Genetic Transformation Of PmPT3 Gene In Plants And Its Involvement In Low Phosphorus Tolerance

Phosphorus is one of the essential nutrient elements for plant growth and development,but soil organic phosphorus cannot be directly absorbed and utilized by plants.Masson pine(Pinus massoniana)is the most widely distributed coniferous species of Pinus genus in my country.In areas with severe phosphorus deficiency,some Masson pine germplasms show good adaptability and viability.Previous studies have found that the phosphorus transporter gene of Masson pine plays an important regulatory role under low phosphorus stress.In this paper,a plant overexpression vector of the PmPT3 gene was constructed and transformed into Arabidopsis thaliana and Populus tomentosa,respectively.The transgenic plants were subjected to low-phosphorus stress resistance studies,aiming to further reveal the function of the PmPT3 gene and to The creation of new germplasm tolerant to low phosphorus provides reference.The main results are as follows:1.Obtainment of PmPT3 gene transgenic plantsThe PmPT3 gene overexpression vector p BWA(V)HS-PmPT3 of Masson pine was constructed,and the inflorescence dip method was used to transform Arabidopsis thaliana and the leaf disc method was used to transform Populus tomentosa.A total of4 T3 generation transgenic Arabidopsis homozygous lines and 9 transgenic plants were obtained Populus tomentosa strains.2.The effect of low phosphorus stress on the growth of PmPT3 ArabidopsisUnder low phosphorus stress,the above-ground dry weight of transgenic Arabidopsis and Populus tomentosa increased by 45.46% and 37.76%,respectively,the root dry weight increased by 55.56% and 50.69%,and the total dry weight increased by 46.15% and 46.15% compared with the wild type.36.67%;root-to-shoot ratios are greater than plants under normal phosphorus supply conditions,indicating that low phosphorus stress has less inhibitory effect on the underground part of the plant than the above-ground part.3.Effects of transformed PmPT3 plants on phosphorus absorption under low phosphorus stressUnder low phosphorus stress conditions,compared with the wild type,the total phosphorus content in the shoots and roots of transgenic Arabidopsis was increased by 1.26 times and 1.74 times,respectively,and the inorganic phosphorus content was increased by 1.38 times and 1.89 times,respectively.The total phosphorus content of the roots,stems and leaves of the transgenic Populus tomentosa was increased by 1.87 times,1.31 times,and 1.72 times,respectively,and the inorganic phosphorus content was increased by 1.77 times,1.34 times,and 1.97 times,respectively.Therefore,overexpression of PmPT3 can increase the absorption and utilization of phosphorus by Arabidopsis and Populus tomentosa.4.Antioxidant ability of transformed PmPT3 plants under low phosphorus stressUnder normal phosphorus supply,the peroxidase(POD),superoxidase(SOD),catalase(CAT)activities and the content of malondialdehyde(MDA)in the same transgenic plants of wild-type Arabidopsis and Populus tomentosa The difference was not significant;under low phosphorus stress,the POD,SOD,and CAT activities of transgenic Arabidopsis and Populus tomentosa were significantly higher than those of wild-type plants,which were 2.17 times,1.59 times,1.81 times,2.85 times and 1.48 times that of wild-type plants,respectively.The MDA content is reduced by 47.58%and 35.65% respectively compared with wild-type plants.Therefore,overexpression of PmPT3 gene can enhance plant protective enzyme activity,reduce MDA content,and enhance the ability to withstand low phosphorus stress.5.Antioxidant ability of transformed PmPT3 plants under low phosphorus stressUnder normal phosphorus supply conditions,there was no significant difference in soluble protein(SP)and soluble sugar(SS)content in the tissues of wild-type and transgenic Arabidopsis and Populus tomentosa.Compared with the wild type,the SP and SS contents of transgenic Arabidopsis were increased by 65.50% and 54.54%,respectively,under low-phosphorus stress conditions,and by 1.37 times and 1.29 times in Populus tomentosa,respectively.Overexpression of PmPT3 has a positive effect on the accumulation of soluble protein and soluble sugar,thereby providing energy for plant growth and development.6.Specific expression of PmPT3 gene in transgenic plants under low phosphorus stressCompared with normal phosphorus supply conditions,Arabidopsis transgenic plants under low phosphorus stress have significantly up-regulated PmPT3 gene expression in their roots and aerial parts,and reach a very significant level in the roots.In the transgenic Populus tomentosa plants,the PmPT3 gene was up-regulated and expressed in roots,stems,and leaves,with the highest expression in the roots,followed by the stems,and relatively low expression in the leaves.Therefore,this gene mainly plays a major role in the root of the plant,and secondly in the stem.