Molecular Detection And Overexpression Characteristics Of Wheat Containing High Photosynthetic Efficiency Gene TaSCL14

The high photosynthetic efficiency breeding in crops is an important research direction for improving crop yields.Genetic engineering,especially the gene transformation,is an effective tool in breeding new photosynthetic efficiency varieties in modern agricultural breeding.The family of GRAS transcription factors（TFs）play a role in the growth and development of plants.The TaSCL14 gene,which encodes a GRAS TF,is a high photosynthetic efficiency gene in wheat.In this study,the T₁-T₃ transgenic lines were derived from the Xiaoyan 39,which have transformed TaSCL14 gene..TaSCL14 gene-specific marker was used to select the positive transgenic plants of TaSCL14 gene in generations of wheat.After that,the hereditary properties,agronomic phenotypes,photosynthetic characteristics and germination characteristics of seeds in stimulated drought conditions of TaSCL14 transgenic wheat were studied.The research results are as follows:1.PCR-specific detection method was used to screen positive transgenic plants of TaSCL14 gene in T1-T3 generations.The results showed that the positive rate of T1 and T2transgenic plants of was 55.9%and 85.6%,respectively.The positive rate of the four transgenic lines of the T₃ generation reached more than 90%.It reveals that the frequency of positive plants is increased.The T₃ generation are mostly homozygous and the TaSCL14 gene can be stably inherited in transgenic offspring that we screened out..2.Meanwhile,the Real-time PCR was performed to detect the expression of TaSCL14 in T₃ lines.The result showed that TaSCL14 have higher expression in transgenic lines than that in the control,even the expression levels of TaSCL14 were different among strains.3.In the same field condition,various agronomic traits of transgenic T₁-T₃ generations lines were detected.The results showed that the wheat plants transformed with TaSCL14 gene could grow normally and the morphological characteristics of transgenic plants have not changed much compared with the control.However,changes were appeared in tillers,spikelet number,grains number per spike and 1000-grain weight of transgenic offspring.The grain number per spike in the T₁ transgenic plants and the capacity of tillering before winter of the T₂ generation were significantly different from the control,and there was a significant difference between and the control.Moreover,the transformation of TaSCL14 gene has a negative effect on the 1000-grain weight of most plants.The grain weight of 75%of transgenic plants in the T₁ and T₂ generation was lower than the control.The coefficient of variation of T₂ generation transgenic plants was less than that of T₁ generation,and the agronomic traits were better than T₁ generation.There was no difference in plant height,ear length and grain number per spike between the 4 transgenic lines of T₃ generation and the control.Tillers before winter,winter tillers and effective tillers were significantly or extremely significantly higher than those of the control.All transgenic lines had a lower 1000-grain weight than controls,which suggest that the transferred TaSCL14 has a great impact on tillering and 1000-grain weight.4.The photosynthetic characteristics and relative chlorophyll content of four transgenic lines of T₃ generation were detected.From the jointing stage to the mature stage,the change trends of stomatal conductance,intercellular carbon dioxide concentration,transpiration rate,and net photosynthetic rate between transgenic and control plants were the same.They all showed the trend of increasing first and then decreasing,then reaching their maximum values at the flowering stage.Moreover,the result showed that the photosynthetic rate of all transgenic lines was higher than that of the control,and the photosynthetic rate was different between some strains and the control at the flowering,filling and maturing stages.The transfer of TaSCL14 gene has positive effect on the photosynthetic rate of transgenic plants,which have increased photosynthetic rate.The results of the stomatal conductance measurement showed that there were significant differences between the strains in the jointing period except the line 3-4 and the control.In the flowering stage,the stomatal conductance of line 3-8 were significantly higher than that in the control.While there was no difference between the transgenic lines and the control in other growth period.The results of intercellular carbon dioxide measurements showed that there was no significant difference between the transgenic lines and the controls at each stage.However,the intercellular carbon dioxide concentrations of lines 3-8 were significantly higher than the control at the jointing stage and the flowering stage.The results of transpiration rate indicated that many strains were significantly or extremely significantly higher than the control in different periods.Strain 3-11 were significantly different from the controls in the remaining four periods except for the mature period.There was no difference in the change trend of the chlorophyll content between the transgenic lines and the control.The chlorophyll content was increased in the flowering period and reach the peak at the booting stage,then decreasing gradually.5.The germination experiment was performed on the harvested seeds of T₃ lines to detect the germination potential,germination rate,and morphological traits of the seedlings.Under normal germination condition,the germination potential and germination rate of all transgenic lines were higher than plants of the control group.Among them,the germination rate and germination rate of line 3-4 and 3-8 were significantly higher than the control.Under simulated drought stress condition with 20%PEG-6000 watering,the germination potential and germination rate of all transgenic lines were significantly higher than those of the control.The germination potential and germination rate of all lines were decreased when treated with20%PEG-6000.While,the decrease of germination potential and rate in the transgenic lines was smaller than that of the control,indicating that the transgenic lines had stronger drought tolerance than the control.The seedling morphology detection reveled that the full-length of root and height of seedlings in transgenic lines were significantly higher than the control,which further confirming the effect of the TaSCL14 gene on plant growth and development.