烟草NtNAC1基因的克隆及其在烟草中的抗旱功能分析

Cloning of NtNAC1 gene from Nicotiana tabacum and its analysis of drought-resistant function

NAC转录因子在植物信号转导及非生物损伤过程中起重要作用。本实验从烟草c DNA文库中克隆了NtNAC1基因,c DNA编码区全长861 bp,编码286个氨基酸。进化树分析结果显示,Nt NAC1基因编码的氨基酸序列与马铃薯同源性最高。农杆菌介导的遗传转化获得37株转基因烟草,用20%PEG6000处理转基因和野生型植株7 d。结果显示,转基因植株的超氧化物歧化酶(SOD)、过氧化物酶(POD)的酶活性都高于野生型,丙二醛(MDA)和脯氨酸(Pro)含量都低于野生型。RT-PCR分析结果显示,Nt NAC1基因以及Nt NAC基因表达高于野生型,脯氨酸合成的2个关键酶吡咯啉-5-羧酸合成酶(P5CS)和鸟氨酸-δ-氨基转移酶(δ-OAT)基因表达低于野生型。选取T_0代转基因和野生型种子,对苗期根系进行耐旱性分析。结果发现,在300 mmol·L^(-1)甘露醇胁迫下,转基因根系比野生型长,野生型根系的生长明显受到抑制。这表明转Nt NAC1基因的表达可能提高了植株的抗旱能力。

NAC transcription factor plays an important role in plant signal transduction and abiotic damage.In this study,the Nt NAC1 gene was cloned from the c DNA library of tobacco,and the coding region was 861 bp in length,encoding 286 amino acids.The phylogenetic tree analysis showed that the amino acid sequence encoded by Nt NAC1 gene was the highest homologous to potato and 37 strains of transgenic tobacco obtained by Agrobacterium tumefaciens were treated with 20%PEG6000 for 7 days.The results showed that the activities of superoxide dismutase（SOD）and peroxidase（POD）in transgenic plants were higher than those in wild type.The contents of MDA and proline were lower than those of wild type.The results showed that the expression of Nt NAC1 and Nt NAC gene were higher than wild type by RT-PCR analysis,and the pyrroline-5-carboxylic acid synthase（P5CS）and ornithine-δ-aminotransferase（δ-OAT）were lower than wild type.The T0 transgenic and wild type seeds were selected to analyze the drought tolerance of seedling roots.The results showed that under the condition of 300 mmol·L（-1） mannitol,the transgenic plant roots were more inhibited than wild type roots.The results showed that the expression of Nt NAC1 gene could increase the drought tolerance of plant.