Time-delayed model of immune response in plants

In the studies of plant infections, the plant immune response is known to play an essential role. In this paper we derive and analyse a new mathematical model of plant immune response with particular account for post-transcriptional gene silencing (PTGS). Besides biologically accurate representation of the PTGS dynamics, the model explicitly includes two time delays to represent the maturation time of the growing plant tissue and the non-instantaneous nature of the PTGS. Through analytical and numerical analysis of stability of the steady states of the model we identify parameter regions associated with recovery and resistant phenotypes, as well as possible chronic infections. Dynamics of the system in these regimes is illustrated by numerical simulations of the model

The paf gene product modulates asexual development in Penicillium chrysogenum

Penicillium chrysogenum secretes a low molecular weight, cationic and cysteine-rich protein (PAF). It has growth inhibitory activity against the model organism Aspergillus nidulans and numerous zoo- and phytopathogenic fungi but shows only minimal conditional antifungal activity against the producing organism itself

Transcriptome characterization and polymorphism detection between subspecies of big sagebrush (Artemisia tridentata)

<p>Abstract</p> <p>Background</p> <p>Big sagebrush (<it>Artemisia tridentata</it>) is one of the most widely distributed and ecologically important shrub species in western North America. This species serves as a critical habitat and food resource for many animals and invertebrates. Habitat loss due to a combination of disturbances followed by establishment of invasive plant species is a serious threat to big sagebrush ecosystem sustainability. Lack of genomic data has limited our understanding of the evolutionary history and ecological adaptation in this species. Here, we report on the sequencing of expressed sequence tags (ESTs) and detection of single nucleotide polymorphism (SNP) and simple sequence repeat (SSR) markers in subspecies of big sagebrush.</p> <p>Results</p> <p>cDNA of <it>A. tridentata </it>sspp. <it>tridentata </it>and <it>vaseyana </it>were normalized and sequenced using the 454 GS FLX Titanium pyrosequencing technology. Assembly of the reads resulted in 20,357 contig consensus sequences in ssp. <it>tridentata </it>and 20,250 contigs in ssp. <it>vaseyana</it>. A BLASTx search against the non-redundant (NR) protein database using 29,541 consensus sequences obtained from a combined assembly resulted in 21,436 sequences with significant blast alignments (≤ 1e^-15). A total of 20,952 SNPs and 119 polymorphic SSRs were detected between the two subspecies. SNPs were validated through various methods including sequence capture. Validation of SNPs in different individuals uncovered a high level of nucleotide variation in EST sequences. EST sequences of a third, tetraploid subspecies (ssp. <it>wyomingensis</it>) obtained by Illumina sequencing were mapped to the consensus sequences of the combined 454 EST assembly. Approximately one-third of the SNPs between sspp. <it>tridentata </it>and <it>vaseyana </it>identified in the combined assembly were also polymorphic within the two geographically distant ssp. <it>wyomingensis </it>samples.</p> <p>Conclusion</p> <p>We have produced a large EST dataset for <it>Artemisia tridentata</it>, which contains a large sample of the big sagebrush leaf transcriptome. SNP mapping among the three subspecies suggest the origin of ssp. <it>wyomingensis </it>via mixed ancestry. A large number of SNP and SSR markers provide the foundation for future research to address questions in big sagebrush evolution, ecological genetics, and conservation using genomic approaches.</p