Recovery Of Transgenic Maize Plants With Salt-tolerance Gene By Pollen-mediated Method And Salt-tolerance Evaluation Of Transgenic Maize Progenies

Maize plays an important role in the national economy. With the improvement of people’s living standard, the demand for maize has increased. Salinization of land area in our country has the trend of increasing. In order to breed for maize varieties with enhanced salt tolerance and make full use of saline-alkali land, we carried out a study on three aspects as follows:(1) BADH gene was introduced into a maize inbred Zheng 58 by pollen-mediated method. Two hundred and forty-six To generation seeds were obtained. After the Km-resistant screening and PCR detection of the T1 generation plants,37 positive maize plants were identified. The transformation rate was 15.04% by taking the To generation seeds as the denominator. The PCR positive rate of the T2 generation plants ranged 55%-63%. Southern blot analysis of positive T2 generation plants showed BADH gene got integrated into the maize genome and could be inherited to the next generation. Our results also proved that pollen-mediated transformation is an economic, effective and practical plant transformation method.(2) Effects of various concentrations of NaCl solution on growth of T2 transgenic and non-transgenic maize plants were investigated. The results indicated that transgenic maize seedlings had an improved resistance to salt, and their growth situation was better than non-transgenic maize seedlings. According to the responses to NaCl and growth status of non-transgenic plants,250 mmol/L of NaCl solution was used to screen transgenic plants. An evaluation on morphological indexes and physiology indexes under the stress of 250 mmol/L NaCl showed that compared with non-transgenic plants, the seedling height of transgenic plants was increased by 10.94%-25.7%, fresh weight was increased by 8.62%-18.2%, dry weight was increased by 9%-18.18%, relative conductivity was decreased by 37.21%-58.14%, chlorophyll content was increased by 15.89%±90.65%, superoxide dismutase activity was increased by 64.92%±148.29%, Malondialdehyde content was decreased by 26.97%-48.05%. In conclusion, introducing Betaine aldehyde dehydrogenase (BADH) gene enhanced salt tolerance of the maize plants.(3) The growth performance, morphological traits and physiology indices between transgenic and non-transgenic maize seedlings (cv. Chang 7-2) under various concentrations of NaCl stress were investigated by Hoagland solution culture. The results showed that transgenic maize seedlings exhibited improved tolerance to salt, and their growth performance was superior compared to non-transgenic seedlings. With the increase of salt concentration, the seedling height, root length, fresh weight, dry weight and chlorophyll content of both transgenic maize seedlings and non-transgenic controls decreased, and MDA content increased. But the changing ranges of transgenic maize seedlings were narrower. Under almost all stress concentrations, the seedling height, root length, fresh weight, dry weight and chlorophyll content of transgenic maize seedlings were significantly higher than those of non transgenic ones, and MDA contents were lower. Therefore, transgenic maize seedlings were apparently tolerant to salt stress than non-transgenic ones.