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Sgt1, but not Rar1, is essential for the RB-mediated broad-spectrum resistance to potato late blight.

Bhaskar PB, Raasch JA, Kramer LC, Neumann P, Wielgus SM, Austin-Phillips S, Jiang J - BMC Plant Biol. (2008)

Bottom Line: Our study shows that silencing of the Sgt1 gene in potato does not result in lethality.In contrast, the Rar1 gene is not required for RB-mediated resistance.These results provide additional evidence for the universal role of the Sgt1 gene in various R gene-mediated plant defense responses.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Horticulture, University of Wisconsin-Madison, Madison, WI 53706, USA. pudota1@wisc.edu

ABSTRACT

Background: Late blight is the most serious potato disease world-wide. The most effective and environmentally sound way for controlling late blight is to incorporate natural resistance into potato cultivars. Several late blight resistance genes have been cloned recently. However, there is almost no information available about the resistance pathways mediated by any of those genes.

Results: We previously cloned a late blight resistance gene, RB, from a diploid wild potato species Solanum bulbocastanum. Transgenic potato lines containing a single RB gene showed a rate-limiting resistance against all known races of Phytophthora infestans, the late blight pathogen. To better understand the RB-mediated resistance we silenced the potato Rar1 and Sgt1 genes that have been implicated in mediating disease resistance responses against various plant pathogens and pests. The Rar1 and Sgt1 genes of a RB-containing potato clone were silenced using a RNA interference (RNAi)-based approach. All of the silenced potato plants displayed phenotypically normal growth. The late blight resistance of the Rar1 and Sgt1 silenced lines were evaluated by a traditional greenhouse inoculation method and quantified using a GFP-tagged P. infestans strain. The resistance of the Rar1-silenced plants was not affected. However, silencing of the Sgt1 gene abolished the RB-mediated resistance.

Conclusion: Our study shows that silencing of the Sgt1 gene in potato does not result in lethality. However, the Sgt1 gene is essential for the RB-mediated late blight resistance. In contrast, the Rar1 gene is not required for RB-mediated resistance. These results provide additional evidence for the universal role of the Sgt1 gene in various R gene-mediated plant defense responses.

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Related in: MedlinePlus

Schematic representation of the potato Rar1 and Sgt1 genes and regions used for RNAi construct development.
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Figure 1: Schematic representation of the potato Rar1 and Sgt1 genes and regions used for RNAi construct development.

Mentions: We developed RNAi constructs for the potato Rar1 and Sgt1 genes. The Rar1 silencing construct contained a 474-bp fragment covering the CHORD II domain. The Sgt1 construct contained a 481-bp fragment that targets the P23/CS domain (Figure 1). These constructs were used for Agrobacterium-mediated transformation of the potato line K41. We obtained 65 and 58 independent transgenic lines for the Rar1 and Sgt1 genes, respectively.


Sgt1, but not Rar1, is essential for the RB-mediated broad-spectrum resistance to potato late blight.

Bhaskar PB, Raasch JA, Kramer LC, Neumann P, Wielgus SM, Austin-Phillips S, Jiang J - BMC Plant Biol. (2008)

Schematic representation of the potato Rar1 and Sgt1 genes and regions used for RNAi construct development.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2267190&req=5

Figure 1: Schematic representation of the potato Rar1 and Sgt1 genes and regions used for RNAi construct development.
Mentions: We developed RNAi constructs for the potato Rar1 and Sgt1 genes. The Rar1 silencing construct contained a 474-bp fragment covering the CHORD II domain. The Sgt1 construct contained a 481-bp fragment that targets the P23/CS domain (Figure 1). These constructs were used for Agrobacterium-mediated transformation of the potato line K41. We obtained 65 and 58 independent transgenic lines for the Rar1 and Sgt1 genes, respectively.

Bottom Line: Our study shows that silencing of the Sgt1 gene in potato does not result in lethality.In contrast, the Rar1 gene is not required for RB-mediated resistance.These results provide additional evidence for the universal role of the Sgt1 gene in various R gene-mediated plant defense responses.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Horticulture, University of Wisconsin-Madison, Madison, WI 53706, USA. pudota1@wisc.edu

ABSTRACT

Background: Late blight is the most serious potato disease world-wide. The most effective and environmentally sound way for controlling late blight is to incorporate natural resistance into potato cultivars. Several late blight resistance genes have been cloned recently. However, there is almost no information available about the resistance pathways mediated by any of those genes.

Results: We previously cloned a late blight resistance gene, RB, from a diploid wild potato species Solanum bulbocastanum. Transgenic potato lines containing a single RB gene showed a rate-limiting resistance against all known races of Phytophthora infestans, the late blight pathogen. To better understand the RB-mediated resistance we silenced the potato Rar1 and Sgt1 genes that have been implicated in mediating disease resistance responses against various plant pathogens and pests. The Rar1 and Sgt1 genes of a RB-containing potato clone were silenced using a RNA interference (RNAi)-based approach. All of the silenced potato plants displayed phenotypically normal growth. The late blight resistance of the Rar1 and Sgt1 silenced lines were evaluated by a traditional greenhouse inoculation method and quantified using a GFP-tagged P. infestans strain. The resistance of the Rar1-silenced plants was not affected. However, silencing of the Sgt1 gene abolished the RB-mediated resistance.

Conclusion: Our study shows that silencing of the Sgt1 gene in potato does not result in lethality. However, the Sgt1 gene is essential for the RB-mediated late blight resistance. In contrast, the Rar1 gene is not required for RB-mediated resistance. These results provide additional evidence for the universal role of the Sgt1 gene in various R gene-mediated plant defense responses.

Show MeSH
Related in: MedlinePlus