A Database for Triticeae and Avena
Wild grown populations of Hordeum spontaneum in Israel represent a
large gene pool for disease resistance. This assumption has been
repeatedly confirmed by different authors (Fischbeck et al., 1976; Wahl
et al., 1978; Moseman et al., 1983; Giles and von Bothmer, 1985; Jahoor
and Fischbeck, 1987a, 1987b, 1987c). Jahoor and Fischbeck (1987b)
reported that many resistance genes for powdery mildew of H. spontaneum
derived lines do not belong to the Ml-a locus. They also aetermined the
presence of Ml-p resistance in the H. spontaneum derived line Diamant
/7B-5A. Schaller and Briggs (1955) located the Ml-p locus on the short
arm of chromosome 5 which has been confirmed by several other authors
including Jensen and Jergensen (1975). In 1985 Jensen mentioned
unpublished data which indicate that Ml-p is not located on chromosome 5,
but did not publish fürther details. Our results (Jahoor and
Fischbeck, 1987) showed again linkage between Ml-a and Ml-p on chromsome 5.
From earlier studies (Fischbeck, 1981), it is known that virulence
against Ml-p resistance is present in the mildew population spread on
wild grown H. spontaneum stands in Israel.
Two H. spontaneum derived lines were crossed with 'Roland'
(susceptiEle reaction against mildew cultures MC-IS-2 and 184-21) as
well as with the isogenic line P 19 which carries the Ml-p mildew
resistance gene. The crosses RS 145/Aramir B//Roland and RS 170-35
/Aramir B//Roland segregated into a 3:1 ratio indicating the presence
of a dominant gene for powdery mildew resistance in both H. spontaneum
derived lines (Table 1). Testcrosses with line P 19 were used to test
allelism with the Ml-p locus. Since no segregation occurred in these
crosses, the conclusion seems justified that the genes of both H.
spontaneum derived lines are allelic to or closely linked with the Ml-p
The reaction pattern of RS 145-1/Aramir B and RS 170-35/Aramir
B with 7 mildew cultures are given in Table 2. The isolates MC-IS-2 and
PS-IS-2 collected from wild grown populations of H. spontaneum in Israel
clearly distinguish the reaction of line RS 145-17Aramir B from
Psaknon. Upon infection with the European mildew culture 201/107, line
RS 170-35/Aramir B reacted as moderately susceptible whereas Psaknon
showed a clearly distinguishable I-II type of reaction. Less noticeable
differences were also observed in the reactions against cultures 184-2
On the account of these results, it is concluded that the
resistance genes present in the two H. spontaneum derived lines are
different from the resistance gene of the cv. Psaknon (Ml-p) to which
they are either allelic or closely linked. Estimates of the 95% upper
confidence limit of recombination resulted in values < 0.095% for line
RS 145-1/Aramir B and < 0.067% for line RS 170-35/Aramir B (Table
1). Therefore it is suggested that the genes present in line RS 145-1/
Aramir B and line RS 170-35/Aramir B should be designated Ml-p2 and
Thanks are due Ms. C. Stockenreiter for technical assistance in
Fischbeck, G. 1981. Ergebnisse von Untersuchungen uber Krank-
heitsresistenz in israelischen Populationen von Hordeum spontaneum im
Hinblock auf Gegenwartsprobleme der Resistenzzuchtung. Tagungsbericht
der "Arbeitsgemeinschaft der Saatzuchtleiter". Gumpenstein 32:3-13.
Fischbeck, G., E. Schwarzbach, Z. Sobel, and I. Wahl. 1976.
Mehltauresistenz aus israelischen Populationen der zweizeiligen
Wildgerste (Hordeum spontaneum).Z. Pflanzenzuchtg. 76:163-166.
Giles, B.E., and R. von Bothmer. 1985. The progenitor of barley
(Hordeum vulgare ssp. spontaneum) - its importance as a gene
resource. Sveriges utsadesforenings Tidskrift 95:53-61.
Jahoor, A., and G. Fischbeck. 1987a. Genetical studies of resistance
of powdery mildew in barley lines derived from Hordeum spontaneum
collected from Israel. Plant Breeding 99:265-273.
Jahoor., A, and G. Fischbeck. 1987b. Sources of resistance to powdery
mildew in barley lines derived from Hordeum spontaneum collected in
Israel. Plant Breeding 99:274-281.
Jahoor, A., and G. Fischbeck. 1987c. Identification of new genes for
the powdery mildew resistance on the Ml-a locus collected in Israel.
Jensen, J., and J.H. Jørgensen. 1975. The barley chromosome 5
linkage map. II. Extention of the map with four loci. Hereditas
Jensen, J. 1985. Coordinator's report. Chromosome 5. BGN 15:74-77.
Kolster, P., L. Munk, 0. Stolen, and J. Loh. 1986. Near-isogenic
barley lines with genes for resistance to powdery mildew. Crop Sci.
Moseman, J.G., E. Nevo, and D. Zohary. 1983. Resistance of Hordeum
spontaneum collected in Israel to infection with Erysiphe graminis
hordei. Crop Sci. 23:1115-1119.
Schaller, C.W., and F.N. Briggs. 1955. Inheritance of resistance to
mildew, Erysiphe graminis hordei, in the barley variety, Black
Russian. Genetics 40:421-428.
Wahl, I., N. Esched, A. Segal, and Z. Sobel. 1978. Significance of
wild relatives of small grains and other wild grasses. In D.M.
Spencer (ed.) The powdery mildew. Academic Press Longdon. pp. 83-100.