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Gene Review

LOC543989  -  systemin

Solanum lycopersicum

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Disease relevance of systemin


High impact information on systemin

  • A gene that encodes systemin, a mobile 18-amino acid polypeptide inducer of proteinase inhibitor synthesis in tomato and potato leaves, has been isolated from tomato, Lycopersicon esculentum [3].
  • The gene has 10 introns and 11 exons, ten of which are organized as five homologous pairs with an unrelated sequence in the eleventh, encoding systemin [3].
  • Systemin is proteolytically processed from a 200-amino acid precursor protein, prosystemin [3].
  • Conversely, an activator of the H+-ATPase (fusicoccin) acidified the growth medium of L. peruvianum cell cultures and suppressed systemin-induced medium alkalinization [4].
  • Systemin is an important mediator of wound-induced defense gene activation in tomato plants, and it elicits a rapid alkalinization of the growth medium of cultured Lycopersicon peruvianum cells [4].

Chemical compound and disease context of systemin


Biological context of systemin

  • Thus, this binding site exhibits the characteristics expected for a functional systemin receptor [5].
  • Binding was also competed by the systemin antagonists syst1-14 and syst-Ala-17 (IC50 of 500 and 1000 nM, respectively) [5].
  • Receptor-mediated tyrosine phosphorylation of a 48-kDa mitogen-activated protein kinase and alkalinization of the medium of suspension-cultured cells in response to systemin and carbohydrate elicitors were also inhibited by suramin [6].
  • A transgenic line with reduced prosystemin expression showed similar susceptibility as Defenseless, whereas a prosystemin-overexpressing transgene was highly resistant [7].

Anatomical context of systemin

  • The isolation to homogeneity of the 160-kDa systemin cell-surface receptor (SR160) from plasma membranes of suspension cultured cells of Lycopersicon peruvianum is reported [8].
  • The activity of a protease capable of processing systemin carboxy-terminal of Lys14 was detected in tomato plasma membranes and may be responsible for the inactivation process [9].
  • At the subcellular level, prosystemin was found compartmentalized in the cytosol and the nucleus of vascular parenchyma cells [10].

Associations of systemin with chemical compounds

  • Tomato CP mRNA was detected within 3 h after wounding, or treatment with systemin or methyl jasmonate [11].
  • To study the molecular basis of perception, we extended the C-terminal end of systemin by a tyrosine residue and radioiodinated it to yield systemin-125I-iodotyrosine [5].
  • Likewise, intact systemin showed stimulatory, syst1-14 antagonistic activity, and syst15-18 showed no activity in leaf pieces of tomato (L. esculentum) plants assayed for the induction of ethylene biosynthesis [5].
  • The inhibition of medium alkalinization by suramin was reversible in the presence of high concentrations of systemin and carbohydrate elicitors [6].
  • The polysulfonated compound heparin did not inhibit systemin-induced medium alkalinization [6].

Regulatory relationships of systemin

  • Tomato plants transformed with an antisense prosystemin complementary DNA exhibited greatly suppressed systemic wound induction of proteinase Inhibitor I and II synthesis in leaves [3].

Analytical, diagnostic and therapeutic context of systemin


  1. Overexpression of the prosystemin gene in transgenic tomato plants generates a systemic signal that constitutively induces proteinase inhibitor synthesis. McGurl, B., Orozco-Cardenas, M., Pearce, G., Ryan, C.A. Proc. Natl. Acad. Sci. U.S.A. (1994) [Pubmed]
  2. Characterization of prosystemin expressed in the baculovirus/insect cell system reveals biological activity of the systemin precursor. Vetsch, M., Janzik, I., Schaller, A. Planta (2000) [Pubmed]
  3. Structure, expression, and antisense inhibition of the systemin precursor gene. McGurl, B., Pearce, G., Orozco-Cardenas, M., Ryan, C.A. Science (1992) [Pubmed]
  4. Modulation of plasma membrane H+-ATPase activity differentially activates wound and pathogen defense responses in tomato plants. Schaller, A., Oecking, C. Plant Cell (1999) [Pubmed]
  5. The plant wound hormone systemin binds with the N-terminal part to its receptor but needs the C-terminal part to activate it. Meindl, T., Boller, T., Felix, G. Plant Cell (1998) [Pubmed]
  6. Suramin inhibits initiation of defense signaling by systemin, chitosan, and a beta-glucan elicitor in suspension-cultured Lycopersicon peruvianum cells. Stratmann, J., Scheer, J., Ryan, C.A. Proc. Natl. Acad. Sci. U.S.A. (2000) [Pubmed]
  7. The role of ethylene and wound signaling in resistance of tomato to Botrytis cinerea. Díaz, J., ten Have, A., van Kan, J.A. Plant Physiol. (2002) [Pubmed]
  8. The systemin receptor SR160 from Lycopersicon peruvianum is a member of the LRR receptor kinase family. Scheer, J.M., Ryan, C.A. Proc. Natl. Acad. Sci. U.S.A. (2002) [Pubmed]
  9. Action of proteolysis-resistant systemin analogues in wound signalling. Schaller, A. Phytochemistry (1998) [Pubmed]
  10. The cellular localization of prosystemin: a functional role for phloem parenchyma in systemic wound signaling. Narváez-Vásquez, J., Ryan, C.A. Planta (2004) [Pubmed]
  11. Characterization and localization of a wound-inducible type I serine-carboxypeptidase from leaves of tomato plants (Lycopersicon esculentum Mill.). Moura, D.S., Bergey, D.R., Ryan, C.A. Planta (2001) [Pubmed]
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