Bayer is holding field trials for new Roma-type tomato varieties that claim an intermediate resistance to tomato brown rugose fruit virus (ToBRFV), which has been dubbed by researchers “the Ebola of plant viruses.”
The trials in Mexico include two varieties that are apparent “symptomless carriers” that show no signs of infection in the fruit and leaves despite the presence of virus particles, company officials say.
If the trials are successful, the varieties could be a valuable answer against ToBRFV, which can quickly devastate tomato crops and spreads easily via farming tools and equipment, workers’ hands, plants, water and soil.
Among the fruit’s apparent benefits is lower transmission of the virus within the crop, which could prevent growers from losing their entire crop if the virus shows up, said Anne Williams, Bayer’s segment lead for strategic marketing.
“You’re getting a much greater level of marketable yield,” the London-based Williams told Farm Press in a Zoom interview. “Potentially it slows (the spread) … You can leave the crop in place with all the investments you’ve made knowing you’ll at least get some return.”
Widespread in Mexico
First identified in Israel in 2014, ToBRFV has since been discovered throughout Europe, Asia and North America, according to researchers. More recently it was reported as widespread in Mexican greenhouses, and it has been found in Arizona, California and Florida.
The virus causes discoloration of fruit and leaves and irregular fruit shape and maturation patterns, among other symptoms. Researchers say it represents a major concern for worldwide tomato production because no tomato varieties are known to be resistant to it.
ToBRFV is seen as primarily a threat to protected culture (greenhouse or screenhouse) production although outbreaks in open fields have been reported in Mexico.
One of California’s larger growers, Houweling’s in Camarillo, last year reported it was stepping up its phytosanitary and operating protocols to prevent the spread of ToBRFV, changing its packing practices and cleaning and disinfecting trucks.
'A very good step'
Bob Gilbertson, who specializes in plant virology and seed pathology at University of California, Davis, calls the Bayer trials “a very good step in the right direction” even though a moderately or intermediately resistant plant can still be a source of the virus for spread.
He notes that other entities are also working with ToBRFV resistance, including Israel’s Volcani Institute, which is getting decent yields from its varieties. Volcani will sell seeds to companies if interested, he said.
“The good news is that resistance to ToBRFV is being identified in cultivated tomato, which makes it much easier to breed with, as opposed to working with wild tomato species,” Gilbertson said in an email.
The “bad news,” he said, was a federal order issued in 2019 that restricted imports of tomato and pepper seed lots, transplants, and fruit from all countries where tomato brown rugose fruit virus exists.
The order “pretends that we do not have the virus in the U.S.,” Gilbertson said. The U.S. should instead focus on improved detection, monitoring and management, he said.
Available in 2021
For its part, Bayer anticipates its new varieties will be available for commercial sale in Mexico in 2021, to later be followed by offerings in other markets. The Mexican tomato industry “was hit early and hard,” Bayer’s Williams said, but the nation’s growers did a “superb” job at putting in place phytosanitary measures to curb the virus’ spread. More varieties are in the pipeline, she said.
Bayer officials say the ToBRFV resistance program is part of their corporate Health for All, Hunger for None campaign, which complements the company’s SHIELD clean seeds program. The more than decade-old SHIELD program has sought to prevent, detect and eliminate pathogens in its own production and processing plants as well as other sites.