| Heterodera glycines is one of the most important pathogenic nematodes causing serious loss of soybean yield in the world.It is mainly distributed in Northeast China and Huang Huai Region in China,and sporadic distribution has been reported in other places recently.At present,the research on population genetics of H.glycines mainly focused on population genetic characteristics,and the research on regional adaptive differentiation has not been clearly confirmed.In this study,the population dynamics of H.glycines in Jilin Province was investigated,the genetic diversity and regional adaptive differentiation of H.glycines populations were assessed from different geographical locations by ISSR and SNP molecular markers,and the effects of ecological factors on population dynamics and genetic diversity were analysed.The aim of this study was to reveal the characteristics of population structure and regional adaptive differentiation of H.glycines,and to provide a theoretical basis for further revealing its spread,transmission and epidemic.The main results are as follows:(1)H.glycines population has three generations in a crop growing season in Changchun,Jilin Province.Among which,the second generation of H.glycines had the largest reproduction and the most serious infection,and diapause and generation overlap were obvious.(2)Genetic diversity based on ISSR markers: The average expected heterozygosity(He)of 13 H.glycines populations in 5 provinces ranged from 0.0330 to 0.1268,and Shannon index ranged from 0.0503 to 0.1881,which indicated that the high level of genetic homogeneity within every population.The largest Nei’s genetic identity(0.9606)of pairwise populations and the smallest genetic distance(0.0402)occurred between HLDQ and HLAD;The minimum genetic identity(0.6305)and the maximum genetic distance(0.4613)occurred between HLJM and JLCC.Genetic identity was weakly correlated with geographical distance.Among populations,the average expected heterozygosity(He)was0.2460,Shannon information index(I)was 0.3755,the total genetic differentiation was high(Gst = 0.7325),and gene flow was weak among populations(Nm = 0.1826),which indicated that the high level of genetic heterogeneity among populations.Cluster analysis showed that the 13 populations were mainly divided into two groups at the genetic similarity coefficient was 0.65.(3)Based on SNP molecular marker technology,the results showed that: The average expected heterozygosity(He)of 16 H.glycines populations in 6 provinces ranged from0.1293 to 0.1871.The low level of genetic diversity index indicated that there was high genetic homogeneity in every population.The minimum genetic differentiation coefficient(Fst)(0.2130)and minimum genetic distance(DR)(0.2395)of pairwise populations occurred in HLAD and HLDQ,the maximum Fst(0.3969)and DR(0.5057)occurred in HBCZ and JLFS.The total average expected heterozygosity(He)among populations was0.2328.There was a very low gene flow(Nm = 0.7437)and a high level of genetic differentiation(Fst = 0.4020)among populations;Cluster analysis and principal component analysis showed that 16 populations were divided into two groups,HBCZ,SXFY,SDJN and IMCF in North China were clustered into one group,while the remaining 15 populations in Northeast China were clustered into another group.Gene structure analysis showed that the 16 H.glycines populations included two different genetic backgrounds,Five populations in North China had the same genetic background and genetic differentiation convergence,while eleven populations in Northeast China had the same genetic background and genetic differentiation convergence,which were different from those in North China.Genetic differentiation coefficient showed a significant moderate positive correlation level with geographical distance,which indicated that geographical distance was an important factor affecting the adaptive genetic differentiation of H.glycines populations,the greater the geographical distance,the more obvious the adaptive differentiation is.(4)The effects of ecological factors on population dynamics and genetic diversity showed that: Temperature had a significant effect on each development stage of H.glycines,and the continuous high temperature(30 ℃ < air temperature<32 ℃)was conducive to the mass incubation of J2,but not conducive to its invasion and development after infection;accumulated precipitation was within the appropriate range(< 428.3 mm),and the more precipitation,the easier J2 infected the host;when accumulated precipitation exceeded428.3 mm,J2 population density decreased significantly(r =-0.791,P = 0.05).The meteorological factors showed that the average value of monthly average maximum temperature in soybean growing period was significantly positively correlated with the genetic diversity of H.glycines population(P = 0.05),and the average precipitation was significantly negatively correlated with the genetic diversity of H.glycines population(P=0.05). |
