Photosynthetic Property Of The Transgenic Arabidopsis Expressing Maize C₄-type PEPC PPDK And NADP-ME Genes

We used the transgenic Arabidopsis thaliana genotypes PC?containing Zmpepc gene?,PK?containing Zmppdk gene?,ME?containing Zmnadp-me gene?,PCK?containing Zmpepc+ppdk gene?,PKM?containing Zmppdk+nadp-me gene?and WT?wild type?as marterials in this study.The transformed gene copy number,gene expression,photosynthetic enzyme activity,net photosynthetic rate and antioxidant enzyme activity of transgenic Arabidopsis thaliana was studied in three different light intensity?250?mol photon m-2s-1,800 ?mol photon m-2s-1,1400 ?mol photon m-2s-1?.The main results were as follows:1.The transgenic Arabidopsis thaliana lines were analyzed by PCR and Southern blot,which indicated that the expected DNA band were amplified and target gene were integrated in Arabidopsis thaliana genome in variation of the copies.Single transgenic lines PC65,PC73,PK73,PK26,PK36,ME4,ME5,ME9 have single copy of target gene,PC90 has two copies of pepc gene;double transgenic lines carried on two or more copies except PCK7 have single copy of pepc and ppdk gene.2.qRT-PCR results showed the exogenous genes were transcription in high level in transgenic Arabidopsis thaliana lines.Western blot results showed that the exogenous genes were translation the corresponding proteins in high level,the PEPC expression of PC?PCK transgenic Arabidopsis thaliana were 2.4?3.7 fold higher than WT;the PPDK expression of PK?PCK?PKM transgenic thaliana were 2.1?1.8?1.7 fold higher than WT;the NADP-ME expression level of ME?PKM transgenic thaliana were 2.8.3.3 fold higher than WT.3.1400 ?mol photon m-2s-1,PEPC,PPDK,NADP-ME,Rubisco activity of transgenic Arabidopsis thaliana increased by 59.2,50.3,106.5,22.8%compared to the WT,the PEPC enzyme activity in transgenic Arabidopsis PCK increased by 97.1%compared with WT,the increased magnitude is greater than that of other transgenic Arabidopsis,the PPDK enzyme activity in transgenic Arabidopsis PCK increased by 76.8%compared with WT,the increased magnitude is greater than that of other transgenic Arabidopsis,the NADP-ME enzyme activity in transgenic Arabidopsis ME increased by 196.9%compared with WT,the increased magnitude is greater than that of other transgenic Arabidopsis,the Rubisco enzyme activity in transgenic Arabidopsis PCK increased by 33.7%compared with WT,the increased magnitude is greater than that of other transgenic Arabidopsis.800 pmol photon m-2s-1,the change trend of photosynthetic enzyme activity and Rubisco enzyme activity of transgenic Arabidopsis thaliana compared with WT was similar to 1400 pmol photon m-2s-1.It indicated that transgenic Arabidopsis lines could keep a higher enzyme activity of C₄ cycle and Rubisco activity of C3 cycle under strong light stress.4.1400 ?mol photon m-2s-1 the net photosynthetic rate of the WT decreased by 52.1%compared with 250 ?pmol photon m-2s-1,the net photosynthetic rate of transgenic Arabidopsis thaliana PC,PK,ME,PCK,PKM were decreased by 42.2%?49.4%?40.4%?22.7%and 20.6%compared with 250 ?mol photon m-2s-1,the decreased magnitude was less than WT,the net photosynthetic rate of transgenic Arabidopsis thaliana PC,PK,ME,PCK,PKM were increased by 53.1%?33.6%?32.2%?131.3%,89.3%compared with WT of 1400 ?mol photon m-2s-1 800 ?mol photon m-2s-1,the change trend of net photosynthetic rate of transgenic Arabidopsis thaliana compared with WT was similar to 1400 ?mol photon m-s-1.It showed that transgenic Arabidopsis thaliana could keep significantly photosynthetic advantage under strong light stress and a strong ability of resistance to strong light stress.5.1400 ?pmol pbhoton m-2s-1,SOD,POD,CAT activity of transgenic Arabidopsis thaliana increased by 25.8,51.9,49.4%compared to the WT;the SOD enzyme activity in transgenic Arabidopsis ME increased by 52.1%compared with WT,the increased magnitude is greater than that of other transgenic Arabidopsis,the POD enzyme activity in transgenic Arabidopsis PKM increased by 73.8%compared with WT,the increased magnitude is greater than that of other transgenic Arabidopsis,the CAT enzyme activity in transgenic Arabidopsis ME increased by 83.8%compared with WT,the increased magnitude is greater than that of other transgenic Arabidopsis.800 ?mol photon m-2s-1,the change trend of antioxidant enzyme activity of transgenic Arabidopsis thaliana compared with WT was similar to 1400 ?mol photon m-2s-1.It indicated that transgenic Arabidopsis had higher antioxidant capacity and reactive oxygen scavenging capacity under strong light stress.