| Due to breaking the balance of chromosomal dosage of the organism,aneuploidy chromosome number variation often causes abundant phenotypic changes and is widely used in plant genetic improvement research.However,the effects on phenotypic variation and molecular mechanisms of chromosome aneuploidy variation of woody plants are still not clear,because of the limitation of research materials.In this study,a population of full-sib alloheteroploid progenies with abundant chromosome number variation types derived from the hybridization between the diploid Populus tomentosa x P.bolleana and the triploid P.alba × P.berolinensis ’Yinzhong’ were used to analyze the chromosome composition of different individuals.Based on this,the variation patterns of height of seedings,ground diameter of seedings and other growth phenotypes were studied,and the DNA methylation patterns were analyzed.The relevant studies have certain theoretical and practical significance for clarifying the types of chromosome combinations associated with important character formation of poplars and guide the development of poplar and tree chromosomal engineering directional breeding strategies.The main findings are as follows:1.The molecular karyotype analysis technique for aneuploidy poplar based on SSR molecular markers was developed,and the chromosome composition of 65 progeny of(P.tomentosa ×P.bolleana)x(P.alba x P.berolinensis ’nzhong’)was analyzed in combination with genome re-sequencing.The study found that there were 2 diploid plants(2n=2x)in 65 hybrid progeny and 26 hyper-diploid plants(2n=2x～3x)with chromosome numbers between 38 and 57,24 hyper-triploid plants(2n=3x～4x)with chromosome numbers between 57 and 76,10 tetraploid plants(2n=4x)and 3 hyper-tetraploid plants with slightly more than 76 chromosomes(2n=4x+).At the same time,some of the progeny plants were detected for structural variations,such as chromosomal deletions and duplications.2.There were differences in the growth of the progeny of the full sib alloheteroploid progeny of(P.tomentosa × P.bolleana)×(P.alba × P.berolinensis ’ Yinzhong’).The investigation and analysis of the annual growth of the grafted seedlings:the average height of the parents was 182.41 cm,the average height of the 2x,4x and aneuploid group were 160 cm,163.75 cm and 112.33 cm,respectively.The average ground diameter of the parents is 13.51mm,the average ground diameter of the the 2x,4x and aneuploid group werel2.32mm,11.34cm and 9.50mm,respectively.In general,the aneuploidy plants were generally at a disadvantage in comparison with parents,diploid,and tetraploid siblings in terms of seedling height,ground diameter,and other growth indicators,but there were also a small number of individuals with excellent growth.The photosynthetic rate of the parents was better than the ploidy of each filial generation.The average photosynthetic rate of the parents was 21.14μmol CO2m-2s-1,the average photosynthetic rate of the euploid group was 18.99μmol CO2m-2s-1.The average photosynthetic rate of aneuploid group was 18.53μmol CO2m-2s-1.Compared with the aneuploid group,the photosynthetic rate did not show obvious advantages.3.Comparing with the parents,the DNA de-methylation was commonly occurred in the progeny of(P.tomentosa ×P.bolleana)×(P.alba ×P.berolinensis ’ Yinzhong’).The MSAP technique was used to analyze the DNA methylation variation in the full sib alloheteroploid population.By using 33 pairs of primers with good polymorphism for MSAP analysis of 65 individuals,a total of 24256 sites were detected.Among all the offspring,there were 14536 types of methylation sites inherited from the parents,and 9720 sites were mutated.The number of non-methylation sites in progeny was 6602,accounting for 52.76%of the methylation level of types of progeny;the number of sites with foll-methylation was 2515,accounting for 20.10%of the methylation levels of types of progeny.The number of sites with hemi-methylation was 3396,accounting for 27.14%of the offspring methylation levels.The level of non-methylation,full-methylation and hemi-methylation in male parent were 36.34%,27.62%and 36.05%,respectively;the level of non-methylation,full-methylation and hemi-methylation in female parent were 12.56%,43.72%and 43.72%,respectively.In summary,de-methylation is common in progeny.In the offspring,the level of aneuploidy and tetraploid methylation was higher than diploid,suggesting that the differences in chromosome doses between siblings had an impact on methylation level. |
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