A potato intragene overexpressing GSL1 confers resistance to Pectobacterium atrosepticum

ABSTRACT

An intragene involves the rearrangement of gene configurations based on switching coding sequences and regulatory regions within a species. The overexpression of specific GSL (Gibberellin Stimulated-Like) genes is known to confer enhanced disease resistance. A potato intragenic expression cassette, with the potato GSL1 gene placed under the regulatory control of the light-inducible Lhca3 gene from potato, was designed and constructed. The resulting intragene was transformed using Agrobacterium-mediated gene transfer into potato cultivar Iwa to investigate whether overexpression of the potato GSL1 intragene can confer disease resistance. The transgenic status of the resulting plants was confirmed by PCR. The majority of the transgenic potato lines were determined to overexpress the GSL1 gene at the mRNA level using quantitative RT–PCR analysis. From these results, seven lines were selected for further characterisation and thoroughly evaluated in bioassays for resistance to Pectobacterium atrosepticum which causes blackleg disease in potato. These pathogenicity bioassays demonstrated that high transcriptional overexpression of GSL1 confers high resistance to blackleg disease. This confirms a functional role of the GSL1 gene in plant defence against pathogens and provides an intragenic approach for disease resistance in potatoes.

KEYWORDS:

• Blackleg disease
• Gibberellin Stimulated-Like proteins
• intragene
• Pectobacterium atrosepticum
• Snakin 1
• Solanum tuberosum

Acknowledgements

The authors thank Stuart Larsen, David Lewis, and Ian King for providing plant growth facilities, and Ruth Butler for help with analysis of the qPCR data to determine the density of P. atrosepticum, and Alasdair Noble for assistance with analysis of variance.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was funded by AGMARDT Agricultural and Marketing Research and Development Trust [grant no 20791]; and Ministry of Business, Innovation and Employment (New Zealand) contract [grant no C02X0202] to The New Zealand Institute for Plant and Food Research Ltd.