Refine
Year of publication
Language
- English (54)
Is part of the Bibliography
- yes (54)
Keywords
- Capsella (4)
- heterostyly (4)
- supergene (4)
- Brassicaceae (3)
- poly(A) polymerase (3)
- Amplicon sequencing (2)
- Arabidopsis (2)
- Arabidopsis thaliana (2)
- CYP734A50 (2)
- Mixed mating (2)
Institute
- Institut für Biochemie und Biologie (54) (remove)
Growth of plant organs relies on cell proliferation and expansion. While an increasingly detailed picture about the control of cell proliferation is emerging, our knowledge about the control of cell expansion remains more limited. We demonstrate the internal-motor kinesin AtKINESIN-13A (AtKIN13A) limits cell expansion and cell size in Arabidopsis thaliana, ion atkinl3a mutants forming larger petals with larger cells. The homolog, AtKINESIN-13B, also affects cell expansion and double mutants display growth, gametophytic and early embryonic defects, indicating a redundant role of he two genes. AtKIN13A is known to depolymerize microtubules and influence Golgi motility and distribution. Consistent his function, AtKIN13A interacts genetically with ANGUSTIFOLIA, encoding a regulator of Golgi dynamics. Reduced AtIGN13A activity alters cell wall structure as assessed by Fourier-transformed infrared-spectroscopy and triggers signalling he THESEUS1-dependent cell-wall integrity pathway, which in turn promotes the excess cell expansion in the atkinl3a mutant. Thus, our results indicate that the intracellular activity of AtKIN13A regulates cell expansion and wall architecture via THESEUS1, providing a compelling case of interplay between cell wall integrity sensing and expansion.
Understanding the molecular basis of morphological change remains a central challenge in evolutionary-developmental biology. The transition from outbreeding to selfing is often associated with a dramatic reduction in reproductive structures and functions, such as the loss of attractive pheromones in hermaphroditic Caenorhabditis elegans and a reduced flower size in plants. Here, we demonstrate that variation in the level of the brassinosteroid-biosynthesis enzyme CYP724A1 contributes to the reduced flower size of selfing Capsella rubella compared with its outbreeding ancestor Capsella grandiflora. The primary transcript of the C. rubella allele is spliced more efficiently than that of C. grandiflora, resulting in higher brassinosteroid levels. These restrict organ growth by limiting cell proliferation. More efficient splicing of the C. rubella allele results from two de novo mutations in the selfing lineage. Thus, our results highlight the potentially widespread importance of differential splicing efficiency and higher-than-optimal hormone levels in generating phenotypic variation.
Leaves and floral organs grow to distinct, species-specific sizes and shapes. Research over the last few years has increased our understanding of how genetic pathways modulate cell proliferation and cell expansion to determine these sizes and shapes. In particular, the timing of proliferation arrest is an important point of control for organ size, and work on the regulators involved is showing how this control is achieved mechanistically and integrates environmental information. We are also beginning to understand how growth differs in different organs to produce their characteristic shapes, and how growth is integrated between different tissues that make up plant organs. Lastly, components of the general machinery in eukaryotic cells have been identified as having important roles in growth control.
Heterostyly represents a fascinating adaptation to promote outbreeding in plants that evolved multiple times independently. While L-morph individuals form flowers with long styles, short anthers, and small pollen grains, S-morph individuals have flowers with short styles, long anthers, and large pollen grains. The difference between the morphs is controlled by an S-locus "supergene" consisting of several distinct genes that determine different traits of the syndrome and are held together, because recombination between them is suppressed. In Primula, the S locus is a roughly 300-kb hemizygous region containing five predicted genes. However, with one exception, their roles remain unclear, as does the evolutionary buildup of the S locus. Here we demonstrate that the MADS-box GLOBOSA2 (GLO2) gene at the S locus determines anther position. In Primula forbesii S-morph plants, GLO2 promotes growth by cell expansion in the fused tube of petals and stamen filaments beneath the anther insertion point; by contrast, neither pollen size nor male incompatibility is affected by GLO2 activity. The paralogue GLO1, from which GLO2 arose by duplication, has maintained the ancestral B-class function in specifying petal and stamen identity, indicating that GLO2 underwent neofunctionalization, likely at the level of the encoded protein. Genetic mapping and phylogenetic analysis indicate that the duplications giving rise to the style-length-determining gene CYP734A50 and to GLO2 occurred sequentially, with the CYP734A50 duplication likely the first. Together these results provide the most detailed insight into the assembly of a plant supergene yet and have important implications for the evolution of heterostyly.
Most flowering plants are hermaphrodites, with flowers having both male and female reproductive organs. One widespread adaptation to limit self-fertilization is self-incompatibility (SI), where self-pollen fails to fertilize ovules.(1,2) In homomorphic SI, many morphologically indistinguishable mating types are found, although in heteromorphic SI, the two or three mating types are associated with different floral morphologies.(3-6) In heterostylous Primula, a hemizygous supergene determines a short-styled S-morph and a long-styled L-morph, corresponding to two different mating types, and full seed set only results from inter morph crosses.(7-9) Style length is controlled by the brassinosteroid (BR)-inactivating cytochrome P450 CYP734A50,(10) yet it remains unclear what defines the male and female incompatibility types. Here, we show that CYP734A50 also determines the female incompatibility type. Inactivating CYP734A50 converts short S-morph styles into long styles with the same incompatibility behavior as L-morph styles, and this effect can be mimicked by exogenous BR treatment. In vitro responses of S-and L-morph pollen grains and pollen tubes to increasing BR levels could only partly explain their different in vivo behavior, suggesting both direct and indirect effects of the different BR levels in S-versus L-morph stigmas and styles in controlling pollen performance. This BR-mediated SI provides a novel mechanism for preventing self-fertilization. The joint control of morphology and SI by CYP734A50 has important implications for the evolutionary buildup of the heterostylous syndrome and provides a straightforward explanation for why essentially all of the derived self-compatible homostylous Primula species are long homostyles.(11)
Background: The outcrossing rate is a key determinant of the population-genetic structure of species and their long-term evolutionary trajectories. However, determining the outcrossing rate using current methods based on PCRgenotyping individual offspring of focal plants for multiple polymorphic markers is laborious and time-consuming.
Results: We have developed an amplicon-based, high-throughput enabled method for estimating the outcrossing rate and have applied this to an example of scented versus non-scented Capsella (Shepherd’s Purse) genotypes. Our results show that the method is able to robustly capture differences in outcrossing rates. They also highlight potential biases in the estimates resulting from differential haplotype sharing of the focal plants with the pollen-donor population at individual amplicons.
Conclusions: This novel method for estimating outcrossing rates will allow determining this key population-genetic parameter with high-throughput across many genotypes in a population, enabling studies into the genetic determinants of successful pollinator attraction and outcrossing.
Background: The outcrossing rate is a key determinant of the population-genetic structure of species and their long-term evolutionary trajectories. However, determining the outcrossing rate using current methods based on PCRgenotyping individual offspring of focal plants for multiple polymorphic markers is laborious and time-consuming.
Results: We have developed an amplicon-based, high-throughput enabled method for estimating the outcrossing rate and have applied this to an example of scented versus non-scented Capsella (Shepherd’s Purse) genotypes. Our results show that the method is able to robustly capture differences in outcrossing rates. They also highlight potential biases in the estimates resulting from differential haplotype sharing of the focal plants with the pollen-donor population at individual amplicons.
Conclusions: This novel method for estimating outcrossing rates will allow determining this key population-genetic parameter with high-throughput across many genotypes in a population, enabling studies into the genetic determinants of successful pollinator attraction and outcrossing.
The growth of plant organs is under genetic control. Work in model species has identified a considerable number of genes that regulate different aspects of organ growth. This has led to an increasingly detailed knowledge about how the basic cellular processes underlying organ growth are controlled, and which factors determine when proliferation gives way to expansion, with this transition emerging as a critical decision point during primordium growth. Progress has been made in elucidating the genetic basis of allometric growth and the role of tissue polarity in shaping organs. We are also beginning to understand how the mechanisms that determine organ identity influence local growth behaviour to generate organs with characteristic sizes and shapes. Lastly, growth needs to be coordinated at several levels, for example between different cell layers and different regions within one organ, and the genetic basis for such coordination is being elucidated. However, despite these impressive advances, a number of basic questions are still not fully answered, for example, whether and how a growing primordium keeps track of its size. Answering these questions will likely depend on including additional approaches that are gaining in power and popularity, such as combined live imaging and modelling.