Developmental transcriptional profiling reveals key insights into Triticeae reproductive development.

Despite their importance, there remains a paucity of large-scale gene expression-based studies of reproductive development in species belonging to the Triticeae. As a first step to address this deficiency, a gene expression atlas of triticale reproductive development was generated using the 55K Affymetrix GeneChip(®) wheat genome array. The global transcriptional profiles of the anther/pollen, ovary and stigma were analyzed at concurrent developmental stages, and co-expressed as well as preferentially expressed genes were identified. Data analysis revealed both novel and conserved regulatory factors underlying Triticeae floral development and function. This comprehensive resource rests upon detailed gene annotations, and the expression profiles are readily accessible via a web browser.

Morphological and molecular analyses of host and nonhost interactions involving barley and wheat and the covered smut pathogen Ustilago hordei.

Ustilago hordei interactions on coleoptiles of barley host cultivars Odessa (compatible), Hannchen (incompatible, carrying the Ruh1 resistance gene), and on nonhost Neepawa wheat were studied using light and fluorescent microscopy. Autofluorescence, mainly caused by callose accumulation, was more rapidly expressed in nonhost wheat at 30 to 72 h compared with the incompatible reaction between 72 and 144 h. Microarray results demonstrated that more than half of the 893 differentially regulated genes were observed in Neepawa; of these genes, 45% fell into the defense- and stress-related classes in Neepawa compared with 25 and 37% in Odessa and Hannchen, respectively. Their expression coincided with the early morphological defense responses observed and were associated with the jasmonic acid and ethylene (JA/ET) signaling pathway. Expression patterns in Odessa and Hannchen were similar, involving fewer genes and coinciding with later morphological defense responses of these varieties. Although no visible hypersensitive response was apparent in Hannchen or Neepawa, specific upregulation of hypersensitivity-related proteins was observed, such as beta-VPE at 48 h. Expression levels of the callose synthase gene were closely associated with callose accumulation. Differential responses in defense-gene expression among disease reaction types included upregulation of PR-1.1b and downregulation of a nonspecific lipid transfer protein in the incompatible and compatible interactions, respectively. Transcript levels of EDS1 and PAD4, involved in both basal resistance and R-mediated resistance to avirulent pathogens, were up-regulated during both nonhost and Ruh1-mediated resistance. Application of methyl-jasmonate, salicylic acid and ET to leaves revealed that only PR1.1b is strongly up-regulated by all three compounds, while the majority of the defense-related genes are only slightly up-regulated by these signaling compounds.

Phylogeny and antigenic relationships of three cervid herpesviruses.

Elk herpesvirus (ElkHV) from North American elk (wapiti, Cervus elaphus nelsoni) is a recently identified alphaherpesvirus related to bovine herpesvirus-1 (BHV-1). In this study, we determined its relationship with European cervid herpesviruses: cervid herpesvirus-1 (CerHV-1) from red deer and rangiferine herpesvirus (RanHV) from reindeer. For phylogenetic analysis, genes for the gC and gD proteins of these viruses were sequenced. These genes demonstrated an extremely high GC content (76-79%). Genetically, ElkHV was found to be closely related to CerHV-1 and both viruses are more closely related to BHV-1 than to RanHV. Antigenically, the same relationships were found. ElkHV shares common neutralizing epitopes with both CerHV-1 and RanHV. A total of 10 epitopes were defined on the gB, gC and gD proteins of these viruses, including a shared neutralizing epitope on gD. The results indicate that ElkHV and CerHV-1 have diverged from a common ancestor virus. Cervid herpesviruses may be useful in determination of evolutionary rates of change for alphaherpesvirus genes.