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Lr67 and Lr34 rust resistance genes have much in common--they confer broad spectrum resistance to multiple pathogens in wheat.

Spielmeyer W, Mago R, Wellings C, Ayliffe M - BMC Plant Biol. (2013)

Bottom Line: Detailed study of Lr34 mutants revealed that subtle changes in resistance response to multiple pathogens were correlated with mutational changes in the predicted protein.Recovery of independent Lr67 mutants indicates that as for Lr34, a single gene at the Lr67 locus is likely to confer resistance to multiple pathogens.The infection phenotypes of Lr67 mutants closely resembled that of Lr34 mutants.

View Article: PubMed Central - HTML - PubMed

Affiliation: CSIRO Plant Industry, GPO Box 1600, Canberra 2601, ACT, Australia. wolfgang.spielmeyer@csiro.au

ABSTRACT

Background: Adult plant rust resistance genes Lr67 and Lr34 confer race non-specific resistance to multiple fungal pathogens of wheat. Induced, susceptible mutants were characterised for both genes.

Results: Three categories of Lr34 mutants were identified that were either partial susceptible, fully susceptible or hyper-susceptible to stripe rust and leaf rust. The likely impact of the mutational change on the predicted Lr34 protein correlated with differences in response to rust infection. Four independent Lr67 mutants were recovered that were susceptible to stripe rust, leaf rust and stem rust pathogens, including one possible hyper-susceptible Lr67 mutant.

Conclusions: Detailed study of Lr34 mutants revealed that subtle changes in resistance response to multiple pathogens were correlated with mutational changes in the predicted protein. Recovery of independent Lr67 mutants indicates that as for Lr34, a single gene at the Lr67 locus is likely to confer resistance to multiple pathogens. The infection phenotypes of Lr67 mutants closely resembled that of Lr34 mutants.

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Diagram of predicted Lr34 protein showing nucleotide binding domains NBD1 and NBD2 and two transmembrane domains. The Lr34 protein differs from the protein encoded by the Thatcher allele by the absence of a phenylalanine residue (F) and a substitution of histidine (H) for tyrosine (T) in first transmembrane domain. Based on different responses to leaf rust and stripe rust infections, mutants were placed into three categories of susceptibility; partial susceptibility caused by single amino acid changes in the first or second NBD (mutants 2G, 4C and 4G), full susceptibility, similar to Thatcher, in which mutants were predicted to encode severely truncated and probably non-functional proteins (mutants 2B, 3E, 3F and 4E) and hyper-susceptibility (more susceptible than Thatcher) represented by mutant 2F which encoded a protein with a deletion of 85 amino acids in the second transmembrane domain.
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Figure 4: Diagram of predicted Lr34 protein showing nucleotide binding domains NBD1 and NBD2 and two transmembrane domains. The Lr34 protein differs from the protein encoded by the Thatcher allele by the absence of a phenylalanine residue (F) and a substitution of histidine (H) for tyrosine (T) in first transmembrane domain. Based on different responses to leaf rust and stripe rust infections, mutants were placed into three categories of susceptibility; partial susceptibility caused by single amino acid changes in the first or second NBD (mutants 2G, 4C and 4G), full susceptibility, similar to Thatcher, in which mutants were predicted to encode severely truncated and probably non-functional proteins (mutants 2B, 3E, 3F and 4E) and hyper-susceptibility (more susceptible than Thatcher) represented by mutant 2F which encoded a protein with a deletion of 85 amino acids in the second transmembrane domain.

Mentions: Single nucleotide transition events (G to A or C to T), characteristic of sodium azide mutagenesis, were present in the Lr34 putative ABC transporter gene in each of the eight mutants (Table 1 and Figure 3) [15]. Three categories of mutants were identified. Four mutants (2B, 3E, 3F and 4E) encoded nonsense mutations in the Lr34 ORF and are predicted to produce truncated and probably non-functional proteins. The responses to stripe rust and leaf rust infection of these mutants were indistinguishable from the susceptible Thatcher parent. Three mutants (2G, 4C and 4G) encoded missense mutations that result in single changes within highly conserved amino acids of the predicted first or second nucleotide binding domain of the protein (Figure 4). All three mutants showed an intermediate accumulation of stripe rust chitin in flag leaves compared with the parental lines, while seedlings of mutants 2G and 4C were also partially susceptible to leaf rust. The hyper-susceptible mutant 2F encoded a mutation at the 3′ splice site of intron 22 resulting in transcripts encoding the predicted wild type protein and alternative transcripts lacking exon 23 (Figure 3), encoding a protein with part of the second transmembrane domain deleted (Figure 4). This mutant was more susceptible to stripe rust and accumulated the highest level of stripe rust biomass in flag leaves under field conditions, in addition to showing enhanced seedling susceptibility to leaf rust at the seedling stage.


Lr67 and Lr34 rust resistance genes have much in common--they confer broad spectrum resistance to multiple pathogens in wheat.

Spielmeyer W, Mago R, Wellings C, Ayliffe M - BMC Plant Biol. (2013)

Diagram of predicted Lr34 protein showing nucleotide binding domains NBD1 and NBD2 and two transmembrane domains. The Lr34 protein differs from the protein encoded by the Thatcher allele by the absence of a phenylalanine residue (F) and a substitution of histidine (H) for tyrosine (T) in first transmembrane domain. Based on different responses to leaf rust and stripe rust infections, mutants were placed into three categories of susceptibility; partial susceptibility caused by single amino acid changes in the first or second NBD (mutants 2G, 4C and 4G), full susceptibility, similar to Thatcher, in which mutants were predicted to encode severely truncated and probably non-functional proteins (mutants 2B, 3E, 3F and 4E) and hyper-susceptibility (more susceptible than Thatcher) represented by mutant 2F which encoded a protein with a deletion of 85 amino acids in the second transmembrane domain.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3716802&req=5

Figure 4: Diagram of predicted Lr34 protein showing nucleotide binding domains NBD1 and NBD2 and two transmembrane domains. The Lr34 protein differs from the protein encoded by the Thatcher allele by the absence of a phenylalanine residue (F) and a substitution of histidine (H) for tyrosine (T) in first transmembrane domain. Based on different responses to leaf rust and stripe rust infections, mutants were placed into three categories of susceptibility; partial susceptibility caused by single amino acid changes in the first or second NBD (mutants 2G, 4C and 4G), full susceptibility, similar to Thatcher, in which mutants were predicted to encode severely truncated and probably non-functional proteins (mutants 2B, 3E, 3F and 4E) and hyper-susceptibility (more susceptible than Thatcher) represented by mutant 2F which encoded a protein with a deletion of 85 amino acids in the second transmembrane domain.
Mentions: Single nucleotide transition events (G to A or C to T), characteristic of sodium azide mutagenesis, were present in the Lr34 putative ABC transporter gene in each of the eight mutants (Table 1 and Figure 3) [15]. Three categories of mutants were identified. Four mutants (2B, 3E, 3F and 4E) encoded nonsense mutations in the Lr34 ORF and are predicted to produce truncated and probably non-functional proteins. The responses to stripe rust and leaf rust infection of these mutants were indistinguishable from the susceptible Thatcher parent. Three mutants (2G, 4C and 4G) encoded missense mutations that result in single changes within highly conserved amino acids of the predicted first or second nucleotide binding domain of the protein (Figure 4). All three mutants showed an intermediate accumulation of stripe rust chitin in flag leaves compared with the parental lines, while seedlings of mutants 2G and 4C were also partially susceptible to leaf rust. The hyper-susceptible mutant 2F encoded a mutation at the 3′ splice site of intron 22 resulting in transcripts encoding the predicted wild type protein and alternative transcripts lacking exon 23 (Figure 3), encoding a protein with part of the second transmembrane domain deleted (Figure 4). This mutant was more susceptible to stripe rust and accumulated the highest level of stripe rust biomass in flag leaves under field conditions, in addition to showing enhanced seedling susceptibility to leaf rust at the seedling stage.

Bottom Line: Detailed study of Lr34 mutants revealed that subtle changes in resistance response to multiple pathogens were correlated with mutational changes in the predicted protein.Recovery of independent Lr67 mutants indicates that as for Lr34, a single gene at the Lr67 locus is likely to confer resistance to multiple pathogens.The infection phenotypes of Lr67 mutants closely resembled that of Lr34 mutants.

View Article: PubMed Central - HTML - PubMed

Affiliation: CSIRO Plant Industry, GPO Box 1600, Canberra 2601, ACT, Australia. wolfgang.spielmeyer@csiro.au

ABSTRACT

Background: Adult plant rust resistance genes Lr67 and Lr34 confer race non-specific resistance to multiple fungal pathogens of wheat. Induced, susceptible mutants were characterised for both genes.

Results: Three categories of Lr34 mutants were identified that were either partial susceptible, fully susceptible or hyper-susceptible to stripe rust and leaf rust. The likely impact of the mutational change on the predicted Lr34 protein correlated with differences in response to rust infection. Four independent Lr67 mutants were recovered that were susceptible to stripe rust, leaf rust and stem rust pathogens, including one possible hyper-susceptible Lr67 mutant.

Conclusions: Detailed study of Lr34 mutants revealed that subtle changes in resistance response to multiple pathogens were correlated with mutational changes in the predicted protein. Recovery of independent Lr67 mutants indicates that as for Lr34, a single gene at the Lr67 locus is likely to confer resistance to multiple pathogens. The infection phenotypes of Lr67 mutants closely resembled that of Lr34 mutants.

Show MeSH
Related in: MedlinePlus