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Publikation

Iglesias, N. G.; Gago-Zachert, S. P.; Robledo, G.; Costa, N.; Plata, M. I.; Vera, O.; Grau, O.; Semorile, L. C.; Population structure of Citrus tristeza virus from field Argentinean isolates Virus Genes 36, 199-207, (2008) DOI: 10.1007/s11262-007-0169-x

We studied the genetic variability of three genomic regions (p23, p25 and p27 genes) from 11 field Citrus tristeza virus isolates from the two main citrus growing areas of Argentina, a country where the most efficient vector of the virus, Toxoptera citricida, is present for decades. The pathogenicity of the isolates was determinated by biological indexing, single-strand conformation polymorphism analysis showed that most isolates contained high intra-isolate variability. Divergent sequence variants were detected in some isolates, suggesting re-infections of the field plants. Phylogenetic analysis of the predominant sequence variants of each isolate revealed similar grouping of isolates for genes p25 and p27. The analysis of p23 showed two groups contained the severe isolates. Our results showed a high intra-isolate sequence variability suggesting that re-infections could contribute to the observed variability and that the host can play an important role in the selection of the sequence variants present in these isolates.
Bücher und Buchkapitel

Vaira, A. M.; Acotto, G. P.; Gago-Zachert, S.; Garcia, M. L.; Grau, O.; Milne, R. G.; Morikawa, T.; Natsuaki, T.; Torov, V.; Verbeek, M.; Vetten, H. J.; Genus Ophiovirus 673-679, (2005) ISBN: 9780080575483 DOI: 10.1016/B978-0-12-249951-7.50014-6

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Publikation

Köck, M.; Groß, N.; Stenzel, I.; Hause, G.; Phloem-specific expression of the wound-inducible ribonuclease LE from tomato (Lycopersicon esculentum cv. Lukullus) Planta 219, 233-242, (2004) DOI: 10.1007/s00425-004-1227-4

Ribonuclease LE (RNaseLE) from tomato (Lycopersicon esculentum Mill. cv. Lukullus) belongs to the widespread RNase T2 family of ribonucleases. With the exception of S-RNases of the solanaceous self-incompatibility system the functions of other members of the RNase T2 family are only barely understood. Using a 2.6-kbp putative promoter sequence of RNaseLE in front of the uidA reporter gene, expression of β-glucuronidase in developing phloem tissue and, especially, in the meristematic and elongation zones at root tips was detected. The tissue-specific expression accords with the range of cis-acting elements detected in the RNaseLE promoter. RNaseLE mRNA was localized in developing phloem cells but not in mature phloem tissue, suggesting association of RNaseLE expression with phloem development. Histochemical staining of β-glucuronidase activity as well as detailed inspection of RNaseLE at mRNA, protein and enzyme activity levels revealed that the wound-induced expression of RNaseLE was also restricted to vascular tissue. RNaseLE transcript accumulation detected by in situ hybridization occurred preferentially in phloem and cambial cells of stem sections upon wounding. The data provide evidence for a role of RNaseLE in a tissue-specific wound response and in wound healing of tomato.
Publikation

Groß, N.; Wasternack, C.; Köck, M.; Wound-induced RNaseLE expression is jasmonate and systemin independent and occurs only locally in tomato (Lycopersicon esculentum cv. Lukullus) Phytochemistry 65, 1343-1350, (2004) DOI: 10.1016/j.phytochem.2004.04.036

Tomato RNaseLE is induced by phosphate deficiency and wounding and may play a role in macromolecular recycling as well as wound healing. Here, we analyzed the role of jasmonate and systemin in the wound-induced RNaseLE activation. The rapid expression of RNaseLE upon wounding of leaves leading to maximal RNase activity within 10 h, appeared only locally. Jasmonic acid (JA) or its molecular mimic ethyl indanoyl isoleucine conjugate did not induce RNaseLE expression. Correspondingly, RNaseLE was expressed upon wounding of 35S::allene oxide cyclase antisense plants known to be JA deficient. RNaseLE was not expressed upon systemin treatment, but was locally expressed in the spr1 mutant which is affected in systemin perception. In tomato plants carrying a PromLE::uidA construct, GUS activity could be detected upon wounding, but not following treatment with JA or systemin. The data indicate a locally acting wound-inducible systemin- and JA-independent signaling pathway for RNaseLE expression.RNaseLE expression was analyzed by pharmacological studies of different tomato lines and upon wounding of leaves. The gene is only locally activated via a new type of wound-induced signaling pathway in a jasmonate/systemin-independent manner.
Publikation

Stenzel, I.; Ziethe, K.; Schurath, J.; Hertel, S. C.; Bosse, D.; Köck, M.; Differential expression of the LePS2 phosphatase gene family in response to phosphate availability, pathogen infection and during development Physiol. Plant. 118, 138-146, (2003) DOI: 10.1034/j.1399-3054.2003.00091.x

In this study, we report the cloning of the three‐member LePS2 gene family of acid phosphatases via subtractive screening of a cDNA library of Pi‐starved cultivated tomato cells (Lycopersicon esculentum Mill. cv. Lukullus). As members of the plant Pi‐starvation response, LePS2 genes were tightly regulated in cultivated cells and tomato seedlings by Pi availability. The LePS2 enzymes which are most likely expressed in the cytoplasma could be involved in processes that are accompanied by degradation of phosphorylated organic substrates. Independently from exogenous phosphate supply LePS2 expression was detected in tomato endosperm during germination. LePS2 genes were differentially induced after infection with the bacterial pathogen Pseudomonas syringae and in the early stages of flower development. Using RT–PCR it was found that the gene LePS2B was the most abundant transcript in phosphate‐depleted cells, but a reduced expression was determined in floral buds and it was not found during pathogen interaction. In this respect, it is interesting that the promoter sequences of the LePS2 genes are also divergent. LePS2 gene products may have functions in developmental processes which are restricted to distinct plant tissues or cell types.
Publikation

Naum-Onganı́a, G.; Gago-Zachert, S.; Peña, E.; Grau, O.; Laura Garcia, M.; Citrus psorosis virus RNA 1 is of negative polarity and potentially encodes in its complementary strand a 24K protein of unknown function and 280K putative RNA dependent RNA polymerase Virus Res. 96, 49-61, (2003) DOI: 10.1016/S0168-1702(03)00172-2

Citrus psorosis virus (CPsV), the type member of genus Ophiovirus, has three genomic RNAs. Complete sequencing of CPsV RNA 1 revealed a size of 8184 nucleotides and Northern blot hybridization with chain specific probes showed that its non-coding strand is preferentially encapsidated. The complementary strand of RNA 1 contains two open reading frames (ORFs) separated by a 109-nt intergenic region, one located near the 5′-end potentially encoding a 24K protein of unknown function, and another of 280K containing the core polymerase motifs characteristic of viral RNA-dependent RNA polymerases (RdRp). Comparison of the core RdRp motifs of negative-stranded RNA viruses, supports grouping CPsV, Ranunculus white mottle virus (RWMV) and Mirafiori lettuce virus (MiLV) within the same genus (Ophiovirus), constituting a monophyletic group separated from all other negative-stranded RNA viruses. Furthermore, RNAs 1 of MiLV, CPsV and RWMV are similar in size and those of MiLV and CPsV also in genomic organization and sequence.
Bücher und Buchkapitel

Abel, S.; Köck, M.; Secretory Acid Ribonucleases from Tomato, Lycopersicon esculentum Mill. Methods Enzymol. 341, 351-368, (2001) DOI: 10.1016/S0076-6879(01)41163-3

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Publikation

Gago-Zachert, S.; Costa, N.; Semorile, L.; Grau, O.; Sequence variability in p27 gene of Citrus Tristeza Virus (CTV) revealed by SSCP analysis Electron. J. Biotechnol. 2, 41-50, (1999) DOI: 10.2225/vol2-issue1-fulltext-3

Citrus tristeza closterovirus (CTV), is a phloem-limited virus transmitted by aphids in a semipersistent manner. The genome of CTV is composed of a ssRNA with two capsid proteins: CP, covering about 95% of the particle length, and a diverged coat protein (dCP), present only in one end of the particle, forming a rattlesnake structure. dCP is the product of p27 gene for which it is also postulated a function in the transmissibility by aphid vectors. Hybridization analysis showed a p27 gene region, which exhibits different patterns with two probes derived from two biological distinct CTV isolates. In an attempt to screen whether that gene region differs in mild and severe strains, six CTV isolates belonging to different biogroups were compared for variations in their p27 gene by analysis of single-strand conformation polymorphism (SSCP). The p27 gene was reverse transcribed and amplified by PCR and thirty clones of each isolate were obtained. From each clone, two fragments of the gene were amplified by PCR: fragment (a), 459 bp long, and fragment (b), 281 bp long. Sequence variations in both gene fragments were studied by SSCP analysis. A variety of SSCP patterns was obtained from each isolate, being isolates belonging to the groups II-IV and III those with the higher and lower number of them. Moreover, SSCP analysis provided a rapid procedure to screen the genetic heterogeneity of the viral isolates reducing considerably the amount of nucleic acid sequenciation necessary to gain that knowledge.
  • Die Leibniz-Gemeinschaft
  • Digitalisierung in der Landwirtschaft
  • Martin-Luther Universität Halle
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