转ZmPEPC与ZmPPDK基因拟南芥对干旱胁迫的反应

Response of Maize C_4-type PEPC and PPDK Transgenic Arabidopsis Plants to Drought-Stress

为探究干旱胁迫对转玉米高光效基因ZmPEPC与ZmPPDK拟南芥的影响,本研究选用2个转PEPC基因株系(PC90,PC73),2个转PPDK基因株系(PK17,PK26),1个转PEPC+PPDK基因株系(PCK110)和对照株系(GLC)为试验材料。在幼苗期分别用150mmol/L和250mmol/L甘露醇(Mannitol)模拟干旱胁迫处理,测定幼苗根长,结果显示,在胁迫处理下,转PEPC、PPDK和PEPC+PPDK基因拟南芥幼苗的平均相对根长分别较对照增加了43.8%,48.4%和50.6%。在成株期进行干旱胁迫处理,测定莲座叶片的叶绿素荧光参数,叶绿素、可溶性糖、可溶性蛋白、丙二醛含量和成株死亡率,结果显示,在胁迫处理下,供试材料F0增加,Fv/Fm减小,对照F0增幅最大,为20.4%,Fv/Fm最小,为0.78;转PEPC、PPDK和PEPC+PPDK基因拟南芥株系平均相对叶绿素含量分别较对照增加12.6%,15.4%和23.1%;可溶性糖含量分别较对照增加3.0%,16.3%和24.4%;可溶性蛋白含量分别较对照增加0.6%,10.8%和15.4%;丙二醛含量较对照降低,分别为对照的93.5%,90.3%和84.10%;死亡率分别为12.3%,13.3%和6.7%,极显著低于对照(87.7%)(P<0.01)。上述结果表明,玉米高光效基因ZmPEPC和ZmPPDK可增强拟南芥抵抗干旱胁迫的能力,且这两个基因的共表达可能存在协同作用。

Transformation and high efficiency expression of key enzymes gene of C 4 photosynthetic characteristics into C 3 plants are supposed to enhance the photosynthetic efficiency and seed yield for C 3 crop. Phosphoen-olpyruvate carboxylase （PEPC） and Pyruvate orthophosphate dikinase （PPDK） are known to play the key roles in C 4 pathway, and it has been confirmed that the photosynthesis and enzymes activities of the PEPC or PPDK were elevated by introducing PEPC or PPDK gene into C 3 plants. In order to determine the drought-Stress tolerance of the trangenic Arabidopsis containing ZmPEPC and ZmPPDK, five T 6 generation purified lines of transgenic plants （2 lines contain the PEPC, 2 lines contain the PPDK and 1 line contains PEPC＋PPDK） and wild Arabidopsis were selected to study their drought-Stress tolerance. When grown in the 1/2MS medium contained 150 mmol/L, 250 mmol/L mannitol, as simulation of drought-stress conditions, The average relative root lengths in transgenic lines PEPC, PPDK, PEPC＋PPDK were 43.8%, 48.4% and 50.6% longer than those in wild type plants, respectively. When 15 days after drought-stress treatment, F0 was increased and Fv/Fm was decreased, the increased range of wild type plants was biggest which was 20.4% , Fv/Fm of wild type plants was minimum which was 0.78. The average contents of chlorophyll in transgenic lines PEPC, PPDK, PEPC＋PPDK were 112.6%, 115.4%, 123.1% times of that in wild type plants, respectively; the average values of soluble sugar and soluble protein contents were 3.0%, 16.3% , 24.4% and 0.6% , 10.8% , 15.4% higher than wild plants, respectively; the malondialdehyde content of transgenic lines was lower than that of wild plants, the average values were 93.5%, 90.3% and 84.1% of that in wild type plants, respectively. When 25 days after drought-stress treatment and re-water, 5 days later, the death rates of transgenic lines PEPC, PPDK, and PEPC＋PPDK were 12.3%, 13.3%, and 6.7%, respectively, which were extremely significantly lower than that of wild type plants （87.7%）. Therefore, it is supposed that PEPC and PPDK might enhance the ability of resist to drought-stress in Arabidopsis thaliana, and co-expression of PEPC and PPDK had synergistic effect on stress tolerance.