Effect Of SOC1-like Gene In Petunia On Chloroplast Biogenesis And Heat Resistance

As one of the three major flowering time integration factors,there have been many studies on SOC1.It is regulated by four pathways to jointly regulate flowering time and flowering patterns.In the previous research,the transgenic tobacco ectopic overexpressed petunia SOC1-like genes FBP21 and FBP22 demonstrated an early flowering phenotype.Under the high temperature conditions,the flower color of transgenic tobacco plant harboring FBP21 and FBP21*22 both showed obvious green tune.Through the content determination of substances,ultrastructural observation and RNA-seq analysis in petals,it indicated that petunia SOC1-like gene FBP21 and FBP22 not only can regulate flowering time,but also can regulate chloroplast development and chlorophyll synthesis to change flower color.Based on the previous results,this study further verification of the effect of target genes on chloroplast biogenesis,at the same time,we studied the target gene in photosynthesis and heat tolerance.The major points are follows:One: study on the influence of SOC1 gene on chloroplast biogenesis.1.The accumulation of photosynthetic proteins was detected by western blotting.There was no significant difference in leaves;under high temperature conditions,it was found that the photosynthetic proteins PsaD and Lhca1 had a higher accumulation of petals in the FBP21 and FBP21*22 transgenic tobacco,and the accumulation of proteins of petals was richer in FBP21*22.It indicated that the high temperature enhanced accumulation of photosynthetic proteins of petals,the expression of genes related to photosynthetic increased,which promoted the photosynthetic efficiency.At the same time,ultrastructural observation of transgenic tobacco leaves.There was a significant difference in the number of chloroplasts in FBP21*22 transgenic tobacco leaves compared to wild-type tobacco under normal temperature conditions;Morphologically,the chloroplast color of leaves of FBP21*22 transgenic tobacco was darker and the grana stacking was clearer under normal temperature conditions.Moreover,the volume of starch granules in the chloroplast stroma of leaves of wild-type tobacco is larger than that of FBP21*22 transgenic tobacco.And through RNA-seq analysis of leaves of wild-type tobacco and FBP21*22 transgenic tobacco under normal temperature and high temperature conditions,it was found that the expression levels of genes related to protein synthesis and photosynthesis of FBP21*22 transgenic tobacco were significantly higher than those of the control under normal temperature condition.2.The morphology and number of chloroplasts of leaves and petals of control GFP tobacco and FBP21 transgenic tobacco were observed by chloroplast GFP fluorescence.There was no obvious difference in the leaves under normal temperature,but strong chloroplast fluorescence signals were generated in the green petals of FBP21 transgenic tobacco after high temperature treatment.And a large number of globular structures were produced in it and they were presumed to be undeveloped chloroplast.Concurrently,the fluorescence signal of leave of control GFP tobacco under normal and high temperature conditions was observed by plant fluorescent in vivo imaging system.It was found that the fluorescence signal intensity of FBP21 transgenic tobacco leaves treated with high temperature was the strongest.3.The FBP21 gene was homologous transformation of petunia,and positive plants were obtained for heat stress.It was found that the phenotype of petals of FBP21 transgenic petunia was not as obvious as tobacco,and only one of the FBP21 transgenic petunia's petals was partially green.Two: study on heat tolerance of SOC1 genes in different periods.Under heat stress,compared with wild-type tobacco,the content of soluble protein and soluble sugar,the maximum photochemical efficiency of photosystem ? were higher of transgenic tobacco.Therefore,overexpression of FBP21 can enhance the high temperature resistance of transgenic tobacco at different stages.In summary,overexpression of FBP21 gene resulted in significant changes in the chloroplast development and photosynthesis in leaves and petals of tobacco,and also enhanced heat tolerance of transgenic tobacco.Meanwhile,there is an need for further study of FBP21 transgenic petunia.