花生维生素C合成相关基因AhPMM及其抗逆作用的验证

Verification of the peanut vitamin C synthesis-related gene AhPMM and its role in stress resistance

摘要:

维生素C在植物抗氧化作用、光合作用、生长发育和代谢过程中发挥重要作用。本研究从花生中克隆了维生素C合成相关基因AhPMM，该基因对低温、氯化钠(NaCl)、聚乙二醇(polyethylene glycol, PEG)和脱落酸(abscisic acid, ABA)等处理均有明显的响应。构建了AhPMM过表达载体，并利用花粉管注射法转入花生品种莒南小红种，对T₃代拟转基因花生植株进行PCR检验，结果显示转基因阳性率为42.3%。利用HPLC测定转基因植株叶片还原性维生素C (reducing vitamin C, AsA)和总维生素C含量，结果表明部分株系还原性维生素C含量显著增加，最高可比对照增加1.90倍；总维生素C含量最高可比对照增加1.63倍。对转基因种子进行了氯化钠和脱落酸耐性试验，结果表明与未转基因对照相比，转基因种子对氯化钠耐性明显增强，对脱落酸敏感性减弱；转基因植株比未转基因对照的耐盐性明显增强。上述结果表明AhPMM基因既可提高花生维生素C含量，又可增加转基因花生种子和植株的耐盐性。本研究可为花生耐盐分子育种提供基因源。

Abstract:

Vitamin C plays an important role in plant antioxidation, photosynthesis, growth and development, and metabolism. In this study, a gene AhPMM, which is involved in vitamin C synthesis and responds significantly to low temperature, NaCl, polyethylene glycol (PEG) and abscisic acid (ABA) treatments, was cloned from peanut. An AhPMM overexpression vector was constructed, and transferred to a peanut variety Junanxiaohong using the pollen tube injection method. PCR test on the T₃ generation transgenic peanut plants showed a transgenics positive rate of 42.3%. HPLC was used to determine the content of reducing vitamin C (AsA) and total vitamin C in the leaves of transgenic plants. The results showed that the content of AsA in some lines increased significantly, up to 1.90 times higher than that of the control, and the total vitamin content increased by up to 1.63 times compared to that of the control. NaCl and ABA tolerance tests were carried out on transgenic seeds. The results showed that the salt tolerance of transgenic seeds was significantly enhanced and the sensitivity to ABA was weakened compared to that of the non-transgenic control. Moreover, the salt tolerance of the transgenic plants was also significantly enhanced compared to that of the non-transgenic control. The above results showed that AhPMM gene not only increased the vitamin C content of peanut, but also increased the salt tolerance of transgenic peanut seeds and plants. This study may provide a genetic source for the molecular breeding of peanut for enhanced salt tolerance.