| The walnut(Jugians regia L.),one of the four major nuts in the world,has a cultivation history of more than 1,500 years in Xinjiang.Xinjiang is one of the main producing areas of walnuts in China.In Xinjiang,because of the long propagation by seeds,the walnuts have variant types,such as leatheroid walnut and thin-shell walnut.In this study,we selected single plant of walnut with better comprehensive properties than the parent from morphological level;used the unique historical advantage of Xinjiang to investigate genetic diversity of walnut by using amplified fragment length polymorphism method;and determined the relationship between the single plant and paternity.The results as follow:1.A survey of nuts biological characteristics was conducted on 13 parents and 102 offspring.According to data analysis,correlation analysis,principal component analysis,factor analysis and cluster analysis,the results showed that the biological characteristics of the nine fruits could be divided into four principal components(the kernel weight factor,the fruit diameter factor,the fruit factor and the kernel rate factor,respectively).The cumulative contribution rate of the four principal components was85.732%.2.According to the data of relevant biological traits of female parent plants,we analyzed the single offspring of 102 offspring about the traits of the average fruit weight,maximum fruit weight,three nut diameters,fruit shape index,shell thickness,kernel weight,and kernel rate.By calculating the factor scores of the main components of the fruit of 115 shell walnut parents and the actual offspring,we find that the single-strains with the highest score were South 7-8 and north 3-8.With the new temperature of185 parents as the reference standard,8 elite seedlings could be selected.The 8 elite seedlings were South 7-8,North 3-17,South 7-7,North 1-18,Medium 4-20,and North 6-18.South 4-16 and North 7-7respectively.3.AFLP method was used to amplify the 123 progeny single plants and 13 parents.A total 583 statistical bands were obtained,and.544(93.30%)were polymorphic.The allele frequencies of the 136 samples ranged from 1.2731 to 1.9206 with an average of 0.7328.The effective allele number was1.0273~1.9969,with an average of 1.4145;the genetic diversity was 0.1301~0.4992 and the average was 0.3346.Shannon's information index was 0.1804~0.5841 with an average of 0.2878.4.The cluster analysis was performed by using the R factor UPGMA program of DPS.The similarity coefficient of most tested samples was between 0.55~0.98.When the enthalpy value was 0.54,136 copies of 123 single-plant seed offspring and 13 candidate male parents could be divided into four categories.According to the similarity coefficient,we could determine the possible male parents of 17 single plants.Among which 4 plants in Xinwen 185 were born offspring,Xinjufeng and Xinwen 91 were5 male progenies in potential male parents,one was Xinwen 611,one was Xinjufeng 81,and one was Xinwen 81.Among them,the parents of Bei 3-8 were Xinwen 81.It indicated that the seeds of the single offspring of this actual generation were pollinated by other trees whose parents were of the same variety.And of course,the possibility of self-pollination was not ruled out.By using the clustering of parents and offspring,we find that the similarity coefficient between the male parent and Northern 1-2(1),Northern1-2(2)Northern 1-18,Northern 1-20 were high,but they were still related to the female parent.It showed that most of the tested offspring were biased towards maternal inheritance. |
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