Population structure and diversity assessment of barley (Hordeum vulgare L.) introduction from ICARDA

This study was undertaken to measure the genetic diversity and population structure of 48 barley accessions introduced from ICARDA using 51 polymorphic simple sequence repeat (SSR) markers to select unique parents for breeding. The mean polymorphic information content was 0.491, suggesting high polymorphism for the selected SSR markers among the barley accessions. The population structure indicated a fine genetic base only with two major clusters. All accessions had 100% membership probability in their respective clusters. Analysis of molecular variance revealed that most (78%) of the variation was attributed between populations, while 22% was due to variation among individuals within populations. Neighbour-joining (NJ) tree was constructed using this distance matrix and two major clusters were observed in it. Cluster 1 had all hulled barley accessions and cluster 2 had all hulless barley accessions. Cluster 2 could be further divided into three subclusters. Principal coordinates analysis results were similar to the NJ tree, where the hulled and hulless barley accessions were grouped into separate clusters. This study established the existence of considerable genetic diversity among the 48 tested accessions. The selected genetic resources will be useful for barley breeding in India and other countries.

Origin, phylogeny, and spread of Mycobacterium tuberculosis Beijing lineage in the five provinces of northern China / 中华流行病学杂志

Objective Using methodology of molecular genetics to explore the origin,phylogen,and gene flow of Mycobacterium tuberculosis (MTB) Beijing lineage in the five provinces from northern China,including Heilongjiang,Jilin,Liaoning,Neimenggu and Ningxia.Methods 234 MTB Beijing lineage strains were genotyped by 24 Variable Number Tandem Repeat (VNTR),and the h (the allelic diversity) value of each VNTR locus was calculated.On individual level of phylogeny,it was constructed Neighbor-Joining (N-J) tree and minimum spanning tree (MST).Phylogenetic tree was built at the population level,and the most recent common ancestor (TMRCA)was estimated through Bayesian model.Molecular variance (AMOVA) was used to understand the gene flow among strains discovered from the five provinces.Results Allelic diversities of the 24VNTR loci were low (h:0.000-0.744).234 strains of MTB Beijing lineage were dispersed in individual branch of the N-J tree,with 62.0％ (145) of them grouped to the same "colonial complexes" in MST.At the population level,the evolution relationship of 234 strains appeared the closest to Beijing lineage,which was from MIRU-VNTRplus database,and the bootstrap was 100.The TMRCA was 5308 (95％ CI:4263-6470) years.Differences of pairwise Fst values acquired by AMOVA between Jilin and Heilongjiang,Liaoning,Neimenggu and Ningxia,were not statistically significant (P＞0.05).Conclusion The genetic similarity of Beijing lineage MTB from the five provinces of northern China was high.The phylogeny branches had no characteristic dispersal in each province.It was speculated that these strains showed an evolution from a clone of MTB Beijing lineage (about 5000 years ago).The gene flow was taking place between neighboring zones.