The Effects Of Cytonuclear Incompatibility On Maintaining Species Status Of Populus Tremula And P.alba In The Irtysh River Region

In plant hybridization,the maintenance of species integrity can be explained by the interaction between plastid and nuclear genome,but plastome-genome incompatibilities have often been neglected in research and analysis.Here,we used nuclear microsatellites and chloroplast genome data to analyz the genetic structure of Populus alba L and P.tremula L hybrid zone in the Irtysh River region of Xinjiang.We also used natural pollination and artificial hybridization,and analyzed the correlation between the evolution rate of the chloroplast RANP gene family and sigma gene family to obtain following results:(1)The analysis of genetic structure of Populus alba and Populs tremula hybrid zone in the Irtysh River region of Xinjiang in China,shows that the differentiation of nuclear genome of them.Hybrid Populus ×canescens is the result of two-way hybridization of parent species,genotypes of individuals in F1 generation were dominant,while those in F2 generation and backcross with P.alba and P.tremula were fewer.(2)P.×canescens carrying different chloroplast types backcrossed with P.alba and P.tremula could produce seeds.After seed germination,seedlings grew normally in glasshouse and Tongzhou experimental base,but no nuclear-cytoplasmic incompatibility was observed during the seedling stage of backcross seeds.(3)The whole chloroplast genome sequence analysis of eight individuals of P.alba,P.tremula and P.×canescens in the Irtysh River showed that the chloroplast genome of P.alba and P.tremula had obvious interspecific differentiation.Mat K,cem A,ndh F,ndh D,ndh H,rpl14,psb C,psb Z,atp A,atp H,atp I,rpo A,rpo B,rpo C1,rpo C2,acc D,ycf1 and ycf4,these 18 coding genes had greater differentiation between P.alba and P.tremula.(4)We found that the transcription-related RANP genes(rpo A,rpo B,rpo C1 and rpo C2)in the chloroplast genomes of P.alba and P.tremula had obvious interspecific differentiation and rapid evolution rate.However,the correlation analysis of evolution rate between chloroplastRANP gene family and sigma gene family of nuclear genome has not found evidence of co-evolution between these two families.We need more data analysis and more experimental materials to supplement and improve the hybridization test,to further clarify whether there is co-evolution between the chloroplast RANP gene family and the nuclear genome sigma gene family by analyzing more data of poplar species in later research,so as to verify whether there is nuclear incompatibility between P.alba and P.tremula hybrid...