@article{SicardKappelJosephsetal.2015, author = {Sicard, Adrien and Kappel, Christian and Josephs, Emily B. and Lee, Young Wha and Marona, Cindy and Stinchcombe, John R. and Wright, Stephen I. and Lenhard, Michael}, title = {Divergent sorting of a balanced ancestral polymorphism underlies the establishment of gene-flow barriers in Capsella}, series = {Nature Communications}, volume = {6}, journal = {Nature Communications}, publisher = {Nature Publ. Group}, address = {London}, issn = {2041-1723}, doi = {10.1038/ncomms8960}, pages = {10}, year = {2015}, abstract = {In the Bateson-Dobzhansky-Muller model of genetic incompatibilities post-zygotic gene-flow barriers arise by fixation of novel alleles at interacting loci in separated populations. Many such incompatibilities are polymorphic in plants, implying an important role for genetic drift or balancing selection in their origin and evolution. Here we show that NPR1 and RPP5 loci cause a genetic incompatibility between the incipient species Capsella grandiflora and C. rubella, and the more distantly related C. rubella and C. orientalis. The incompatible RPP5 allele results from a mutation in C. rubella, while the incompatible NPR1 allele is frequent in the ancestral C. grandiflora. Compatible and incompatible NPR1 haplotypes are maintained by balancing selection in C. grandiflora, and were divergently sorted into the derived C. rubella and C. orientalis. Thus, by maintaining differentiated alleles at high frequencies, balancing selection on ancestral polymorphisms can facilitate establishing gene-flow barriers between derived populations through lineage sorting of the alternative alleles.}, language = {en} } @misc{HepworthLenhard2014, author = {Hepworth, Jo and Lenhard, Michael}, title = {Regulation of plant lateral-organ growth by modulating cell number and size}, series = {Current opinion in plant biology}, volume = {17}, journal = {Current opinion in plant biology}, publisher = {Elsevier}, address = {London}, issn = {1369-5266}, doi = {10.1016/j.pbi.2013.11.005}, pages = {36 -- 42}, year = {2014}, abstract = {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.}, language = {en} } @article{CzesnickLenhard2015, author = {Czesnick, Hj{\"o}rdis and Lenhard, Michael}, title = {Size Control in Plants-Lessons from Leaves and Flowers}, series = {Cold Spring Harbor perspectives in biology}, volume = {7}, journal = {Cold Spring Harbor perspectives in biology}, number = {8}, publisher = {Cold Spring Harbor Laboratory Press}, address = {Cold Spring Harbor, NY}, issn = {1943-0264}, doi = {10.1101/cshperspect.a019190}, pages = {16}, year = {2015}, abstract = {To achieve optimal functionality, plant organs like leaves and petals have to grow to a certain size. Beginning with a limited number of undifferentiated cells, the final size of an organ is attained by a complex interplay of cell proliferation and subsequent cell expansion. Regulatory mechanisms that integrate intrinsic growth signals and environmental cues are required to enable optimal leaf and flower development. This review focuses on plant-specific principles of growth reaching from the cellular to the organ level. The currently known genetic pathways underlying these principles are summarized and network connections are highlighted. Putative non-cell autonomously acting mechanisms that might coordinate plant-cell growth are discussed.}, language = {en} } @article{SasMuellerKappeletal.2016, author = {Sas, Claudia and Mueller, Frank and Kappel, Christian and Kent, Tyler V. and Wright, Stephen I. and Hilker, Monika and Lenhard, Michael}, title = {Repeated Inactivation of the First Committed Enzyme Underlies the Loss of Benzaldehyde Emission after the Selfing Transition in Capsella}, series = {Current biology}, volume = {26}, journal = {Current biology}, publisher = {Cell Press}, address = {Cambridge}, issn = {0960-9822}, doi = {10.1016/j.cub.2016.10.026}, pages = {3313 -- 3319}, year = {2016}, abstract = {The enormous species richness of flowering plants is at least partly due to floral diversification driven by interactions between plants and their animal pollinators [1, 2]. Specific pollinator attraction relies on visual and olfactory floral cues [3-5]; floral scent can not only attract pollinators but also attract or repel herbivorous insects [6-8]. However, despite its central role for plant-animal interactions, the genetic control of floral scent production and its evolutionary modification remain incompletely understood [9-13]. Benzenoids are an important class of floral scent compounds that are generated from phenylalanine via several enzymatic pathways [14-17]. Here we address the genetic basis of the loss of floral scent associated with the transition from outbreeding to selfing in the genus Capsella. While the outbreeding C. grandiflora emits benzaldehyde as a major constituent of its floral scent, this has been lost in the selfing C. rubella. We identify the Capsella CNL1 gene encoding cinnamate: CoA ligase as responsible for this variation. Population genetic analysis indicates that CNL1 has been inactivated twice independently in C. rubella via different novel mutations to its coding sequence. Together with a recent study in Petunia [18], this identifies cinnamate: CoA ligase as an evolutionary hotspot for mutations causing the loss of benzenoid scent compounds in association with a shift in the reproductive strategy of Capsella from pollination by insects to self-fertilization.}, language = {en} }