Progress report only, no summary.
Funding was requested to curate the UC Davis Viticulture Herbarium, which consists of two main collections. The first collection is the original viticulture herbarium, ca. 1000 specimens dating from 1885 to the 1920s (pre-prohibition era), which document an impressive number of the wine grape cultivars grown in California at that time (collected from both vineyards and agricultural stations). The second collection is that of Harold P. Olmo and his assistant Albert Koyama; their specimens were collected between the 1930s and the 1960s and document the grape cultivars that they collected from a number of countries in Europe, the Middle East, Asia, and South, Central, and North America (including California).
Herbarium specimens consist of a dried and pressed plant sample mounted on paper and a label, which includes information on the name of the plant, the location and date of collection, and the collector?s name. At the time this project was funded, the folders (and associated labels) of the original viticulture herbarium were crumbling, and we were in danger of losing the label information stating the cultivar name and location and date of collection. In addition, the collections of Olmo and Koyama had never been labeled or mounted on paper, and we were in danger of losing their collection information, due to the advanced ages of their collectors.
The project was carried out at the UC Davis Herbarium between October 2000 and March 2001. Kate Borland proved to be an excellent person to carry out the project. In curating the Olmo and Koyama collection, she communicated effectively with Olmo and Koyama, deciphered their collection notebooks, checked species and cultivar names in the appropriate literature resources, typed collection data for nearly 2,000 specimens into our Access label-generating database, generated the labels on archival-quality paper, and placed the new labels with the correct specimens. The Olmo and Koyama specimens still require mounting onto archival paper. For the original viticulture herbarium, Kate cut the original labels off their crumbling folders, xeroxed them onto archival-quality paper, and placed the new labels with the specimens. Undergraduate students then glued the new labels onto archival folders and placed the pressed specimen into the folders, securing them with linen tape. We did not glue these specimens, so that they can be used easily be future researches for both morphological and molecular studies.
Crosses – About 1,300 seedlings from the 54 crosses made in 1994 were planted in the vineyard. Most of these crosses were designed to produce rootstocks resistant to root knot and/or dagger nematodes. We now have about 11,500 seedlings in the campus vineyard. Most of the 1995 crosses were designed to study the nematode resistance and taxonomy of Vitis champinii. Champinii is one of the best sources of nematode resistance within Vitis, but it is a poorly described species. Some of the taxonomists consider champinii to be a true species and others describe it as a hybrid complex between rupestris and candicans. We made crosses among all of the species whose ranges overlap in central Texas where champinii is found. Many of these should produce offspring with strong resistance to root knot and dagger nematodes. Peter Cousins (a PhD student working on the champinii project) is also examining our previous crosses within champinii (9207, 9208, 9209, 9210 and F9301) to genetically characterize the heritability of root knot nematode resistance within champinii, and investigate molecular markers (DNA and protein-based) linked to nematode resistance. These crosses and the ones completed this year will identify other sources of nematode resistance within champinii and may also identify less vigorous selections ofchampinii. Lower vigor forms of champinii with equivalent or greater nematode resistance would be very valuable. 1989 Seedlings – Two of the 1989 rupestris x rotundifolia seedlings, excelled in Mike McKenry’s field tanks with aggressive root knot nematode strains – 8913-02 and 8913-21. About 250 of the 1989 seedlings have been tested for Xiphinema index resistance. 8913-02 and 8913-21 were highly resistant, as were many of the 8916 seedlings. The best rooting and most resistant of the seedlings have been bench-grafted (successfully this year!) and are destined for field trials in Rutherford, Ripon and Paso Robles. The 8925 (berlandieri x rufotomentosa) population also had excellent resistance to X. index, but are very difficult to root. We also identified X. index resistance in champinii collections I made in Texas. Mapping X. index resistance – Yimin Jin (a MS student of mine) has identified RAPD (randomly amplified polymorphic DNA) bands in the rupestris x rotundifolia populations that are linked (associated with) to X. index resistance. The two primers that give the tightly linked bands are OP A 12 and OPU-1. He is also mapping X. index resistance with RAPDs. This will give us the bench marks for future genetic studies with this group, and allow us to pre-screen seedlings for X. index resistance, accelerating the evaluation process. 34 In vitro Phylloxera Resistance Screen – Evaluation of a tissue culture-based screen for phylloxera resistance is completed and the data is now being analyzed. We tested 4 selections from each of the following species: aestivalis, berlandieri, californica, champinii, cinerea, girdiana, labrusca, riparia, rotundifolia, rufotomentosa and rupestris, and 1 selection of amurensis and vinifera. Feeding success, reproduction, total phylloxera numbers and root and leaf damage were scored. Among the most interesting results were moderate susceptibility in the tested champinii; extreme resistance in cinerea, while berlandieri was more susceptible with one selection very susceptible; feeding and damage on rufotomentosa, but no reproduction; some susceptibility in aestivalis; high susceptibility on the leaves, but not roots of californica; high susceptibility in girdiana; and although St. George was a relatively good host, two other selections were highly resistant. Pest Diversity – Our DNA based studies of Californian phylloxera which found relatively high levels of diversity, were published. Jeffrey Granett and I are investigating native phylloxera populations in Arizona and New York where we found surprisingly low levels of diversity. We also continue to study the basis by which rootstocks and Vitis species alter phylloxera, and how phylloxera adapts to grape roots. A project to develop microsatellite (SSR) primers for phylloxera DNA was recently funded by the Viticulture Consortium and will allow Hong Lin (a post-doc in the lab) to produce a much more reliable and precise means of examining differences in phylloxera populations, both in California and the US. We have almost completed a project to examine the genetic diversity (based on RAPDs) in dagger nematode (Xiphinema index) populations across the state. We are analyzing data from populations we collected in Kern, Madera, Mendocino, Monterey, Napa, Santa Clara, San Joaquin and Sonoma counties. This study will help determine if dagger nematodes are different and will lead to studies on their ability to vector fanleaf virus and damage grape roots. Rootstock Identification – My lab adapted Carole Meredith’s microsatellite (SSR) primers to use in testing rootstock DNA and has produced a very precise means of identifying rootstocks. Like our previous isozyme-based test this test uses cambial tissue enabling the identification of rootstocks without leaves, or after they been grafted however this DNA technique is much more precise. We now have a unique profile for 58 rootstocks.
About 8,000 seeds from the 1993 crosses were planted during the winter of 1993-94. We planted 6,675 of these seedlings in the vineyard during the summer of 1994. Over half of these seedlings were from crosses designed to produce resistance to a variety of nematodes including root knot, dagger and nematode complexes; tolerance to drought and salinity; combining phylloxera resistance in all backgrounds; and appropriate levels of vigor. Fifty-four crosses were made in 1994 to address these same issues; 2326 seeds were produced from these crosses, about 1,000 are ready for planting as soon as the vineyard site is prepared. Progress with the 1989 seedlings has been slow because of repeated failures with the bench-grafting crew. These mistakes have been identified and the same series of materials is being bench-grafted again this winter. Grafting success with these seedlings has been good, however the soil mix into which they are planted after callusing, and the greenhouse culture they have been receiving, has been poor. These problems have been remedied, however they will not be completely solved until I have my own field and grafting crew. Mike McKenry, at the UC Kearney Ag Center, has completed screening the best of these seedlings for resistance to a complex nematode population consisting of his most aggressive root knot races. Three of these seedlings 8913-02 (rupestris A. de Serres X rotundifolia Trayshed), 8913-21 and 8916-02 (rupestris Wichita Refuge X rotundifolia Dixie) did well in his screen and are ready for field testing. A paper detailing a screening of Vitis species for resistance to root knot nematode has been published (Walker, Ferris and Eyre. 1994. Resistance in Vitis and Muscadinia species to Meloidogyne incognita. Plant Disease 78:1055-1058). Several interesting new sources of resistance were discovered and we are preparing to use them in crosses next year to improve rooting ability of known resistant species that root poorly. A graduate student of mine finished a manuscript (Fong, Walker, and Granett. RAPD assessment of California phylloxera diversity. Journal of Molecular Ecology, In Press), which details our discovery that phylloxera biotype definitions are groups of genotypes and not single types. This means that B type phylloxera are not spreading from a single point of origin, but are capable of evolving wherever AXR#1 is used. We have also begun a project to examine the genetic variability in dagger nematode (Xiphinema index) populations across the state. We have completed collections from San Joaquin, Sonoma, Napa, Monterey, Kem and Fresno counties. This study will examine the diversity that exists in populations of X. index, (high levels would not be expected from a predominantly parthenogenetic and imported pest) and will lead to studies on their ability to vector fanleaf virus and damage grape roots. We will then be able to utilize the most aggressive nematode populations in screening tests and be able to study differences in GFLV that may exist.
Progress in rootstock breeding was made in a variety of areas in 1993. The best of the 1989 seedlings, crosses of rupestris x rotundifolia, and one solonis x rotundifolia, have almost completed testing at the UC Kearney Ag. Center in Mike McKenry’s nematode tanks with 3 of his most aggressive Meloidogyne races. Several of the 1989 seedlings have good resistance. Dormant cuttings of some of these seedling selections have been grafted with Chardonnay and are destined for planting in a nematode/phylloxera trial in Ripon. These were also grafted to Flame Seedless for establishment in a root knot trial in Fowler. 926 1992 seedlings of an original 1,888 were recently planted in the new breeding block. 1,671 1993 seedlings have also been planted in this block. Ninety three new crosses designed for the production of nematode (both dagger and root knot) resistant rootstocks were produced in 1993. These utilized selections that L.A. Lider produced utilizing arizonica, candicans, champinii, and longii. We crossed these Lider selections with species selected to improve rooting, nematode resistance and drought tolerance. We also made 55 crosses designed to allow study of the taxonomic relationships among the North American Vitis species. Some of these may also prove very valuable as potential rootstocks. The 1994 pollinations emphasized the same objectives as the 1993. Thus far, forty-four crosses have been made. We completed the second round of a screening of Vitis and Muscadinia for resistance to Meloidogyne incognita. Resistance was common in aestivalis, champinii, and rotundifolia, it was also found in cinerea and rufotomentosa. Evaluation of an embryo-rescued population of Thompson Seedless seedlings for resistance to fanleaf virus continues, thus far all seedlings allow virus replication. This was expected since resistance to fanleaf appeared to be a rare recessive trait in earlier studies. We have made significant progress in developing an in vitro co-culture system for phylloxera using only root cultures. This system is now being tested to confirm that resistant and susceptible species act as expected in tissue culture. We have had trouble finishing our studies of DNA diversity in phylloxera, but procedures are now working and the data ready for final analysis. Preliminary examinations of the data show that phylloxera are variable within and among biotypes. There are no consistent A or B genetic markers. This suggests that B type phylloxera are not spreading, but that they are selected for at different AXR#1 sites.
Objectives: Continue a rootstock breeding program initiated in the Department of Viticulture and Enology, University of California, Davis in 1988, addressing resistance to soil-borne pests and diseases. Evaluate seedling populations from crosses with Muscadinia rotundifolia and a range of Vitis species of North American, Middle Eastern, and Asian origin for resistance to phylloxera, fanleaf degeneration, and root knot nematodes, and for viticultural characteristics such as propagatability. Increase of understanding of the nature of phylloxera and fanleaf degeneration resistance under Californian conditions, by utilizing tissue culture and whole plant methods, and apply the knowledge to seedling evaluations. Produce additional crosses, as indicated by preliminary information from seedling screenings, to further emphasize ease of propagation and enhanced resistance. Begin field evaluation of selected genotypes leading to the release of new rootstock cultivars. This project is a part of a broadly focused rootstock breeding program. This specific project emphasizes rootstocks tailored for use with wine grapes. Many of the objectives are shared with a similar project jointly funded by the California Table Grape Commission and the California Raisin Advisory Board which emphasizes table and raisin grape rootstock development.