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Beijing Forestry University (2019)

Crossover Interference Analysis of Populus Euphratica Genome

王平;

Titre : Crossover Interference Analysis of Populus Euphratica Genome

Auteur : 王平;

Grade : Master’s Theses 2019

Université : Beijing Forestry University

Résumé
In the process of meiosis,the occurrence of one crossover interferes with the simultaneous occurrence of another crossover on the same pair of chromosomes.This phenomenon has been referred as crossover interference(CO interference).This phenomenon has been discovered more than a century,and it was first discovered between homologous parent chromosomes in the prophase of meiosis and its distribution was non-random.The enormous role of crossover interference in expanding and maintaining genetic diversity through gender,stress,and age-induced differentiation,this phenomenon is ubiquitous in eukaryotes and plays a vital role in the evolution of eukaryotes.Populus euphratica,as the only arbor species in the desert area of northwest China,plays a vital role in maintaining the ecological balance in the arid-semi-arid regions of Northwest China.At present,due to climate change and the impact of human activities,the area of natural P.euphratica forest has been sharply reduced,and ecological security and agriculture are facing severe challenges in northwestern China.However,so far,biological research are not very clear about its crossover interference mechanism at the genome-wide level.Therefore,based on the genetic map data of P.euphratica constructed by 408 individuals,the four-point linkage analysis model is used to characterize the detailed distribution of three types(crossover interference in adjacent intervals,crossover interference in one interval,and crossover interference in three intervals)of crossover interference in P.euphratica,in the article,we refer to the phenomenon that the three intervals interfere with each other as high dimensional crossover interference.study the relationship between chromosome length and overall high dimensional crossover interference strength,and study the relationship between chromosome location and overall high dimensional crossover interference were studiedThe following main results were obtained through research :(1)High dimensional crossover interference is distributed in 19 linkage groups,with different distribution and strength on each chromosome ;and there is strong intensity of high dimensional crossover interference in the fourth linkage group and the fifth linkage group,and the high dimensional crossover interference strength of the eleventh linkage group is low,and the crossover interference strength of one interval is obviously much lower than that of the adjacent interval.(2)By analyzing the characteristics of high dimensional crossover interference strength on each chromosome,the fitting study of the data found that the high dimensional crossover interference strength of the 2,3,4 and 6 linkage groups has a strong linear relationship with its length and its correction coefficient(R2=0.85) ;the high dimensional crossover interference strength of other chromosomes and the length of the chromosomes exist in a linear relationship with another slope.(3)The study also found differences in the high dimensional crossover interference strength between the three equal parts of the chromosome(according to the genetic distance from small to large,they are named:NO.1,No.2 and No.3.)in each linkage group:the difference ratios of NO.1-NO.2,N0.2-N0.3 and NO.1-NO.3 are represented by blue line,green line and red line in the figure,respectively,and their ranges are 0.1429-0.9474,0.0952-1.1250 and 0.2353-0.8750 respectively.Through this study,we found that high dimensional crossover interference exists in P.euphratica,and its frequency of occurrence is significantly different from the other two types of crossover interference.The high dimensional crossover interference strength has a linear relationship with the length of the chromosome,and the strength of high dimensional crossover interference at different positions on different chromosomes is different.This further indicates that high dimensional crossover interference may play an important role in complex mechanisms such as growth,reproduction,and adaptation to stress environment.

Mots clés : Euphrates poplar; genetic interference; Mapping population; Meiotic crossover; four-point analysis;

Présentation (CNKI)

Page publiée le 29 avril 2020