Klamath Experiment Station
Evaluation of Russet Norkotah, Russet Burbank, and Shepody Clones with
Transgenic Resistance to Potato Virus Y, 1997
K.A. Rykbost 1 and J. Maxwell'
bstract
Genetic engineering techniques were used
at Oregon State University to insert
resistance to Potato Virus Y (PVY) into Russet
Burbank, Shepody, and Russet Norkotah varieties. Over several years, the resulting clones have
been propagated to increase seed supplies,
selected to eliminate off-type plants and tubers,
and challenged with PVY to determine their
response. In 1997, sufficient seed of the most
promising selections was available to conduct
replicated yield trials at three locations. Eleven
transformed Russet Norkotah and two transformed Shepody selections were compared with
standard Norkotah and Shepody in one trial. Ten
transformed clones of Russet Burbank were
compared with two standard lots of Russet
Burbank in a second trial at Klamath Experiment
Station (KES). Similar trials were conducted at
Powell Butte and Hermiston.
Tests at Hermiston confirmed that seven
Norkotah, both Shepody, and seven Russet
Burbank transgenic clones evaluated are resistant
to PVY. At KES, five Norkotah, one Shepody,
and five Russet Burbank clones were equal to
standard varieties in yield of No.ls. Most of the
clones were similar to untransformed standards in
plant characteristics, tuber type, specific gravity,
and susceptibility to external and internal defects.
Based on PVY resistance status and agronomic
performance across three locations, three
Norkotah, both Shepody, and three Russet
Burbank transgenic selections have been retained
for further evaluation.
Introduction
Russet Norkotah and Shepody have
become the dominant varieties in the Klamath
Basin and Treasure Valley, respectively. Both
varieties are very susceptible to PVY but foliage
symptoms are masked. Seed growers have
difficulty rouging infected plants, leading to a rapid
buildup of infection in seed lots. While these
varieties are playing a very important role in the
fresh market and French fry industry, they are
creating a serious problem for seed growers. The
insertion of PVY resistance through genetic
engineering techniques would be very beneficial to
the industry. Seed of transformed selections of
five commercially important varieties with PVY •
resistance is available from NatureMark ® . PVY
resistance has also been inserted in an Oregon
State University project. This report summarizes
the 1997 evaluation at KES of transformed
potato selections from this project.
Procedures
Selections were evaluated in two
randomized, complete-block experiments with
four replications. One experiment included 11
V Superintendent/Professor and Biological Sciences Research Technician DU, respectively, Klamath
Experiment Station, Klamath Falls, OR.
Acknowledgments: Funding provided by the USDA/ARS and the Oregon Potato Commission is gratefully recognized. A summary of results over three locations is available from Mr. Steve James at the Central
Oregon Agricultural Research Center, Madras, OR.
Klamath Experiment Station 1997 35
Klamath Experiment Station
Evaluation of Russet Norkotah, Russet Burbank, and Shepody Clones with
Transgenic Resistance to Potato Virus Y, 1997
transgenic Russet Norkotah selections, 2
transgenic Shepody selections, 2 Colorado
Norkotah strain selections, and standard
Norkotah and Shepody seed lots. The
second trial included 10 Russet Burbank
transgenic selections and 2 standard Russet
Burbank seed lots. Seed was hand cut to 1.5
to 2.0 oz, treated with Tops 2.5, and suberized at 55 °F and 95 percent relative humidity
for two weeks before planting on May 19. All
plots were single rows with 30 hills. Seed
spacing was 8.7 inches for Russet Norkotah
and Shepody and 12 inches for Russet
Burbank in 32-inch rows. Other cultural
practices are described on page 13.
Vines were desiccated with Diquat
applied at 1.0 pint/acre on September 2 and
7 on Norkotah and Shepody and on September 7 and 11 on Russet Burbank plots.
Potatoes were harvested on September 26
and September 29, respectively. All tubers
from all plots were stored until grading in midOctober. Ten tubers from the 8- to 12-oz No.
1 size fraction in each plot were measured to
determine length-to-width ratios. Ten large
tubers from each plot were cut lengthwise and
inspected for internal defects. Specific gravity
was measured by the weight-in-air, weight-inwater method, using approximately 10
pounds of 8- to 12-oz No. ls. Yield, grade,
specific gravity, and length-to-width ratio data
were subjected to statistical analyses using
MSUSTAT software.
Results and Discussion
Plant stands exceeded 90 percent for
all Norkotah and Shepody selections except
one standard Norkotah seed lot (Table 1).
36 Klamath Experiment Station 1997
Several transgenic Norkotah selections had less vine
vigor and earlier maturity than the standard lots. The
Colorado strains, CORN-3 and CORN-8 had later
vine maturity than standard Norkotah lots, as observed in the western regional trial. CORN-3 was
also significantly higher in specific gravity than most
other Norkotah selections. Shep-RC4-124-1 was
similar to the standard Shepody in vine habit, while
Shep-RC4-129-1 had less vigorous vines and earlier
maturity. Specific gravity varied little among selections
in either variety, with the exception noted for CORN3. Several Norkotah selections exhibited significantly
higher length-to-width ratios than standard lots. While
hollow heart incidence was fairly high in several
selections, it should be noted that internal defects
were measured from large tubers that often weighed
over 1 lb.
Yields and grades for Norkotah and
Shepody selections are presented in Table 2.
CORN-3 was significantly higher in No. 1 and total
yield than all other selections. Five transgenic
Norkotah selections were equal to the standard in
yield of No. ls. In most cases, the selections with
high yields had greater vine vigor and later maturity
than selections with low yields. Two selections with
relatively high yields at KES (N 12-024 and NP3138) were highly resistant to PVY in tests at
Hermiston. NP3-138 produced the highest yield of
No.ls among transgenic selections at KES and also
in a similar trial at Prosser, Washington, in 1997.
N43-191 and N43-192 were found to be susceptible to PVY at Hermiston. Following review of data
from all locations, the selections N 12-024 and N43138 were retained for further evaluation.
Transgenic Shepody selections were similar in
No. I yield averaged over three locations in 1997
and two locations (Powell Butte and Hermiston) in
1996. Shep-RC4-124-1 produced the highest No. 1
Klamath Experiment Station
Evaluation of Russet Norkotah, Russet Burbank, and Shepody Clones with
Transgenic Resistance to Potato Virus Y, 1997
and total yield at KES and Prosser, Washington,
in 1997. Both transgenic Shepody selections
produced more off-type tubers than the standard
lot at KES. Both selections were resistant to
PVY and will be kept for further testing.
All Russet Burbank selections achieved
excellent stands (Table 3). Minor differences
were observed in vine vigor. All selections were
rated the same for vine maturity. The incidence of
hollow heart was minimal. Most selections were
similar to the standards in specific gravity and
length/width ratios.
All transgenic Russet Burbank selections
with an R4 designation were equal to the standards in yield of No. I s at KES (Table 4). The
RBN and RP selections produced lower No. I
and total yields than the Powell Butte standard
lot. Most transgenic selections produced fewer
No. 2s and culls than either of the standard lots.
The selections R40-007, R46-455, and R45456 were resistant to PVY and will be continued
in an evaluation program.
The future for these transgenic selections
is uncertain. Oregon State University holds a
patent on the gene constructs used to insert PVY
resistance. Private patents are held on a genetic
marker gene and a promoter used in the transformation process. If further evaluations warrant the
release of one or more of these selections, some
agreement between OSU and the owner of
private patents must be arranged. The importance of PVY in Russet Norkotah is well documented in a separate report. Shepody has
experienced similar yield reductions because of
seedbome PVY infections in preliminary studies
conducted at Hermiston. Both varieties mask
PVY symptoms, resulting in undetected buildup
of PVY in seed crops. The availability of trans-
formed clones with excellent PVY resistance and
comparable agronomic performance to standard
varieties would be very beneficial for seed and
commercial production of these varieties; which
account for-the second and third largest acreages
of potato production in North America.
Seed supplies of the selections are
currently limited to less than 100 lb. In 1998,
seed will be increased in sufficient quantities to
enter the best selections for evaluation in the
Western Regional Trial in 1999.
Klamath Experiment Station 1997 37
Klamath Experiment Station
Table 1. Characteristics of Russet Norkotah and Shepody clones and standard varieties grown at Klamath
Falls. OR, 1997.
Variety/
Plant
Vine
Vine
Hollow
Specific
Length/width
selection
stand
vigori
maturity2
heart
gravity
ratio
N12-024
N42-045
N43-191
N43-192
N43-206
97
98
97
98
99
2.5
2.3
2.5
2.5
2.0
2.3
2.0
2.5
2.5
2.0
25
5
25
10
10
1.070
1.072
1.070
1.073
1.070
1.70
1.71
1.87
1.84
2.08
N43-214
N13 7-020
NP3-131
NP3-138
NP3-144
NP3-155
99
100
100
100
97
99
1.8
2.8
2.0
3.0
2.0
1.5
1.5
1.8
2.5
1.8
1.8
2.8
3
10
23
15
20
30
1.066
1.072
1.071
1.076
1.069
1.072
1.90
1.84
1.83
1.75
1.83
1.83
CORN-3
CORN-8
98
100
2.8
2.8
3.5
2.8
18
18
1.078
1.074
1.75
1.91
Norkotah TG
Norkotah PB
96
88
2.8
2.5
2.3
2.3
13
13
1.073
1.073
1.77
1.65
Shep-RC4-124-1
Shep-RC4-129-1
92
93
2.8
2.3
3.0
2.5
3
3
1.083
1.081
1.78
1.76
Shepody
96
3.0
3.0
0
1.083
1.69
Mean
CV (c7c)
LSD (P= 0.05)
97
2.4
2.4
14
1.074
0.3
0.004
1.81
6
0.14
'1 Vine vigor rating: l for small and weak, to 5 for large, robust.
2
/ Vine maturity rating: 1 for early to 5 for late maturing plant.
38 Klamath Experiment Station 1997
Klamath Experiment Station
Table 2. Yield, grade, and tuber size distribution of Russet Norkotah and Shepody clones and standard
varieties grown at Klamath Falls, OR, 1997.
Variety/
selection
4-8 oz
Yield U.S. No. is
8-12 oz
> 12 oz
total
Bs
Yield
culls
No. 2s
total
cwt/A
N12-024
N42-045
N43-191
N43-192
N43-206
183
172
149
136
152
175
127
166
160
135
88
60
134
131
85
446
359
449
427
372
41
49
- 28
37
30
8
16
25
20
13
6
1
10
8
6
501
425
512
491
420
N43-214
NP2-020
NP3-131
NP3-138
NP3-144
NP3-155
135
191
166
208
133
139
109
113
142
176
126
122
27
79
120
86
68
102
271
382
428
469
327
363
27
54
32
43
28
34
5
15
4
12
8
12
2
10
3
5
6
4
305
461
467
529
369
413
CORN-3
CORN-8
102
106
140
119
333
268
575
492
16
22
27
16
29
24
646
554
Norkotah TG
Norkotah PB
117
105
164
153
155
192
435
450
33
28
24
21
19
26
511
525
Shep-RC4-124-1
Shep-RC4-129-1
96
86
90
93
240
163
426
342
13
21
62
83
51
42
552
487
Shepody
83
101
216
400
17
43
37
497
136
22
43
134
20
39
141
23
46
412
12
70
31
37
16
23
59
19
16
106
24
481
10
65
Mean
CV (c7c)
LSD (P= 0.05)
Klamath Experiment Station 1997 39
Klamath Experiment Station
Table 3. Characteristics of transgenic Russet Burbank clones and standard Russet Burbank grown at KES,
Klamath Falls, OR, 1997.
Variety/
selection
Plant
Vine
Vine
stand
vigor'
R40-007
R42-035
R43-174
R46-455
R46-456
100
100
99
98
98
RBN-RC4-103-4
RBN-RC4-144-2
RBN-RC4-146-2
RBN-RC4-147-3
RP6-510
maturity2
Hollow
heart
Specific
gravity
2.3
3.0
2.5
2.8
2.8
4.0
4.0
4.0
4.0
4.0
0
0
0
5
5
1.085
1.086
1.080
1.085
1.084
2.02
2.05
2.11
1.91
2.00
100
100
99
98
97
2.3
2.8
2.5
2.5
2.3
4.0
4.0
4.0
4.0
4.0
3
8
5
0
8
1.088
1.083
1.086
1.083
1.084
2.06
2.09
2.13
2.12
2.13
Russet Burbank PB
Russet Burbank KC
95
94
3.3
2.0
4.0
4.0
5
3
1.088
1.085
1.99
1.98
Mean
CV (%)
LSD (P = 0.05)
98
2.6
4.0
4
1.085
0.3
0.004
2.05
7
NS
1/
2/
40
Vine vigor rating: 1 for small and weak, to 5 for large, robust.
Vine maturity rating: 1 for early, to 5 for late maturing plant.
Klamath Experiment Station 1997
Length/width
ratio
Klamath Experiment Station
Table 4. Yield, grade, and tuber size distribution of transgenic selections and standard Russet Burbank
grown at Klamath Falls, OR, 1997.
Variety/
selection
4-8 oz
Yield U.S. No. is
8-12 oz
> 12 oz
total
Yield
No. 2s culls
Bs
total
cwt/A
R40-007
R42-035
R43-174
R46-455
R46-456
140
160
148
125
108
99
98
106
96
107
72
51
78
110
102
310
309
332
330
317
38
37
38
37
34
31
29
27
50
47
36
58
31
70
64
415
433
428
488
462
RBN-RC4-103-4
RBN-RC4-144-2
RBN-RC4-146-2
RBN-RC4-147-3
RP6-510
142
141
140
129
107
76
90
99
65
77
57
56
44
25
71
275
288
283
218
255
47
43
36
39
23
16
19
28
21
18
40
44
63
25
71
378
393
410
303
367
R. Burbank PB
R. Burbank KC
111
85
99
90
99
88
309
262
24
30
53
28
91
61
477
381
Mean
CV (%)
LSD (I) 0.05)
128
10
35
92
25
NS
71
38
39
291
17
NS
35
34
NS
31
64
NS
54
48
37
411
12
73
,
Klamath Experiment Station 1997 41