The Changes Of Gene Expression And Three Enzymes' Activities In The Synthetic Hexaploid Allopolyploid Wheats

Hybridization and polyploidization are the most important processes of plant speciation and evolution. The hybridization can bring about a new combination of genomes, and polyploidization will increase the number of genomes, which can maintain the normal meiosis and improve the fertility of hybrid. Common wheat (Triticum aestivum L.) is an allohexaploid which has experienced allopolyploidization twice. The genome of hexaploid common wheat is AABBDD, which comprises three genomes A, B and D, and each genome has seven chromosomes. Although the process of formation of this plant species is clear, it is not well understood regarding the changes in the genomes, gene expression and the enzymes activities at the initional stages of polyploid wheat formation.In the present dissertation, we undertook a comparative study on the changes of gene expression between the synthetic hexaploid allopolyploid wheats and their parents. The experimental materials were three synthetic hexaploid wheats (symbols AT5, AT6 and AT9), three tetraploid wheats (symbols TTR04, TTR19 and TTH01) and one diploid goat grass (symbol TQ27). The result indicated that polyploidization can induce nonadditive gene expression which is not randomly distributed. We found the genes which are diffentially expressed in the parents are preferred to non-additive expression in the offsprings. We also analyzed the changes of gene expression in the synthetic hexaploid individual wheat (symbol AT6). The rate of differential expressed genes was 14.6%, and the level of the same gene expression are identical in most of individuals.We also investigated three important enzymes, activities in the early period of allopolyploidization in common wheat by using the synthetic hexaploid allopolyploid wheat (symbol, AT5) between tetraploid wheat, T. turgidum ssp.durum cv.Inbar, accession TTR04 and a diploid goat grass, Ae.tauschii, accession TQ27 as experimental materials. The results showed that the activity for a given enzyme in AT5 and its parents (TTR04 and TQ27) were different. The amylases, activity were measured when the wheats germinated for 96.5 hours. The ratio ofα-amylase, activities in AT5, TTR04 and TQ27 is 1.00:1.88:2.47, and the ratio ofβ-amylases, activities is 1.00:1.47:1.73. Obviously, both amylases, activities showed significant difference (p <0.05). Theβ-glucosidase, activities in the leaves of 17 days, wheats were also tested, which showed significant difference (p <0.05) between AT5 and its parents, but it had no significant difference (p <0.05) between TTR04 and TQ27. The ratio ofβ-glucosidases, activities in AT5, TTR04 and TQ27 was 1.00: 2.68: 2.58.