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Enhancing drought tolerance of crops has been a great challenge in crop improvement. Here, we report the maize phosphoenolpyruvate carboxylase ( PEPC) gene was able to confer drought tolerance and increase grain yield in transgenic wheat ( Triticum aestivum L.) plants. The improved of drought tolerance was associated with higher levels of proline, soluble sugar, soluble protein, and higher water use efficiency. The transgenic wheat plants had also a more extensive root system as well as increased photosynthetic capacity during stress treatments. The increased grain yield of the transgenic wheat was contributed by improved biomass, larger spike and grain numbers, and heavier 1000-grain weight under drought-stress conditions. Under non-stressed conditions, there were no significant increases in these of the measured traits except for photosynthetic rate when compared with parental wheat. Proteomic research showed that the expression levels of some proteins, including chlorophyll A-B binding protein and pyruvate, phosphate dikinase, which are related to photosynthesis, PAP fibrillin, which is involved in cytoskeleton synthesis, S-adenosylmethionine synthetase, which catalyzes methionine synthesis, were induced in the transgenic wheat under drought stress. Additionally, the expression of glutamine synthetase, which is involved in ammonia assimilation, was induced by drought stress in the wheat. Our study shows that PEPC can improve both stress tolerance and grain yield in wheat, demonstrating the efficacy of PEPC in crop improvement. [ABSTRACT FROM AUTHOR]

Using particle bombardment transformation, we introduced maize pepc cDNA encoding phosphoenolpyruvate carboxylase (PEPC) and ppdk cDNA encoding pyruvate orthophosphate dikinase (PPDK) into the C crop wheat to generate transgenic wheat lines carrying cDNA of pepc (PC lines), ppdk (PK lines) or both (PKC lines). The integration, transcription, and expression of the foreign genes were confirmed by Southern blot, Real-time quantitative reverse transcription PCR (Q-RT-PCR), and Western blot analysis. Q-RT-PCR results indicated that the average relative expression levels of pepc and ppdk in the PKC lines reached 10 and 4.6, respectively, compared to their expressions in untransformed plants (set to 1). The enzyme activities of PEPC and PPDK in the PKC lines were 4.3- and 2.1-fold higher, respectively, than in the untransformed control. The maximum daily net photosynthetic rates of the PKC, PC, and PK lines were enhanced by 26.4, 13.3, and 4.5 %, respectively, whereas the diurnal accumulations of photosynthesis were 21.3, 13.9, and 6.9 %, respectively, higher than in the control. The F/F of the transgenic plants decreased less than in the control under high temperature and high light conditions (2 weeks after anthesis), suggesting that the transgenic wheat transports more absorbed light energy into a photochemical reaction. The exogenous maize C-specific pepc gene was more effective than ppdk at improving the photosynthetic performance and yield characteristics of transgenic wheat, while the two genes showed a synergistic effect when they were transformed into the same genetic background, because the PKC lines exhibited improved photosynthetic and physiological traits. [ABSTRACT FROM AUTHOR]

With 7 figures and 2 tables Abstract Attempts have been made to transform C3 crops with C4 genes to improve the photosynthetic rate of C3 plants. In our study, a full-length cDNA for phosphoenolpyruvate carboxylase gene ( pepc) was isolated from Zea mays by PCR. The pepc gene was introduced into wheat plants ( Triticum aestivum) by particle bombardment transformation. The integration, transcription and expression of the pepc gene were confirmed by Southern blot, RT-PCR and Western blot analysis. Physiological studies showed that phosphoenolpyruvate carboxylase activity in the transgenic plants was 140% higher than that of the untransformed plants. The highest rate of photosynthesis in the transgenic plants was 31.95 μmol CO2/m2/s, which was 26% greater than the rate in untransformed plants. The light saturation point and carboxylation efficiency of pepc transgenic wheat were 20% and 22.57% higher, respectively, than those of untransformed wheat. As a result, the weight of seed per spike and thousand-grain weight were 0.23 g and 1.21 g higher than those of untransformed wheat. Our research will facilitate the further study of the function of the pepc gene in wheat plants. [ABSTRACT FROM AUTHOR]