To understand the genetic diversity of porcine reproductive and respiratory syndrome virus (PRRSV) in South China, we collected 231 clinical samples from pigs with suspected PRRSV infection in Guangdong between 2007 and 2009. We found that 74 of 231 samples were positive by RT-PCR. The PCR products of the ORF5 gene of 35 isolates from different farms were sequenced and their DNA sequences were compared to 23 other PRRSV isolates in the GenBank. We found that the nucleotide similarity among all South China isolates ranged from 87.6% to 100%, and all belonged to the North American genotype. Most of them were classified into subgenotype I, but the rest mapped to subgenotypes III, V or VI. Those in subgenotypes I and III were found to be highly variable in the primary neutralising epitope (PNE) with a specific amino acid mutation (F39/L39→I39), and a few isolates in subgenotypes I and III isolates also had a mutation at L41 (L41→S41). PRRSV isolates in subgenotypes III, V and VI had less potential glycosylation sites than those in subgenotype I. Our data contribute to the understanding of molecular variation of PRRSV in South China.
A set of 24 microsatellite markers was used for assessing the genetic diversity of 40 obsolete and modern Bulgarian winter wheat (Triticum aestivum L.) varieties. The total number of alleles detected was 215 with the average per locus 8.96 and varying from 4 (Xgwm480, Xgwm333) to 15 (Xgwm291). The obsolete varieties of interest were created in the period between 1911 and 1938 through selection of local populations, originating from three Bulgarian regions. The number of alleles detected in those old varieties was 182 with an average of 7.58, out of which 2.67 were rare. Regional differences in the allelic richness and diversity were also observed. Greater number of alleles was found in the old varieties, originating from South Bulgarian and Northeast landraces. Modern wheat breeding in Bulgaria has led to a decrease in the alleles per locus ratio and an increase in the allelic frequency. The same process has invalidated 44.2% of the old wheat alleles, preserved 40.9% and made possible an inflow of 14.9% new alleles. The artificial selection tolerated the preservation of a big number of the alleles of some loci found in old varieties (Xgwm205 and Xgwm160), while others experienced loss of alleles (Xgwm291, Xgwm312, Xgwm219 and Xgwm261). The genealogical analysis of 94 Bulgarian varieties, created in the period 1940-2000, showed that 27.7% of those varieties were based on Bulgarian landraces.
Authors:X.L. Liu, B.Y. Lu, C.Y. Wang, Y.J. Wang, H. Zhang, Z.R. Tian, and W.Q. Ji
The aphid Sitobion avenae F. is one of the most harmful pests of wheat growth in the world. A primary field screening test was carried out to evaluate the S. avenae resistance of 527 wheat landraces from Shaanxi. The results indicated that 25 accessions (4.74%) were resistant to S. avenae in the three consecutive seasons, of which accession S849 was highly resistant, and seven accessions were moderately resistant. The majority of S. avenae resistant accessions come from Qinling Mountains. Then, the genetic variability of a set of 33 accessions (25 S. avenae resistant and 8 S. avenae susceptible) originating from Qinling Mountains have been assessed by 20 morphological traits and 99 simple sequence repeat markers (SSRs). Morphological traits and SSRs displayed a high level of genetic diversity within 33 accessions. The clustering of the accessions based on morphological traits and SSR markers showed significant discrepancy according to the geographical distribution, resistance to S. avenae and species of accessions. The highly and moderately resistant landrace accessions were collected from the middle and the east part of Qinling Mountains with similar morphology characters, for example slender leaves with wax, lower leaf area, and high ear density. These S. avenae resistant landraces can be used in wheat aphid resistance breeding as valuable resources.
Authors:Z. Jurković, K. Dugalić, M. Viljevac, I. Piližota, A. Vokurka, B. Puškar, and I. Pejić
, E., Cosson, P., Tavaud, M., Aranzana, M. J., Poizat, C., Zanetto, A., Arus, P., Laigret, F. (2002): Development of microsatellite markers in peach [
(L.) Batsch] and their use in geneticdiversityanalysis in peach and sweet cherry
Geleta, N. (2003):
Morpho-agronomical and molecular marker based geneticdiversityanalysis and quality evaluation of sorghum
. Ph.D. dissertation. University of the Free State, Blomfontein, South