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Over-expression of snakin - 2 and extensin - like protein genes restricts pathogen invasiveness and enhances tolerance to Clavibacter michiganensis subsp. michiganensis in transgenic tomato ( Solanum lycopersicum )

Balaji, Vasudevan ; Smart, Christine

In: Transgenic Research, 2012, vol. 21, no. 1, p. 23-37

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    Titre
    • Over-expression of snakin - 2 and extensin - like protein genes restricts pathogen invasiveness and enhances tolerance to Clavibacter michiganensis subsp. michiganensis in transgenic tomato ( Solanum lycopersicum )
    Auteur
    • Balaji, Vasudevan. Department of Plant Pathology and Plant-Microbe Biology, New York State Agricultural Experiment Station, Cornell University, 14456, Geneva, NY, USA
    • Smart, Christine. Department of Plant Pathology and Plant-Microbe Biology, New York State Agricultural Experiment Station, Cornell University, 14456, Geneva, NY, USA
    Type de document
    • Postprint
    Identifiant OAI-PMH
    • oai:doc.rero.ch:311778
    Summary
    Two tomato proteins were evaluated by over-expression in transgenic tomato for their ability to confer resistance to Clavibacter michiganensis subsp. michiganensis (Cmm). Snakin-2 (SN2) is a cysteine-rich peptide with broad-spectrum antimicrobial activity in vitro while extensin-like protein (ELP) is a major cell-wall hydroxyproline-rich glycoprotein linked with plant response to pathogen attack and wounding. Tomato plants, cultivar Mountain Fresh, were transformed via Agrobacterium tumefaciens harboring a binary vector for expression of the full-length SN2 gene or ELP cDNA under the regulation of the CaMV 35S promoter. Molecular characterization of PCR-positive putative T0 transgenic plants by Northern analysis revealed constitutive over-expression of SN2 and ELP mRNA. Junction fragment analysis by Southern blot showed that three of the four SN2 over-expressing T0 lines had single copies of complete T-DNAs while the other line had two complete T-DNA copies. All four ELP over-expressing T0 lines had a single copy T-DNA insertion. Semi-quantitative RT-PCR analysis of T1 plants revealed constitutive over-expression of SN2 and ELP. Transgenic lines that accumulated high levels of SN2 or ELP mRNA showed enhanced tolerance to Cmm resulting in a significant delay in the development of wilt symptoms and a reduction in the size of canker lesions compared to non-transformed control plants. Furthermore, in transgenic lines over-expressing SN2 or ELP bacterial populations were significantly lower (100-10,000-fold) than in non-transformed control plants. These results demonstrate that SN2 and ELP over-expression limits Cmm invasiveness suggesting potential in vivo antibacterial activity and possible biotechnological application for these two defense proteins