Evaluating Grape Rootstocks for Nematode Susceptibility

Unfortunately the Phylloxera contamination could not be tolerated due to the risk that these pests could escape the microplots and become established at the Kearney Agricultural Center, and because Phylloxera could interact with plant-parasitic nematodes in damaging the vines, thus confounding tests designed to determine nematode resistance. To address these issues, all vines will be removed from their microplots, and the microplot soils will be steam-treated to kill any insect or insect eggs that may be remaining. After this sterilization procedure, the microplots will be prepared for replanting. New plant material will be collected and propagated, and the experiment re-initiated.

Breeding Rootstocks Resistant to Aggressive Root-Knot Nematodes

The USDA Agricultural Research Service (USDA-ARS) grape rootstock improvement program in Geneva, NY, has undergone significant changes in the past several years as a result of the resignation of Peter Cousins from his ARS rootstock breeder position and the abolishment of the vacated rootstock breeder position by ARS due to the federal budget cuts. However, a continued effort has been made to ensure that promising rootstock selections from previous years of breeding effort are maintained and carried through the evaluation process. To meet this challenge, a multi-discipline and –institution cooperative research team has been formed under encouragement and endorsement of the California grape industry. Matthew Fidelibus of University of California-Kearney Agricultural Research and Extension Center (UC-KARE) now leads the effort for evaluation of horticultural characteristics and graft performance of the rootstock selections generated from the Geneva rootstock breeding program. Gan-Yuan Zhong of the USDA-ARS Grape Genetics Research Unit (GGRU) in Geneva, NY, on the other hand, leads the effort for maintaining rootstock breeding populations and evaluating these populations and selections for root-knot nematode (RKN) resistance and propagation ability. The new team has been in operation since 2013 and demonstrated its success in evaluating more than 600 rootstock selections and identifying 5 leading rootstock selections for further grafting evaluation. During 2016-2017, the Geneva Team received $15,000 grant support for this project, which was only about 20{aed9a53339cdfc54d53cc0c4af03c96668ab007d9c364a7466e3349a91bf0a23} of what was requested. The team maintained about 150 rootstock mothervines in Geneva, evaluated 22 for RKN resistance and propagation ability, and transferred 27 to  Matthew Fidelibus to grow at the UC KARE in Parlier, CA.

Breeding Rootstocks Resistant to Aggressive Root-Knot Nematodes

The USDA Agricultural Research Service (USDA-ARS) grape rootstock improvement program in Geneva, NY has undergone some significant changes in the past two years as a result of the resignation of Dr. Peter Cousins from his ARS rootstock breeder position and the abolishment of the vacated rootstock breeder position by ARS due to the federal budget cuts. However, a consistent effort has been made to ensure that promising rootstock selections from previous years of breeding effort are maintained and carried through the evaluation process. To meet this challenge, a multi-discipline and –institution cooperative research team has been formed under the encouragement and endorsement of the California grape industry. Matthew Fidelibus of University of California-Kearney Agricultural Research and Extension Center (UC-KARE) has lead the effort for evaluation of horticultural characteristics and graft performance of the rootstock selections generated from the Geneva rootstock breeding program. Gan-Yuan Zhong of the USDA-ARS Grape Genetics Research Unit (GGRU) in Geneva, NY, on the other hand, has lead the effort for creating rootstock breeding populations and evaluating these populations and advanced selections for root-knot nematode (RKN) resistance and propagation ability.

By forming such a team, we have effectively leveraged our complementary expertise and capabilities to meet the overall project objectives in a timely and efficient manner. The new team has been in operation since 2013. During the 2014-2015 funding year, we maintained several hundreds of resistant rootstock selections/mothervines at the UC KARE in Parlier, CA. With the help of nursery representatives, Andy Walker of UC-Davis, and others, we evaluated the horticultural characteristics of these rootstock mothervines and identified 30 of them for further evaluation. We evaluated the rooting ability and RKN resistance of the 30 selections and identified 6 with desirable rooting ability and resistance to RKNs. These 6 selections will be further evaluated in 2015-2016. During 2014-2015, we have also maintained about 200 rootstock mothervines in the USDA-ARS rootstock breeding program in Geneva, NY. These mothervines will need to be further evaluated and transferred to grow in UC KARE in Parlier, CA. We also screened a population for nematode resistance marker development. We continued the effort in evaluating 22 selections, grafted to Syrah, in replicated rootstock trials at the UC-KARE. Matador, Minotaur, and Kingfisher rootstocks, released by this USDA ARS grape rootstock breeding program in 2010, are being distributed by Foundation Plant Services and planted by California nurseries.

 

Breeding Rootstocks Resistant to Aggressive Root-Knot Nematodes

Summary:
The USDA Agricultural Research Service (USDA-ARS) grape rootstock improvement program in Geneva, NY has gone through some significant personnel and management changes in the past two years as a result of the resignation of Dr. Peter Cousins from his ARS rootstock breeder position and the abolishment of the vacated rootstock breeder position by ARS due to the recent federal budget cuts. However, there are many promising rootstock selections in the current Geneva rootstock breeding pipeline and it is vital to ensure that these selections are maintained and carried through the breeding process. To meet this challenge, a multi-discipline and –institution cooperative research team has been formed under the encouragement and endorsement of the California grape industry. Dr. Matthew Fidelibus of University of California-Kearney Agricultural Research and Extension Center (UC-KARE) will lead the effort for evaluation of horticultural characteristics and graft performance of the rootstock selections generated from the Geneva rootstock breeding program. Dr. Gan-Yuan Zhong of the USDA-ARS Grape Genetics Research Unit (GGRU) in Geneva, NY, on the other hand, will lead the effort for creating rootstock breeding populations and evaluating these populations and advanced selections for root-knot nematode (RKN) resistance and propagation ability. By forming such a team, we can effectively leverage complementary expertise and capabilities from different organizations to meet the overall project objectives in a timely and efficient manner.

The new team has been in operation since summer of 2013. In spite of the transition, we accomplished all the major goals of 2013. We maintained 687 resistant rootstock selections/mothervines at the UC KARE in Parlier, CA. We worked with nursery representatives and identified 30-40 of the selections for further evaluation on the basis of horticultural characteristics. We screened 854 grape rootstock seedlings for resistance to aggressive root-knot nematodes and retained more than 100 candidate selections for further evaluation. We select only those seedlings which completely suppress nematode reproduction and show zero nematode egg masses. We tested the propagation ability of 49 selections which are currently planted in KARE (already tested once for nematode resistance). We also screened a population, which also is qualified for consideration as rootstocks, for nematode resistance marker development. We continued the effort in evaluating 22 selections, grafted to Syrah, in replicated rootstock trials at the UC-KARE. Matador, Minotaur, and Kingfisher rootstocks, released by this USDA ARS grape rootstock breeding program in 2010, are being distributed by Foundation Plant Services and planted by California nurseries.

Breeding Rootstocks Resistant to Aggressive Root-Knot Nematodes

The USDA Agricultural Research Service grape rootstock improvement program, based at the Grape Genetics Research Unit, is breeding rootstocks resistant to aggressive root-knot nematodes. We define aggressive root-knot nematodes as those which feed on and damage the rootstocks Freedom and Harmony. We screened candidate grape rootstock seedlings for resistance to aggressive root-knot nematodes. We select only those seedlings which completely suppress nematode reproduction and show zero nematode egg masses. Selected seedlings are propagated and then planted into the vineyard. We tested the propagation ability of 168 selections (already tested once for nematode resistance). We also screened a population, which also is qualified for consideration as rootstocks, for nematode resistance marker development. We evaluated 22 selections, grafted to Syrah, in replicated rootstock trials at the University of California Kearney Agricultural Research and Extension center. We pollinated 661 clusters of crosses in more than 60 unique combinations specifically aimed at the breeding of improved rootstocks with resistance to aggressive root-knot nematodes and collected rootstock cross seeds. Matador, Minotaur, and Kingfisher rootstocks, released by this USDA ARS grape rootstock breeding program in 2010, are being distributed by Foundation Plant Services and planted by California nurseries.

Search for, and Development of, Nematode Resistance in Grape Rootstocks

This year we have focused our attention on obtaining a broader genetic base for resistance to virulent pathotypes of root-knot (Meloidogynespp.) and dagger nematodes (Xiphinema index),broadening our search for resistance to ring nematode (Mesocriconema xenoplax) and to sources of resistance to pin nematode (Paratylenchus sp.). We have invested considerable effort into developing sterile dual-culture techniques which will allow us to understand the mechanisms of resistance provided by various genetic sources. We continue with our efforts to develop culture techniques for Xiphinema americanum and in monitoring the performance of resistant rootstocks in field trials. We continue to expand and to improve accessibility to the database for plant resistance to nematodes and for selection of rotation and cover crops. Further we have disseminated results of our research to end users and in scientific media.

Search for, and Development of, Nematode Resistance in Grape Rootstocks

This year we have focused our attention on obtaining a broader genetic base for resistance to root-knot (Meloidogyne spp.) and dagger nematode (Xiphinema index) and broadening our search for resistance to the root lesion nematode (Pratylenchus vulnus), and the citrus nematode (Tylenchulus semipenetrans). We tested the durability of resistance to root-knot nematodes in the UCD-GRN series rootstocks under fluctuating soil temperature conditions. We have continued our tissue culture studies for better understanding of the nature of resistance to nematodes in different rootstocks. We have commenced monitoring ongoing field trials with the UCD-GRN series rootstocks to determine their performance in diverse situations. We have considerably expanded and improved accessibility to the database for plant resistance to nematodes and for selection of rotation and cover crops.

Search for, and Development of, Nematode Resistance in Grape Rootstocks

This year we have focused our attention on sources of resistance to the ring nematode. Criconemoides xenoplax; and to obtaining a broader genetic base for resistance to root-knot (Meloidogyne spp) and dagger nematode (Xiphinema index). We have also initiated and are repeating trials to find resistance to the citrus nematode, Tylenchulus semipenetrans, and the root-lesion nematode, Pratylenchus vulnus.

Breeding rootstocks resistant to aggressive root-knot nematodes

The USDA grape rootstock improvement program, based at the Grape Genetics Research Unit, is breeding grape rootstocks resistant to aggressive root-knot nematodes. We define aggressive root-knot nematodes as those which feed on and damage the rootstocks Freedom and Harmony. In 2008 we screened 3572 candidate grape rootstock seedlings for resistance to aggressive rootknot nematodes. We select only those seedlings which completely suppress nematode reproduction and show zero nematode egg masses. Selected seedlings are propagated and then planted into the vineyard. We screened an additional 480 seedlings were screened for nematode resistance breeding and genetics studies. We tested the propagation ability of 82 selections and retested 65 selections to confirm nematode resistance in replicated trials. We identified twelve selections for a new rootstock trial to be planted at the University of California Kearney Ag Center in 2009. We pollinated 233 clusters of crosses in 31 unique combinations specifically aimed at the breeding of improved rootstocks with resistance to aggressive root-knot nematodes.

An additional 268 clusters in 32 cross combinations were pollinated specifically for rootstock genetic study.

Search for, and Development of, Nematode Resistance in Grape Rootstocks

We released, to the grape industry, five rootstocks with broad and durable resistance toIhe root-knot nematode (Meloidogyne incognita race 3), two strains of root-knot nematode that overcome the resistance of Harmony rootstock (Meloidogyne arenariastrain A and Meloidogyne incognita strain C), and the dagger nematode (Xiphinemaindex), with resistance to Grape Phylloxera, and with a range of rooting characteristics.We continue our search in Vitis and Muscadinia spp. for sources of resistance to nematode species that are important in California vineyards. This year we have focused our attention on the ring nematode. Criconemoides xenoplax; we have evaluated accessions of wild species and many crosses among Muscadinia and various Vitis species.