MHC-DRB1/DQB1 Gene Polymorphism and Its Association with Resistance/Susceptibility to Cystic Echinococcosis in Chinese Merino Sheep

The aim of this study was to analyze the relationship between polymorphism of the MHC-DRB1/DQB1 gene and its resistance to Cystic Echinococcosis (C.E), as well as to screen out the molecular genetic marker of antiechinococcosis in Chinese Merino sheep. The MHCII-DRB1/DQB1 exon 2 was amplified by polymerase chain reaction (PCR) from DNA samples of healthy and hydatidosis sheep. PCR products were characterized by restriction fragment length polymorphism (RFLP) technique. Five restriction enzymes (Mval, HaeIII, SacI, SacII, and Hin1I) were employed to cut DRB1, while seven restriction enzymes (MroxI, ScaI, SacII, NciI, TaqI, Mval, and HaeIII) were employed to cut DQB1.Results showed that frequencies of patterns Mvalbb (P<0.01), SacIab in DRB1 exon 2 (P<0.05), and TaqIaa, HaeIIInn (P<0.01) in DQB1 exon 2 were significantly higher in the healthy group compared with the C.E individuals, which implied that there was a strong association between these genotypes and hydatidosis resistance or susceptibility. Chi-square test showed that individuals with the genic haplotype DRB1-SacIab/DRB1-Mvalbb/DQB1-TaqIaa/DQB1-HaeIIInn (P<0.01) were relatively resistant to C.E, while individuals with the genic haplotypes DRB1-Mvalbc/DQB1-Mvalyy/DQB1-TaqIab/DQB1-HaeIIImn (P<0.01) and DRB1-Mvalbb/DQB1-Mvalcc/DQB1-TaqIab/DQB1-HaeIIImn (P<0.01) were more susceptible to C.E. In addition, to confirm these results, a fielding experiment was performed with Chinese Merino sheep which were artificially infected withE.g. The result was in accordance with the results of the first study. In conclusion, MHC-DRB1/DQB1 exon 2 plays an important role as resistant to C.E in Chinese Merino sheep. In addition, the molecular genetic marker of antiechinococcosis (DRB1-SacIab/DRB1-Mvalbb/DQB1-TaqIaa/DQB1-HaeIIInn) was screened out in Chinese Merino sheep.

Molecular genetic marker-based analysis of species-differentiated phenotypic characters in an interspecific ryegrass mapping population

The genus Lolium (ryegrasses) exhibits substantial variation between species for annual-perennial growth habit. The genetic bases of this trait, and other characters that are differentiated between taxa, have been investigated through molecular genetic marker-based mapping of an interspecific mapping population derived from pair-wise crossing of single genotypes from Lincoln, a long-lived cultivar of perennial ryegrass, and Andrea, a cultivar of annual-type Italian ryegrass. The Andrea1246 and Lincoln1133 parental maps contained 122 loci on eight linkage groups (LGs), and 169 loci on seven LGs, respectively. A total of 10 phenotypic traits were measured, including annuality-perenniality index, date of head emergence, number of spikes per plant, number of spikelets per spike, number of floret per spike, flag leaf length, flag leaf width, spike length, stem length, and extent of regrowth. A total of 31 putative quantitative trait loci (QTLs) were detected. Regions of significance were identified on Andrea1246 LGs 1, 2, 3 and 6. An annuality-perenniality index QTL on LG2 accounted for ~30% of trait-specific phenotypic variance (Vp). In addition, LG2 contained coincident QTLs for the number of spikes per plant and head emergence date traits. The Lincoln1133 genetic map displayed QTL-containing regions of significance on LGs 1, 4, 5 and 7, accounting individually for 10–22% of Vp. QTLs identified in this study provide potential targets for ryegrass breeding in order to improve vegetative yield, persistence and seed yield.