Spinach genes beef up citrus trees' resistance to greening

03/26/2012 05:56:00 PM
Citrus + Vegetable Magazine Staff

erik mirkovCourtesy Texas AgriLife ResearchTexas AgriLife researcher Erik Mirkov inspects a citrus tree that contains two spinach genes to ward off citrus greening.Spinach, that same green leafy vegetable used by Popeye to pump up, also may help citrus trees resist greening disease, or huanglongbing.

Erik Mirkov, a Texas AgriLife Research palnt pathologist in Weslaco, has transferred two genes from spinach into citrus, apparently imparting greening resistance, according to a news release.

After passing greenhouse trials, the transgenic trees will soon be planted in Florida for field testing.

The research is funded by Southern Gardens Citrus of Clewiston, Fla.

Mirkov's work, which originally sought resistance for citrus canker, took a turn when citrus greening began ravaging Florida's citrus industry.

He knew that spiniach proteins provided broad-spectrum resistance to several bacteria and fungi.

“We injected canker into the leaves of transgenic plants with one spinach gene and found that the bacterial lesions didn’t spread,” he said in the release. “But we also showed that transgenic plants infected in the rootstock with citrus greening disease flourished and produced lots of leaves, while the non-transgenic trees produced just one leaf.”

Those trees were moved to the field in 2009. After 25 months of growth, some of the transgenic trees showed no infection whereas 70 percent of the non-transgenic control trees did.

Mirkov developed subsequent generations by adding a second spinach gene and improving how and where the genes expressed themselves.

During the research, he found that the genes are synergistic and work better as a pair than each one did individually.

Mirkov's work involves Rio Red and Ruby Red grapefruits, Hamlin and Marrs sweet oranges, Rhode Red Valencia oranges and the Flying Dragon, C22 and Carrizo rootstocks.

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Ventura CA  |  April, 03, 2012 at 04:19 AM

The process is the problem. Inserting genes into a plant causes mutations and the promoter in the introduced cassette turns on genes along the chromosome. The result is increased levels of toxins and allergens in the plant. See http://responsibletechnology.org/ These new varieties may be a tremendous advancement in horticulture, but we will be taking the fruits of these into our bodies, a very intimate process. Each variety will need to be tested for toxicity to make sure it is wholesome food.

May, 13, 2013 at 03:48 AM

no. thats a nice scare tactic but lets look at some basic flaws in your logic. first of all most DNA is junk dna and serves no function. most of that dna is not likely to be mutated into functionally expressed dna by the type of technology used here. statistically speaking that is just not as likely. even less likely is it coding for something that negatively affects us. plants already mutate on their own. it happens when the seeds develop, sometimes when pollen is exposed to UV light... mutations are not the end of the world in edible foods. it is a good thing to be suspicious of gm crops that have used genes from non edible plant sources, but this technology is safe and you are being irrational.

June, 23, 2013 at 05:39 AM

Well said, for this. I'm going to recommend spinach as a secondary base crop for citrus. Maybe get some takers to start over. Cole crops are already recommended for boosting early colonies of parasitic wasps for aphid control. Thanks for sharing.

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