The Case for Blueberry by Cranberry Hybridization

– Welcome everyone to Wednesday Nite @ the Lab.

My name is Dyllen Brewer and I’m a student worker here at the Biotech Center.

On behalf of the Biotechnology Center, UW-Madison Division of Extension, PBS Wisconsin, Wisconsin Alumni Association, and UW-Madison Science Alliance, welcome to Wednesday Nite @ the Lab.

This is the last Wednesday Nite @ the Lab before a long-term hiatus.

It is my pleasure of introducing Fernando de la Torre.

Tonight, he will be sharing about Vaccinium hybrids.

Before we get started, we’re gonna ask him a couple questions.

Fernando, where were you born?

– I was born in Los Angeles, California.

– And where did you attend high school?

– Chula Vista High School in South Bay, San Diego.

– Where did you go for undergrad?

– I went to UCLA.

– And what did you study there?

– It’s a big long title, but molecular cell developmental biology.

MCDB, that’s what we call it.

– There we go.

And where did you go for any advanced degrees?

– Well, I’m currently doing that now here.

– Awesome; good place to be.

– Great place to be.

Yes, absolutely.

– All right, ladies and gentlemen, please join me in welcoming Fernando de la Torre.

[audience applauding] – Good evening, everybody.

I would just introduce, my name is Fernando de la Torre.

I’m excited to be giving this public lecture to everybody today.

If you haven’t done so, feel free to take some cranberries and blueberries here.

We’re gonna participate, if you wanna participate in a tasting later.

I guess I’ll start by saying that every time I tell people about my research, that I cross blueberries with cranberries, 100% of the time, people ask me, “What do they look like?”

So I’m just gonna kick us off and show you what they look like.

So you see in the middle, actually on the top right-hand corner is a cranberry.

In Wisconsin, we know them very well.

And then below that, a blueberry.

And then in the center there, we have a blueberry by cranberry hybrid fruit.

And you might appreciate that they don’t really quite look like any of the two parents.

They look quite intermediate.

And so I’ll be talking more about these plants later on in the presentation.

But I think it’s fun to talk about berries with people.

I think most people can use berries to conceptualize something very common that we do in agriculture, which is called hybridization.

And hybridization is one of the methods that plant breeders use to systematically improve the edible parts of crop plants for human consumption.

And hybridization can lead to the increase of size or flavor of a berry, or improvement of similar characteristics.

So like I said, with berries, it’s very easy to visualize because I think people intuitively understand that to breed a blueberry with a cranberry is like trying to bring together the best qualities of each into a single fruit.

But to accomplish hybridization, we have to mate two distinct plants.

And that hasn’t always been easy for blueberries and cranberries.

And the path forward wasn’t really revealing itself until about five years ago.

Even though blueberries and cranberries are very closely-related species, they are sufficiently distinct to deter interspecific hybridization.

So interspecific hybridization is a term that we use to describe when two distinct species come together to produce offspring.

The blueberry and the cranberry are two distinct species.

And the challenge of interspecific hybridization, especially with two fruits as unique as a blueberry and a cranberry, is to find two parents that can come together and produce enough hybrid offspring that then we can select from.

So that’s the story of what we do at the USDA Cranberry Genetics and Genomics Laboratory here in Madison.

We dedicate some of our resources to finding plants within the group called genus Vaccinium.

That includes cranberries and blueberries to find compatible pairs of plants to produce hybrid offspring.

And one of our goals, of course, is to produce hybrid populations and extend them into second and third generation so that we can select the best ones for cultivation.

So that plant that you see there is the one that I have here tonight, although I guess three weeks later.

[audience chuckling] Yeah, so the objective generally seems pretty straightforward, but it has actually taken decades of systematic testing and cross-pollination to find the compatible pairs of plants.

And the blueberry by cranberry hybrid population that I’ll be talking about near the end of the presentation is the product of finding two of these compatible parents.

So with that said, I wanna accomplish three things with this talk.

One, I wanna introduce the group of plants that contain blueberry and cranberry called genus Vaccinium.

And I’ll cover a brief history of blueberry and cranberry crop improvement.

Then we’ll also explore why we would wanna breed a blueberry and a cranberry to begin with.

Some people might say they’re fine as they are, but for that, like I said, I invite you to take a Dixie cup with some berries in it and then we can go through a tasting exercise.

And then we’ll also cover the last 30 years of interspecific hybridization attempts.

And then lastly, I’ll show you some of the measurements that I’ve gathered on the population of blueberry by cranberry hybrids that I work with.

And like I said in the announcement, I will be picking some random people to try a hybrid berry here tonight.

And so that’ll be at the end of the presentation.

So yeah, let’s just get started here.

As I mentioned previously, blueberry and cranberry are both plants within the group of plants called genus Vaccinium.

And the commercial blueberry that you buy at the store goes by the common name highbush blueberry, and it has the Linnaean name of Vaccinium corymbosum.

And the commercial cranberry goes by the common name American cranberry, and its Linnaean name is Vaccinium macrocarpon.

This genus is very special to us because it’s a group of plants native to North America with distribution along the East Coast and in the northern regions of the continent.

This is very different, for example, than tomatoes or apples, which originate elsewhere in the world.

For example, tomatoes are originally from the Andean region of South America.

And as much as we associate tomato sauce with Italy, tomatoes were not part of Italian cuisine until the Columbian exchange in the 16th century.

Similarly, apples were originally from Central Asia, east of the Caspian Sea.

And in fact, there was once a medieval settlement near the capital of Kazakhstan called Almatau, which means “apple mountain.”

But cranberry and blueberry have their centers of origin in the northeast of the USA.

This allows us to directly observe these plants in their natural population, in their natural habitats, and select from the original gene pools with minimal geographical and political constraints.

So to talk about Vaccinium and the earliest indications that we could potentially breed between them, we can start by talking about Canadian botanist Sam Peter Vander Kloet.

He and his family immigrated to Canada from the Netherlands in 1947, and he would eventually become professor at Acadia University in Nova Scotia and one of the top authorities in blueberry classification.

And if one of the really famous books that he wrote called The Genus Vaccinium in North America, in reading that book, you start to realize that he was very frustrated with blueberry classification at the time that he finished his graduate degree in 1972.

In the preface of this book, The Genus Vaccinium in North America, he noticed that twigs from single colonies of low bush blueberries, both in New York and Ontario, when fully exposed to sunlight, were sometimes referable as Vaccinium brittani, when partially shaded as Vaccinium angustifolium, and when completely in the shade as Vaccinium lamarckii.

“This is patent nonsense,” he said.

“Any existing classification “that gives such ambiguous answers brings taxonomy into disrepute.”

So what he’s trying to say with this is that he believed that the system at the time was a source of many misidentifications in the genus.

And so for this reason, he went out to document many blueberry and cranberry Vaccinium species across the continent and extensively surveying natural populations.

He collected continuous characters.

So what do we mean by continuous characters?

They’re traits such as corolla, width, and length, which captures the shape of the flower, the crown, and the petals.

Anther lengths, which the anther is the flower organ that produces the pollen, and as well as the diameter of the pollen itself, which if you can believe, varies across the different species.

And so he did this for 184 Vaccinium populations in North America between 1969 and 1981.

And he also collected soil samples and took notes of the habitats.

So I mean, with that much experience, it makes sense why he became an authority in the field.

And so based on the distribution of the Vaccinium populations and the soil that he was gathering, he proposed an origin story for the genus Vaccinium, which was in some agreement with his predecessor, a really important botanist called Wendell Holmes Camp.

And so the hypothesis involves the last glaciation period of the quaternary, which is also called the Pleistocene glaciation.

And many of you are familiar with this concept because of how glaciation forged the terrain here in Wisconsin.

So from studying ice cores, geologists have described this period of Earth’s history as having glacial and interglacial periods, as you can see up there, where the ice would nucleate or start from the American cordillera and then proceed towards the 38th parallel.

And that’s a line of longitude.

And so during interglacial periods, the ice would go back towards the mountain range, and then during glacial periods, it would advance again.

And this happened several times, and each time the ice sheet advanced, it displaced many plant populations east and south and also flattened much of the land, which is what you see across Wisconsin.

And so the interglacial periods might have been responsible for promoting the evolution of proto Vaccinium populations.

It’s a complicated story to tell, but I just wanted to give you a sense for the natural selection that took place by the time that Vander Kloet and Camp and other botanists surveyed North America for these populations.

I should also mention that Vaccinium populations do exist as far south as the Andes in South America and on islands across the world.

And this can be explained by migrations that occurred much earlier in Earth’s history, where there were land masses that are nonexistent today.

But that’s beyond the scope of this talk this evening.

So ultimately what I wanna get at, what is relevant to us tonight is that Vander Kloet and Camp, they found naturally-occurring hybrid populations in their surveys.

And so here I’m showing a couple of independent examples of hybrid zones described by these botanists along Florida and New York.

And the hybrid zone is a region where two distinct plant populations can cross-pollinate, generate hybrid seed, and have that population take over a region of the geography.

And so the two plant populations need to be something we call sympatric.

So they have to flower at the same time and they have to have a pollinator that they share for the cross-pollination to occur.

And so Vaccinium hybrids are still found naturally today.

And there’s a recent example in the San Bruno mountains in California there up top.

So given what Vander Kloet, Camp, and others did, you know, we had a better understanding of how we organize Vaccinium plants today.

We have the main genus Vaccinium, and then it’s further subdivided into subgenera called sections.

And when Vander Kloet and Camp were doing these surveys, they only had morphology to work with.

And now, all of us know we have DNA technology to help clarify the relationships between different plants.

And so the most comprehensive work that was done on this front was by a professor called Kathleen Kron.

And right before I get to that, these are the kind of maps that Vander Kloet and Camp could put together given the distribution, where they found the plants, and then the morphology that they shared between them.

But again, this is not complete given that we have DNA information today.

And so Kathleen did a lot of this work as a professor of biology and molecular systematics at Wake Forest University.

And she spent her whole career studying a larger family of plants called Ericaceae, which contain the lineages that gave rise to Vaccinium.

And so you can see the plants that she surveyed shaded on the world map, and then these more sort of refined relationships that she was able to decipher with DNA.

So returning to that diagram then, because with Vander Kloet, Camp, and Kron, now we have a better idea of how the genus is subdivided.

These hybrid zones that Camp and Vander Kloet described were between members of the section Cyanococcus.

And so cyano means blue and coccus means sphere.

So you can already infer what that means.

It’s all the blueberries that you see naturally and at the store.

And so you might be… At the time, this was the best example that we had of being able to cross between species in the same section.

And it’s the reason why we have blueberry in store shelves today.

And so I’m gonna go over a little bit of the improvements that were done to blueberry, quick history.

And we have to start in 1908 with Frederick Coville and Elizabeth White, who was the daughter of a cranberry grower in New Lisbon, New Jersey.

And Frederick Coville was a USDA botanist.

And up until 1908, you could only harvest blueberries from the wild because farmers didn’t know how to culture them in garden soil.

And so in his book from 1910 called Experiments in Blueberry Culture, Coville describes the experiments that he performed to ultimately discover that blueberry plants need acidic peat that is not overwatered to grow successfully.

And so peat is a compost of leaves and wood and moss that can be found in bogs and surfaces of pine woods.

And so Elizabeth White read the book and was very excited about the opportunity of growing blueberries commercially ’cause they weren’t doing that at the time.

And so she offered Coville the use of her land in New Jersey that was ideally suited for blueberry growing because that’s where blueberries came from, and her labor force to begin the first breeding efforts to increase the berry’s size.

To provide a breeding example, Dr. Coville brought a wild selection that he had from a neighbor called Brooks.

And he crossed it with a wild selection that White made near her farm called Sooy.

And then they would cross them and then evaluate the size of the berries, take really careful notes.

And Elizabeth White continued breeding way after the partnership between Coville ended.

And so I just want to clarify a point here with wild selection, what I mean by a wild selection.

And so I guess I’ll…

Yes, here we go.

So wild selection is simply a plant chosen from a naturally-occurring population.

So here’s a little short video of wild cranberries growing near a lake at the Kemp Natural Resources Station near Minocqua, Wisconsin.

And if you wanted to make a wild selection of these cranberry plants, you would go grab some vines and propagate them based on something that you observed, like better berries or vigorous growth.

So that being said, cranberry culture was mainly based in wild selections until the initial cranberry improvement cycles that were undertaken as a response to a false blossom in 1929.

That’s very different than blueberry ’cause in blueberry, they wanted to increase the size, but in cranberry, there was a disease that took over.

And then when false blossom emerged, it threatened the cranberry industry because it didn’t have a cure.

So false blossom is caused by a bacteria that is carried by an insect called the leafhopper, in particular the blunt-nosed leafhopper.

And it transmits a bacteria that prevents the cranberry flower from assuming its down formation.

You can see how a healthy cranberry in fluorescence will have, like, a crane formation.

And when it’s diseased, it won’t be able to assume that formation, and therefore the fruit can’t develop properly.

And so the two researchers that wanted to find a solution to this problem were R.B.

Wilcox and USDA entomologist Charles S. Beckwith because at the time, the industry by 1929 had already advanced beyond Massachusetts and New Jersey into Wisconsin.

And so if you have a disease that’s out there that has no cure, it can potentially decimate the local economies and people’s livelihoods.

So what they were able to figure out, Wilcox and Beckwith, was that some of the wild selections that were actively grown in Massachusetts called McFarlin and Early Black were the most resistant to this disease.

And in a future improvement cycle between 1934 and 1950, the cultivar Stevens was shown to be the most resistant, which came from a cross between two wild selections, one from Massachusetts and one from Wisconsin.

So I wanna note that even though Coville, White, Wilcox, and Beckwith were very successful in their improvement efforts, those improvements were largely regionalized to a certain extent because even though blueberries could be cultured, they still required…

They still required cold temperatures to break out of dormancy because we know that, well, now we know that as fall approaches and day lengths shorten, less light is available for plant growth.

And so for this reason, the plants enter dormancy to slow their growth, strengthen their roots, and conserve energy.

So the prolonged exposure to cold temperature is important for breaking out of dormancy because it begins the process of releasing sugar stored in starch in the plant cells.

And then as winter ends, the day lengths increase, and then the plants can use the starch to promote their growth in spring.

So at the time, now we know this, but at the time, during Coville’s improvement cycle for blueberry, people thought that if you just put a plant and growth in the warm, in a warm temperature, that it would actively grow.

And so Coville showed that chilling hours were important for blueberries to exit the dormancy.

So then how did we go, to bring it all back to interspecific hybridization, how did we go from a regional crop like a blueberry that only grew in the Northeast to now, what is the global production of blueberry?

And that actually was through the interspecific hybridization of highbush blueberry with the evergreen blueberry.

So these are two plants in the same section.

And the evergreen blueberry up top had been selected naturally by the temperatures in Florida.

This is a Florida native.

And so if you could cross the blueberry that has a higher requirement for chilling hours with a blueberry that has a lower requirement for chilling hours, then you could have progeny that you can select from that have lower chilling requirements.

And so that’s essentially the answer.

So that interspecific hybridization between two different species in the same section led to what is now global production of blueberry.

So breeders, seeing that interspecific hybridization was possible within a section.

So just to clarify, we have different species in a section, and then they’re able to cross amongst each other, right?

But the genus has so many sections, so much variation.

So plant breeders really wanted to know if they could cross between sections to be able to harness the speciation across the entire genus.

And so why would they wanna do this?

Like I posed the question earlier.

A blueberry’s probably fine, a cranberry’s probably fine, but if you look across the whole genus, you can potentially unlock a lot of variation and customize different berries for different climates, which would be really helpful for nutrition and berry enthusiasts, if there are any out there.

[audience member cheering] Right, so now I’ve been talking for a few minutes and I wanted us to explore the tasting.

I’m not sure if any of you have berries or if you’ve eaten them yet.

[audience chuckling] So I’m gonna take a couple here.

And I want us to try a cranberry just first on its own.

[cranberry crunching] [audience laughing] It doesn’t get any easier.

[audience laughing] And can I get some responses, some one-word responses about what people are, yeah.

Very tart.

– Audience Member 1: Are these all the same?

– Yes, they’re all the same; yes.

Anything else?

– Audience Member 2: Little bitter, sometimes.

– Audience Member 3: Crunchy.

– Yeah, crunchy; that’s a good one, yeah.

Right; so, I think that’s…

So you can kind of see why we would wanna improve, make improvements by hybridizing with other species.

[audience chuckling] So let’s just try a blueberry to, you know… – Audience Member 4: Clean your palate.

– Clean the palate, exactly.

[audience chuckling] And so what are you tasting here?

– Audience Member 5: Sweet.

– Yeah.

– Audience Member 6: Can you repeat the responses?

– Yeah, so sweet, somebody said sweet.

– Audience Member 7: Mushy.

– Mushy; true, true.

What was that?

– Audience Member 8: More chewable.

– Yeah, more chewable; absolutely.

– Audience Member 9: Juicy.

– Juicy, yeah.

– Audience Member 10: Yummy.

– Yummy.

[all laughing] Yeah, that’s exactly the point.

So now let’s just, like, eat them both together and see maybe potentially how, if you took genes from both of them, could you improve the experience here?

[crunching] Yeah, I didn’t grimace that time.

[audience laughing] Okay, well, thank you for participating.

I’m interested– I’m curious that nobody brought up the skin of both fruits.

The formal term is a cuticle, and that’s the barrier between the interior flesh and the outside world.

And there’s this waxy layer called, yeah, there’s a layer of wax and some biological polyester called cutin.

And so you might’ve noticed that after buying blueberries at the store and leaving them in the refrigerator for a little bit, they start to shrivel.

And so you might conceive that a blueberry could be improved by taking the cuticle of a cranberry, which doesn’t really lose water.

You can keep them for weeks and they’ll still be as firm and tart and sour.

But a blueberry doesn’t do that, right?

And so that could be an improvement made to blueberry, right?

You improve the cuticle and you extend shelf life.

And then we don’t have to go very far in terms of the cranberry.

It’s tart; it’s very sour.

And the sugar in a blueberry could really improve the taste for the fresh market because most of us are familiar with cranberry through our cultural experience of Thanksgiving in a sauce.

But that has a lot of sugar.

So for the fresh market, there can be an improvement.

Right, so let’s see.

So these are the combinations that I was referring to when I was talking about unlocking the potential across the genus between all the sections.

If we could figure out a way to cross between them, then we can customize berries for different regions of the world, different palates, et cetera.

Great, so I’m gonna go through a little bit of the history of the scientists and the breeders that have tried to accomplish this goal over the last 30 years.

So Sylvia Brooks and Paul Lyrene in 1996 had similar ideas here.

So they wanted to take the Vaccinium arboreum, which is called a sparkleberry, and they wanted to cross it with highbush blueberry because the sparkleberry has a larger growing region than Vaccinium corymbosum, the blueberry.

So you could potentially expand growth and commerce to different areas.

And so they did some interesting findings here because they realized that they couldn’t take a blueberry and a sparkleberry and cross them directly together.

They had to go through an intermediary called Vaccinium darrowii.

And so this was called the evergreen blueberry.

This is the one that lowered the chilling requirements for Vaccinium corymbosum.

So this plant is very interesting.

And so they took an intermediate hybrid between Vaccinium darrowii and arboreum, and then they were able to cross to highbush blueberry.

So what was interesting about that is that they figured out two things.

They figured out that they could cross between sections, in this case, section Cyanococcus, which has all the blue spheres, all the blueberries, and section Batodendron, which is where the sparkleberry is organized.

And secondly, that maybe you do need to have one hybridization before your target to have genetic exchange that you want.

Then in 1997, Zeldin and McCown here at UW, they used a very interesting plant called Vaccinium reticulatum or the Ohelo ai berry from Hawaii.

It grows on volcanic soils on the islands.

And they figured out some interesting things here because they were able to cross directly between Ohelo ai and cranberry, and then Ohelo ai and lingonberry.

Lingonberry is very famous in Swedish cuisine in jams and all that.

So they were able to cross when Vaccinium reticulatum was used as a mother.

So they could only really put pollen from a cranberry or pollen from a lingonberry onto an Ohelo ai flower, but not the other way around.

So this shows you that there’s some unidirectionality in some of the crosses.

And so that in itself is interesting.

But now, before I continue on with the history, I kind of want to go through some of the mechanics of how you would even hybridize.

So I’m talking about crossing these two plants together to potentiate all the variation across the genus.

But how would you do that?

So here I’m showing that all flowers have a stigma and a style where they receive pollen from either the same species or another species.

And so when flowers are ready to accept pollen, they usually have this little, this exudate that will hydrate the pollen and begin the process of fertilization.

So what do I mean by hydrating pollen?

So here on the left, I have dry pollen from Vaccinium macrocarpon or the American cranberry, the variety Stevens.

And then when it’s exposed to this exudate at the tip of the stigma of a flower, it will then expand.

And this begins the process of the pollen sending down their genes.

And so here I’m showing a pollen tube that emerges from the aperture of a pollen grain of Vaccinium crassifolium.

And at the tip of this pollen tube, you can see on the right, the little red pollen tube, at the tip are the nuclei that belong to… that are the genetic material of the male in the cross.

And so this is really genetic transport.

And so then as the pollen tube, as the pollen is hydrated at the tip of the stigma and pollen tube elongation commences, it goes down the style of the flower towards fertilization.

So here you can actually see, I cut a little window in a style and stained it so you can actually see the pollen tubes up top, but actually in the flower organ.

And if that wasn’t clear, the style is that little organ that’s protruding, for example, from this flower of Vaccinium macrocarpon, and then the pollen tube and the genetic information is traveling down towards the ovules, which eventually become the seeds.

And so that’s what I mean by fertilization.

So that’s what you would do in an interspecific cross is you would take the pollen from one plant and then you would take the flower of the other, and then put the pollen on the flower, and then hope that the genetic… the pollen elongates, goes down to the ovules, and eventually gives you a seed.

And that seed is gonna be the hybrid, potentially hybrid plant that you would grow up like you see here.

So I’m gonna kind of go through this a little more briefly here.

There are some really important advances here that kind of still suggested the same thing.

For example here, Nikolai Vorsa and Jessica Cicalese-Johnson, they figured out that again, you do need an intermediate.

So in order for you to cross darrowii with the evergreen blueberry, with macrocarpon, you need an intermediary hybrid with oxycoccus, which is a small cranberry.

And then Mark Ehlenfeldt and Jim Polashock, they were able to figure out that somehow if you were to find Vaccinium species that are very distant on remote islands, like, for example, the Ohelo ai berry, in this case, you have Vaccinium padifolium, which is on an island off the coast of Portugal.

And they can mediate hybridization as well.

But I do want to bring up one person here is Paul Lyrene.

So you can see here that from 1996 with Sylvia Brooks all the way until 2018, he’s been trying different hybridizations.

And so it takes an entire career of testing different combinations to get the populations.

And in this case, Paul Lyrene, he was doing crosses in a very classical way.

So here he was taking highbush blueberry, which is again the one that we eat, and he was crossing it to deerberry, which is the picture I have there with Vaccinium stamineum, and he was generating a first-generation hybrid that he would then use the pollen from to backcross to the highbush blueberry.

And this is how you get a little bit of genetic exchange, but you mainly maintain the identity of the plant that you want, which is highbush blueberry here.

And so it takes a long time, right?

And so now in the present, this is the real development now that is the core of my graduate studies here, and it’s here in 2017, Mark Ehlenfeldt and Jim Ballington would find a plant that, for reasons that are still unclear, would be able to cross to both highbush blueberry, lingonberry, and cranberry, which are all the commercial species.

So this is exactly what we’d been looking for, a plant that could be a mediator for genetic exchange across the entire genus.

And so just wanted to point out this plant here.

It’s called the Andean blueberry or Vaccinium meridionale.

And so you find it in the mountains of Antiochia in Colombia, and people call it there in Spanish, they call it agraz or mortio.

And it’s found in the Colombian Cordillera or basically the Colombian part of the Andes.

And you can see there what the plant looks like.

And so for a long time, this plant was basically harvested from the wild.

And so I wanted to just put a human element to this.

A lot of the local people there didn’t really… they would just use it to eat and not really realize that it could actually have this implication in science.

And so it’s very interesting.

The only thing I wanted to point out here is that now they’re going through the process of commercialization in the same way that Elizabeth White and Frederick Coville did in the 1910s where they were creating markets for different berries.

And that’s how now with the right markets, they’re able to then fund their breeding programs and actually make it something that’s cultivated on a farm rather than just it being wild and for personal harvesting.

And so Mark Ehlenfeld and Jim Ballington, yeah, they were able…

The first thing that they figured out is that the Andean blueberry can generate many hybrids.

So generally speaking, in previous attempts throughout the years there, you can see that the frequency of getting a hybrid by an interspecific cross is very low.

I mean, four hybrids in 3,300 crosses.

I mean, those are pretty slim odds there.

And so with Vaccinium meridionale, they were able to get way better odds, 190 out of 1,900.

And so why is this important, right?

And I’ll get to that in a little bit.

But basically the odds, just to drive this point home, the odds now between a cross or the frequency of generating hybrids between Vaccinium meridionale and macrocarpon now is 500 F1 hybrids per 30 pollinations.

That’s something that you can do in five minutes.

And so why would we want so many hybrids?

And here the idea is that for a hybrid to be successful, you need a large starting population.

Why?

Because you need all the genetic combinations.

You want to generate enough genetic combinations that can display the full array of all the characteristics that you wanna see.

So then you can select the ones that are gonna be the best.

And not only that, but you also need the plant to be self-fertile.

So you need it to produce fruit and you need the fruit to have seed so that you can advance the hybrid populations into a second and a third generation.

And so now this part of the presentation, I’m gonna start talking about this F1 hybrid that I’m studying here thanks to plants that Mark Ehlenfeldt has sent over from New Jersey, and basically it’s Vaccinium meridionale by Vaccinium macrocarpon as an F1 hybrid.

And something you can see that’s quite odd is that the berries don’t quite look like the mom or the dad.

They don’t look like the cranberry or the blueberry, right?

It’s kind of in the middle.

So now I’m gonna go into the metrics, like I said.

So what are we seeing here with all the hybrids that are being generated between this cross?

And so they all come in different sizes, and after about two, three years of growth, the sizes have been consistent.

So there are some seeds that are gonna be generated that are never gonna produce a big plant.

And then there’s some seed that is gonna produce a big plant.

And that’s exactly what I meant by large population because then we get all the genetic combinations for selection.

Furthermore, not all the F1 hybrids are flowering.

So those are one of the requirements for being able to select a good hybrid.

You need the hybrid to have fruit so that you can take the seed and continue advancing the hybrid population.

And then lastly, not all the F1 hybrids produce fruit.

But the good thing is that because we started with a large population, we have about, right now, we’re hosting 200 or so plants here of these F1s from the original 500 that were generated from the 30 pollinations.

And I think it’s like 40% of them are flowering.

But had the cross only generated a small amount of hybrids, you would have less plants that are flowering.

So the the point is that this is exactly why you want large populations.

And then the curious thing here, and the reason why we’re gonna continue advancing the population is ’cause not all the F1 hybrids are producing the same fruit.

So some of the plants will only produce cranberry-like fruit, and then some of them, only the blueberry-like fruit.

And then some plants produce a mixture.

And I’m not exactly sure why that is, but what you can appreciate here is that the internal flesh is very different.

So in the ones that look more like blueberry, you have a red sort of flesh with potentially a softer cuticle, a softer sort of waxy or less waxy skin versus the ones that are red that are more cranberry-like.

But I’m comparing it next to a cranberry fruit.

And I wanna make a point here because you notice that a cranberry fruit, generally speaking, has holes in it.

I don’t know if you got a chance when you were grimacing after eating one of these, but yeah.

If you, I’m not gonna, oh… [cranberry crunching] Yeah… You can see that it has holes in it, right?

And so as we continue selecting, we’re gonna have to take this into account because it actually plays a really important role.

We don’t wanna disturb agronomic practices, harvesting practices.

And so many of you are familiar with this image here.

As I mentioned before, a lot of cranberry beds, they start off as, like, single plants on the bottom of a pool-like excavation that has sand on it.

And after the flowers bloom and the fruit matures, then they flood the bed and then the berries will then float.

But the holes do contribute to flotation, but also the fruit density.

It’s the same reason why apples float, but they don’t have holes.

And so in our selection screening, we’re noticing here, I’m playing a couple videos of just dropping the berries.

So that’s one of the purple berries that the hybrid produces.

And the flotation is a little less fast coming back up.

But then some of the red berries, they float just as well, even if they don’t have holes.

So this is one of the things where we don’t want to disturb the industry, and so we have to consider that we want to improve flavor, but we also don’t wanna affect the density of the berry.

Something else we do is we test the different levels of firmness.

And so here we have this machine.

I tried to be as still as I could, but basically it’s a machine that will press the berry and it will generate these curves that will give you the maximum compression force.

And so basically that kind of tells you how well does the berry compress.

And so if it’s softer like a blueberry, the curve is gonna be lower as you can see down.

All the blueberry curves are really low, right?

And cranberry as expected is a very firm, very crunchy berry, right?

But what’s great is that the F1 hybrids are producing variation that we can select ’cause some of them are softer, some of them are firmer.

And so that’s what we want, and that’s why we’re so interested in this cross.

And then lastly, the F1 hybrids show vigor for seed potential.

So remember what we had talked about was that you need a large starting population, you need the flowering plants to produce seed.

So here, what I did is I dissected out the ovules from different flowers.

And so I had mentioned that the ovules are where the pollen tube will finally do the fertilization and then those ovules will become seed.

So if you open up the flower and count how many ovules, you can get an idea of potentially how many seed it’s gonna produce.

And so what you can see here, I compared the two parents versus the F1 hybrids.

And you can see something that we call hybrid vigor.

And so that’s when there’s enough divergent genetics that the F1 hybrid will be greater than the sum of its parents.

That’s sort of, like, the easiest way to understand it.

And lastly, and this is the part where I want to go back to the cuticle example that I had talked about.

So I wanted to test if my idea for improving the shelf stability of a blueberry could be possible.

So with the F1 hybrid, so we know, like I had mentioned that a blueberry, here I left some blueberries out at room temperature.

And you can see that in six days, they’re kind of shriveled, but a cranberry keeps very well.

And so we have variation in the F1 that we can select.

And so I wanted to know if exposure to just room temperature and having it dehydrate, if the cuticle, which I can see here, the blueberry-like one has less of a waxier cuticle than the cranberry one, if that has an effect on the loss of water or basically dehydration.

So at the time, I didn’t have the F1 hybrid berries, but I did have this plant here.

And so I’m gonna introduce…

I wish it had a name, but I’m gonna introduce this plant here.

But basically it’s a very similar plant to the original Andean blueberry by cranberry, only this one’s a little further along.

So the ones that I work with are the F1s that were generated by Mark Ehlenfeldt in New Jersey.

And then this plant here is the second generation hybrid.

So it’s a little further advanced.

It’s been selected, so the seed from the hybrid fruit was germinated and it gave us this plant.

And so what you can see here is I took some cranberries, I took two types of blueberries, and I took the hybrid berry, and I just left them out.

And you can see here that cranberry hardly loses any water at room temperature.

And the blueberries just plummet because they shrivel.

But the F2 hybrid on average doesn’t lose water as quickly.

And so you can see that physically in the berry, right?

And so there’s some indication that this is also an effect that is seen in the hybrid fruit itself, in the F1 that I’m working with.

I didn’t have a large sample size, but basically I took some of the red berries and I compared them to some of the purple berries versus cranberry.

This isn’t a great test ’cause I didn’t have a lot of fruit at the time, but you can see here is that the rate of dehydration is higher for a blueberry, for the blueberry-like F1 hybrid than the cranberry-like F1 hybrid.

So in order to…

So I felt like that was…

I’ll be running more tests, but essentially, there’s promise here to kind of improve the shelf stability of a berry that’s a little sweeter.

We are working with a USDA food scientist right now to actually describe quantitatively the flavor of the berry.

But there’s a lot more to do.

But I think this is kind of a proof of concept that you can increase the shelf stability by using more of a red phenotype, selecting for a blueberry or a berry that’s sweeter but that has more cuticle to maintain its shelf life.

So yeah, that’s it.

And like as promised, I just wanted to have one person randomly come up and then pick a berry, and then now you’ve tried a blueberry, now you’ve tried a cranberry.

And this is very similar.

The lingonberry is very similar to the cranberry.

It’s just a little smaller.

The flavor’s a little bit more complex, but this is kind of what you could expect from an improved variety.

So I wanted to have somebody randomly come up, any volunteers just to pick one out and then tell me.

Right here, both of you, yes.

[audience chatting] – Do you have any tips for picking a right berry here?

– No, let’s see, pick them on this side though, so the audience, that people can see.

– Take the place of this.

– Yes, and then just look for something that you think might taste good.

The redder, the better.

[audience chuckling] That’s probably as much as I can say.

You’ve tried the cranberry, you tried the blueberry, right?

So we’ll have you go first, and then I want you to describe the taste to the audience here.

– Oh, that’s good.

– Yeah?

– It’s, like, similar to the cranberry kind of in, like, the firmness of it.

Like, it has that kind of waxy skin, a little bit tougher, but it’s not as tart; it’s sweeter.

– Great, okay, we’ll have our second participant here.

– It’s definitely a lot sweeter than just the plain cranberry that you can definitely taste, like, the sour aspect that comes through, but it’s, like, it’s countered really well by the sweetness.

And then as you said, the cuticle is definitely a little tougher, but it’s nowhere near as tough as the cuticle of the cranberry.

– There you go.

Well, you heard it here first, I guess.

[audience applauding] Thank you.

All right, you can have one more; go ahead.

[audience laughing] – Audience Member 12: Guess if they’re good enough, they want– – Yeah, so that’s essentially it.

I just wanted, before I wrap this up, I just wanna thank some important people.

These are all my advisors here, Anna Edlund, who has been really helpful in showing me all the techniques for imaging the pollen that you saw so that I could communicate effectively how the fertilization happens.

And of course, Mark Ehlenfeldt, who’s a research geneticist, a blueberry breeder in Chatsworth, New Jersey.

And of course my advisor here on campus, Juan Zalapa, who is a research geneticist as well, a cranberry breeder with USDA ARS as well.

And you can see that this project is complex.

So it’s unique.

So it needs unique fields to be explained and to be able to, you know, hopefully someday potentially be able to cross across all the sections and get interesting-tasting berries so that people can enjoy them.

And then lastly, I have a small team here.

One of my undergrad mentees, Jordan Cargill.

Eric Wiesman is a research technician as well with USDA ARS, but secretly he’s our lab manager.

So he really helps with logistics and we’re really grateful.

And then our technician, Ivan Hernandez, who works with us as well.

And so that’ll be it.

I’ll take any questions now.

[audience applauding]