Disease Devils: Assessing the Threats and our Readiness
Disease Devils: Assessing the Threats and our Readiness
Disease Devils: Assessing the Threats and our Readiness
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<strong>Disease</strong> <strong>Devils</strong>: <strong>Assessing</strong> <strong>the</strong><br />
<strong>Threats</strong> <strong>and</strong> <strong>our</strong> <strong>Readiness</strong><br />
Brian Steffenson<br />
Department of Plant Pathology<br />
University of Minnesota<br />
St. Paul<br />
Next Generation Barley Varieties III, San Diego, CA<br />
January 16, 2012
Stem rust: virulent African races<br />
Spot blotch: virulent isolate ND4008<br />
Spot form net blotch<br />
<strong>Disease</strong> <strong>Devils</strong><br />
Powdery mildew, scald & BYDV (winter barley)
Stem Rust<br />
Causal agents: Puccinia<br />
graminis f. sp. tritici & P. g. f. sp.<br />
secalis<br />
One of <strong>the</strong> most devastating<br />
plant diseases known<br />
Caused severe epidemics last in<br />
<strong>the</strong> last century
Stem Rust Resistance<br />
Rpg1 gene<br />
Seedling stage Adult stage
Stem Rust Resistance<br />
Rpg1 gene<br />
Rpg1 is effective against many, but not all races:<br />
e.g. QCCJ <strong>and</strong> rye stem rust<br />
In 1990, race QCCJ caused some damage to<br />
barley cultivars in USA & Canada<br />
QCCJ no longer poses a threat due to largely<br />
resistant wheat crop<br />
Notwithst<strong>and</strong>ing <strong>the</strong> minor outbreak of<br />
race QCCJ, Rpg1 has protected barley<br />
from serious losses since 1942
New Threat to Wheat<br />
African stem rust<br />
In 1998, an isolate attacking wheats with gene<br />
Sr31 was collected from Ug<strong>and</strong>a<br />
Ug99 keyed to race TTKSK on <strong>the</strong> st<strong>and</strong>ard single<br />
gene wheat differentials
Keying Stem Rust Races on Single Gene Wheats<br />
Set Line Sr gene 04KEN156<br />
1 ISr5Ra 5 4<br />
T.m.deri. 21 3+<br />
Verstein 9e 4 T<br />
ISr7bRa 7b 3<br />
2 ISr11Ra 11 4<br />
ISr6Ra 6 4<br />
ISr8Ra 8a 4 T<br />
CnsSr9g 9g 4<br />
3 W2691SrTt-1 36 0<br />
W2691Sr9b 9b 4<br />
BtSr30Wst 30 4 K<br />
Comb. VII 17+13 2++<br />
4 ISr9aRa 9a 4<br />
ISr9dRa 9d 4<br />
W2691Sr10 10 4 S<br />
CnsSrTmp Tmp 2+<br />
Race: TTKS (K)<br />
B RRRR<br />
C RRRS<br />
D RRSR<br />
F RRSS<br />
G RSRR<br />
H RSRS<br />
J R S S R<br />
K R S S S<br />
L SRRR<br />
M SRRS<br />
N S R S R<br />
P S R S S<br />
Q S S R R<br />
R S S R S<br />
S S S S R<br />
T S S S S
Distribution & Spread of Ug99 Group<br />
Races
TTKSK Also Attacks Barleys with Rpg1!<br />
Early tests conducted in Kenya<br />
revealed susceptibility of barley<br />
cultivars carrying Rpg1<br />
TTKSK is a global threat to wheat &<br />
barley
Resistance to Race TTKSK<br />
Advances in combating TTKSK came as a result<br />
of research done on race QCCJ in early 1990’s<br />
Q21861 is resistant to race TTKSK; controlled<br />
by genes rpg4 <strong>and</strong> Rpg5<br />
Fur<strong>the</strong>r evaluations were done to identify o<strong>the</strong>r<br />
resistance s<strong>our</strong>ces & assess vulnerability of barley
Screening for Resistance to Race TTKSK<br />
Of <strong>the</strong> 1,902 cultivated barleys screened, only<br />
42 (2.3%) exhibited some resistance—but many<br />
carry <strong>the</strong> same resistance genes<br />
Of <strong>the</strong> 935 wild barleys screened, only 16<br />
(1.7%) exhibited some resistance<br />
Thus, over 97% of Hordeum germplasm is<br />
susceptible to race TTKSK<br />
I<br />
T<br />
=<br />
I<br />
T<br />
=
Association Mapping of Novel QTL<br />
<strong>Disease</strong> reduction due to<br />
allele:<br />
APR to Race TTKSK<br />
4-21% under high disease<br />
23-55% under low<br />
disease
African Stem Rust<br />
Causes severe yield loss under right conditions<br />
Widely virulent on >97% of Hordeum germplasm<br />
Many variants exist in Ug99 lineage<br />
Fungicides can be used to control this disease<br />
Exists only in Africa & Middle East right now...<br />
<strong>Disease</strong> devil threat rating:
Spot Blotch of Barley<br />
Midwest USA<br />
Historically, one of <strong>the</strong> most important diseases<br />
in <strong>the</strong> Midwest<br />
Epidemics frequent with yield losses >40%<br />
Also affects malting & feed quality by reducing<br />
kernel plumpness
Durable Spot Blotch Resistance<br />
Midwest Six-rowed Cultivars<br />
All 6-row cultivars have NDB112<br />
resistance & are planted on >1.5<br />
m ha annually<br />
Pathogen is ubiquitous &<br />
capable of causing epidemics<br />
over a range of conditions<br />
Epidemics have not been<br />
observed on any six-rowed<br />
cultivars since 1964
Ephemeral Spot Blotch Resistance<br />
Midwest Two-rowed Cultivars<br />
Two-rowed cultivars were once bred primarily for<br />
feed & are grown in <strong>the</strong> western Dakotas<br />
‘Bowman’ was considered moderately resistant<br />
when first released in 1984<br />
In 1990, Bowman <strong>and</strong> its progeny were severely<br />
infected by spot blotch
Reaction of Two-rowed Barley<br />
Isolates from Bowman were compared with a<br />
st<strong>and</strong>ard C. sativus isolate used in screening<br />
These isolates exhibited a distinctly higher<br />
virulence than <strong>the</strong> st<strong>and</strong>ard isolate<br />
Isolate: ND85F ND90Pr<br />
Bowman Barley
Durable Resistance Haplotype<br />
Barley CAP<br />
Bowman has identical haplotype,<br />
but is less resistant to isolate<br />
ND85F <strong>and</strong> completely susceptible<br />
to ND90Pr
Danger Below Ground!<br />
In 2005, Sanjaya Gyawali collected a C. sativus<br />
isolate (ND4008) from a barley subcrown<br />
Subsequent disease phenotype assays revealed<br />
virulence on NDB112!<br />
NDB112 Bowman<br />
Seedling Stage<br />
NDB112<br />
Adult Stage
NDB112-Virulent Isolates<br />
Distribution of such NDB112-virulent isolates in<br />
<strong>the</strong> Midwest is unknown, but caution is being<br />
used in all research<br />
Possible similar virulence types were reported in<br />
Canada <strong>and</strong> also <strong>the</strong> subtropics<br />
Urgency for identifying s<strong>our</strong>ces of resistance
One half of barley core collection evaluated at<br />
seedling stage<br />
# of barley lines<br />
600<br />
500<br />
400<br />
300<br />
200<br />
100<br />
0<br />
1 2 3 4 5 6 7 8 9<br />
Ave. disease score<br />
Seedling assays<br />
PI235186 PI290193 NDB112 Bowman
NDB112-Virulent Spot Blotch Isolates<br />
Isolate ND4008 is a threat to barley production<br />
Resistance has been identified but is rare<br />
Association mapping is being used to position <strong>the</strong><br />
gene(s) <strong>and</strong> tag <strong>the</strong>m for marker assisted selection<br />
Fungicides can be used to control this disease<br />
<strong>Disease</strong> devil threat rating:
Spot Form Net Blotch<br />
Pathogen: Pyrenophora teres f. maculata (Drechlera<br />
teres f. teres)<br />
Causes different symptom type than net blotch<br />
pathogen, P. teres f. teres<br />
Net Form Spot Form<br />
Previously reported in adjacent regions in Canada<br />
<strong>and</strong> Montana
Spot Form Net Blotch<br />
Initial Report in Upper Midwest<br />
1st confirmed in ND in 2006 from Fargo <strong>and</strong> 2008<br />
from Langdon
Spot Form Net Blotch<br />
Now a widespread problem & supplanting net form<br />
net blotch<br />
Losses >40% are possible
SFNB-Fargo<br />
SFNB-Langdon<br />
SFNB-Denmark<br />
NFNB-California<br />
Spot Form Net Blotch<br />
Phenotypes on cv. Robust
Host Reactions: Spot Form Net Blotch<br />
Six-Rowed<br />
Variety<br />
Reaction to <strong>Disease</strong> % <strong>Disease</strong><br />
Severity<br />
SB NFNB SFNB<br />
Robust MR/R MS/S MS/S 5.3<br />
Lacey MR/R MS/S MR 3.0<br />
Tradition MR/R MS/S MS 5.3<br />
Stellar-ND MR/R MS/S MS 6.3<br />
Rasmusson MR/R MS/S MS 7.0<br />
Celebration MR/R MS/S MS 3.7<br />
Quest MR/R MS/S MR 3.7<br />
Innovation MR/R MS/S MS 5.3
Host Reactions: Spot Form Net Blotch<br />
Two-Rowed<br />
Variety<br />
Reaction to <strong>Disease</strong> % <strong>Disease</strong><br />
Severity<br />
SB NFNB SFNB<br />
Conlon MS MR/R MR 5.3<br />
Rawson MR MS MS 5.3<br />
Pinnacle MR MS S 6.3<br />
AC Metcalfe MS MS MS 5.3<br />
Haxby MS -- MS 4.7<br />
CDC Copel<strong>and</strong> MS MR MS 8.0<br />
Conrad -- -- MS 15.0<br />
Lilly S MR/R MS/S 8.0<br />
Moravian 133 -- -- -- 8.0
Spot Form Net Blotch<br />
TCAP Resistance Screening<br />
1050 barley core lines screened with two isolates<br />
(ND & AUS isolate) at seedling stage in greenhouse<br />
Same core lines screened at three locations in field<br />
at adult stage in natural <strong>and</strong> inoculated nurseries<br />
Association mapping studies will be conducted<br />
Resistant core <strong>and</strong> ND lines identified <strong>and</strong> crosses<br />
to characterize resistance are underway
Yield Response of 6-Rows to Fungicides<br />
Leaf Spot <strong>Disease</strong>: Langdon<br />
Yield, Bu/A<br />
180<br />
160<br />
140<br />
120<br />
100<br />
80<br />
60<br />
40<br />
20<br />
0<br />
unsprayed<br />
sprayed
Yield Response of 2-Rows to Fungicides<br />
Leaf Spot <strong>Disease</strong>: Langdon<br />
Yield, Bu/A<br />
180<br />
160<br />
140<br />
120<br />
100<br />
80<br />
60<br />
40<br />
20<br />
0<br />
unsprayed<br />
sprayed
Spot Form Net Blotch<br />
SFNB is a new component of <strong>the</strong> foliar leaf spot<br />
complex in North Dakota<br />
Most current cultivars are susceptible<br />
Moderately resistant cultivars are available &<br />
additional resistant lines are in <strong>the</strong> pipeline<br />
Fungicides can be effective in controlling <strong>the</strong><br />
disease <strong>and</strong> provide a positive yield response<br />
<strong>Disease</strong> devil threat rating:
Winter Barley in <strong>the</strong> Midwest<br />
2011-12 Winter<br />
Barley Trial<br />
St. Paul<br />
Powdery Mildew Leaf Scald BYDV
Summary<br />
Next generation barley cultivars must be<br />
competitive to gain acreage vs. o<strong>the</strong>r crops<br />
Resistance to biotic constraints must be part of <strong>the</strong><br />
genetic package<br />
Stem rust, spot blotch, <strong>and</strong> spot form net blotch<br />
are real threats to barley production<br />
Resistance has been identified for all diseases<br />
<strong>and</strong> is being incorporated into advanced lines<br />
Fungicides are also an option for control
Yue Jin, USDA-ARS<br />
Robert Brueggeman, NDSU<br />
Tim Friesen, USDA-ARS<br />
Shaobin Zhong, NDSU<br />
American Malting Barley Association<br />
Lieberman-Okinow Endowment<br />
Barley CAP<br />
Triticeae CAP<br />
Acknowledgments<br />
Durable Rust Resistance of Wheat: Cornell University
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