German
barley cv. ‘Franka’ possesses two different resistance genes to barley yellow
mosaic virus (BaYMV) and barley mild mosaic virus (BaMMV)
Takeo Konishi1
and Masahiko Furusho2
1 294 Okada, Mabi-cho,
Kibi-gun, Okayama 710-1311, Japan
2 Fukuoka Agricultural
Research Center, Chikushino, Fukuoka 818-8549, Japan
Barley yellow mosaic virus (BaYMV) is a serious
pathogen to European winter barley and East Asian two-rowed malting barley, and
often attacks barley seedlings as the mixed infection with barley mild mosaic
virus (BaMMV). As the economical and
satisfactory protection from these soil-borne viruses is to grow the resistant
cultivars, extensive surveys have been conducted to find suitable genetic
resources of the resistance. German
cultivars including ‘Franka’ are resistant to BaYMV and BaMMV, and possess the
common resistance gene ym4 to BaMMV
introduced from a Dalmatian barley landrace, Ragusa (Friedt et al. 1990). Meanwhile, ‘Ishuku Shirazu’ and ‘Ea 52’
carrying ym3 are resistant to BaYMV,
but susceptible to BaMMV in Germany (Ordon et al. 1993). In Japan, the similar reaction is recognized
in BaYMV resistant cultivars carrying ym5,
‘Misato Golden’ and ‘Asaka Gold’, which are susceptible to BaMMV (Konishi and
Kaiser-Alexnat 2000). These results suggest
that German resistant cultivars to BaYMV and BaMMV may possess another
resistance gene to BaYMV together with the BaMMV resistance gene ym4.
‘Franka’ was crossed with a linkage stock for
chromosome 3HL, Choshiro-hen (susceptible to BaYMV and BaMMV), since ym4 of the BaMMV resistant cv. ‘Franka’
is closely linked with the esterase isozyme marker (Est1) on chromosome 3HL (Graner and Bauer 1993). The F2 plants were grown in the
field free from the both viruses and harvested individually. About 30 kernels per F3 line were
sown in two isolated fields infested with BaYMV in Fukuoka and BaMMV in
Yamaguchi, respectively. From the
segregation within each F3 line, F2 genotypes were
determined for resistance to BaYMV and BaMMV, and markers (uzu for uzu or semi-brachtyic, cur2
for curly 2 and Est1 for esterase
isozyme 1) on chromosome 3HL.
Segregation
of BaYMV reaction and markers on chromosome 3HL in the F3 lines was
investigated in 1994 and 1998, using different F3 lines (Table
1). As the infection of BaYMV was mild
in 1994, heterogeneous lines could not be distinguished from homogeneous lines
for susceptibility to BaYMV.
Segregation of BaYMV reaction in each year well fit to a ratio of 1:3 or
1:2:1, suggesting that resistance to BaYMV in ‘Franka’ is governed by a
recessive gene. Segregation of BaMMV
reaction in the F3 lines also indicates that the resistance is
controlled by a recessive gene.
Significantly distorted segregation from the expected 1:2:1 ratio was
found at the uzu and cur2 loci in the proximal region of
chromosome 3HL, although the normal segregation was observed at the Est1 locus in the distal region of the
same chromosomal arm.
A linkage analysis reveals that resistance to
BaYMV in the F3 lines is completely independent of resistance to
BaMMV, suggesting that the BaYMV resistance gene differs from the BaMMV
resistance gene (Table 2). Further
analysis shows that the BaYMV resistance gene is also independent of three
markers, uzu, cur2 and Est1, on
chromosome 3HL, while the BaMMV resistance gene is linked with cur2 and Est1. The BaMMV resistance
gene may be ym4 resistant to German
BaMMV, although some questions still remain.
The ym4 is located 4.7 cM
proximal from Est1 (Graner and Bauer
1993) and linked to Est1 with recombination
values of 3.41±1.82% and 8.32±2.01% in F2
populations, respectively (Le Gouis et al. 1995). The present data, however, indicates that the BaMMV resistance
gene is loosely linked with and distal from Est1
(15.9±7.7%). Difference in the chromosomal localization
of the ym4 locus might be caused by
insufficient infection with BaMMV in the present investigation. Moreover, it should be noted that when
Choshiro-hen was one of the parents for linkage analysis, this BaMMV resistance
gene was located distal from Est1 on
chromosome 3HL as well as ym5
(Konishi et al. 1997), whereas rym5
(=ym5) was reported proximal from Est1 (Graner et al. 1999).
From these results, it is concluded that ‘Franka’
possesses two different resistance genes, one is ym4 to BaMMV and another is the resistance gene to BaYMV
independent of ym4, strongly
indicating that resistance to BaYMV in ‘Franka’ is not pleiotropically
controlled by ym4.
Table 1.
Segregation of reactions to BaYMV and BaMMV, and markers on chromosome
3HL in F3 lines (‘Franka’ x Choshiro-hen)
|
Character |
Year |
P1-type |
Hetero |
P2-type |
Total |
x2 |
|
BaYMV |
1994 |
56 |
138 |
194 |
1.55 |
|
|
|
1998 |
44 |
100 |
39
|
183 |
1.85 |
|
BaMMV |
1998 |
49 |
124 |
173 |
1.02 |
|
|
Uzu
type |
1994 |
62 |
105 |
27 |
194 |
13.95** |
|
(Uzu uzu) |
1998 |
74 |
84 |
25 |
183 |
27.47** |
|
Curly
2 |
1994 |
61 |
94 |
39 |
194 |
5.18 |
|
(Cur2 cur2) |
1998 |
50 |
98 |
25 |
183 |
14.31** |
|
Esterase |
1994 |
53 |
101 |
40 |
194 |
2.07 |
|
(Est1PrEst1 Af) |
1998 |
149 |
35 |
184 |
3.51 |
|
** : Significant at the 1% level.
Table 2.
Linkage relationships between reactions to BaYMV and BaMMV, and
markers
on chromosome 3HL in F3 lines (‘Franka’ x Choshiro-hen)
|
Gene
pair A B |
Year |
Segregation# |
Total |
x2L |
Recombination
value (%) |
|
ym＄ mm＄＄ |
1998 |
24:13/68:26/32:10#2 |
173 |
1.13 |
(Independent) |
|
ym uzu |
1994 |
44:18/74:31/20:7#3 |
194 |
0.34 |
(Independent) |
|
|
1998 |
18:15:6/35:52:13/21:17:6 |
183 |
3.37 |
(Independent) |
|
ym cur2 |
1994 |
39:22/69:25/30:9#3 |
194 |
3.65 |
(Independent) |
|
|
1998 |
15:19:5/31:58:11/14:21:9 |
183 |
2.80 |
(Independent) |
|
ym Est1 |
1994 |
35:18/74:27/29:11#3 |
194 |
1.21 |
(Independent) |
|
|
1998 |
27:12/83:17/38:6#2 |
183 |
3.87 |
(Independent) |
|
mm uzu |
1998 |
49:23/61:18/14:8#3 |
173 |
3.02 |
(Independent) |
|
mm cur2 |
1998 |
38:18/64:31/22:0#3 |
173 |
7.92* |
39.9
± 4.3 |
|
mm Est1 |
1998 |
90:34/48:1 |
173 |
13.88** |
15.9
± 7.7 |
|
uzu cur2 |
1994 |
23:25:14/31:53:21/7:16:4 |
194 |
4.09 |
(Independent) |
|
|
1998 |
30:34:10/22:52:10/8:12:5 |
183 |
11.90* |
39.8
± 3.6 |
|
uzu Est1 |
1994 |
14:37:11/31:52:22/8:12:7 |
194 |
3.18 |
(Independent) |
|
|
1998 |
60:14/67:17/21:4#2 |
183 |
0.52 |
(Independent) |
|
cur2 Est1 |
1994 |
29:28:4/21:63:10/3:10:26 |
194 |
66.53** |
24.5
± 2.6 |
|
|
1998 |
56:4/84:14/8:17#2 |
183 |
30.64** |
20.3
± 3.6 |
# : AABB:AABb:AAbb/AaBB:AaBb:Aabb/aaBB:aaBb:aabb or A-B-:A-bb/aaB-:aabb.
#2: AAB-:AAbb/AaB-:Aabb/aaB-:aabb #3: A-BB:aaBB/A-Bb:aaBb/A-bb:aaAbb
* and ** : Significant at the 5% and 1% levels,
respectively.
＄ and ＄＄ : Tentative resistance
genes to BaYMV and BaMMV, respectively.
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