NtPHGPx基因过表达和敲除对烟草苗期耐盐性的影响

为研究NtPHGPx基因对烟草耐盐性的影响，通过转基因技术获得NtPHGPx基因过表达和CRISPR/Cas9敲除材料，利用150 mmol/L NaCl对转基因材料处理14 d，研究盐处理下转基因材料根长、GPx酶活性、丙二醛（MDA）和过氧化氢（H₂O₂）含量的变化。结果表明，NtPHGPx基因表达在盐胁迫3 h后即受到诱导；盐处理显著抑制了野生型烟草根部的生长，提高了丙二醛和过氧化氢的积累；盐胁迫下过表达株系的根长比野生型更长，MDA和H₂O₂含量较低，而基因敲除材料根的生长则进一步受到抑制，GPx酶活性明显降低，地上部MDA和H₂O₂的积累显著高于野生型。综上所述，过表达NtPHGPx基因提高了烟草的耐盐性，而敲除NtPHGPx基因则减弱了烟草的耐盐性，推测NtPHGPx基因可能通过影响烟草体内活性氧物质的清除活性参与植株对盐害的胁迫响应。

Overexpression and Knockout of NtPHGPx Altered Salt Tolerance of Tobacco Seedlings

In order to study the effects of NtPHGPx on salt tolerance of tobacco, NtPHGPx gene overexpression (OX) and CRISPR/Cas9 knockout (Cri) lines were obtained. Two OX and one Cri lines were subjected to 150 mmol/L NaCl treatments for 14 d, and root length, GPx activity, malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) contents were determined. The results showed that the expression of NtPHGPx was induced by NaCl 3 h after treatment. Salt treatments significantly inhibited root growth of wild type tobacco and increased the accumulation of MDA and H₂O₂. Under salt stress, root length of the OX lines was longer than that of wild type and the contents of MDA and H₂O₂ were lower. However, root growth of the Cri line was further inhibited, and the activity of GPx was significantly decreased. The accumulation of MDA and H₂O₂ in shoots was significantly higher than that of wild type. In conclusion, overexpression of NtPHGPx improved, however knockout of NtPHGPx attenuated salt tolerance of tobacco, which indicated that NtPHGPx may be involved in plant response to salt stress by affecting the scavenging activity of reactive oxygen species in tobacco.