Relationship Between Differential Gene Expression Patterns And Heterosis In Soybean Seedling Stage

The 4×5 NCâ…¡design was used for the material, the heterosis of the soybean agronomicand quality traits was measuresed and the relationship between differential gene expressionpatterns and heterosis was analyzed in the thesis. In this foundation, an obvious superiorityhybrid combination (3×12) was selected according to the yield. Twenty-two differentiallyexpressed of cDNA fragments between hybrids and their parents were cloned. They wouldoffer valuable information on the relationship between differential gene expression patterns andheterosis in soybean in the future. The main results as follows:The agronomic and quality traits of twenty hybrids and nine parents were observed andmeasured. Parents involve Jilin30 (code name2), Jilin38 (code name3), 2002 selected plant(code name17), Jilin47 (code name19), yi3 (code name6), PEMVy (code name9),EXP (code name12), ARIRA (code name13) and SAPPRO (code name14) .Measured traits:plant height, No. of nodes per stem, No. of branches per plant, No. of pods per plant, No. ofseeds per plant, insect infected grain , stem diameter, 100-seed weight, yield per plant andthe content of the oil and protein.The mid-parent heteriosis (MPH) and the better parents heterosis (BPH) were computedin the soybean different combination. It was discovered that the soybean exists an obviousheteriosis. The average MPH of each trait in the twenty combinations respectively. The MPHof plant height was 0.26%. The MPH of No. of nodes per stem was 0.61%. The MPH of No. ofbranches per plant was 20.60%. The MPH of No. of pods per plant was 28.78%. The MPH ofNo. of seeds per plant was 32.72%. The MPH of insect infected grain was -15.68%. The MPHof stem diameter was 12.99%. The MPH of 100-seed weight was 7.75%. The MPH of yield perplant was 43.90%. The MPH of oil was 1.02%. The MPH of protein was -0.11%.Most of thesecombinations of the heteriosis of stem diameter, 100-seed weight and the yield per plant werepositive advantage, however plant height, No. of branches per plant and insect infected grainwere negative advantage, none of traits was positive advantage or negative advantage in thetwenty different combinations. The yield per plant was the biggest advantage and the MPH ofthe combination (3×12) was 139.73%. The average BPH of soybean different combinations was computed. The BPH of plantheight was -7.44%. The BPH of No. of nodes per stem was -4.14% The BPH of No. ofbranches per plant was -4.55%. The BPH of No. of pods per plant was 14.67%. The BPH of No.of seeds per plant was 17.00%. The BPH of insect infected grain was 15.14%. The BPH ofstem diameter was 7.28%. The BPH of 100-seed weight was 3.42%. The BPH of yield perplant was 25.40%. The BPH of oil was -3.64%. The BPH of protein was -2.98%. Most of thesecombinations of the BPH of 100-seed weight and the yield per plant were positive advantage,however the plant height, oil and protein was negative advantage. The yield per plant was thebiggest advantage and the BPH of the combination (3×13) was 117.45%.The combining ability of the agronomic and quality traits on the twenty combinations wasanalyzed. To the general combining ability (GCA), only the GCA of the plant height, 100-seedweight and the protein in the female and male parents came to 0.1 remarkability. In the female,the GCA of No. of seeds per plant and the yield per plant came to 0.01 remarkability. The GCAof No. of pods per plant, stem diameter and 100-seed weight came to 0.05 remarkability. TheGCA of plant height, oil and protein came to 0.10.In male parent, the GCA of the plant height,the No. of nodes per stem and the protein came to 0.01 remarkability. The GCA of 100-seedweight came to 0.05.The GCA No. of branches per plant came to 0.10.In special combiningability (SCA), only the SCA of the oil came to 0.01.The SCA of other traits wereunremarkable.In order to understand the molecular mechanism of soybean heterosis, the differentialgenes expression level between 20 hybrids and their parents in a soybean diallel cross wasanalyzed by using differential display technique. The results showed that the expression patternof genes differentially expressed between hybrids and their parents could be divided into sixcategories:(1)bands present in female parent and F₁ but absent in the male parent(110),(2) bandspresent in male parent and F₁ but absent in the female parent(011),(3)bands observed in bothparents but not in the F₁(101),(4)bands only occurring in female parent but not in the F₁ andmale parent(100),(5) bands only occurring in male parent but not in the F₁ and femaleparent(001)and(6)bands detected only in the F₁ but neither of the parents(010).Relationshipbetween six differential gene expression patterns and heterosis of eleven traits was evaluated byusing data form DDRT-PCR and field experiment. The results showed that there were positivecorrelation between heterosis and the 101,100 and 100 pattern respectively for 100-seed weight, oil and No. of nodes per stem. But the negative correlation between heterosis and the 011pattern for 100-seed weight. The correlation coefficient respectively was 0.52^*, 0.47^*, 0.51^*and -0.54^*. In the seedling stage of soybean, the correlation analysis was carried between thesix differential gene expression patterns and the MPH of eleven traits. It showed that 4 of 66Correlation coefficient achieved remarkable or extremely remarkable level. Among them,between the MPH of No. of branches per plant, No. of pods per plant, No. of seeds per plantand the 110 pattern appears remarkable negative correlation (correlation modulus respectivelyis-0.44^*, -0.52^*, -0.54^*).Between yield per plant and the 110 pattern appears extremelyremarkable negative correlation (correlation coefficient -0.56^**). The correlation analysis wascarried between the six differential gene expression patterns and the BPH of eleven traits. Itshowed that 4 of 66 correlation coefficient achieved remarkable or the extremely remarkablelevel. Among them, the BPH of No. of pods per plant and the 110 pattern appears on negativecorrelation (correlation coefficient is -0.51^*).The BPH of No. of seeds per plant, yield per plantand the 110 pattern appears on extremely negative correlation (correlation coefficient is-0.57^**,-0.61^**).The BPH of insect infected grain and the parents altogether silence pattern(101) assume extremely negative correlation (correlation coefficient is -0.59^**). Above theresults to explain the differential gene expression and the heterosis formation had definitecorrelation.Twenty-two differential expressed cDNAs were cloned .By comparing with thehomologous genes in GenBank, it showed that two differential expressed genes were CaMbinding protein which might be involved in the pathways of signal transduction. Two fragmentswere the 18S ribosome body genes, a fragment was the 26S ribosome body gene, possiblyparticipated in the protein synthesis. A fragment was soybean satellite DNA. A fragment wasthe soybean acid phosphatase, possibly playing the vital role in the soybean carbohydratetransformation and in the protein synthesis, it also had the close relationship with the soilorganic phosphorus decomposition and the adult plant in vivo phosphorus recycles. There weretwo soybean chlorophyll a/b union proteinâ…¡(Cab-6) genes, one was the soybean chloroplast PI437654 genes, which possibly played the vital role in photosynthesis and the other was thesoybean PPR protein, which possibly through the body with the cell organ union, playing thevery important role in the plastochondria or the chloroplast. Functions of other cDNAfragments were not known.