Development of Grape Rootstocks with Broad and Durable Nematode Resistance
Final Report - December 2002 (Updated May 2003)
Principal Investigators:
Howard Ferris, Professor
Dept. of Nematology
University of California, Davis
One Shields Avenue
Davis, CA 95616
Phone: (530) 752-8432
Email: hferris@ucdavis.edu
FAX: (530)-752-5809
Co-Investigator:
M. Andrew Walker
Department of Viticulture and Enology
University of California, Davis
One Shields Avenue
Davis, CA 95616
Phone: (530) 752-0902
Email: Awalker@ucdavis.edu
Cooperators:
County Farm Advisors (third year)
Location of Project:
Phase One - UC Davis, Davis, Yolo County
Phase Two - San Joaquin Valley and central coast counties
Commodity:
Grape
Funding:
| Year 1 | Year 2 | Year 3 | |
| SAREP | 49,832 | 25,272 | 25,640 |
| CCGPRVE, AVF, GRC, TGC* | 29,650 | 30,055 |
Table of Contents:
1. To continue the development of grape rootstocks with resistance to a broad
range of nematodes species and aggressive strains.
2. To evaluate the durability of resistance in advanced selections with multiple
nematode resistance.
3. Field testing of selected rootstocks for horticultural characteristics and
durability of nematode resistance.
4. To develop and employ new rootstocks with resistance to a broad range of
key nematode species as a sustainable alternative to the use of preplant fumigation.
Several species of plant-feeding nematodes are present in most vineyards, however few rootstocks have resistance to more than one species. Our project screened rootstock candidates against the root knot nematode (Meloidogyne incognita race 3), two strains of root-knot nematode that overcome the resistance of Harmony rootstock (Meloidogyne arenaria strain A and Meloidogyne incognita strain C), and the dagger nematode (Xiphinema index). Crosses made among a series of Vitis and Muscadinia species resulted in selection of candidate rootstocks with multiple nematode resistance. Of the 6,000 seedlings produced from these crosses, only 12 graduated through rooting trial and individual nematode screening trials with broad resistance to all four nematodes. These rootstock selections were tested for their susceptibility to the ring nematode, Mesocriconema xenoplax. Several appeared to have some resistance to this nematode as well.
To test the durability of the resistance, rootstock selections resistant to all four nematodes when inoculated individually were exposed to all of the species at the same time. When inoculated together there was a very small amount of galling on some of the broadly resistant lines. Two rootstock candidates (9407-14 and 9449-27) appeared to have broad resistance to dagger nematode and three root-knot nematode strains when exposed concurrently. These are extremely valuable plants. There are no other known examples of rootstocks for perennial crops selected for broad (multi-species) nematode resistance.
Some rootstock candidates have now progressed to field trials for tests of horticultural characteristics and to assess the durability of the resistance against field populations of nematodes in a range of environments. Ongoing and future studies will test the durability of resistance to root-knot and dagger nematodes when the plants are inoculated with other nematode species not yet tested, including citrus, pin and lesion nematodes. The research will also determine under what conditions, if any, the resistance breaks down. Preliminary experiments suggest that the resistance to root-knot and dagger nematodes may break down at high soil temperatures in some of the selections.
The sources of plant material used in this study are crosses made by Walker in the UC Grape Rootstock Breeding Program:
| Year | Included in Parentage |
| 1989 | Vitis rupestris, Muscadinia rotundifolia |
| 1993 | V. rufotomentosa, V. champinii, V. candicans |
| 1994 | V. riparia, V. champinii, V. candicans |
| 1994 | V. rufotomentosa, V. cinerea |
Seedlings from the crosses were established in the field. Dormant cuttings from
the vines that resulted from the seedlings were evaluated for rooting. Selections
in which at least 90% of the cuttings rooted were advanced for nematode testing.
The initial nematode screening in a group of 33 selections from the 1993 populations,
two groups of 38 and 17 from the 1994 populations with resistance to of the
common root-knot nematode species Meloidogyne incognita race 3, and
a group of 50 selections from the 1989 populations with resistance to the dagger
nematode (Xiphinema index).
All selections with resistance to Meloidogyne incognita race 3 were screened for resistance to Xiphinema index; those with resistance to Xiphinema index were screened against Meloidogyne incognita race 3. All selections with resistance to either or both nematodes were then screened against two strains of root-knot nematode that overcome the resistance of Harmony rootstock (Meloidogyne arenaria strain A and M. incognita strain C). The trials were repeated several times to accommodate rooting failures and to clarify ambiguous results.
Our root-knot nematode screening procedure is to inoculate five replicates of rooted cuttings of each selection with 1,000 root-knot nematode juveniles each. Six weeks after inoculation the plants are scored for nematode reproduction. The number of nematode egg masses visible after staining (one hour in 0.25g/L eosin-Y) is used as a measure of resistance. Resistance screening for the dagger nematode is conducted by inoculating five replications of each selection with 300 dagger nematode individuals. After three months, root tip galling is assessed as a measure of resistance.
Our criteria for graduation of the selections to the next level of screening are absence of nematode reproduction and absence of obvious feeding damage or symptoms. For root-knot nematodes, the absence of galls and egg masses is a necessary indicator of acceptable resistance. The same measures are also applied to dagger nematode (root tip galls). If any one of the five replications exhibits symptoms or egg masses, that selection is considered susceptible.
We have begun testing the durability of the resistance in the 12 rootstock candidates that were resistant to all nematode species when exposed to each species individually. Selections that graduated through the screening trials with resistance to all the nematode species individually were inoculated with all the selections at the same time. Some additional candidate selections, identified in other screening programs, have been included in these tests and some of the original selections have been omitted due to poor rooting characteristics.
Broad Resistance
Of the plants from the 1989, 1993 and two 1994 crosses, 1, 6, 5 and 0, respectively,
(Tables 1-4) were resistant to the four nematodes tested
individually. That means that of thousands of seedlings produced in these crosses,
only 12 have survived the rooting and nematodes screens (Table
5). Those should provide a rich source for field testing as rootstocks and
most were planted in nematode sites in Fresno and Kern counties last year (Table
7).
Durable Resistance
The susceptible response to all the nematodes tested is root galling. On the
selections with broad resistance (Table 5), there was
no galling, or only trace evidence of galling, with any of the species when
inoculated alone. However, some of the selections exhibit a small amount of
galling when all nematode species are inoculated together (Table
6). Two (9332-43 and 9334-03) exhibited both dagger and root-knot nematode
galls; of these, 9332-43 had tested susceptible to M. arenaria strain
A in previous tests (Table 2). Selection 9403-107 also
exhibited root-knot galling, consistent with previous evidence of its susceptibility
to M. arenaria strain A (Table 2).
Only two selections (9407-14 and 9449-27) have shown no evidence of symptoms in repeated multiple-species tests (Table 6). Unfortunately, none of the 9449 selections roots well and they are only useful as parents in future crosses.
The appearance of symptoms when several nematode species/strains are inoculated simultaneously raises some questions on the mechanisms of resistance. If the nematodes individually do not feed, how are they altering root response in combination? We need to test durability of resistance to root-knot and dagger nematodes when the plants are inoculated with other nematode species, including ring, pin and lesion nematodes. In addition, we need to determine the susceptibility of these broadly-resistant rootstock candidates to other nematode species commonly found in vineyard soils.
Crosses made among a series of Vitis and Muscadinia species have resulted in selection of candidate rootstocks with multiple nematode resistance. Two rootstock candidates (9407-14 and 9449-27) appear to have broad resistance to dagger nematode and three root-knot nematode strains, even when exposed to all four at the same time.
Some rootstock candidates have now progressed to field trials for tests of horticultural characteristics and to assess the durability of the resistance against field populations of nematodes in a range of environments (Table 7). We will continue testing durability of the resistance when plants are exposed to other nematode species. We determine whether the broad resistance effective against other nematodes not yet tested and under what conditions, if any, the resistance breaks down.Table 1. One genotype of a series of 1989 selections had broad resistance to the four nematode species.
| Genotype | X index | M. incognita 3 | Harmony C | Harmony A |
| 8901-01 | R | S | S | |
| 8913-13 | R | S | S | |
| 8909-08 | R | S | ||
| 8909-20 | R | S | ||
| 8909-23 | R | S | ||
| 8909-25 | R | S | ||
| 8913-08 | R | S | ||
| 8913-09 | R | S | ||
| 8913-11 | R | S | ||
| 8913-14 | R | S | ||
| 8913-26 | R | S | ||
| 8913-28 | R | S | ||
| 8913-49 | R | S | ||
| 8916-04 | R | S | ||
| 8916-07 | R | S | ||
| 8916-08 | R | S | ||
| 8916-09 | R | S | ||
| 8916-16 | R | S | ||
| 8916-17 | R | S | ||
| 8916-23 | R | S | ||
| 8916-26 | R | S | ||
| Schwarzman | R | S | ||
| 1616c | R | S | ||
| 8909-04 | R | R | S | S |
| 8909-11 | R | R | S | |
| 8909-17 | R | R | S | |
| 8909-19 | R | R | S | |
| 8909-24 | R | R | S | S |
| 8913-02 | R | R | S | |
| 8913-04 | R | R | S | |
| 8913-16 | R | R | S | |
| 8913-29 | R | R | S | |
| 8913-45 | R | R | S | |
| 8913-46 | R | R | S | |
| 8916-12 | R | R | S | |
| 8916-19 | R | R | S | |
| 8916-20 | R | R | S | |
| 8916-22 | R | R | S | S |
| 8904-04 | R | R | R | S |
| 8909-05 | R | R | R | R |
| 8909-15 | R | R | R | S |
| 8913-21 | R | R | R | S |
| 8913-38 | R | R | R | S |
| 8913-40 | R | R | R | S |
| 8913-43 | R | R | R | S |
| 5C | R | R | * | * |
| 5BB | R | R | * | * |
| Borner | R | R | * | * |
| 101-14 | R | R | * | * |
| 8913-39 | R | * | R | * |
Table 2. Five genotypes of a series of 1993 selections had broad resistance to the four nematode species.
| Genotype | M. incognita race 3 | X. index | M. arenaria - Harmony A | M incognita - Harmony C |
| 9362-09 | R | S | S | R |
| 9310-80 | R | S | S | |
| 9310-96 | R | S | S | |
| 9310-102 | R | S | S | |
| 9327-55 | R | S | S | |
| 9359-09 | R | S | S | |
| 9310-87 | R | S | R | |
| 9309-05 | R | S | ||
| 9310-39 | R | S | ||
| 9310-43 | R | S | ||
| 9310-58 | R | S | ||
| 9310-70 | R | S | ||
| 9310-94 | R | S | ||
| 9352-11 | R | S | ||
| 9327-96 | S | |||
| 9327-37 | R | R | S | R |
| 9327-43 | R | R | S | R |
| 9357-05 | R | R | S | R |
| 93100-27 | R | R | S | R |
| 9328-17 | R | R | S | S |
| 9310-86 | R | R | S | |
| 9317-06 | R | R | R | R |
| 9332-43 | R | R | S | R |
| 9344-03 | R | R | R | R |
| 9363-16 | R | R | R | R |
| 9365-43 | R | R | R | R |
| 9365-62 | R | R | R | R |
| 9365-85 | R | R | R | R |
| 9327-67 | R | R | * | * |
| 9309-42 | R | R | * | R |
| 9310-34 | R | R | * | R |
| 9327-62 | R | R | * | R |
| 9309-33 | R | R | * | S |
| 9350-02 | R | * | S | R |
Table 3. Five genotypes of a series of 1994 selections had broad resistance to the four nematode species.
| Genotype | M. incognita race 3 | X. index | M. arenaria - Harmony A | M. incognita -Harmony C |
| 9420-4 | S | S | S | |
| 9401-31 | S | R | S | |
| 9401-32 | S | R | S | |
| 9401-49 | S | R | S | |
| 9402-3 | S | R | S | |
| 9403-13 | S | R | S | |
| 9403-16 | S | R | S | |
| 9403-40 | S | R | S | |
| 9403-110 | S | R | S | |
| 9406-01 | S | R | S | |
| 9420-9 | S | R | S | |
| 9420-11 | S | R | S | |
| 9401-37 | S | S | ||
| 9401-18 | R | S | S | |
| 9401-51 | R | S | S | |
| 9403-18 | R | S | S | |
| 9420-5 | R | S | S | |
| 9438-31 | R | S | S | |
| 9401-10 | R | R | S | |
| 9401-35 | R | R | S | |
| 9401-42 | R | R | S | |
| 9401-48 | R | R | S | |
| 9401-52 | R | R | S | |
| 9403-17 | R | R | S | |
| 9407-5 | R | R | S | |
| 9420-8 | R | R | S | |
| 9420-13 | R | R | S | S |
| 9403-35 | R | R | R | R |
| 9403-107 | R | R | S | R |
| 9407-14 | R | R | R | R |
| 9438-18 | R | R | R | S |
| 9449-17 | R | R | R | R |
| 9449-23 | R | R | R | R |
| 9449-25 | R | R | R | S |
| 9449-27 | R | R | R | R |
| 9403-44 | R | R | * | * |
| 9403-37 | R | * | * | * |
| 9420-3 | R | * | * | * |
Table 4. None of a series of seventeen 1994 selections had broad resistance to the four nematodes species.
| Genotype | M. Incognita race 3 | X. index | M. arenaria - Harmony A | M. incognita - Harmony C |
| 9409-3 | R | S | S | S |
| 9409-9 | R | R | S | S |
| 9409-15 | S | |||
| 9409-18 | R | * | S | S |
| 9409-20 | S | |||
| 9409-22 | R | S | S | S |
| 9409-28 | S | S | S | S |
| 9409-35 | R | * | S | R |
| 9409-36 | S | R | ||
| 9409-39 | S | S | S | S |
| 9409-42 | R | R | S | S |
| 9409-54 | R | * | S | S |
| 9409-55 | R | R | S | S |
| 9413-07 | S | |||
| 9413-10 | S | |||
| 9414-97 | R | R | S | S |
| 9414-105 | R | S | S | S |
Table 5. Summary Table: Genotypes with broad resistance to four nematodes when inoculated individually.
| Genotype | X. index | M. incognita race 3 | M. arenaria - Harmony A | M. incognita - Harmony C |
| 8909-5 | R | R | R | R |
| 9317-06 | R | R | R | R |
| 9344-03 | R | R | R | R |
| 9363-16 | R | R | R | R |
| 9365-43 | R | R | R | R- |
| 9365-62 | R | R | R | R |
| 9365-85 | R- | R | R | R |
| 9403-35 | R | R | R- | R- |
| 9407-14 | R | R | R | R |
| 9449-17 | R | R | R | R |
| 9449-23 | R | R | R | R |
| 9449-27 | R | R | R | R |
| Control Group: | ||||
| 1616C | S | R | R- | R- |
| Harmony | S | R | S | S |
| French Colombard | S | S | S | S |
R = Resistant, no gall symptoms or egg masses observed
R- = Trace infection
S = Susceptible, symptoms present, nematode reproduction supported
Table 6. Summary Table: Response of broadly-resistant genotypes to four nematodes inoculated concurrently.
Genotype |
Xiphinema index |
Meloidogyne |
9317-06 |
0.3 c |
0.0 b |
9332-43 |
2.7 bc |
1.3 b |
9344-03 |
4.0 b |
1.0 b |
9365-43 |
0.0 c |
0.7 b |
9365-62 |
0.3 c |
2.0 b |
9365-85 |
1.0 c |
0.7 b |
9403-107 |
0.0 c |
2.3 b |
9403-35 |
0.3 c |
1.3 b |
9407-14 |
0.0 c |
0.0 b |
9449-23 |
0.3 c |
0.0 b |
9449-25 |
0.3 c |
0.0 b |
9449-27 |
0.0 c |
0.0 b |
Control Group: |
||
1616C |
9.0 a |
2.3 b |
Harmony |
||
St. George |
4.7 b |
40.7 |
French Colombard |
335a |
Table 7. Rootstock candidates currently in field trials.
| Fresno County Rootstock Trial (Scion=Fiesta) | Kern County Rootstock Trial (Scion=Thompson Seedless) |
| 9365-62 | 9365-85 |
| 9365-85 | 9365-43 |
| 9365-43 | 9365-62 |
| 9344-03 | 9317-06 |
| 9317-06 | 9344-03 |
| 9449-27 | 9449-27 |
| 9403-35 | |
| 9403-107 | |
| 9332-43 | |
| 9449-23 | |
| 9407-14 | |
| 8913-38 | |
| 8913-02 | |
| 9350-02 | |
| 8904-04 | |
| 8916-22 |