Advance on wheat breeding to leaf rust resistance
C. Turra, A. L. Barcellos*, A. A. Baggio, S. B. Rosa
OR Melhoramento de Sementes Ltda., Av. Rui Barbosa, 1300, Passo Fundo, RS, Brazil, 99050-120.
*[email protected]
Introduction
The Brazilian climate, humid by the frequent rains principally during
the reproductive stages, and the susceptible wheat cultivars result
in the occurrence of many diseases reducing the yield. Among these
diseases, the leaf rust stands out because of its frequency and
damage. It is not rare cultivars with race specific leaf rust resistance
to turn susceptible after few years of release, caused by selection in
the fungi population. In Brazil, 112 cultivars are indicated to be
cultivated in the moment. Among these, 59 cultivars have different
levels of susceptibility to leaf rust. The aim of this study was the
introduction of leaf rust durable resistance genes in the best
Brazilian wheat cultivars.
Material and Methods
The introduction of durable genes was started in 2002 in the
breeding company OR Melhoramento de Sementes Ltda. The study
was conducted in Passo Fundo, RS, Brazil at OR Sementes laboratory
and in experimental field nurseries in Coxilha, RS, Brazil. Durable
resistance genes Lr34, Lr21, Lr13 plus minor genes in Frontana, and
unindentified genes in Kukuna, Fundacep 30, Toropi (Trp1, Trp2) and
Pampeano were introduced in the cultivars OR1, Ônix and Quartzo
through backcrossing. The OR cultivars Ametista, Topázio, Jadeíte 11
and ORS Vintecinco were also evaluated, as well as OR advanced
lines. Mixture of MDT-MR 4002 Virulence, MCS-LN, TFT-MT, TFP-HT
and TFT-PT races were artificially inoculated in the field in rows (8,92
m2) in 2013. To evaluate the efficiency of the durable resistance
genes to reduce the rust damage was sprayed fungicide
(epoxiconazol and piraclostrobine, 500 mL/ha) to manage the
disease. The rows were divided in area with and without fungicide.
The yield (Kg/ha) was compared among the susceptible cultivars and
the lines of each cultivar with additional resistance genes. The lines
Kukuna/2*OR1, Toropi/2*OR1, Toropi/2*Ônix were developed
following the One Backcross methodology (Singh, RP et al., CIMMYT).
Table 1. Yiel.d of cultivars and their lines with the introduction of durable resistance
genes (DRG) derived from backcrossing with and without fungicide application.
8000
Yield (Kg/ha)
7000
6000
Susceptible
cultivar
(OR1, Ônix or
Quartzo
X
Amadina
Chapio
Frontana
Kukuna
Tukuru
Toropi
20 F1 spikes X Susceptible 
of each
cultivar
cross
1600 RC2 plants/cross






F1
F1
F1
F1
F1
F1
400 - 500 seeds RC1
RC1, RC2 and RC3: selection of low to
intermediate leaf rust severity
1000 RC3-RC5 plants/cross
RC4 e RC5: low severity
RC6 lines evaluated for rust, agronomy, other diseases, etc.
Selected lines were evaluated for yield.
Results and Conclusion
Effectiveness of durable genes comparing the yield difference between
susceptible cultivar and a line of it with durable resistance genes:
OR1 and OR1+GRD: 4.198 Kg/ha
Ônix and Ônix+GRD: 3.595 Kg/ha
Quartzo and Quartzo+GRD: 4.428 Kg/ha
5000
High yield of Jadeíte 11 (5.199 Kg/ha) and ORS Vintecinco (5.509 Kg/ha)
without fungicide indicated the efficiency of their genetic resistance.
4000
3000
The study showed the progress of the breeding for leaf rust
resistance by the introduction of adult durable resistance genes
and pyramidization of genes through backcrossing and selection
of individually plants in the field.
2000
1000
0
Com fungicida
Sem fungicida
OR Sementes has improved OR1, Ônix e Quartzo to be
cultivated by wheat growers. Lines with better and
durable leaf rust resistance, higher yield and with
economical and environmental advantages.
Advance on wheat breeding to leaf rust resistance
C. Turra, A. L. Barcellos*, A. A. Baggio, S. B. Rosa
OR Melhoramento de Sementes Ltda., Av. Rui Barbosa, 1300, Passo Fundo, RS, Brazil, 99050-120.
*[email protected]
Introduction
The Brazilian climate, humid by the frequent rains principally during
the reproductive stages, and the susceptible wheat cultivars result in
the occurrence of many diseases reducing the yield. Among these
diseases, the leaf rust stands out because of its frequency and
damage. It is not rare cultivars with race specific leaf rust resistance
to turn susceptible after few years of release, caused by selection in
the fungi population. In Brazil, 112 cultivars are indicated to be
cultivated in the moment. Among these, 59 cultivars have different
levels of susceptibility to leaf rust. The aim of this study was the
introduction of leaf rust durable resistance genes in the best Brazilian
wheat cultivars.
Material and Methods
The introduction of durable genes was started in 2002 in the
breeding company OR Melhoramento de Sementes Ltda. The study
was conducted in Passo Fundo, RS, Brazil at OR Sementes laboratory
and in experimental field nurseries in Coxilha, RS, Brazil. Durable
resistance genes Lr34, Lr21, Lr13 plus minor genes in Frontana, and
unindentified genes in Kukuna, Fundacep 30, Toropi (Trp1, Trp2) and
Pampeano were introduced in the cultivars OR1, Ônix and Quartzo
through backcrossing. The OR cultivars Ametista, Topázio, Jadeíte 11
and ORS Vintecinco were also evaluated, as well as OR advanced
lines. Mixture of MDT-MR 4002 Virulence, MCS-LN, TFT-MT, TFP-HT
and TFT-PT races were artificially inoculated in the field in rows (8,92
m2) in 2013. To evaluate the efficiency of the durable resistance
genes to reduce the rust damage was sprayed fungicide
(epoxiconazol and piraclostrobine, 500 mL/ha) to manage the
disease. The rows were divided in area with and without fungicide.
The yield (Kg/ha) was compared among the susceptible cultivars and
the lines of each cultivar with additional resistance genes. The lines
Kukuna/2*OR1, Toropi/2*OR1, Toropi/2*Ônix were developed
following the One Backcross methodology (Singh, RP et al., CIMMYT).
Table 1. Yiel.d of cultivars and their lines with the introduction of durable resistance
genes (DRG) derived from backcrossing with and without fungicide application.
8000
Yield (Kg/ha)
7000
6000
5000
Susceptible
cultivar
(OR1, Ônix or
Quartzo
X
Amadina
Chapio
Frontana
Kukuna
Tukuru
Toropi
20 F1 spikes X Susceptible 
of each
cultivar
cross
1600 RC2 plants/cross






F1
F1
F1
F1
F1
F1
400 - 500 seeds RC1
RC1, RC2 and RC3: selection of low to
intermediate leaf rust severity
1000 RC3-RC5 plants/cross
RC4 e RC5: low severity
RC6 lines evaluated for rust, agronomy, other diseases, etc.
Selected lines were evaluated for yield.
Results and Conclusion
Cultivar
Yield (Kg/ha)
No fungicide
OR1
Ônix
533
1.777
Advanced line
One Backcross Methodology
Kukuna/2*OR1
Toropi/2*OR1
Toropi/2*Ônix
4.731
4.376
4.386
Effectiveness of durable genes comparing the yield difference between
susceptible cultivar and a line of it with durable resistance genes:
OR1 and OR1+GRD: 4.198 Kg/ha
Ônix and Ônix+GRD: 3.595 Kg/ha
Quartzo and Quartzo+GRD: 4.428 Kg/ha
High yield of Jadeíte 11 (5.199 Kg/ha) and ORS Vintecinco (5.509 Kg/ha)
without fungicide indicated the efficiency of their genetic resistance.
4000
3000
The study showed the progress of the breeding for leaf rust
resistance by the introduction of adult durable resistance genes and
pyramidization of genes through backcrossing and selection of
individually plants in the field.
2000
1000
0
Com fungicida
Sem fungicida
OR Sementes has improved OR1, Ônix e Quartzo to be
cultivated by wheat growers. Lines with better and
durable leaf rust resistance, higher yield and with
economical and environmental advantages.