A giant NLR gene confers broad-spectrum resistance to Phytophthora sojae in soybean.

Phytophthora root and stem rot caused by P. sojae is a destructive soybean soil-borne disease found worldwide. Discovery of genes conferring broad-spectrum resistance to the pathogen is a need to prevent the outbreak of the disease. Here, we show that soybean Rps11 is a 27.7-kb nucleotide-binding site-leucine-rich repeat (NBS-LRR or NLR) gene conferring broad-spectrum resistance to the pathogen. Rps11 is located in a genomic region harboring a cluster of large NLR genes of a single origin in soybean, and is derived from rounds of unequal recombination. Such events result in promoter fusion and LRR expansion that may contribute to the broad resistance spectrum. The NLR gene cluster exhibits drastic structural diversification among phylogenetically representative varieties, including gene copy number variation ranging from five to 23 copies, and absence of allelic copies of Rps11 in any of the non-Rps11-donor varieties examined, exemplifying innovative evolution of NLR genes and NLR gene clusters.

Cross reactivity among the swine mycoplasmas as identified by protein microarray.

Mycoplasmas are cell wall-less bacteria that infect a variety of animals in a species-specific manner. In swine, Mycoplasma hyopneumoniae is the most virulent and presents the most disease and economic problems to the swine industry. Serological assays are commonly used to assess colonization and disease, but antigenic cross-reactivity between M. hyopneumoniae and other mycoplasma species, most notably Mycoplasma hyorhinis, Mycoplasma hyosynoviae and Mycoplasma flocculare, is a concern. The extent of cross-reactivity has not been thoroughly investigated. These studies were designed to identify M. hyopneumoniae proteins that are recognized by rabbit hyperimmune sera raised against the other swine mycoplasmas. Our results indicate extensive cross-reactivity between M. flocculare and M. hyopneumoniae, which explains previous reports seen with ELISA assays. Only three of the thirty-nine M. hyopneumoniae proteins tested showed no cross reactivity with the other three swine mycoplasmas, mhp182 (42kDa C-terminal fragment), mhp638 and mhp684 (C-terminal fragment). Two proteins, mhp384 and mhp511, were cross-reactive with hyperimmune sera generated against three of the four species. None of the anti-M. hyorhinis hyperimmune sera reacted to any of the M. hyopneumoniae proteins. These results suggest that inapparent M. flocculare infections could produce positive responses in M. hyopneumoniae serological assays due to cross-reactivity, and that M. hyosynoviae infections are less likely to do so and M. hyorhinis infections unlikely to affect assay results.

Mhp493 (P216) is a proteolytically processed, cilium and heparin binding protein of Mycoplasma hyopneumoniae.

Mycoplasma hyopneumoniae induces respiratory disease in swine by colonizing cilia causing ciliostasis, cilial loss and epithelial cell death. Heparin binds to M. hyopneumoniae cells in a dose-dependent manner and blocks its ability to adhere to porcine cilia. We show here that Mhp493 (P216), a paralogue of the cilium adhesin P97 (Mhp183), is cleaved between amino acids 1040 and 1089 generating surface-accessible, heparin-binding proteins P120 and P85. Antiphosphoserine antibodies recognized P85 in 2-D immunoblotting studies and TiO(2) chromatography of trypsin digests of P85 isolated a single peptide with an m/z of 917.3. A phosphoserine residue in the tryptic peptide (90)VSELpSFR(96) (position 94 in P85) was identified by MALDI-MS/MS. Polyhistidine fusion proteins (F1(P216), F2(P216), F3(P216)) spanning Mhp493 bound heparin with biologically significant Kd values, and heparin, fucoidan and mucin inhibited this interaction. Latex beads coated with F1(P216), F2(P216) and F3(P216) adhered to and entered porcine kidney epithelial-like (PK15) cell monolayers. Microtitre plate-based assays showed that sequences within P120 and P85 bind to porcine cilia and are recognized by serum antibodies elicited during infection by M. hyopneumoniae. Mhp493 contributes significantly to the surface architecture of M. hyopneumoniae and is the first cilium adhesin to be described that lacks an R1 cilium-binding domain.