Cultivating Resilience: Precision Breeding for Florida Citrus

In the idyllic groves of orange trees, a silent battle rages on—one that threatens the very essence of these beloved fruits. Citrus canker and greening, formidable foes to the citrus industry worldwide, have wreaked havoc on our groves, challenging growers to find resilient solutions. Amidst this challenge, a promising ally emerges: gene editing through precision breeding. This innovative approach not only offers hope but also the tangible potential to cultivate orange trees that stand strong against these devastating diseases. Let us embark on a journey into the world of precision breeding, where science and nature converge to safeguard the future of citrus cultivation.

But first, a clarification of terms. Talking about “gene editing” can conjure mental images of GMOs – Genetically Modified Organisms. GMOs are created when foreign genetic material is artificially inserted into a plant to create a desired effect. Such changes are potentially controversial and the subject of many moral and ethical conversations. They are not, however, the subject of this one. 

Selective breeding for traits has been a part of the study of genetics since before Gregor Mendel discovered the science while breeding pea plants. Even without human intervention, natural selection will gradually delete certain genetic weaknesses or abnormalities over several generations to build up an ingrained immunity to diseases that would have largely wiped out previous generations.

Through a process first pioneered by Jennifer Doudna, Emmanuelle Charpentier and Feng Zhang called CRISPR (Clustered Regularly Interspaced Short Palindromic Repeat), genetic changes that would have previously taken multiple generations of plants can instead be made in a single generation. Dr. Nian Wang at University of Florida/IFAS, pioneered practical improvements to Citrus targeting bacterial diseases HLB and Canker via CRISPR/Cas genome editing.

The important distinction here is that these are changes that could have happened on their own, given enough time. The USDA and EPA issued guidance that they will not regulate CRISPR precision breeding that could occur naturally. 

Among the researchers embracing the CRISPR method is Soilcea, which has exclusive commercial licenses to patents to HLB and canker target susceptibility genes and optimized CRISPR transformation methods for citrus developed by Dr. Nian Wang’s lab.

Through its efforts, Soilcea has introduced novel citrus varieties demonstrating resistance to canker and early signs of resistance to greening. The company assessed greening resistance by grafting their CRISPR-edited trees onto trees affected by HLB disease, observing that the disease did not transfer to the edited trees.

With the effective use of CRISPR precision breeding technology, Soilcea looks forward to developing fresh and juice citrus varieties with enhanced disease resistance, reducing the need for pesticides. Yianni Lagos, CEO of Soilcea, says, “We are excited to partner with growers and nurseries to get new canker- and HLB-resistant trees in the field, and to help restore the Florida citrus industry.”

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