New Functional Studies Of Two Cytosolic Fructose Bisphosphate Aldolase Genes In Arabidopsis

Frutose-1,6-bisphosphate aldolase (FBA) is a key metabolic enzyme in living organisms.It is involved not only in the glycolytic/gluconeogenic pathway, but also in the pentosephosphate cycle and the Calvin cycle. In addition, FBAs in animal and bacteria also take partin the assembling of cytoskeleton and microtubule, the endocytosis of cells, the trafficking ofvesicles and the infection process of pathogenic bacteria. However, the researches on FBAs inplants remains limited compared to animal and pathogenic bacteria. Currently, the studies ofFBAs in plants mainly focus on its influence on growth and biomass accumulation, inaddition, they were reported to be involved in the stress-responsiveness.In Arabidopsis, there were eight members in FBA family. But their functions andmechanisms are unclear. So, in this study, we further studied the functions of two highlyhomologic members--AtFBA6and AtFBA8. The results are as follows:(1) We amplified the full length of the AtFBA6gene by PCR and introduced it into theplasmid of pBI121to construct35S::AtFBA6and35S::AtFBA6-GFP vectors. Transformedinto Arabidopsis plants by flower dipping method, the expression level of AtFBA6wasdetected by qRT-PCR. The results indicated that the transgenic plants could be used forfurther analysis.(2) The subcellular location by the laser scanning confocal microscope was carried outand the observation results suggested that AtFBA6was located in the cytosol.(3) We also bought the T-DNA insertional mutant of AtFBA6. The phenotype of fba6showed no changes compare with the wile-type plants, but the AtFBA6overexpression plantsshowed faster growth than the wile-type, with higher fresh weight than that of the wild-typeplants.(4) The optics observation indicated that the AtFBA6-overexpressors showed the samecell number, but larger size compared to the wild-type plants. The biochemical analysis indicated that the transgenic plants contained higher amount of the total sugar and ATP thanthe wild-type. These data suggested that the AtFBA6overexpression transgenic plants possessmore efficient metabolism and better energy supply.(5) Phenotype analysis of the two different mutants of AtFBA8showed that both mutantshave lower siliques maturing rate compared to the wild-type.(6) The observations of the floral physical appearance displayed that the mutant did notshow any diversities in petal, stamen, pistil, length of the filament and development of style.The results of the reciprocal crosses indicated that the male gamete of two fba8wereimpaired.(7) Alexander staining and DAPI (4,6-diamidino-2-phenylindole) staining proved thatthe development, maturity and vitality of the pollen grain were normal.(8) The germination rate of pollen grains in vitro showed that the disruption of theAtFBA8gene led to the unusual pollen germination.