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Angiosperm stigmas exhibit high levels of peroxidase activity when receptive to pollen. To explore possible function(s) of this peroxidase activity we investigated amounts of reactive oxygen species (ROS), particularly hydrogen peroxide, in stigmas and pollen. Because nitric oxide (NO) was recently implicated in pollen tube growth, we also investigated(More)
Allopolyploidy, which involves genome doubling of an interspecific hybrid is an important mechanism of abrupt speciation in flowering plants [1-6]. Recent studies show that allopolyploid formation is accompanied by extensive changes to patterns of parental gene expression ("transcriptome shock") [7-15] and that this is likely the consequence of(More)
Angiosperm stigmas have long been known to exhibit high levels of peroxidase activity when they are mature and most receptive to pollen but the biological function of stigma peroxidases is not known. A novel stigma-specific class III peroxidase gene, SSP (stigma-specific peroxidase) expressed exclusively in the stigmas of Senecio squalidus L. (Asteraceae)(More)
Hybrid zone theory provides a powerful theoretical framework for measuring and testing gene flow and selection. The Senecio aethnensis and Senecio chrysanthemifolius hybrid zone on Mount Etna, Sicily, was investigated to identify phenotypic traits under divergent selection and to assess the contributions of intrinsic and extrinsic selection against hybrids(More)
Unilateral pollen-pistil incompatibility within the Brassicaceae has been re-examined in a series of interspecific and intergeneric crosses using 13 self-compatible (SC, Sc) species and 12 self-incompatible (SI) species from ten tribes. SC x SC crosses were usually compatible, SI x SC crosses showed unilateral incompatibility, while SI x SI crosses were(More)
microRNAs (miRNAs) are short noncoding regulatory genes that perform important roles in plant development and physiology. With the increasing power of next generation sequencing technologies and the development of bioinformatic tools, there has been a dramatic increase in the number of studies surveying the miRNAomes of plant species, which has led to an(More)
Senecio squalidus (Oxford ragwort) is a well-known introduction to the British flora that has proved to be an extremely successful colonist over the last 150 years. Unusually for a colonizing species, S. squalidus is self-incompatible (SI). Being a member of the Asteraceae, SI in S. squalidus is expected to be sporophytic. This paper presents genetic data(More)
Self-incompatibility (SI) in Brassica species is controlled by a single polymorphic locus (S) with multiple specificities. Two stigmatically expressed genes that have been cloned from this region encode the S locus glycoprotein (SLG) and S receptor kinase (SRK). Both appear to be essential for the operation of SI. It is believed that rejection of(More)
Plants and fungi show an astonishing diversity of mechanisms to promote outbreeding, the most widespread of which is sexual incompatibility. Sexual incompatibility involves molecular recognition between mating partners. In fungi and algae, highly polymorphic mating-type loci mediate mating through complementary interactions between molecules encoded or(More)
Interspecific hybridization is an important process through which abrupt speciation can occur. In recent years, genetic changes associated with hybrid speciation have been identified through a variety of techniques, including AFLP/SSR mapping, GISH/FISH and cDNA-AFLP differential display. However, progress in using microarray technology to analyse whole(More)