Overexpression of snakin‐1 gene enhances resistance to Rhizoctonia solani and Erwinia carotovora in transgenic potato plants

Abstract

Snakin-1 (SN1), a cysteine-rich peptide with broad-spectrum antimicrobial activity in vitro, was evaluated for its ability to confer resistance to pathogens in transgenic potatoes. Genetic variants of this gene were cloned from wild and cultivated Solanum species. Nucleotide sequences revealed highly evolutionary conservation with 91-98% identity values. Potato plants (S. tuberosum subsp. tuberosum cv. Kennebec) were transformed via Agrobacterium tumefaciens with a construct encoding the S. chacoense SN1 gene under the regulation of the ubiquitous CaMV 35S promoter. Transgenic lines were molecularly characterized and challenged with either Rhizoctonia solani or Erwinia carotovora to analyse whether constitutive in vivo overexpression of the SN1 gene may lead to disease resistance. Only transgenic lines that accumulated high levels of SN1 mRNA exhibited significant symptom reductions of R. solani infection such as stem cankers and damping-off. Furthermore, these overexpressing lines showed significantly higher survival rates throughout the fungal resistance bioassays. In addition, the same lines showed significant protection against E. carotovora measured as: a reduction of lesion areas (from 46.5 to 88.1% with respect to the wild-type), number of fallen leaves and thickened or necrotic stems. Enhanced resistance to these two important potato pathogens suggests in vivo antifungal and antibacterial activity of SN1 and thus its possible biotechnological application.

Expression, purification and characterization of the recombinant cysteine-rich antimicrobial peptide snakin-1 in Pichia pastoris

“…Enhanced resistance to pathogen infections has also been reported in plants that express snakin genes [28,29]. Snakin peptides are thus considered important candidates for producing biotic stress tolerance in crops.…”

“…Both cause rapid aggregation of pathogens, although this response is not directly related with their antimicrobial activity [11,26]. Transgenic plants over-expressing the SN-1 and SN-2 genes have been shown to exhibit increased resistance to a wide range of invading phytopathogens [28,29].…”

One new kind of phytohormonal signaling integrator: Up-and-coming GASA family genes

“…Antibacterial experiments and in vivo experiments showed that potato Snakin-1 and Snakin-2 proteins have the anti-bacterial and -fungi capacity. 16,17,48,49,50 The CaSn protein of the pepper has the ability to anti-root-knot nematode (Meloidogyne spp.). 30 French bean Snakin-2-like protein may be formed an approximately 42 kDa protein complex (FBCBP) with the proline-rich protein PRP to participate in the plant defense process.…”

Antimicrobial peptides

“…108,115,119,124,132 Regarding specificity, the activity of metchnikowin on orchid mycorrhiza Piriformospora indica 133 has been studied in detail.…”

“…Though it has been reported that the degree of antimicrobial activity is not dependent on the AMP production level in transgenic plants, 106 most of the publications furnish clear evidence for peptides' doseeffect activity. 82,100,107,108 Some investigators emphasize the possibility of synergism among different AMPs. [109][110][111] In vivo data for different antibacterial peptides show that defensins and linear peptides work in-synergy, 112,113 as exemplified by synergism between LL-37 and human b-defensin HBD-2.…”