Reduction of As Accumulation by Heterologous Expression of Halomonas Peripheral Phosphate-binding Protein Gene PBP in Transgenic Tobaccos
In order to explore the biological function of PBP gene in transgenic tobaccos and select the low arsenic(As)accumulation parent tobacco germplasm,taking T2 generation seeds of transgenic tobacco with PBP gene and wild-type tobacco(Nicotiana tabacum K326)seeds as materials,Real-time PCR was used to study the spatial and temporal expression profile of exogenous PBP in transgenic tobaccos,and the activities of antioxidant enzymes(AOEs)in transgenic tobacco lines under As stress were also determined.AOEs activity showed that SOD and POD activities reached the maximum value of 80.25 U/g and 152.02 U/g in CK plants at 5 d after As stress,which were significantly higher than those in transgenic plants.Also,H2O2 and MDA contents in CK plants were significantly higher than those in transgenic plants at the later stage of As stress(3-5 d).Additionally,at 7 d and 14 d after stress,the content of As in transgenic tobacco plants was significantly reduced.Based on the expression profiling of ion transporter genes,the results showed that As stress not only induced significant up-regulation of PBP in transgenic plants,but also caused significant up-regulation of channel protein genes such as HAK1 and PHT4 in transgenic and CK plants,and the average expression levels of HAK1 and PHT4 in CK were 1.5 and 3.75 times of that in transgenic plants.The introduction of exogenous PBP gene can effectively reduce the accumulation of As in transgenic tobaccos.
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