Study On The Biomass Interaction Of Tetraploid Of BBCC Genome By Rubisco Gene

Cytonuclear Interaction, namely the interaction between cytoplasmic genome(usually refers to the chloroplast and mitochondrial genomes) and nuclear genome, had been considered as an effective mean for eukaryotes that could produce diverse phenotypes, and improve the competitiveness of the survival and reproduction.Rubisco located in chloroplasts stroma is the most abundant protein on Earth with the functions of stabilizing CO2, involving in light respiratory metabolic pathways and nitrogen cycling and participation. Rubisco consists of 8 large and 8 small subunits. The large subunit(LSU) was coded by the chloroplast rbcL gene, and the small subunit(SSU) was coded by the nucleus rbcS multigene family. Here, using the Rubisco as an example, we studied the characteristics of the cytonuclear interaction and evolutionary patterns of 3 BBCC genome species in the Oryza genus(O. malampuzhaensisryza, O. minuta, and O. punctata), the main results were as the follows.First, using rbcL and rbcS sequences comparison, we found that only one copy of the rbcL gene was conserved in the 3 tetraploids, and this copy type was as same as the maternal rbcL genes. By contrast, rbcS genes, which coded by 5 gene members, were all duplicated in the 3 tetraploids, i.e. 10 sequences copies of their parental B and C genomes were both retained, and any copy was not lost.Second, by comparing the three-dimensional protein structures, we found that the proteins that translated by divergent homoeologs of the same rbcS gene had obviously different interaction surfaces. The possible reason for the difference is that there was several amino acids substitution between biparental homoeologs. Using the yeast two-hybrid method. We also found that the interaction strength between each rbcS and rbcL protein was different obviously. In addition, except the rbcS2 protein, the paternal copy of other rbcS proteins showed significantly stronger interaction strength with rbcL protein.Third, by the method of quantitative PCR, we found the different rbcS genes and their duplicates with B or C genome had different expression levels in different tissues, organs and development stages in the 3 tetraploids.Fourth, after dark and recovery treatment, we checked the expression levels of rbcL and 5 rbcS genes of O. punctata- BB diploid through qRT-PCR method, and found these genes are sensitive to the duration of light.Fifth, by analyzing the sequences of rbcS1 in B/C genome diploids and tetraploids, we found that some nucleotides were deleted in the transit peptide fragments of the rbcS. However, when cutting out the transit peptides, the proteins translated by the rbcL and rbcS1 genes were easy to interact with each other by yeast two-hybrid method. Additional three-dimensional protein structure analysis displayed that rbcS1 and rbcS2-5 had similar three-dimensional structure, but different protein surface.