What is the history of GM sunflowers?

Expert response from Community Manager

Moderator for GMOAnswers.com

Friday, 22/05/2015 12:24

You might be surprised by this, but there are no GM sunflowers. BASF developed the Clearfield sunflower, which is an herbicide-tolerant sunflower. The herbicide-tolerant traits were bred into the sunflower through traditional plant breeding. Chris Barbey, a PhD student in plant molecular genetics and cell biology at the University of Florida, explores a related question regarding crops that use selective breeding for herbicide resistance, here.

The National Sunflower Association also provides background and history on the Clearfield sunflower here. Please see excerpts below.

“The Clearfield system consists of sunflower hybrids bred specifically for use with Beyond™ herbicide, delivering broad-spectrum postemergence grass and broadleaf weed control in all tillage systems.

“The Clearfield trait for sunflower was first identified by Kansas State University researchers in 1997, when it was found in a population of wild sunflowers. The wild sunflowers had been growing in a soybean field with seven years of continuous ALS-inhibitor herbicide use. Using traditional non-GMO plant breeding procedures, USDA sunflower geneticist Jerry Miller, Fargo, ND, crossed the resistant wild sunflower to four USDA-cultivated sunflower genetic stocks. The tolerance trait was maintained through several backcross generations and the germplasm lines made available to commercial seed companies.

“By incorporating the tolerance trait from these germplasm lines into their most advanced breeding stock, plant breeders developed new, elite Clearfield breeding lines and hybrids. Field studies were established across major sunflower growing areas to test hybrids, herbicide rates, application timing and necessary additives. Herbicide-tolerance trials established with seed companies developing Clearfield sunflowers ensured that finished hybrids have complete natural tolerance to Beyond herbicide.

“Mycogen Seeds and Seeds 2000 were two companies that offered Clearfield sunflower hybrids in 2003; they will be joined by other seed companies, including Interstate Seed and Proseed, to offer Clearfield hybrids in 2004. BASF is the commercial developer of the Clearfield system and manufacturer of Beyond herbicide, which received full label approval by EPA in 2003.

“Because it is safe to birds, fish, mammals and other nontarget species, Beyond is considered environmentally friendly and carries the least restrictive word designation for a pesticide (‘caution’). However, there are a number of critical factors that need to be made clear about the Clearfield production system in sunflower: 

1) Clearfield is not the same chemistry as Roundup-ready (glyphosate). Beyond herbicide is a member of the imidazolinone chemical family. Its active ingredient is imazamox, and it is a member of the herbicide family of AHAS or ALS inhibitors. Members of this family control susceptible weeds by inhibiting the acetohydroxyacid sythase enzyme.

2) While the Clearfield system is available for several different field crops, including corn, wheat, rice and canola, the “imi” chemical formulations are not interchangeable. Thus, for example, Lightning is labeled only for use on Clearfield corn hybrids, not Clearfield sunflower hybrids. As well, one would not apply Beyond on Clearfield corn hybrids.

3) Clearfield sunflower hybrids are not cross-tolerant to the sulfonylurea (SU) family of herbicides, which are also ALS or AHAS inhibitors.

4) Beyond must be applied only to Clearfield hybrids. Application of Beyond in conventional, non-Clearfield sunflower will result in significant crop injury and plant death (see photo).

5) Clearfield is not a complete weed control program for sunflower. It helps growers manage pigeongrass/foxtail, wild oats, wild mustard, cocklebur and other tough grasses and broadleaf weeds that plague sunflower growers (see table of weeds controlled) but does not take the place of other herbicide treatments that may still be needed in sunflower, such as preplant treatments.”