玉米自交系B73丙酮酸磷酸双激酶基因的克隆及低氮对PPDK表达的影响

Cloning of C_4 PPDK Gene from Maize Inbred Lline B73 and the Effect of Low N on PPDK Expression

以玉米B73自交系为实验材料,克隆了玉米B73叶片C4型丙酮酸磷酸双激酶(PPDK)基因即C4PPDK基因的c DNA全长并测序,研究了低氮胁迫对典型C4作物玉米PPDK蛋白表达的影响。结果表明,B73玉米C4PPDK基因有19个外显子,18个内含子。无论在高氮还是低氮条件下,玉米野生型与ppdk突变杂合子在表型上均无显著差异。野生型植株中PPDK表达量约为杂合子的2倍;与高氮处理相比,低氮处理下PPDK野生型和杂合子中PPDK蛋白表达量显著升高,表明PPDK蛋白可能参与了对低氮胁迫的响应。该实验为进一步研究PPDK与氮代谢的关系奠定了基础。

The number of exons and introns of maize C4 PPDK gene is uncertain in the existing references and the annotation was incorrect in the database of maize inbred line B73 whose genome has been sequenced. We successfully cloned the c DNA of C4 PPDK gene from the leaves of the maize inbred line B73. The sequencing results indicated there were 19 exons and 18 introns in the PPDK of the maize line B73,which were different from those in the previous publication. We further characterized the function of C4 PPDK and its response to the low nitrogen treatment. There is no dramatic phenotypic difference between the wild type and the heterozygous ppdk mutant under either high or low N condition. However,the homozygous mutant could not survive without PPDK gene. The western blotting indicated that PPDK was involved in the low N response since the low N induced the accumulation of PPDK protein. These results provided useful information for identification of the relationship between PPDK and N metabolism.