer, the V4 region of 16S rRNA gene, and a species-specific bacterial marker based on a fragment of gyrB. Sequence analyses revealed important variations in microbial community composition between seed samples. Moreover, we found that emergence strongly influences the structure of the microbiota, with a marked reduction of bacterial and fungal diversity. This shift in the microbial community composition is mostly due to an increase in the relative abundance of some bacterial and fungal taxa possessing fast-growing abilities. Altogether, our results provide an estimation of the role of the seed as a source of inoculum for the seedling, which is crucial for practical applications in developing new strategies of inoculation for disease prevention.
Group II introns are large catalytic RNAs that are ancestrally related to nuclear spliceosomal introns. Sequences corresponding to group II RNAs are found in many prokaryotes and are particularly ...prevalent within plants organellar genomes. Proteins encoded within the introns themselves (maturases) facilitate the splicing of their own host pre-RNAs. Mitochondrial introns in plants have diverged considerably in sequence and have lost their maturases. In angiosperms, only a single maturase has been retained in the mitochondrial DNA: the matR gene found within NADH dehydrogenase 1 (nad1) intron 4. Its conservation across land plants and RNA editing events, which restore conserved amino acids, indicates that matR encodes a functional protein. However, the biological role of MatR remains unclear. Here, we performed an in vivo investigation of the roles of MatR in Brassicaceae. Directed knockdown of matR expression via synthetically designed ribozymes altered the processing of various introns, including nad1 i4. Pull-down experiments further indicated that MatR is associated with nad1 i4 and several other intron-containing pre-mRNAs. MatR may thus represent an intermediate link in the gradual evolutionary transition from the intron-specific maturases in bacteria into their versatile spliceosomal descendants in the nucleus. The similarity between maturases and the core spliceosomal Prp8 protein further supports this intriguing theory.
Dated molecular phylogenies are the basis for understanding species diversity and for linking changes in rates of diversification with historical events such as restructuring in developmental ...pathways, genome doubling, or dispersal onto a new continent. Valid fossil calibration points are essential to the accurate estimation of divergence dates, but for many groups of flowering plants fossil evidence is unavailable or limited. Arabidopsis thaliana, the primary genetic model in plant biology and the first plant to have its entire genome sequenced, belongs to one such group, the plant family Brassicaceae. Thus, the timing of A. thaliana evolution and the history of its genome have been controversial. We bring previously overlooked fossil evidence to bear on these questions and find the split between A. thaliana and Arabidopsis lyrata occurred about 13 Mya, and that the split between Arabidopsis and the Brassica complex (broccoli, cabbage, canola) occurred about 43 Mya. These estimates, which are two- to threefold older than previous estimates, indicate that gene, genomic, and developmental evolution occurred much more slowly than previously hypothesized and that Arabidopsis evolved during a period of warming rather than of cooling. We detected a 2- to 10-fold shift in species diversification rates on the branch uniting Brassicaceae with its sister families. The timing of this shift suggests a possible impact of the Cretaceous–Paleogene mass extinction on their radiation and that Brassicales codiversified with pierid butterflies that specialize on mustard-oil–producing plants.
The Brassicaceae family is unique in not fostering functional symbiosis with arbuscular mycorrhiza (AM). The family is also special in possessing glucosinolates, a class of secondary metabolites ...predominantly functioning for plant defence. We have reviewed what effect the glucosinolates of this non‐symbiotic host have on AM or vice versa. Isothiocyanates, the toxic degradation product of the glucosinolates, particularly the indolic and benzenic glucosinolates, are known to be involved in the inhibition of AM. Interestingly, AM colonization enhances glucosinolate production in two AM‐host in the Brassicales family‐ Moringa oleifera and Tropaeolum spp. PHOSPHATE STARVATION RESPONSE 1 (PHR1), a central transcription factor that controls phosphate starvation response also activates the glucosinolate biosynthesis in AM non‐host Arabidopsis thaliana. Recently, the advances in whole‐genome sequencing, enabling extensive ecological microbiome studies have helped unravel the Brassicaceae microbiome, identifying new mutualists that compensate for the loss of AM symbiosis, and reporting cues for some influence of glucosinolates on the microbiome structure. We advocate that glucosinolate is an important candidate in determining the mycorrhizal status of Brassicaceae and has played a major role in its symbiosis‐defence trade‐off. We also identify key open questions in this area that remain to be addressed in the future.
Flowering plants have evolved numerous intraspecific and interspecific prezygotic reproductive barriers to prevent production of unfavourable offspring
. Within a species, self-incompatibility (SI) ...is a widely utilized mechanism that rejects self-pollen
to avoid inbreeding depression. Interspecific barriers restrain breeding between species and often follow the SI × self-compatible (SC) rule, that is, interspecific pollen is unilaterally incompatible (UI) on SI pistils but unilaterally compatible (UC) on SC pistils
. The molecular mechanisms underlying SI, UI, SC and UC and their interconnections in the Brassicaceae remain unclear. Here we demonstrate that the SI pollen determinant S-locus cysteine-rich protein/S-locus protein 11 (SCR/SP11)
or a signal from UI pollen binds to the SI female determinant S-locus receptor kinase (SRK)
, recruits FERONIA (FER)
and activates FER-mediated reactive oxygen species production in SI stigmas
to reject incompatible pollen. For compatible responses, diverged pollen coat protein B-class
from SC and UC pollen differentially trigger nitric oxide, nitrosate FER to suppress reactive oxygen species in SC stigmas to facilitate pollen growth in an intraspecies-preferential manner, maintaining species integrity. Our results show that SRK and FER integrate mechanisms underlying intraspecific and interspecific barriers and offer paths to achieve distant breeding in Brassicaceae crops.
Pollen Acceptance or Rejection: A Tale of Two Pathways Doucet, Jennifer; Lee, Hyun Kyung; Goring, Daphne R.
Trends in plant science,
December 2016, 2016-Dec, 2016-12-00, 20161201, Letnik:
21, Številka:
12
Journal Article
Recenzirano
While the molecular and cellular basis of self-incompatibility leading to self-pollen rejection in the Brassicaceae has been extensively studied, relatively little attention has been paid to ...compatible pollen recognition and the corresponding cellular responses in the stigmatic papillae. This is now changing because research has started to uncover steps in the Brassicaceae ‘basal compatible pollen response pathway’ in the stigma leading to pollen hydration and germination. Furthermore, recent studies suggest that self-incompatible pollen activates both the basal compatible pathway and the self-incompatibility pathway in the stigma, with the self-incompatibility response ultimately prevailing to reject self-pollen. We review here recent discoveries in both pathways and discuss how compatible pollen is accepted by the stigma versus the rejection of self-incompatible pollen.
Following pollination, two signaling pathways in the Brassicaceae stigma interact to regulate pollen acceptance or rejection: the basal compatible pollen response pathway and the self-incompatibility pathway.
Key signaling players in the basal compatible pollen response pathway are unknown, although a recent breakthrough has led to the identification of a pollen ligand candidate, the PCP-B pollen coat protein. Cellular responses include the requirement of the exocyst complex for polarized secretion in the stigmatic papilla following pollen contact.
Although key signaling players are well-characterized in the self-incompatibility pathway, additional unknown signaling components remain to be identified. Recent discoveries include a large Ca2+ influx and the inhibition of GLO1 as part of this pathway. Ultimately, these signaling steps disrupt exocytosis in the stigmatic papilla following pollination.
The present study is focused on the cytogenetic and morphological criteria for distinguishing new taxa belonging to Fibigia sect. Purpureae. This section in Iran is revised, and three new species (F. ...kermanshahensis Ranjbar & Karami, F. khoshyelaqensis Ranjbar & Rostami, and F. tabriziana Ranjbar & Karami) are described and illustrated from Kermanshah, Gorgan and Azarbaijan Sharqi Provinces. These are closely related to F. suffruticosa (Vent.) Sweet. but differs from it in morphological characters such as plant indumentums, fruits size and shape, lateral sepals saccate at base and stigma size and shape. The meiotic chromosome number and behavior were studied in F. kermanshahensis and F. suffruticosa. F. kermanshahensis is a diploid plant and possesses the chromosome number 2n = 2x = 14, inconsistent with the base number of F. suffruticosa witch shows 2n = 2x = 16. The general meiotic behavior in both species was regular, with bivalent pairing and normal chromosome segregation at meiosis. However, some meiotic abnormalities were observed including varied degrees of sticky chromosomes with laggards, a precocious division of centromeres in metaphase I and metaphase II, bridges in anaphase II, laggard chromosomes, micronucleus, asynchronous nucleus and cytomixis. Finally, a key to all four species of this section is presented.
For decades a small number of model species have rightly occupied a privileged position in laboratory experiments, but it is becoming increasingly clear that our knowledge of biology is greatly ...improved when informed by a broader diversity of species and evolutionary context. Arabidopsis thaliana has been the primary model organism for plants, benefiting from a high-quality reference genome sequence and resources for reverse genetics. However, recent studies have made a group of species also in the Brassicaceae family and closely related to A. thaliana a focal point for comparative molecular, genomic, phenotypic and evolutionary studies. In this Review, we emphasize how such studies complement continued study of the model plant itself, provide an evolutionary perspective and summarize our current understanding of genetic and phenotypic diversity in plants.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SBMB, UILJ, UKNU, UL, UM, UPUK
Specific members of complex microbiota can influence host phenotypes, depending on both the abiotic environment and the presence of other microorganisms. Therefore, it is challenging to define ...bacterial combinations that have predictable host phenotypic outputs. We demonstrate that plant-bacterium binary-association assays inform the design of small synthetic communities with predictable phenotypes in the host. Specifically, we constructed synthetic communities that modified phosphate accumulation in the shoot and induced phosphate starvation-responsive genes in a predictable fashion. We found that bacterial colonization of the plant is not a predictor of the plant phenotypes we analyzed. Finally, we demonstrated that characterizing a subset of all possible bacterial synthetic communities is sufficient to predict the outcome of untested bacterial consortia. Our results demonstrate that it is possible to infer causal relationships between microbiota membership and host phenotypes and to use these inferences to rationally design novel communities.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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