Distribution Of Genetic Groups Research Articles

Status of population genetic structure and distribution of Bemisia tabaci genetic groups in vegetable crops and others in India

Whitefly, Bemisia tabaci is one of the polyphagous pests infesting wide variety of crop plants and is vectors of plant viruses belonging to begomivruses whose transmission efficiencies have been reported to be varying. Therefore, we have conducted a series of extensive surveys during 2019-21 to monitor and collect B. tabaci populations across the country and studied the distribution of its genetic groups. Further, PCR amplification, purification, cycle sequencing and partial CO-I gene sequencing has been done to understand population genetic structure and the distribution of genetic groups B. tabaci in India. Data analysis revealed a total of 11 genetic groups of which Asia II-3, Asia II-6 & Asia III were new to India reported for the first time from Chhattisgarh, Andhra Pradesh and Maharashtra for the first time in India. These studies will help farmers and other stakeholders to effectively manage whitefly and whitefly borne begomoviruses for increased vegetables and in turn vegetable oil production.

Himalayan mountains imposing a barrier on gene flow of wheat yellow rust pathogen in the bordering regions of Pakistan and China

The wheat yellow rust pathogen has been shown to be diverse and potentially originated in the Himalayan region. Although Himalayan populations of Pakistan, Nepal and Bhutan have been previously compared, little is known about the relative divergence and diversity in Puccinia striiformis populations in the bordering regions of Pakistan and China. To assess the relative diversity and divergence in these regions of Pakistan (Gilgit-Baltistan, Hazara and Azad Jammu Kashmir) and China (Xinjiang, Qinghai, Tibet, Sichuan, Guizhou and Yunnan), a total of 1245 samples were genotyped using 17 microsatellite SSR markers. A clear divergence was observed between the bordering regions of Pakistan and China (FST = 0.28) without any resampling of genetic groups and multilocus genotypes across two sides of the Himalayan mountains. The closest subpopulations across the two countries were Xinjiang and Gilgit-Baltistan (Nei’s distance = 0.147), which were close geographically. A very high diversity and recombinant population structure was observed in both populations, though slightly higher in China (Genotypic diversity = 0.970; r¯d = 0.000) than in Pakistan (Genotypic diversity = 0.902; r¯d = 0.065). The distribution of genetic groups and resampling of MLGs revealed more gene flow across Yunnan, Guizhou and Sichuan regions in China, while between Hazara and Azad-Jammu Kashmir in Pakistan. The lack of gene flow between Pakistan and China populations is due to geographical barriers and a large patch of land without wheat. The information on the relative diversity and divergence in different geographical zones of the pathogen center of diversity and neighboring region should be considered in resistant wheat deployment while considering the invasion potential of the pathogen at regional and global contexts.

Inferring the biogeography of New Zealand’s only endemic holoparasitic plant, the threatened Dactylanthus taylorii (Mystropetalaceae)

ABSTRACT Despite a rich history of botanical research, little is known about the distribution of genetic variation within New Zealand plant species. With a native vascular flora that consists of ∼80% endemics, nearly one-half of which are threatened, there is a dire need for a better understanding of intraspecific diversity for individual plant species and of biogeographic patterns for the wider New Zealand flora. To these ends, we have investigated population genetic structure in the endemic root holoparasite, Dactylanthus taylorii (pua o te Rēinga, Mystropetalaceae). A total of 235 individuals from 31 locations across the North Island of New Zealand (Te Ika-a-Māui, Aotearoa) were genotyped for a suite of nuclear microsatellite loci. Genotype data were analysed at the individual and population levels to assess genetic diversity within and among populations and to investigate the geographic distribution of genetic variation within the species. Population structure was assessed using Bayesian clustering, discriminant analysis of principal components, and a Neighbor-Net analysis. A hierarchical pattern of genetic diversity was revealed, with evidence for three broad geographic regional groupings (West, East, and Central Volcanic Plateau (CVP)). Upon further analysis, each of the three geographic groups further subdivide hierarchically into two or three genetic subgroups. Genetic diversity was found to be relatively high in this endangered species but varies considerably across populations. The distribution of genetic groups appears to have been influenced by past volcanic activity as the CVP group is largely coincident with a distinct tephra isopach from the 1.8 ka Taupō eruption and the West and East groups may have diverged due to recurring volcanic activity in the Central Volcanic Zone. The genetic structure resolved here provides important information for the management of D. taylorii specifically and for our understanding of New Zealand biogeography generally.

CONFORMAÇÃO CORPORAL DE EQUINOS DE DIFERENTES GRUPOS GENÉTICOS

Resumo Qualquer atividade equestre exig e equino com aptidão adequada, podendo ser identificada através da conformação corporal (IC), calculada pela combinação de medidas biométricas. Objetivou-se avaliar IC de 86 equinos, pertencentes aos grupos genéticos (GG): Crioulo (CR), Brasileiro de Hipismo (BH), Árabe (ARB), Quarto de Milha (QM), Puro Sangue Inglês (PSI) e mestiços com pequena estatura corporal, rotulado Petiço (PE). Avaliaram-se relação cernelha garupa, peso corporal estimado, torácico, corporal, corporal relativo, conformação, compacidade e carga 1 e 2, carga na canela e dáctilo-torácico. Analisaram-se efeito de sexo (S), GG e interação S*GG; correlações entre IC; componentes principais, elaborando-se diagrama de dispersão com biplot, para se verificar a distribuição dos GG em relação aos IC; e cluster para verificar distância entre GG. Os efeitos foram responsáveis por variações (P<0,05) nos IC. Considerou-se o PE elipométrico e os demais, eumétricos. Considerou-se o PSI mediolíneo e os demais, brevilíneos. Equinos PSI, QM e PE apresentaram-se aptos para executar atividades com sela até tração leve e o restante, até tração pesada. Equinos BH e ARB apresentaram maior capacidade de suportar peso sem esforço exagerado sobre o dorso, trabalhando a passo e ao galope. Observaram-se maior similaridade entre QM e CR e menor entre PE com os GG.

How to Use an Article About Genetic Association

In the first article of this series, we reviewed the basic genetics concepts necessary to understand genetic association studies. In this second article, we enumerate the major issues in judging the validity of these studies, framed as critical appraisal questions. Was the disease phenotype properly defined and accurately recorded by someone blind to the genetic information? Have any potential differences between disease and nondisease groups, particularly ethnicity, been properly addressed? In genetic studies, one potential cause of spurious associations is differences between cases and controls in ethnicity, a situation termed population stratification. Was measurement of the genetic variants unbiased and accurate? Methods for determining DNA sequence variation are not perfect and may have some measurement error. Do the genotype proportions observe Hardy-Weinberg equilibrium? This simple mathematic rule about the distribution of genetic groups may be one way to check for errors in reading DNA information. Have the investigators adjusted their inferences for multiple comparisons? Given the thousands of genetic markers tested in genome-wide association studies, the potential for false-positive and false-negative results is much higher than in traditional medical studies, and it is particularly important to look for replication of results.