Septoria and Stagonospora Diseases of Cereals - CIMMYT ...

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Sources of Resistance to Septoria passerinii in Hordeum
vulgare and H. vulgare subsp. spontaneum
H. Toubia-Rahme and B.J. Steffenson (Poster)
North Dakota State University, Department of Plant Pathology, Fargo, ND, USA
Abstract
Septoria speckled leaf blotch (SSLB), incited by Septoria passerinii and Stagonospora avenae f. sp. triticea, has
become one of the most serious diseases of barley in the Upper Midwest region of the USA. In barley SSLB can cause
significant losses in both the yield and quality. The major malting and feed barley cultivars in the Upper Midwest are very
susceptible to SSLB. Resistance breeding is the most effective strategy for controlling this disease. A diverse group of barley
germplasm including Hordeum vulgare subsp. spontaneum accessions, advanced midwestern breeding lines, and
commercial cultivars was evaluated at the seedling stage in the greenhouse for reaction to S. passerinii. Of 200 accessions
tested, 79 were found resistant. Most of H. vulgare subsp. spontaneum accessions (17 of 24) were resistant to S. passerinii.
These accessions all originated from the Middle East, except one that was from Tibet. Most of the advanced midwestern
breeding lines found resistant to this pathogen have Gloria”S”/Copal”S” (an ICARDA/CIMMYT barley line) in their
pedigree, which is believed to be a source of resistance to S. passerinii. From this study, it is evident that many barley
accessions possess resistance to S. passerinii. Additional evaluations will be made on this germplasm to S. avenae f. sp.
triticea to identify accessions that possess effective resistance to both SSLB pathogens.
Septoria speckled leaf blotch
(SSLB), caused by Septoria passerinii
and Stagonospora avenae f. sp.
triticea, has become an increasingly
important disease of barley
(Hordeum vulgare L.) over the past
decade in the Upper Midwest
region of the USA. In surveys of
North Dakota barley fields in 1998,
S. passerinii and S. avenae f. sp.
triticea were recovered from 45%
and 37% of leaves exhibiting leaf
spot symptoms, respectively
(Krupinsky and Steffenson, this
volume). Yield losses of 20% have
been recorded in barley due to S.
passerinii infection (Green and
Bendelow, 1961). In recent trials
conducted in North Dakota, yield
losses of 23% to 38% were
observed in Robust barley infected
with SSLB (J. Lukach and B.
Steffenson, unpublished data). In
addition to reducing yield, SSLB
also reduces kernel plumpness and
malt extract, which are important
malt quality characters (Green and
Bendelow, 1961).
Host plant resistance provides
the most practical and
environmentally safe method of
disease control. Unfortunately, all
major malting and feed barley
cultivars in the Upper Midwest
region are susceptible to SSLB. The
objectives of this study were to 1)
identify sources of resistance to S.
passerinii in commercial barley
cultivars, agronomically advanced
midwestern breeding lines, and
Hordeum vulgare subsp. spontaneum
accessions; and 2) evaluate
previously reported sources of S.
passerinii resistance to a
midwestern isolate of this
pathogen.
Materials and Methods
In total, 200 barley entries
including 24 H. vulgare subsp.
spontaneum accessions were
evaluated at the seedling stage in
the greenhouse. Five seeds of each
entry were planted in pots (10 x 10
cm) filled with a potting mix
consisting of peat moss (75%) and
perlite (25%). Slow-release (14-14-
14, N-P-K, 2 g/pot) and watersoluble
(15-0-15, N-P-K, 2 g/pot)
fertilizers were added at the time of
planting. All seedlings were grown
in the greenhouse at 20±3ºC with a
14-h photoperiod. The fungal
isolate (ND97-15) used in this
study was obtained from naturally
infected barley leaves collected
from a commercial field in
Bottineau county, North Dakota, in
1997. For inoculum production, the
isolate was grown on yeast malt
agar (YMA) (Eyal et al., 1987) in
plastic Petri dishes at 21ºC with a
12-h photoperiod (cool-white
fluorescent tubes). When pycnidia
developed and sporulated, mass
spore transfers were made by
removing with a sterile needle
cirrhi from pycnidia and
transferring them to other YMA
plates. After 4-5 days of incubation
under the same conditions,
pycnidia were harvested by
flooding the surface of the plates