Preprotein import into chloroplasts depends on macromolecular machineries in the outer and inner chloroplast envelope membrane （TOC and TIC）. It was suggested that both machineries are interconnected by components o...Preprotein import into chloroplasts depends on macromolecular machineries in the outer and inner chloroplast envelope membrane （TOC and TIC）. It was suggested that both machineries are interconnected by components of the intermembrane space （IMS）. That is, amongst others, Tic22, of which two closely related isoforms exist in Arabidopsis thaliana, namely atTic22-III and atTic22-IV. We investigated the function of Tic22 in vivo by analyzing T-DNA insertion lines of the corresponding genes. While the T-DNA insertion in the individual genes caused only slight defects, a double mutant of both isoforms showed retarded growth, a pale phenotype under high-light conditions, a reduced import rate, and a reduction in the photosynthetic performance of the plants. The latter is supported by changes in the metabolite content of mutant plants when compared to wild-type. Thus, our results support the notion that Tic22 is directly involved in chloroplast preprotein import and might point to a particular importance of Tic22 in chloroplast biogenesis at times of high import rates.展开更多
This contribution is focused on applications of spectroscopic methods for the precise control of deposition processes. In this context, the present study gives a review on selected combinations of conventional and ion...This contribution is focused on applications of spectroscopic methods for the precise control of deposition processes. In this context, the present study gives a review on selected combinations of conventional and ion deposition techniques with different broadband online spectrophotometric systems. Besides two systems operating in the VIS- and NIR-spectral range in combination with ion processes, also a monochromator system developed for conventional deposition processes in the DUV/VUV-spectral range will be discussed. The considerations will be concluded by a comparison of the major advantages of the specific combinations of processes with online monitoring concepts and by a brief outlook concerning future challenges.展开更多
Brassinosteroids(BR) are involved in the control of several developmental processes ranging from root elongation to senescence and adaptation to environmental cues. Thus, BR perception and signaling have to be precise...Brassinosteroids(BR) are involved in the control of several developmental processes ranging from root elongation to senescence and adaptation to environmental cues. Thus, BR perception and signaling have to be precisely regulated. One regulator is BRI1-associated kinase 1(BAK1)-interacting receptor-like kinase 3(BIR3). In the absence of BR, BIR3 forms complexes with BR insensitive 1(BRI1) and BAK1.However, the biophysical and energetic requirements for complex formation in the absence of the ligand have yet to be determined. Using computational modeling, we simulated the potential complexes between the cytoplasmic domains of BAK1, BRI1 and BIR3. Our calculations and experimental data confirm the interaction of BIR3 Rewith BAK1 and BRI1, with the BAK1 BIR3 interaction clearly favored. Furthermore, we demonstrate that BIR3 and BRI1 share the same interaction site with BAK1. This suggests a competition between BIR3 and BRI1 for binding to BAK1, which results in preferential binding of BIR3 to BAK1 in the absence of the ligand thereby preventing the active participation of BAK1 in BR signaling. Our model also suggests that BAK1 and BRI1 can interact even while BAK1 is in complex with BIR3 at an additional binding site of BAK1 that does not allow active BR signaling.展开更多
Seed size critically affects grain yield of crops and hence represents a key breeding target.The develop-ment of embryo-nourishing endosperm is a key driver of seed expansion.We here report unexpected dual roles of th...Seed size critically affects grain yield of crops and hence represents a key breeding target.The develop-ment of embryo-nourishing endosperm is a key driver of seed expansion.We here report unexpected dual roles of the transcription factor EIN3 in regulating seed size.These EIN3 functions have remained largely undiscovered because they oppose each other.Capitalizing on the analysis of multiple ethylene biosynthesis mutants,we demonstrate that EIN3 represses endosperm and seed development in a pathway regulated by ethylene.We,in addition,provide evidence that EIN3-mediated synergid nucleus disintegration promotes endosperm expansion.Interestingly,synergid nucleus disintegration is not affected in various ethylene biosynthesis mutants,suggesting that this promoting function of EIN3 is inde-pendent of ethylene.Whereas the growth-inhibitory ethylene-dependent EIN3 action appears to be encoded by sporophytic tissue,the growth-promoting role of EIN3 is induced by fertilization,revealing a generation conflict that converges toward the key signaling component EIN3.展开更多
Dear Editor, Phytohormones have been described as essential regula- tors of various processes throughout plant life, forming a strong interactive network. Because of this important func- tion, they are central and in...Dear Editor, Phytohormones have been described as essential regula- tors of various processes throughout plant life, forming a strong interactive network. Because of this important func- tion, they are central and integrative modulators form- ing a physiological key interface between plant responses and primary parameters such as genotype, environmental conditions, and developmental status. Consequently, the determination of the phytohormone signature as a key physiological parameter is necessary to understand the correlations between genotype and phenotype, as well as the influence of exogenous modulations on the phenotype （Yin et al., 2004）. Thus, evaluation of the phytohormone signature has to be considered for physiological phenotyp- ing, especially for the improvement of crops or developing strategies for plant protection. This includes the important trait plant immunity, which is determined also by distinct and fine-tuned modulations of phytohormones （Robert- Seilaniantz et al., 2011）.展开更多
文摘Preprotein import into chloroplasts depends on macromolecular machineries in the outer and inner chloroplast envelope membrane （TOC and TIC）. It was suggested that both machineries are interconnected by components of the intermembrane space （IMS）. That is, amongst others, Tic22, of which two closely related isoforms exist in Arabidopsis thaliana, namely atTic22-III and atTic22-IV. We investigated the function of Tic22 in vivo by analyzing T-DNA insertion lines of the corresponding genes. While the T-DNA insertion in the individual genes caused only slight defects, a double mutant of both isoforms showed retarded growth, a pale phenotype under high-light conditions, a reduced import rate, and a reduction in the photosynthetic performance of the plants. The latter is supported by changes in the metabolite content of mutant plants when compared to wild-type. Thus, our results support the notion that Tic22 is directly involved in chloroplast preprotein import and might point to a particular importance of Tic22 in chloroplast biogenesis at times of high import rates.
文摘This contribution is focused on applications of spectroscopic methods for the precise control of deposition processes. In this context, the present study gives a review on selected combinations of conventional and ion deposition techniques with different broadband online spectrophotometric systems. Besides two systems operating in the VIS- and NIR-spectral range in combination with ion processes, also a monochromator system developed for conventional deposition processes in the DUV/VUV-spectral range will be discussed. The considerations will be concluded by a comparison of the major advantages of the specific combinations of processes with online monitoring concepts and by a brief outlook concerning future challenges.
基金the CRC 1101“Molecular Encoding of Specificity in Plant Processes”of the German Research Foundationthe Klaus Tschira Foundation for funding+1 种基金the Schmeil Foundation(Heidelberg)the Heidelberg Graduate School of Mathematical and Computational Methods for the Sciences(HGS Math Comp)for support。
文摘Brassinosteroids(BR) are involved in the control of several developmental processes ranging from root elongation to senescence and adaptation to environmental cues. Thus, BR perception and signaling have to be precisely regulated. One regulator is BRI1-associated kinase 1(BAK1)-interacting receptor-like kinase 3(BIR3). In the absence of BR, BIR3 forms complexes with BR insensitive 1(BRI1) and BAK1.However, the biophysical and energetic requirements for complex formation in the absence of the ligand have yet to be determined. Using computational modeling, we simulated the potential complexes between the cytoplasmic domains of BAK1, BRI1 and BIR3. Our calculations and experimental data confirm the interaction of BIR3 Rewith BAK1 and BRI1, with the BAK1 BIR3 interaction clearly favored. Furthermore, we demonstrate that BIR3 and BRI1 share the same interaction site with BAK1. This suggests a competition between BIR3 and BRI1 for binding to BAK1, which results in preferential binding of BIR3 to BAK1 in the absence of the ligand thereby preventing the active participation of BAK1 in BR signaling. Our model also suggests that BAK1 and BRI1 can interact even while BAK1 is in complex with BIR3 at an additional binding site of BAK1 that does not allow active BR signaling.
基金support from tho Europoan Rosearch Council to R.G.(ERC Consolidator Grant"bi-BL OCK"ID 646644,ERC Proof of Concept Grant"TnVolve"ID 957547).
文摘Seed size critically affects grain yield of crops and hence represents a key breeding target.The develop-ment of embryo-nourishing endosperm is a key driver of seed expansion.We here report unexpected dual roles of the transcription factor EIN3 in regulating seed size.These EIN3 functions have remained largely undiscovered because they oppose each other.Capitalizing on the analysis of multiple ethylene biosynthesis mutants,we demonstrate that EIN3 represses endosperm and seed development in a pathway regulated by ethylene.We,in addition,provide evidence that EIN3-mediated synergid nucleus disintegration promotes endosperm expansion.Interestingly,synergid nucleus disintegration is not affected in various ethylene biosynthesis mutants,suggesting that this promoting function of EIN3 is inde-pendent of ethylene.Whereas the growth-inhibitory ethylene-dependent EIN3 action appears to be encoded by sporophytic tissue,the growth-promoting role of EIN3 is induced by fertilization,revealing a generation conflict that converges toward the key signaling component EIN3.
文摘Dear Editor, Phytohormones have been described as essential regula- tors of various processes throughout plant life, forming a strong interactive network. Because of this important func- tion, they are central and integrative modulators form- ing a physiological key interface between plant responses and primary parameters such as genotype, environmental conditions, and developmental status. Consequently, the determination of the phytohormone signature as a key physiological parameter is necessary to understand the correlations between genotype and phenotype, as well as the influence of exogenous modulations on the phenotype （Yin et al., 2004）. Thus, evaluation of the phytohormone signature has to be considered for physiological phenotyp- ing, especially for the improvement of crops or developing strategies for plant protection. This includes the important trait plant immunity, which is determined also by distinct and fine-tuned modulations of phytohormones （Robert- Seilaniantz et al., 2011）.
