The Genetic Transformation Of The High-affinity Potassium Transporter Gene ZmHAK1in Maize And Resistance To The Stress From A Low Amount Of Potasssium

The maize as the most important food crops, plays an important role in both ourcountry and the whole world. K+is an essential macronutrient required by plants tocomplete their life cycle. It fulfills irreplaceable functions and potash is widely usedas a fertilizer to increase crop production. However, potassium is severely deficient incultivated soil while potash resources are scarce. So, potassium fertilizer is heavilydependent on imports. Therefore potassium deficiency has become a limiting factor toincrease the quality and yield of maize. In order to effectively resolve this conflict,some scholars suggested we should take advantage of the genetic diversity of plants innature, to exploit the superior genotypes of maize and modify maize to create efficientpotassium-uptake breed by genetic engineering technology to improve the efficiencyof maize to absorb and utilize potassium.In our study, pCambia1301-ZmHAK1plasmid with the high-affinity potassiumtransporter gene ZmHAK1was transformed into Agrobacterium EHA105, and theZmHAK1was successfully transferred into the potassium-sensitive inbred lines ofmaize by the pollen tube method. The transgenic plants were screened by0.1%Bastasolution on the three-leaf stage. After selecting, the PCR results of BAR gene andtarget gene showed positive plants have been gotten.The same trace screening was done on T2,and further RT-PCR and qRT-PCRvalidation showed the target gene had been transcribed in maize. The ZmHAK1geneexpression analysis showed the more amount of expressions of the target gene were inroots and stem. Moreover, the expression was induced by the stress of a low-amountpotassium. Transgenic maize were tested under different time during a low-amountpotassium stress. The results showed the expression of ZmHAK1in root reached thepeak at72h. The transgenic maize and inbred controls were treated under the stress of alow-amount potassium in hydroponic experiments. The results suggested the multiplepotassium nutrition indicators including AKA、 KUI and root morphology oftransgenic maize were higher than that of inbred control. The transgenic maizeperformed a certain resistance to low-amount potassium. A series of physiologicalindicators such as SOD activity, MDA content and proline content were determined inorder to study the degree of resistance and the extent of injury in plant. The resultsshowed that the degree of injury in the cells of the transgenic maize was lower thanthat in inbred control under the stress of a low-amount of potassium. It was the furtherexplanation of the evidence that the resistance of the transgenic maize under the stressfrom a low-amount of potassium were significantly improved than that of maizeinbred.