Joerg Stockhaus - Academia.edu (original) (raw)

Papers by Joerg Stockhaus

Plant molecular biology, 2001

We are interested in the regulatory mechanisms responsible for the mesophyll-specific expression ... more We are interested in the regulatory mechanisms responsible for the mesophyll-specific expression of C4 phosphoenolpyruvate carboxylase (PEPCase). A one-hybrid screen resulted in the cloning of four different members of a novel class of plant homeodomain proteins, which are most likely involved in the mesophyll-specific expression of the C4 PEPCase gene in C4 species of the genus Flaveria. Inspection of the homeodomains of the four proteins reveals that they share many common features with homeodomains described so far, but there are also significant differences. Interestingly, this class of homeodomain proteins occurs also in Arabidopsis thaliana and other C3 plants. One-hybrid experiments as well as in vitro DNA binding studies confirmed that these novel homeodomain proteins specifically interact with the proximal region of the C4 PEPCase gene. The N-terminal domains of the homeodomain proteins contain highly conserved sequence motifs. Two-hybrid experiments show that these motifs ...

Plant molecular biology, 1998

C4 photosynthesis is functionally dependent on metabolic interactions between mesophyll and bundl... more C4 photosynthesis is functionally dependent on metabolic interactions between mesophyll and bundle-sheath cells. Although the C4 cycle is biochemically well understood many aspects of the regulation of enzyme activities, gene expression and cell differentiation are elusive. Protein kinases are likely involved in these regulatory processes providing links to hormonal, metabolic and developmental signal transduction pathways. We have identified several protein kinases that are differentially expressed in mesophyll and bundle-sheath cells of the C4 plant Sorghum bicolor. Here we describe the characterization of two putative protein kinases that show high similarity to the SNF1/AMPK family of protein serine/threonine kinases. The mRNA of both kinases accumulates to much higher levels in mesophyll cells than in the bundle-sheath and can also be detected in root tissue. Complementation experiments with a snf1 mutant of Saccharomyces cerevisiae indicate that the S. bicolor protein kinase S...

The EMBO journal, Jan 15, 1994

Genetic studies in Arabidopsis and Antirrhinum showed that petal determination requires the conco... more Genetic studies in Arabidopsis and Antirrhinum showed that petal determination requires the concomitant expression of two homeotic functions, A and B, whereas the A function alone determines sepal identity. The B function is represented by at least two genes. The Petunia homeotic gene green petal (gp) is essential for petal determination as demonstrated by a Petunia gp mutant that has sepals instead of petals. We have used ectopic expression of the gp gene as a tool to study flower development in Petunia. CaMV 35S-gp expression leads to homeotic conversion of sepals into petaloid organs when expressed early in development. This demonstrates that a single homeotic gene is sufficient to induce homeotic conversion of sepals to petals, suggesting that other petal determining genes are regulated in part by ectopically expressed gp. Indeed, two other MADS-box-containing genes, pmads 2 and fbp 1, which show homology to the Antirrhinum B function gene globosa, are activated in the converted...

Plant & cell physiology, 1995

A cDNA (PHYA) for the phytochrome A apoprotein (PHYA) of rice and three mutated sequences (phyA S... more A cDNA (PHYA) for the phytochrome A apoprotein (PHYA) of rice and three mutated sequences (phyA S/A, the first ten serine residues in the N-terminal domain of PHYA were changed to alanine residues; phyA ND, the first 80 N-terminal amino acids were deleted; phyA CD, the amino acids of the C-terminal domain from 689 to 1,128 were deleted) were expressed in yeast, and the wild-type and mutant apophytochromes were allowed to combine in vitro with the chromophore phycocyanobilin (PCB). The PCB-attached product of phyA S/A gave very similar spectrophotometric peaks to the PhAr and PhyAfr forms of wild-type product. By contrast, the peak of the product of phyA CD in the Pfr form was significantly shifted towards a shorter wavelength, an indication that, whereas the C-terminal domain is not crucial for the PCB attachment, it greatly influences the absorption maximum of PhyAfr. The rate of 50% reversion from PhyAfr to PhAr in darkness was 3 h at 27 degrees C with all of the samples, showing ...

The EMBO journal, 1990

A chimeric gene encoding an anti-sense RNA of the 10 kd protein of the water-splitting apparatus ... more A chimeric gene encoding an anti-sense RNA of the 10 kd protein of the water-splitting apparatus of photosystem II of higher plants under the control of the CaMV 35S promoter was introduced into potato using Agrobacterium based vectors. The expression of the anti-sense RNA led to a significant reduction of the amounts of the 10 kd protein and RNA in a number of transgenic plants. In three out of 36 plants tested, the level of the 10 kd protein was only up to 1-3% compared with the wild-type control. The drastic reduction of the 10 kd protein did not influence the accumulation of other photosystem II associated polypeptides at both the RNA and protein level. Furthermore no phenotypic differences were observed between potato plants expressing wild-type and drastically reduced levels of the 10 kd protein with respect to growth rate, habitus or ultrastructure of the chloroplasts. Measurements of the relaxation of the flash-induced enhancement in the fluorescence quantum yield as determi...

THE PLANT CELL ONLINE, 1989

The nuclear gene ST-LS1 from potato encodes a 10-kilodalton protein that is a component of the ox... more The nuclear gene ST-LS1 from potato encodes a 10-kilodalton protein that is a component of the oxygen-evolving complex of photosystem II. Analysis of the expression of a reporter gene driven by chimeric promoters, consisting of ST-LS1 upstream sequences and a truncated cauliflower mosaic virus 35s promoter, suggests that a strong positive regulatory element is located between position -345 and -261, whereas both the region -261 to +11 and the more upstream region -1600 to -530 are devoid of autonomous strong positive elements detectable by this approach. The ST-LS7 upstream region contains redundant elements conferring light-regulated and organ-specific expression, one of them being located between position -130 and +11. In addition, enhancer-like sequences conferring light-regulated as well as organ-specific expression to heterologous promoters were identified. These sequences are functional not only when located 5'-upstream of the coding region but also when placed 3'downstream of the polyadenylation signal, thus representing one of the first examples of a plant gene-derived enhancer being able to induce a truncated heterologous promoter from a position 3'-downstream of the transcription unit.

THE PLANT CELL ONLINE, 1997

The function of the C4 mechanism of photosynthesis depends on the strict compartmentation of the ... more The function of the C4 mechanism of photosynthesis depends on the strict compartmentation of the enzymes involved. Here, we investigate the regulatory mechanisms that ensure the mesophyll-specific expression of the C4 isoform of phosphoenolpyruvate carboxylase. We show that 2 kb of the 5' flanking region of the Flaveria trinervia C4 PpcA7 gene is sufficient to direct mesophyll-specific expression of the P-glucuronidase reporter gene in transgenic F. bidentis (C, ) plants. In young leaves of seedlings, the activity of this promoter is dependent on the developmental stage of the mesophyll cells. It is induced in a basipetal fashion (leaf tip to base) during leaf development. The promoter region of the orthologous nonphotosynthetic Ppc gene of F. pringlei (CJ induces reporter gene expression mainly in the vascular tissue of leaves and stems as well as in mesophyll cells of transgenic F. bidentis plants. Our experiments demonstrate that during the evolution of the C4 Flaveria species, cis-acting elements of the C4 Ppc gene must have been altered to achieve mesophyll-specific expression.

Proceedings of the National Academy of Sciences, 1987

ST-LS] is a light-inducible, single-copy gene from potato that is expressed only in photosyntheti... more ST-LS] is a light-inducible, single-copy gene from potato that is expressed only in photosynthetic tissues. Various sequences derived from the 5'-upstream region of this gene were fused to the coding region of the chloramphenicol acetyltransferase (CAT) gene and to the gene 7 termination region of the transfer DNA (T-DNA) from the Agrobacterium Ti plasmid pTiACH5 and transferred to tobacco using Ti-plasmid vectors. After regeneration of whole plants, tissues were assayed for the expression of the CAT gene. Sequences derived from the 5'-upstream region of the ST-LS] gene comprising positions -334 to +11 were sufficient to confer a leaf/stemspecific as well as a light-inducible expression of the CAT gene. Destruction of chloroplasts by treatment with the herbicide norfluorazon and subsequent exposure to light drastically reduced the expression of the CAT gene indicating that this upstream sequence most likely interacts with a chloroplastdependent signal. When sequences from position -98 to position +675 were fused to a truncated inactive fragment of the cauliflower mosaic virus 35S promoter in a head-to-head manner, the corresponding chimeric genes were again expressed in photosynthetic tissues only, indicating that these sequences have enhancer-like properties.

Planta, 1995

Overexpression of phytochrome A results in an increased inhibition of hypocotyl elongation under ... more Overexpression of phytochrome A results in an increased inhibition of hypocotyl elongation under red and far-red light. We used this approach to assay for the function of N-terminal mutations of rice (Oryza sativa L.) phytochrome A. Transgenic tobacco seedlings that express the wild-type rice phytochrome A (RW), a rice phytochrome A lacking the first 80 amino acids (NTD) or a rice phytochrome A with a conversion of the first 10 serines into alanine residues (S/A) were compared with untransformed wild-type tobacco (Nicotiana tabacum L. cv. Xanthi) seedlings. Experiments under different fluence rates showed that RW and, even more strongly, S/A increased the response under both red and far-red light, whereas NTD decreased the response under far-red light but hardly altered the response under red light. These results indicate that NTD not only lacks residues essential for an increased response under red light but also distorts the wild-type response under far-red light. Wild-type rice phytochrome A and, even more so, S/A mediate an enhanced phytochrome A as well as phytochrome B function, whereas NTD interferes with the function of endogenous tobacco phytochrome A as well as that of rice phytochrome A when co-expressed in a single host. Experiments with seedlings of different ages and various times of irradiation under far-red light demonstrated that the effect of NTD is dependent on the stage of development. Our results suggest that the lack of the first 80 amino acids still allows a rice phytochrome A to interact with the phytochrome transduction pathway, albeit non-productively in tobacco seedlings.

Planta, 1999

To study the metabolic interactions between mesophyll and bundle-sheath cells of C 4 plants, prot... more To study the metabolic interactions between mesophyll and bundle-sheath cells of C 4 plants, protein kinases possibly involved in the regulatory processes and signal transduction pathways have been cloned and characterized. A receptor-like protein kinase (RLK) cDNA clone from the C 4 plant Sorghum bicolor (L.) Moench has been identi®ed. The deduced protein was designated SbRLK1 for receptor-like protein kinase from S. bicolor. The putative cytoplasmic domain of SbRLK1 contains all amino acids that are characteristic of protein kinases. The extracellular domain contains ®ve leucine-rich repeats. The mRNA of the SbRLK1 gene accumulated to much higher levels in mesophyll cells than in the bundle-sheath and was almost undetectable in roots. This expression pattern indicates that SbRLK1 might be involved in the regulation of speci®c processes in mesophyll cells.

Plant Science, 1999

The Mehler–Ascorbate–Peroxidase cycle is a protection system against reactive oxygen species (ROS... more The Mehler–Ascorbate–Peroxidase cycle is a protection system against reactive oxygen species (ROS) occurring during over-excitation of the photosynthetic apparatus. In the cultivated tomato, Lycopersicon esculentum, long-term chilling under moderate light leads to oxidation of the Calvin cycle key enzyme, ribulose-1,5-bisphosphate carboxylase (rubisco), presumably by generation of ROS. In contrast, high-altitude lines of the wild tomato species L. peruvianum were tolerant

Botanica Acta, 1998

ABSTRACT :We have identified several protein kinases that are differentially expressed in mesophy... more ABSTRACT :We have identified several protein kinases that are differentially expressed in mesophyll and bundle sheath cells of the C4 plant Sorghum bicolor. Here we describe the characterization of a protein kinase homologue that shows a high amino acid sequence similarity to the SNF1/AMPK family of protein serine/threonine kinases. The mRNA of this gene accumulates to much higher levels in mesophyll cells than in the bundle sheath and can also be detected in root tissue.

Nucleic Acids Research, 1987

ST-LS1, a single copy gene from potato displaying a leaf/stem specific gene expression, was tagge... more ST-LS1, a single copy gene from potato displaying a leaf/stem specific gene expression, was tagged by an exon modification and introduced into both potato and tobacco cells using Agrobacterium vectors. After regeneration of whole plants, the expression of the tagged gene was analyzed with respect to its organ specifity and compared to the expression of the corresponding resident gene. The expression of the transferred gene in transgenic plants closely followed the expression of the resident gene. No marked influence of the plant species serving as host was observed. The level of expression of the introduced gene varied by a factor of at least 100 in independent transformants when normalized to the expression of the resident gene. Southern analysis performed on the transformed plants indicated a correlation between copy number of the introduced gene and its expression level. The activity of the tagged gene as well as of the resident gene was significantly inhibited by treatment of the transgenic plants with the herbicide norfluorazon, indicating that this gene activity is dependent on the presence of functional chloroplasts in the leaves.

Molecular and General Genetics MGG, 1998

C 4 photosynthesis is functionally dependent on metabolic interactions between mesophyll-and bund... more C 4 photosynthesis is functionally dependent on metabolic interactions between mesophyll-and bundle-sheath cells. Although the C 4 cycle is biochemically well understood, many aspects of the regulation of enzyme activities, gene expression and cell dierentiation are elusive. Protein kinases are likely involved in these regulatory processes, providing links to hormonal, metabolic and developmental signal-transduction pathways. Here we describe the cloning and characterization of 14 dierent putative protein kinase leaf cDNA clones from the C 4 plant Sorghum bicolor. These genes belong to three dierent protein kinase subfamilies: ribosomal protein S6 kinases, SNF1-like protein kinases, and receptor-like protein kinases. We report the partial cDNA sequences, mesophyll/bundle-sheath steady-state mRNA ratios, mesophyll/etiolated leaf steady-state mRNA ratios, and the positions of 14 protein kinase genes on the genetic map of S. bicolor. Only three of the protein kinase genes described here are expressed preferentially in mesophyll cells as compared with the bundle-sheath.

Genes & Development, 1992

We have used a tobacco transgenic plant system to assay the structure/function relationship of ph... more We have used a tobacco transgenic plant system to assay the structure/function relationship of phytochrome A (phyA), a plant photoreceptor. The amino terminus of phyA from different plant species is very rich in serine residues. To investigate whether these serine residues are required for phytochrome function, the first 10 serine codons encoding amino acid residues 2-4, 10-14, 19, and 20 in the amino-terminal domain of the rice phyA gene (phyA) were changed to alanine codons. The mutant (S/A phyA), as well as the wild-type phyA cDNA, was placed under the control of the 35S promoter, and the chimeric genes were transferred into the tobacco genome by Agrobacterium-mediated transformation. Transgenic tobacco plants expressing either wild-type or S/A phyA showed similar phenotypic alterations, including dwarfism and dark-green leaves. However, hypocotyl elongation experiments revealed that transgenic seedlings expressing S/A phyA showed a higher amplitude of the red light response with respect to the inhibition of hypocotyl elongation. The observed difference is not correlated with expression levels of the transgene. The chromophore is attached to the mutant phyA apoprotein (PHY A), and the mutant photoreceptor is photoreversible, giving a difference spectrum indistinguishable from that of the rice phyA. Our results indicate that the S/A mutant has a higher biological activity as compared with the wild-type rice phyA.

Australian Journal of Plant Physiology, 1997

... The non-photosynthetic isoforms of PEPC are known to be involved in basic cell metabolism (La... more ... The non-photosynthetic isoforms of PEPC are known to be involved in basic cell metabolism (Latzko and Kelly 1983; Basra and Malik 1996), but the actual functions of the non-photosynthetic isoforms of ... Peter Westhoff AD , Per Svensson B , Karin Ernst C , Oliver Bläsing A , ...

Archives of Biochemistry and Biophysics, 2003

C4 plants are known to be of polyphyletic origin and to have evolved independently several times ... more C4 plants are known to be of polyphyletic origin and to have evolved independently several times during the evolution of angiosperms. This implies that the C4 isoform of phosphoenolpyruvate carboxylase (PEPC) originated from a nonphotosynthetic PEPC gene that was already present in the C3 ancestral species. To meet the special requirements of the C4 photosynthetic pathway the expression program of

Planta, 2004

Suppression subtractive hybridisation was used to isolate 21 cDNAs ( bmi1- bmi21) up-regulated 1-... more Suppression subtractive hybridisation was used to isolate 21 cDNAs ( bmi1- bmi21) up-regulated 1-5 h post-inoculation (hpi) in a barley ( Hordeum vulgare L. cv. Pallas) near-isogenic line (NIL) P11 ( Mla13) challenged with either avirulent or virulent isolates of Blumeria graminis f. sp. hordei. Transcriptional changes at these time-points are crucial for the Mla-mediated hypersensitive response [W.R. Bushnell and Z. Liu (1994) Physiol Mol Plant Pathol 44:389-402]. Seven sequences were up-regulated by 1 hpi, when the pathogen has formed only the primary germ tube. Some transcripts were similar to genes with a role in regulating programmed cell death in animals, including NF kappaB and oxysterol-binding protein. Moreover, bmi7, similar to rice resistance gene Xa21, was rapidly up-regulated in both compatible and incompatible interactions, but was then down-regulated by 5 hpi in the virulent interaction. Only nine of the transcripts were up-regulated in mlo5 resistance in cv. Pallas NIL P22, confirming differential pathway induction between Mla13 and mlo5. However, eight sequences up-regulated in the Mla13 response in P11 were already highly elevated in uninoculated mlo5 mutant P22, suggesting that they may be negatively regulated by wild-type Mlo. Regulation of bmi sequences was investigated using salicylic acid, methyl jasmonate, ethylene, H(2)O(2), abscisic acid, wounding and a glucan elicitor. No single stimulus up-regulated all genes, suggesting either combinations of these stimuli, or additional stimuli, are involved in early Mla13 and mlo5 resistances. Whereas H(2)O(2) up- or down-regulated 17 of the transcripts detected in Northern analyses, salicylic acid stimulated only down-regulation of 5 transcripts.