Artificial selection reveals the role of transcriptional constraints in the maintenance of life history variation

This is the final version. Available on open access from Wiley via the DOI in this recordThe trade‐off between reproduction and self‐maintenance is a cornerstone of life history theory, yet its proximate underpinnings are elusive. Here, we used an artificial selection approach to create replicated lines of Japanese quail (Coturnix japonica) that differ genetically in their reproductive investment. Whole transcriptome sequencing revealed that females from lines selected for high reproductive output show a consistent upregulation of genes associated with reproduction but a simultaneous downregulation of immune genes. Concordant phenotypic differences in immune function (i.e., specific antibody response against keyhole limpet hemocyanin) were observed between the selection lines, even in males who do not provide parental care. Our findings demonstrate the key role of obligate transcriptional constraints in the maintenance of life history variation. These constraints set fundamental limits to productivity and health in natural and domestic animal populations.Universität ZürichKAKENHISchweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschun

An Arabidopsis Rhomboid homolog is an intramembrane protease in plants

AbstractRegulated intramembrane proteolysis (RIP) is a fundamental mechanism for controlling a wide range of cellular functions. The Drosophila protein Rhomboid-1 (Rho-1) is an intramembrane serine protease that cleaves epidermal growth factor receptor (EGFR) ligands to release active growth factors. Despite differences in the primary structure of Rhomboid proteins, the proteolytic activity and substrate specificity of these enzymes has been conserved in diverse organisms. Here, we show that an Arabidopsis Rhomboid protein AtRBL2 has proteolytic activity and substrate specificity. AtRBL2 cleaved the Drosophila ligands Spitz and Keren, but not similar proteins like TGFα, when expressed in mammalian cells, leading to the release of soluble ligands into the medium. These studies provide the first evidence that the determinants of RIP are present in plants

Data from: Pollen–pistil interactions in reproductive interference: comparisons of heterospecific pollen tube growth from alien species between two native Taraxacum species

1. Reproductive interference (RI), any negative interspecific interaction during the reproductive process, has been gaining increasing attention due to its potential explanatory power for the mutually exclusive distribution of closely related species. RI in plants may occur during any of three stages: pollen transfer, pollen–pistil interactions or hybridization. Pollen–pistil interactions may be especially important as most studies of RI have suggested the involvement at this stage. Details of these interactions are required to fully explore RI and are especially relevant in considering the impact of RI in the field. 2. We present a plausible explanation of how RI functions in the pollen–pistil interaction stage using two Japanese native dandelions, Taraxacum japonicum and Taraxacum longeappendiculatum, of which only the former is vulnerable to RI from an alien congener, Taraxacum officinale. We conducted a series of hand pollinations in these native dandelions and compared pollen tube behaviour to examine differences associated with vulnerability and imperviousness to RI from the alien. 3. The two native dandelions differed in terms of the absence/presence of pollen tube elongation after heterospecific pollination (pollination with only T. officinale): pollen tubes grew through the ovaries of the vulnerable T. japonicum, but not through those of the impervious T. longeappendiculatum. In vitro hand pollination verified that the alien pollen tubes could extend into the ovaries of T. japonicum. 4. Our results show that RI from the alien dandelion consumed ovules by heterospecific pollen deposition. The pistils of the impervious native species could prevent growth of the alien pollen tubes, thereby sparing the ovules for fertilization by conspecific pollen. The pistils of the vulnerable species lacked interspecific incompatibility against the alien, and thus, the alien pollen tube entered the ovary, eliminating an opportunity for conspecific pollen fertilization. This consumption of ovules by heterospecific pollen tubes would cause a seed set failure, leading to reduced abundance and a further exertion of RI in the next generation, which explains displacement of the vulnerable species by the alien in the field

KOMPEITO, an Atypical Arabidopsis Rhomboid-Related Gene, Is Required for Callose Accumulation and Pollen Wall Development

Fertilization is a key event for sexually reproducing plants. Pollen–stigma adhesion, which is the first step in male–female interaction during fertilization, requires proper pollen wall patterning. Callose, which is a β-1.3-glucan, is an essential polysaccharide that is required for pollen development and pollen wall formation. Mutations in CALLOSE SYNTHASE 5 (CalS5) disrupt male meiotic callose accumulation; however, how CalS5 activity and callose synthesis are regulated is not fully understood. In this paper, we report the isolation of a kompeito-1 (kom-1) mutant defective in pollen wall patterning and pollen–stigma adhesion in Arabidopsis thaliana. Callose was not accumulated in kom-1 meiocytes or microspores, which was very similar to the cals5 mutant. The KOM gene encoded a member of a subclass of Rhomboid serine protease proteins that lacked active site residues. KOM was localized to the Golgi apparatus, and both KOM and CalS5 genes were highly expressed in meiocytes. A 220 kDa CalS5 protein was detected in wild-type (Col-0) floral buds but was dramatically reduced in kom-1. These results suggested that KOM was required for CalS5 protein accumulation, leading to the regulation of meiocyte-specific callose accumulation and pollen wall formation