Dynamic Change of Genetic Diversity in Conserved Populations with Different Initial Genetic Architectures

Maintenance and management of genetic diversity of farm animal genetic resources （AnGR） is very important for biological, socioeconomical and cultural significance. The core concern of conservation for farm AnGR is the retention of genetic diversity of conserved populations in a long-term perspective. However, numerous factors may affect evolution of genetic diversity of a conserved population. Among those factors, the genetic architecture of conserved populations is little considered in current conservation strategies. In this study, we investigated the dynamic changes of genetic diversity of conserved populations with two scenarios on initial genetic architectures by computer simulation in which thirty polymorphic microsatellite loci were chosen to represent genetic architecture of the populations with observed heterozygosity （Ho） and expected heterozygosity （He）, observed and mean effective number of alleles （Ao and Ae）, number of polymorphic loci （NP） and the percentage of polymorphic loci （PP）, number of rare alleles （RA） and number of non-rich polymorphic loci （NRP） as the estimates of genetic diversity. The two scenarios on genetic architecture were taken into account, namely, one conserved population with same allele frequency （AS） and another one with actual allele frequency （AA）. The results showed that the magnitude of loss of genetic diversity is associated with genetic architecture of initial conserved population, the amplitude of genetic diversity decline in the context AS was more narrow extent than those in context AA, the ranges of decline of Ho and Ao were about 4 and 2 times in AA compared with that in AS, respectively, the occurrence of first monomorphic locus and the time of change of measure NP in scenario AA is 20 generations and 23 generations earlier than that in scenario AS, respectively. Additionally, we found that NRP, a novel measure proposed by our research group, was a proper estimate for monitoring the evolution of genetic diversity in a closed conserved population. Our study suggested that current managements of conserved populations should emphasize on initial genetic architecture in order to make an effective and feasible conservation scheme.

Genetic architecture, epigenetic influence and environment exposure in the pathogenesis of Autism

Autism spectrum disorder(ASD) is a spectral neurodevelopment disorder affecting approximately 1% of the population. ASD is characterized by impairments in reciprocal social interaction, communication deficits and restricted patterns of behavior. Multiple factors, including genetic/genomic, epigenetic/epigenomic and environmental, are thought to be necessary for autism development. Recent reviews have provided further insight into the genetic/genomic basis of ASD. It has long been suspected that epigenetic mechanisms, including DNA methylation, chromatin structures and long non-coding RNAs may play important roles in the pathology of ASD. In addition to genetic/genomic alterations and epigenetic/epigenomic influences, environmental exposures have been widely accepted as an important role in autism etiology, among which immune dysregulation and gastrointestinal microbiota are two prominent ones.

How can we harness quantitative genetic variation in crop root systems for agricultural improvement?

Root systems are a black box obscuring a comprehensive understanding of plant function,from the ecosystem scale down to the individual. In particular,a lack of knowledge about the genetic mechanisms and environmental effects that condition root system growth hinders our ability to develop the next generation of crop plants for improved agricultural productivity and sustainability. We discuss how the methods and metrics we use to quantify root systems can affect our ability to understand them,how we can bridge knowledge gaps and accelerate the derivation of structurefunction relationships for roots,and why a detailed mechanistic understanding of root growth and function will be important for future agricultural gains.

Identification and fine mapping of quantitative trait loci for the number of vascular bundle in maize stem

Studies that investigated the genetic basis of source and sink related traits have been widely conducted.However, the vascular system that links source and sink received much less attention. When maize was domesticated from its wild ancestor, teosinte, the external morphology has changed dramatically; however, less is known for the internal anatomy changes. In this study, using a large maize-teosinte experimental population, we performed a high-resolution quantitative trait locus（QTL） mapping for the number of vascular bundle in the uppermost internode of maize stem.The results showed that vascular bundle number is dominated by a large number of small-effect QTLs, in which a total of 16 QTLs that jointly accounts for 52.2% of phenotypic variation were detected, with no single QTL explaining more than 6% of variation. Different from QTLs for typical domestication traits, QTLs for vascular bundle number might not be under directional selection following domestication.Using Near Isogenic Lines（NILs） developed from heterogeneous inbred family（HIF）, we further validated the effect of one QTL qVb9-2 on chromosome 9 and fine mapped the QTL to a 1.8-Mb physical region. This study provides important insights for the genetic architecture of vascular bundle number in maize stem and sets basis for cloning of qVb9-2.