Grape breeding at Cornell University

Hi, I'm Bruce Reich. I'm a professor in horticulture, and my work is all in grape breeding, grape genetics. We're at a no-spray, disease-resistant breeding block here. My responsibilities are to both develop new grape varieties for eastern viticulture, especially for New York, and also study the genetics of underlying traits, traits of great importance, such as disease resistance, winter hardiness, and quality, which goes hand-in-hand with the two. So grape breeding at New York State Agricultural Experiment Station, we're now Cornell Agritech, began around 1885. And initially, the primary goal was to breed table grapes for many years. It was a table grape breeding program, and later, in the early, mid-1900s, it was a seedless grape breeding program. It wasn't really until the 1940s or 50s that the project turned to wine grape breeding, and most of the effort now, more than two-thirds of the effort, is in wine grape breeding for disease resistance, hardiness, and factors that make it easy to harvest and grow consistently in New York. So we're standing at a no-spray breeding block that was first planted in the late 80s, early 1990s. And in this block, we took the most resilient selections that we could find in the program, selections that were grown under neglect, almost under no-spray conditions. But germplasm that I found in the program when I first started, that was really just held for use in germplasm collections. I scoured through that material to find the most disease-resistant material possible, and started to grow it actively under no-spray conditions. We developed mapping populations. We developed in our program some of the first genetic maps that were published in grape vines, first with isozymes, then with rapids, more recently with GBS SNP-based markers and RAMP-Seq-based markers. So a variety of technologies have come along to improve the mapping and the work to locate genes for traits of interest in the program. So early on, it was very empirical in approach. If it was disease-resistant in the nursery, it would make it out to a permanent vineyard, to this site. It would be tested, and crosses would be made with higher quality grapes to combine quality with resistance that came from the many wild species that we utilize in the program. The VitusGen projects came along, two different USDA-funded specialty crop research initiative projects, of which I co-lead the second one. I was leader of the first one. And with the team of fantastic scientists that we work with, scientists from USDA, scientists from across the country, we've developed a very directed approach to stacking genes for disease resistance and to studying genes that relate to fruit quality, to acidity, and other characteristics of fruit quality. I think the best instances I can describe for you are disease-resistance genes, some of which were found within our project, within our VitusGen projects, some of which were found here, located in germplasm that we were growing here at Cornell Agrotech, and others of which we've acquired, utilized, and developed good marker systems to identify. The marker systems allow us to stack these genes together for use in the program. We would not possibly be able to combine different sources of resistance without having the markers that we have now. The markers and the combination of genes, to me, are really important to try to develop long-term stability and durability of the resistance genes. We do know that over time, the activity of these genes can erode. We've seen some of these genes that seemed ironclad at the very start. Now, though they are powdery mildew resistance genes, we've seen some powdery mildew growing on vines that we know harbor these genes. Not a lot. It's still a very useful source. But we do know pathogens can mutate and overcome these resistance genes. So here we are, June 15th, and we're wrapping up our crossing season. We've made more than 20 different crosses. I don't have the exact tally, but since it's crossing season, grapes are flowering all around us. These are grape flowers. Not the easiest things to work with. They're very small, and they are perfect flowers. They have both viable pollen as well as stigma-style ovary. And almost all cultivated grapes have perfect flowers. But in the wild, vines of each species are either male or female. Within the VitusGen project, my colleagues, Zhu Cheng, Chi Sun, Lance Cadel Davidson, Jason Londo, have studied the structure of the hermaphrodite locus, the flower sex locus in grapes. And a paper was just published a couple of months ago in Proceedings of the National Academy of Sciences based on this study, which to me tells you a lot about the domestication of grapes and the fact that there were two different instances of the arising of hermaphrodite flowers in these species that either were male vines or female vines. So take a look for that paper if you're interested in an in-depth analysis. This particular dead vine came to me as a seed stock from Hungary, where a muscadine grape from down in southern United States, a 40-chromosome species, was hybridized in the 1920s, early 1920s, late teens or so, over a century ago, to make a cross with bunch grapes. Most of our grape species have 38 chromosomes. So a very difficult cross to make. Some viable progeny were obtained and later found their way to Alain Bouquet in southern France, who made further crosses as he noticed that these hybrids between muscadines and vinifera had high levels of powdery mildew resistance. Studies were made. The gene was located. It's a very strong locus for powdery mildew resistance. Adjacent to that locus is another very strong gene for downy mildew resistance. And eventually that source, I then utilized in the 1980s and 90s, that source of powdery mildew resistance, which had now been introgressed into a background which I could cross with freely, found its way into some slightly more winter-hardy germplasm, which a colleague of mine in Hungary, Paul Kosma, shared with me. And this is some of the germplasm he shared with me, a vine that's struggling to survive after mild winters. But the first year that it did produce flowers after a very mild winter, I jumped on those flowers sight unseen. I knew the vines were powdery mildew resistant. And I've been successful in introgressing this gene, the two-gene locus, powdery and downy mildew resistance, combined into more well-adapted germplasm, which I'll show you next. So with the seeds that I obtained from my colleague in Hungary, the first couple of years they had a chance to flower. They did not. Again, too much winter damage. But in 2006, they did flower. And I crossed them with other disease-resistant germplasm with reasonable quality, good winter hardiness. And this is one of the seedlings that then resulted. We have a plot here of six vines of New York 06-514-06, which is highly disease-resistant. It combines, by the scenarios, REN2 locus for powdery mildew resistance with the resistance of the muscadine grape. And this is a red wine grape with some chocolate and raspberry notes that's gone out for trials more broadly beyond Cornell. So in this vineyard, as you can see, we've placed QR codes here and throughout the vineyard. And we're using an imaging system, a camera drawn on an ATV, to image these vines. And one project is aimed at detecting phylloxera on leaf tissue. Phylloxera, which is an important insect, has in the past wiped out European viticulture. And we're trying to envision phylloxera on leaf tissue because that can be a problem with hybrid grapes. And using the imaging system and algorithms to pick out leaf phylloxera on tissues, we're trying to quantify that in this mapping population and study the genetics of phylloxera resistance. In addition, we're cooperating with Katie Gold, an assistant professor in plant pathology here at Cornell, on use of spectral analyses, UV, near-infrared, visible spectra analyses, to understand physiochemical properties of leaf and developing fruit tissues. This location I wanted to show you, not necessarily the oldest vine in the program, but one of the vines with the biggest trunk that I've ever grown. We just don't seem to grow trunks like this in New York State. This is a vine I picked out early on to initiate some of the disease-resistance breeding here. It was growing so well winter-hardiness-wise and disease-resistance-wise. It was growing so well under neglect. We've located, by the scenario parent of this, the REN2 locus for powdery mildew resistance. This is the source vine for that study. This one happens to be a male, so no fruit quality to judge. But we come such a long ways in the program from the wild grapes that we started with in the 1800s, late 1800s, 1900s, and to the present day, where we're now domesticating these wild species. And this rupestrous-bisonaria hybrid, the muscadine grape, a couple of species from China, by this Piazzeschii, by this Romanettii, are sources of disease-resistance genes that we utilize. We're bringing these into the program, and in the course of domesticating these wild species, we've developed somewhere over 60 different grape varieties. In my time at Cornell Agrotech, it's more than 10 different grape varieties that we've developed. Mostly wine grapes, but Everest seedless, a jumbo-sized, concord-type seedless grape, was the last one we released. Probably the first seedless grape in about 20 years to be released from the program. It happens to be a tetraploid grape, so associated with having double the number of chromosomes, you have a very large berry size, an average of 5 to 7 grams per berry. Similar flavor to concord, but twice the size of a concord berry, and seedless. Wine grapes, Traminette was one of our most successful. It was a release from 1996, and 20 years later or so, it was named the Outstanding Fruit Cultivar by the American Society for Horticultural Sciences Fruit Breeding Working Group. It's garnered major awards. It's very similar in wine quality to its Gewurztraminer parent, so you could almost not tell the difference with Gewurztraminer, yet it's much more winter-hardy, much more disease-resistant than Gewurztraminer. So that's been widely grown in New York and elsewhere. It's great fun to go to the wineries and see Traminette selling at many wineries in the Finger Lakes and elsewhere. In addition, some more recent releases include Aramella, a highly aromatic seedling of Traminette, much more winter-hardy even than Traminette, and Arendelle, the first cultivar that we named out of this no-spray breeding block, a red wine grape with high levels of disease resistance, and several wineries in New York, Kansas, and Virginia are making very good wines now with Arendelle. Each year, each of these varieties is responsible for between $5 and $15 million worth of wine production just in New York state alone. So we see, over time, a cumulative economic impact in the tens of millions of dollars. This has been a production of Cornell University, on the web at cornell.edu.