转TfdA基因提高玉米抗除草剂2,4-D的能力

Improvement of 2,4-D resistance by introduction of TfdA gene via genetic transformation in Zae mays

本研究以玉米(Zea mays)为材料,通过农杆菌(Agrobacterium tumefaciens)介导的茎尖转化法将对除草剂2,4-二氯苯氧乙酸(2,4-D)降解的Tfd A基因转入玉米,筛选出对除草剂2,4-D具有高抗性的转基因玉米植株。研究表明,喷施20 g·L^(-1)的2,4-D溶液7 d后,91%的野生型玉米植株出现根和茎肿胀畸形且横向生长、叶片枯黄脱落等现象,而转基因植株生长良好,未出现明显的受害症状。随2,4-D处理时间的推移,转基因和非转基因玉米植株的叶绿素含量均逐渐下降,但后者的降幅极显著高于前者。二氨基联苯胺(DAB)染色后发现,经2,4-D处理的野生型植株叶片H_2O_2积累显著高于转基因植株,且前者的丙二醛(MDA)含量也显著高于后者,分别为3.34和2.08μmol·g-1(蛋白)。在2,4-D处理3 d后,转基因植株的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)活性峰值分别为34.88、4.10和31.56 U·mg-1(蛋白),是其野生型的1.65、1.4和1.7倍(差异极显著)。综上结果表明,转Tfd A基因玉米显著提高了对除草剂2,4-D的抗性。

In this study, the herbicide 2,4-dichlorophenoxyacetic acid（2,4-D）-degradating gene Tfd A was introduced into Zea mays via the Agrobacterium tumefaciens-mediated stem-tip transformation and 2,4-D-resistance maize plants were identified. After spraying 20 g·L^-1 2,4-D solution for 2 days, we found that 91% of wild-type maize plants developed damage symptoms of root and stem swelling deformities, lateral growth, leaf yellowing, etc., while the transgenic plants grew well with little symptoms. Over time, the chlorophyll content in both transgenic and non-transgenic maize plants began to decrease gradually after 2,4-D treatment, but the decreasing amplitude of chlorophyll content in the latter was highly significantly higher than that in the former. After 2,4-D treatment, the results of the H_2O_2-staining by diaminobenzidine（DAB） and malonaldehyde（MDA） contents detection showed that there were highly significantly higher H_2O_2 accumulation and MDA content in the leaves of wild-type plants compared to those in transgenic maize plants. The MDA contents in non-transgenic and transgenic plants were 2.09 and 3.34 μmol·g^-1（protein）, respectively. At 3 days after 2,4-D treatment, the maximum of enzyme activities of superoxide dismutase（SOD）, catalase（CAT） and peroxidase（POD） in transgenic maize plants were 34.88, 4.10 and 31.56 U·mg^-1（protein）, respectively, which were 1.65, 1.4 and 1.7 folds higher than these in wild-type ones. In summary, the introduction of Tfd A gene improves 2,4-D resistance in transgenic maize plants significantly.