| Four kinds of soybean leaf materials were used as parents in this study, they respectively were Jilin47(code name 19), EXP(code name12), Jilin38(code name3) and Yi3(code name6),according to the complete diallel crosses design and get 12 hybrid combinations.Use four parents and 12 hybrid combinations as the experimental materials, and through test indoor and use MSAP method to test the level of DNA methylation and the situation of inheritance and variation, to find the correlation between DNA methylation and the heterosis of soybean,providing theoretical basis for the utilization of soybean heterosis. The results of the study are as follows:Investigation on agronomic traits of soybean were: plant height,and 100-seed weight,yield per plant,No. of pods per plant,No. of seeds per plant,No. of branches per plant,insect infected grain,stem diameter, No.of nodes per stem and height of the end pod per plant, a total of ten traits. And two quality traits were the content of oil and protein. The mid-parent heterosis(MPH)and the better parent heterosis(BPH) were computed in the different of soybean combination, it was discovered that 12 hybrid combinations of soybean exists the obvious heterosis on one or more traits, The average MPH of each trait in the 12 hybrid combinations repectively were followed. The MPH of plant height was 8.62%, the MPH of No. of node per stem was 7.79%,the MPH of No. of branches per plant was 192.96%, the MPH of height of the end pod per plant was-46.44%, the MPH of No. of pods per plant was 215.38%, the MPH of No. of seeds per plant was 226.46%, the MPH of insect infected grain was-53.94, the MPH of 100-seed weight was 12.93%, the MPH of yield per plant was 263.49%, the MPH of stem diameter was 74.83%,the MPH of oil was-3.37% and the MPH of protein was-3.37%. The average MPH of height of the end pod per plant,insect infected grain and content of oil in 12 hybrid combinations showed the negative advantage. The average MPH of plant height,and 100-seed weight,yield per plant,No. of pods per plant,No. of seeds per plant,No. of branches per plant,stem diameter and No.of nodes per stem in 12 hybrid combinations showed the positive advantage. Only one combination showed the positive advantage and the other showed the negative advantage for the average MPH of content of protein in 12 hybrid combinations. The biggest MPH advantage was appeared on the trait of yield per plant in combination 12x6, and the MPH of combination 12x6 is 534.44%. The average BPH of each trait in the 12 hybrid combinations repectively were followed. The BPH of plant height was-1.26%, the BPH of No. of node per stem was 2.63%,the BPH of No. of branches per plant was 117.64%, the BPH of height of the end pod per plant was-55.10%, the BPH of No. of pods per plant was 189.43%, the BPH of No. of seeds per plant was 211.87%, the BPH of insect infected grain was-60.82%, the BPH of 100-seed weight was5.87%, the BPH of yield per plant was 228.34%, the BPH of stem diameter was 69.78%, the BPH of oil was-8.37% and the BPH of protein was 2.78%. The average MPH of height of the end pod per plant,insect infected grain and content of oil in 12 hybrid combinations showed the negative advantage. The average MPH of yield per plant,No. of pods per plant,No. of seeds per plant,No. of branches per plant and stem diameter in 12 hybrid combinations showed the positive advantage. 100-seed weight,No. of nodes per stem and content of protein, these 3 traits were each have 3 combinations to show the negative advantage, and the other 9 combinations showed the positive advantage. The BPH of plant height showed the negative advantage in 7combinations and the other 5 combinations showed the positive advantage. The biggest BPH advantage was appeared on the trait of yield per plant in combination 12x6, and the BPH of combination 12x6 is 497.84%. Under the trait of content of protein, the expression of each pair of reciprocal cross combination were same like. Have one pair of reciprocal cross combination12x19 and 19x12, the expression of combination 12x19 was better than 19x12 in all of the 12 traits, and the other pair of reciprocal cross combination found no consistent rule. In all aspects of the performance, combination 6x19 was the best combination in 12 hybride combination.MSAP method was used to test the level of DNA methylation and the situation of inheritance and variation of 16 soybean leaf materials, it was discovered that the level of DNA methylation of 16 copies of the materials was 41.33%-58.89%, the average of it was 49.63%,the level of inside cytosine methylation(double strands) was higher than the external cytosine methylation(single strand). the level of DNA methylation of hybrid F1 were all lower than average of parents, it showed that the methylation of the most hybrid F1 was lower than that of the parent. The inheritance of methylation of 12 combinations was more than that of the variation, for the phenomenon of inheritance, the phenomenon of hybrid F1 was inherited from one parent was more than it was inherited from the parents. There are three ways to appear most for the inheritance, the first was hybrid F1 inherited inside cytosine methylation(double strands)from the parents( A1 type), the second was hybrid F1 inherited external cytosine methylation(double strands) or inside and external cytosine methylation(double strands) from the male parent(B4 type), the third one was hybrid F1 inherited external cytosine methylation(double strands) or inside and external cytosine methylation(double strands) from the female parent(B8type). For the variation of hybrid F1 methylation, there is one way to appear most, the way is hybrid F1 have not ihherited external cytosine methylation(double strands) or inside andexternal cytosine methylation(double strands) from the parents, but it showed the variation of external cytosine methylation(single strand)(D2 type). Above four types(A1,B4,B8 and D2)were appeared in high frequency in all the combinations.Do the correlation analysis between level and inheritance and variation of DNA methylation with expression and heterosis of hybrid F1. From the view of expression of hybrid F1, the correlation between level of DNA methylation with expression of hybrid F1was: between level of total methylation and No. of seeds per plant appears remarkable positive correlation; between level of half methylation with insect infected grain appears remarkable negative correlation;The correlativity between different types of inheritance and variation of DNA methylation with expression of hybrid F1 was: between A1 type which belong to the general type that methylation pattern of hybrid F1 was inherited from parents with the content of fat appears extremely remarkable negative correlation; and with the content of protein appears remarkable positive correlation; between A2 type which belong to the general type that methylation pattern of hybrid F1 was inherited from parents with the content of fat appears remarkable negative correlation; between B2 type which belong to the general type that methylation pattern of hybrid F1 was inherited from one parent with the content of protein appears remarkable positive correlation; between B4 type which belong to the general type that methylation pattern of hybrid F1 was inherited from one parent with insect infected grain appears remarkable negative correlation; between C1 type which belong to the general type that methylation pattern of hybrid F1 showed more than parents with 100-seed weight and stem diameter all appear remarkable positive correlation; between C2 type which belong to the general type that methylation pattern of hybrid F1 showed more than parents with 100-seed weight appears remarkable positive correlation; and with the content of fat appears extremely remarkable negative correlation;between D1 type which belong to the general type that methylation pattern of hybrid F1 showed less than parents with height of the end pod per plant appears remarkable negative correlation.From the view of mid-parent heterosis, the correlation between level of DNA methylation with mid-parent heterosis was: between level of total methylation with No. of seeds per plant appears remarkable positive correlation; between level of entire methylation with height of the end pod per plant appears remarkable positive correlation; between level of half methylation with height of the end pod per plant appears remarkable negative correlation. The correlativity between different types of inheritance and variation of DNA methylation with mid-parent heterosis was: between B1 type which belong to the general type that methylation pattern of hybrid F1 was inherited from one parent with 100-seed weight appears remarkable positive correlation; between C1 type which belong to the general type that methylation pattern of hybridF1 showed more than parents with stem diameter appears remarkable positive correlation;between D1 type which belong to the general type that methylation pattern of hybrid F1 showed less than parents with stem diameter appears remarkable negative correlation; between C2 type which belong to the general type that methylation pattern of hybrid F1 showed more than parents with No. of node per stem and height of the end pod per plant all appear remarkable negative correlation; between D4 type which belong to the general type that methylation pattern of hybrid F1 showed less than parents with No. of node per stem appears remarkable positive correlation.From the view of better-parent heterosis, the correlation between level of DNA methylation with better-parent heterosis was: between level of total methylation with No. of seeds per plant appears remarkable positive correlation; between level of entire methylation with height of the end pod per plant appears remarkable positive correlation. The correlativity between different types of inheritance and variation of DNA methylation with better-parent heterosis was: between B5 type which belong to the general type that methylation pattern of hybrid F1 was inherited from one parent with plant height appears remarkable negative correlation; between C1 type which belong to the general type that methylation pattern of hybrid F1 showed more than parents with stem diameter appears remarkable positive correlation; between D1 type which belong to the general type that methylation pattern of hybrid F1 showed less than parents with stem diameter appears remarkable negative correlation. |
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