While the genetically edited tree has only been tested so far in the lab and the greenhouse, it is one of the most promising discoveries to date in a challenge that has plagued growers, researchers and consumers as Florida’s citrus industry has plummeted over the past two decades.

The approach involves inserting a gene into a citrus tree that produces a protein that can kill baby Asian citrus psyllids, the bugs that transmit the greening disease.

University of Florida officials recognized Rossi’s precision planning and innovational research initiatives to confront the most serious citrus disease worldwide and advance alternative crops into diversification models with a promotion. Citrus greening, a disease that has impacted the crop in all the world’s production regions, is the highest priority in Rossi’s research laboratory at the University of Florida’s Indian River Research and Education Center in Fort Pierce. The center is part of UF’s statewide Institute of Food and Agricultural Sciences (UF/IFAS).

Rossi’s promotion to associate professor this month reveals his robust research program and talents to empower graduate students and form international collaborative work teams.

Dr. Rossi achieved early tenure with rigorous pursuit,” said Mark Kistler, director of the UF/IFAS Indian River Research and Education Center and Rossi’s immediate supervisor. “Dr. Rossi understands our local growers’ needs and pursues solutions to keep them in business with relentless pursuit.”

NIFA, part of the U.S. Department of Agriculture, split funding into five grants.

UF/IFAS researchers are looking for ways to manage greening, known scientifically as Huanglongbing or HLB. Greening is caused by the bacterium Candidatus Liberibacter asiaticus, or CLas. The Asian citrus psyllid can transmit (“vector,” in scientific terms) CLas into a citrus tree, and CLas can eventually become HLB.

“These five funded projects illustrate the breadth and depth of our world-class citrus research program,” said Robert Gilbert, UF interim senior vice president for agriculture and natural resources, dean for UF/IFAS Research, and director of the Florida Agricultural Experiment Station. “We need every tool in our toolbox to combat HLB in an integrated manner, and this USDA-NIFA funding will be extremely helpful to UF/IFAS and our stakeholders.”

HLB is a worldwide, devastating citrus disease caused by Candidatus Liberibacter asiaticus (CLas), a bacterium that settles into the tree’s phloem — its interior vascular system — eventually killing the tree. Since first found in Florida in 2005, it has infected virtually every grove in Florida and cost the citrus industry billions of dollars.

UF/IFAS’ Nian Wang’s most recent research describes in detail how HLB causes damage to citrus trees and presents the case that HLB is a pathogen-triggered immune disease. A pathogen-triggered immune disease is a disease that results from the activation of an organism’s immune cells fighting a pathogen (a virus, bacteria, or parasite) that invades an organism, in this case, the citrus plant.

The psyllid, a bug the size of a pin, injects citrus tree leaves with a bacterium that can cause Huanglongbing, commonly known as citrus greening disease.

New research from Alferez shows that citrus trees grown under individual protective covers (IPCs) show no signs of the greening disease. Specifically, scientists found that psyllids cannot penetrate the bags (IPCs) under which the trees are growing because the diameter of their openings is smaller than the insects.

“Our research has confirmed that the IPCs are effective in keeping the trees free from HLB at least until they start producing fruit,” said Alferez, an assistant professor of horticultural sciences at the Southwest Florida Research and Education Center. “This is important because until now, once the trees were planted, they were exposed to the psyllid, which carries the disease. So, they became infected with greening in a matter of months.”

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The USDA National Institute of Food and Agriculture (NIFA) Emergency Citrus Disease Research and Extension Program recently awarded over $2.2 million in three grants to UF Institute of Food and Agricultural Sciences faculty to advance the known science to fight the disease.

In addition, UF/IFAS researchers are serving in leadership roles in two other multi-million-dollar grants awarded to colleague institutions from across the nation.

Collectively, these projects provide an aggressive strategy to finding viable, realistic solutions in the fight against citrus greening and represent over $3.5 in federal funding for UF/IFAS research. More importantly, UF/IFAS researchers are participating in each of the five grants awarded in this funding cycle.

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Meanwhile, efforts to combat citrus greening disease, which for nearly two decades has devastated groves, could soon lead to a new University of Florida-backed variety of citrus on the market.

Michael Rogers, director and professor at the University of Florida IFAS Citrus Research and Education Center, said among new varieties that are more tolerant to citrus greening — technically called huanglongbing, or HLB — is a “Gator Bites” brand.

The bites look similar to the California clementines commonly known by the brand names cuties or halos. However, Rogers said the Florida variety has a sweeter taste without an increase in sugar content.

“This makes the cuties and halos taste like cardboard, in my opinion,” Rogers told members of the Senate Agriculture Commission. “It’s an easy peeler. Seedless. It doesn’t get your hands messy. Tastes very sweet and it’s HLB tolerant. So, this is going to be our first opportunity in Florida for growers to diversify a little bit if they’ve not been planting fresh fruit.”

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In a new study, published in Nature Communications, UF’s Institute of Food and Agricultural Sciences collaborated with an international team of scientists and analyzed 69 genomes from the East Asian mandarin family, alongside their mainland Asian relatives, revealing a far-ranging story of isolation, long-distance travel and hybridization.

“It is humbling to realize that the fruit we grow and eat today is the result of millions of years of both wild evolution and domestic cultivation,” said Fred Gmitter, UF/IFAS horticulture professor and member of the international research team. “Our findings raise more questions about what other citrus hybrids are out there and what characteristics may be beneficial to us as we look to breed more disease-resistant and environmental stress-resilient varieties. Understanding the past is really a window to the future.”

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The discovery was made by Kirsten Pelz-Stelinski, an associate professor of entomology and nematology at the UF/IFAS Citrus Research and Education Center.

Pelz-Stelinski and her team were able to reduce the HLB disease pathogen in the psyllid and in citrus, leading to less transmission and a potential reduction in disease severity. 

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With the Sunshine State’s $9 billion annual citrus crops plagued by a fruit-souring disease, researchers and businesses are tapping AI to help rescue the nation’s largest producer of orange juice.

University of Florida researchers are developing AI applications for agriculture. And the technology – computer vision for smart sprayers – is now being licensed and deployed in pilot tests by CCI, an agricultural equipment company.

The efforts promise to help farmers combat what’s known as ‘citrus greening,’ the disease brought on by bacteria from the Asian citrus psyllid insect hitting farms worldwide.

“It’s having a huge impact on the state of Florida, California, Brazil, China, Mexico – the entire world is battling a citrus crisis,” said Yiannis Ampatzidis, assistant professor at UF’s Department of Agricultural and Biological Engineering focusing on automation in agriculture.

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