Boundless Science Season 2: Orange Ya Glad?

Wondering about the rising problems in Florida’s Citrus Industry? Or intrigued by the ways they are being tackled? If that’s you, grab a bottle of orange juice and orange slices and tune into this episode. Hosted by UF CALS junior Brenna Sturgis and joined by UF Citrus Research and Education Center Assistant Professor, Dr. John Chater, listeners can embark on a journey focusing on the future of Florida’s citrus! This episode will have you thinking “Orange Ya Glad” tuned in! 

Transcript

Orange Ya Glad? 

Brenna Sturgis: Hey listeners, welcome back to another episode of the Streaming Science Podcast, Boundless Science Series. I am your host for this episode, Brenna Sturgis, and I am a junior studying Agricultural Education and Communication at the University of Florida. For this episode, we will be diving into Florida's citrus industry with a special guest, Dr. John Chater. Dr. Chater and I discuss current issues in the citrus industry, ways we're tackling them, and what the future of the industry looks like. I hope you enjoy this episode.

Well, we're going to start with some introductions. So I'm currently a student, I'm a junior at the University of Florida studying agricultural education and communication. I grew up in Plant City, Florida, which is about 20 minutes outside of Tampa. And that is a really agricultural community, heavy focus on strawberries, so I've just grown up running around strawberry fields. Dr. Chater, why don't you just give a little bit of background information about yourself.

Dr. John Chater: Okay, I'm John Chater. I'm a, assistant professor at the Citrus Research and Education Center. My, home department is the Horticultural Sciences Department. I'm in the citrus breeding team here, the plant improvement team for citrus here at the Citrus Research and Education Center. I've been in this position for a little over two years now. Little bit about my, educational background. I did my undergraduate degree in, Caton, California and University of California, Santa Barbara, where I studied environmental sciences or environmental studies. And for my master's degree, I went to Cal Poly San Luis Obispo, where I studied, more horticulture. I got a master's degree in agriculture and crop science specialization. And then after my master's degree at Cal Poly San Luis Obispo, I completed a PhD at University of California, Riverside in plant science with emphasis in ecology. And I was a postdoctoral scholar there for about five years in a, statistical genomics, lab, working on citrus, pomegranates, and, human cancer, research. And then, the end of that, I was recruited to work at University of Florida in the citrus breeding program. 

Brenna Sturgis: That's really interesting! I know you're probably working on some really great things at the University of Florida over these past two years. So Citrus has always been such a big powerhouse for Florida with all the success and the production, but it has rapidly declined over the years. So are there any threats that the citrus industry is currently facing?

Dr. John Chater: Yeah, the primary, threat is HLB Huanglongbing. Also known as citrus greening, it's caused by a bacteria called liberobacter. What we call it here in Florida is Candidatus liberobacter asiaticus. There are different types of liberobacter. We seem to have one of the worst, strains of this bacteria. It's a bacterial disease that, infects the phloem and causes the trees to decline, reduces the amount of sugars that are, shuttled off to the juice oranges, so it reduces the sugar content in the fruit known as the total soluble solid content, or the bricks, degreased bricks. This affects the sugar content and the growers are paid with how much sugar is in that juice and how much yield is coming off of those trees so it affects their returns or their ability to profit off of, growing juice oranges. It also devastates fresh market citrus. Grapefruit are particularly susceptible as are sweet orange, and so the grapefruit growers have been also devastated just as the juice orange growers. Another problem, another threat is canker. Canker is another bacterial disease that forms these kind of lesions or blemishes on the fruit leaves and stems. It can cause trees to decline. There are different species of canker. And, you can treat it with copper and maybe some other products, but, this disease was so much of a threat that in previous years, if they were to find any canker lesions on fruit in a grove, they would destroy the grove. So there was a time where if there was some canker found in a very large citrus grove, the folks would show up and determine it was canker, and then they'd have to burn those trees. They have to push and burn out every single tree, and that caused a lot of devastation. Another threat to citrus that's kind of historical in Florida is freeze. So when it freezes, the citrus trees can die. There are some varieties like Satsumas up in the North that are able to survive freeze. But weather can be devastating to the citrus industry, as we saw with Hurricane Ian. We're still seeing the effects of hurricanes are another threat to the citrus industry. And then, something that as somebody who is from California and grew up in a citrus growing region of Ventura County that has historically grown most of the lemons in the United States, the development. So some of you, I'm sure, as somebody from Plant City, you've might have seen some recent developments occurring and this is happening in Polk County and other counties in Florida. And so development is kind of a permanent, um, has permanency to it, right? Once you put a bunch of houses and that real estate value skyrockets, it's very unlikely that those houses will be replaced by citrus in the near future. And so a major kind of permanent threat, um, that several people point to is the threat of development in Florida's precious agricultural lands. Plant city, like you said, is a ag based city, strawberries and other crops grow well there. And there's a lot of displacement of our precious arable agricultural lands to development. 

Brenna Sturgis: Yeah, I think you definitely have brought a lot of good points up with the different diseases, the different threats, the weather, the development, and something that you said in the beginning about citrus greening that I never realized was, I thought it was more focused on discoloration and the abnormal shaping, but I didn't know it actually affected the sugar content. That's something I never had realized when learning about it. So that definitely puts into perspective of why it's such a huge effect on the industry and the canker burning all the fields, I had never heard of that either. So You know, one small thing can really just impact an entire industry. You also mentioned, the hurricanes so I have some statistics about hurricane Ian, which was 2022, that it says it estimated up to 247 million dollars of impact of losses in the citrus industry alone. So, I just didn't know how the hurricanes has impacted the citrus industry, like the specifics of that. 

Dr. John Chater: Okay, so as you can imagine, the high winds from the hurricane, they damage trees. So these trees can be defoliated, the fruit can be ruined, , the fruit can be sheared off the tree, and basically the high winds knock the fruit off of the tree, they damage the fruit, the trees can completely topple over, and so you have trees that lean all the way down, trees that move, typically trees don't get up, move, but a hurricane can move, especially a young tree, and trees are still affected now, so I'm seeing leaning trees and trees that are still recovering. There are some situations where some groves are more protected than others, it's a benefit of windbreaks in some cases, or just the geographic location can reduce the effects of hurricanes. Florida is a, state that doesn't have too many changes in elevation, relatively speaking to some other states, and this allows the high winds and, disastrous conditions to move quite readily across the landscape.

Brenna Sturgis: That's crazy. I know the damage, like, I don't get to see it, and I just hear about it, but just think about these trees, uprooted. It's just crazy how powerful these hurricanes are. So kind of on the topic of hurricanes, I have a question of a myth maybe that I've always heard about citrus greening, and I don't know if it's true, and I feel like you would have the answer. So I always heard that citrus greening came over with the 2004 hurricanes, Charlie, Francis, Ivan, and Gene, and that's how it started in Florida and how it started to spread. Is this true? 

Dr. John Chater: That's a good question. And that probably warrants a investigation. I think people have looked into that and I've have heard people, I've heard academics state that theory as well. In my opinion, it's very difficult to kind of go back in time and identify exactly when it got here. Something that's interesting from my experience, in California is there was a situation where somebody had ordered a pomelo graft. So budwood from a pomelo from another country. And so there's somebody in another country that had HLB sent a piece of budwood from this pomelo or pomelo to this, Los Angeles County house. And this person grafted this pomelo onto the tree. And it turned out that piece of plant material had liberobacter in it. So it was introduced by human means where somebody illegally and maybe they knew the law maybe they didn't know the law, illegally transported infected material into the state of California. And that's 1 entry point. And this could happen 1 time, 5 times a dozen times. You never know, how things are moving, you know, we live in a globalized world and with things like the Internet and eBay and all these marketplaces, even on social media, they have marketplaces where people are trading and illegally transporting infected material across state lines or country lines and introducing different diseases into our environment. So it's difficult for me to say that, it was a hurricane event in terms of probability or, using reason or logic. It seems like a logical explanation looking at the timeline. But you have a lot of citrus growers here in Florida. How the psyllid exactly got here and how Liberobacter also came here? These are, unanswered questions, again, I've only been here for two years. I've spoken to a lot of academics about this and I believe that we're at the theory level and we haven't completely solved that mystery yet.

Brenna Sturgis: Yeah, and I don't know if we ever will just because we can't go back in time and figure it out. But that's crazy about the graft coming overseas. It kind of makes it sound like an invasive species just coming in and wiping everything out. So what is next for the citrus industry? What direction do we think that this industry is going? If it has a positive outlook? Or, you know, what is next for the rising problems that we are seeing? 

Dr. John Chater: Um, I want to be an optimist. Right now there are new therapies that are being developed for HLB. An example is antimicrobials being injected into the tree trunk to mitigate the damage that liberobacter has caused the industry. We're hoping that we can cure trees. That's the best case scenario is we inject these materials, in some cases people are looking at multiple materials and trying to clear the tree of liberobacter trying to destroy the bacteria in the tree, or at least stop it so that as the tree is developing the new materials clean and healthy. We're trying to conventionally breed our way out of citrus as well by using crosses and other non GMO biotechnology technological methods to, improve citrus in a way that would allow it to grow. Right here, I have an OLL late sweet orange here that is considered one of these tolerant sweet oranges that was developed by Dr. Grosser and Dr. Gmitter's breeding program. So I was just in the field this morning and into the afternoon showing growers and USDA and other stakeholders some of these types of trees, some of these types of varieties, some of these, Rootstock scion combinations that appear to be tolerant. There is stark differences. Brenna, I know that you are from plant city and you ever are interested in seeing, any of these trees, I can show you or anybody who's interested listening to these podcasts, these differences among citrus selections, their response to HLB. And so I am highly optimistic that we can conventionally breed our way out of citrus using the techniques that we know and have developed. There's also CRISPR. Some of you folks listening might've heard of this gene editing technology where we basically leverage, the molecular machinery of other species in order to edit certain parts of a genome. So looking at sequence and looking for genes and looking at parts of genes that impact. phenotype, which genes do we target? What part of that gene do we target? We edit that part of the gene. Then again, we have to grow up those plants and see how that edit works. But people are trying to edit our way out of this, out of this problem. Right now, , um, University of Florida in Gainesville is, developing this new transformation facility. And by transformation facility, it's mainly plant transformation, where we are trying to transform these plants, either using CRISPR or transgenics, which I'll talk about a little bit later, in order to select the proper genes, transform the plant, and create a sweet orange or a Fresh market piece of fruit that can survive in this HLB environment. So with GMOs, you might've heard of genetically modified organisms, but GMOs are special plants that have basically, received a gene or a piece of genetic information or material from another species. So in science, we like to call these things transgenics or trans genes. So moving a gene from one species to another species, like taking a spinach gene and putting it in citrus. And people have been doing this for quite a while now. And there's synthetic biology. That's very interesting that I won't go into, but there's also the idea of exclusion. So some growers have been putting these IPCs, individual protective covers over citrus trees. And so sometimes if you drive down highway or the freeway, you might see a bunch of young trees that are covered in these white kind of I don't know what you'd call them, like, almost like a outfit or something. It's just completely covering them. There's like a ring around it as this mesh screen so the tree can breathe, but that little psyllid can't get inside to infect the tree. And so I think we have a future that may include. more orange like hybrids. So right now, only 10 percent of the juice stream, 10 percent of the juice that goes into these orange juice containers can be not citrus sinensis. Something that's similar has that nice, beautiful orange color, has enough sugar content, has a good citrus flavor. This is allowed to go into the juice stream, 10%. Right now there's talk bringing that up to 15% and so if we can identify HLB tolerant varieties that are very orange like it's possible that these will become more part of the landscape. If we can have some of these orange like varieties be considered equal to Citrus sinensis and they can fit in that 90 percent part of the juice stream, we might even be a step closer to solving this problem. And it's a problem that needs to be solved quickly because of the Because of the development problem, the longer we wait, the longer it takes for a solution, the more growers drop out, the more packers drop out of the industry, the more processors, the less harvesting crews that we have. And so, you know, once, once these processors shut down, you know, we're talking hundreds of millions or up to a billion dollar investment there to get them back up. So it's extremely important, all players involved work together to solve this problem, as soon as possible.

Brenna Sturgis: Yeah, I totally agree. I think it definitely has been such a long road that we've had to overcome so many problems, and I know we still have a long road ahead of us, but it really sounds like we're moving in the right direction. We have a lot of people working together, collaborating on ideas, experimenting. I had no clue about the resistant varieties that you're working with and that shows a lot of promise there that we've already been able to come up with these varieties that are resistant to these pests and these diseases. So that's something that consumers can look forward to that we are headed in the right direction. It's just going to take a little bit to get there. 

Dr. John Chater: If I can just, yeah. So, and this is something that, uh, you know, in the sciences, it's an important distinction and the growers as well. So, we have what's known as HLB tolerance and we have HLB resistance. Okay, so in an HLB resistant tree, this would be a tree that either doesn't become infected by liberobacter, or it becomes infected and the tree is able to fight it off. Okay, we can't test positive and then it, plant defense kicks in and it's no longer there anymore. That would be resistance and so we believe to have some varieties that are resistant that they either test positive in the test negative or they haven't tested positive after four or five years in the field. And it usually takes about a year or two typically to do for these things to test positive after being infected. Then you have tolerance and tolerant trees can get infected. We have many candidates that are tolerant. That still get the disease, but they're able to produce fruit for the market in that case. So just so that, if there are any growers that are listening, or processors and they want to make sure that message is clear that if we can get a resistant juice orange, the problem is solved. Or if we can get a root stock that is able to move something to the scion, to the top part of the plant. This is the sweet orange part of the plant that's able to suppress liberobacter, destroy it. We can get a rootstock to transmit something, we've solved the problem. 99 percent of the problem is solved. And some of the grants that I've acquired are looking at some of these resistant varieties and another major, Grants that I've acquired are looking at these tolerant varieties. And right now, we're kind of consolidating the breeding program. We have over 120 acres in the breeding team, that have all sorts of things going on, breeding populations, very rare, breeding parents or very rare crosses that, that could be the key to the future. And so right now we're trying to consolidate this 120 acres and get everything that's tolerant and resistant in the whole breeding program. And then to propagate them off and to even move them with tree spades into a centralized location to help some of these folks who are working with GMOs or with CRISPR, to try to identify the genes. That these different citrus, individuals are using the mechanisms that they're using, the strategies to become tolerant. So why does this tree have a full canopy and it's not declining after 12 years? what genes are implicated in that? And then if we have hundreds of individuals, we might find multiple mechanisms. And this can lead these folks working on CRISPR to identify the correct candidate genes to edit to create a tolerant or resistant tree.

Brenna Sturgis: I think that's something that I'm so glad you're able to specify for farmers or even young students that there is a difference and that you are working with both of them. So that's really impressive that we have this technology to be able to overcome these problems that a hundred years ago, it would just wipe out a whole industry. So I think that's something that students, you know, future generations who might be interested in going into the citrus industry or going into research opportunities, that they might be really interested in this because there's been so much done already, but there's so much more to go. I really appreciate talking with you, Dr. Chater. I think this has been very eye opening, , to, an age range, like, all across the board. I think a lot of people will get a benefit out of just hearing you speak about your different research and your perspective on the different problems. Optimism we have through these problems. I just want to thank you so much for coming on this podcast today.

Dr. John Chater: Oh, thanks for having me, Brenna. Anytime. And thank you so much for the opportunity to talk about my research in the citrus industry. 

Brenna Sturgis: Thanks for listening to this boundless science episode. Stay connected with us on our website, streaming science. com and other social media platforms, Facebook, and Instagram. Once again, I'm your host, Brenna Sturgis. See you next time.