Database Product Description
- Host Organism
- Lens culinaris (Lentil)
- Imidazolinone herbicide tolerance, specifically imazethapyr.
- Trait Introduction
- Chemically induced seed mutagenesis
- Proposed Use
Production for human consumption and livestock feed.
- Product Developer
- BASF Inc.
Summary of Regulatory Approvals
Summary of Introduced Genetic Elements Expand
Characteristics of Lens culinaris (Lentil) Expand
Modification Method Expand
Characteristics of the Modification Expand
Environmental Safety Considerations Expand
Food and/or Feed Safety Considerations Expand
This product was not subject to regulation in any jurisdiction except Canada since the development of this herbicide-tolerant line did not employ recombinant DNA technologies. In Canada, regulatory approval is required for environmental release, as well as for use as human food and livestock feed.
Lentil (Lens culinaris Medik.) was grown as a crop in 51 countries in 2004, with a combined harvest of 3.8 million metric tonnes. The major producers of lentils in 2004 were India, Canada, Turkey, Australia, Nepal, the United States and China. Lentil is a member of the Leguminosae (Fabaceae) family and is a nutritionally important food crop. The plant produces pods which bear one or two flattened, lens shaped seeds. The seeds are consumed as an important source of dietary protein, especially in India, Southwest Asia and the Mediterranean (CFIA, 2003).
Weeds are a significant production problem in lentil cultivation. Lentil seedlings are small, are slow to establish, and thus compete poorly with weeds. In Canada, perennial weeds such as Canada thistle (Cirsium arvense (L.) Scop.) and sow thistle (Sonchus arvensis L.) are especially troublesome and their elimination is recommended prior to cultivation. Volunteer cereals (e.g., wheat, barley) from previous rotations are difficult to control in the crop, and to clean from the harvested seeds. Weed control measures include planting lentils on weed-free fields, crop rotation to reduce weed populations, early seeding to increase the competitiveness of the seedlings prior to weed seed germination, and the use of herbicides. Post-emergence herbicides such as metribuzin and diclofop-methyl are used to control annual broadleaf and grassy weeds.
The lentil line RH44 was developed to allow the use of imidazolinone herbicides as a weed control option in lentil production. The mode of action of imidazolinones consists of inhibiting the activity of acetohydroxyacid synthase (AHAS), an enzyme in plants active in glycolysis and in the biosynthesis of the branched-chain amino acids isoleucine, leucine and valine. The result of the inhibition of AHAS activity is a decrease in protein synthesis, and in an accumulation of toxic levels of alpha-ketoglutarate, all of which causes the eventual death of the plant. While unmodified lentil is not tolerant to imidazolinone, the line RH44 has been modified to survive an otherwise lethal application of this herbicide. RH44 was developed using chemically induced seed mutagenesis and whole plant selection procedures. The herbicide tolerance is due to a mutation in the AHAS gene, which codes for an alteration in the binding site for imazethalpyr in the AHAS enzyme.
RH44 lentil was field tested in Canada from 1999 to 2002 in the provinces of Manitoba, Saskatchewan, and Alberta. These trials were conducted, in part, to compare the agronomic performance and disease susceptibility of RH44 with its unmodified counterpart, and other conventional lentil cultivars.
The potential for transfer of the herbicide tolerant trait from RH44 lentil to other unmodified lentil plants, or to wild relatives of lentil, has been investigated. Lentil (L. culinaris) is predominantly self-pollinating, with less than one percent cross-pollinaiton (CFIA, 2003). As such, an isolation distance of only 3 metres is required for pedigreed seed production in Canada (Canadian Seed Growers Association, 2000). The potential for introgression of the herbicide tolerance trait into unmodified lentil plants is therefore negligible.
Lentil can successfully hybridize with its wild progenitor Lens orientalis. This wild relative of lentil grows in the Near East, and from the western Mediterranean area to Ethiopia. Introgression of the herbicide tolerance trait from RH44 plants into L. orientalis is therefore possible in these regions. Neither L. orientalis, nor any other wild relative of lentil grow in Canada.
Lentil does not exhibit characteristics that would render it weedy. While some lentil pods shatter at harvest, these seeds do not normally volunteer in any subsequent crop. In Canada, seeds that germinate in the fall do not survive the winter. Those seeds that do germinate the following spring compete poorly with other crops and weeds. Unlike legumes species such as alfalfa or red clover, lentil seed does not exhibit dormancy characteristics such as hard seed.
The food and livestock feed safety of RH44 lentil was based on: the evaluation of the similarity of AHAS, in structure and function, to the enzyme naturally present in food and livestock feeds; the lack of toxicity or allergenicity of AHAS from plants; and, studies on the function, heat stability, and gastric digestibility of this enzyme in RH44 compared to its unmodified counterpart. The nutritional equivalence and wholesomeness of RH44 was demonstrated by the analysis of key nutrients, including proximates (protein, crude fat, crude fibre, ash and carbohydrates), amino acid and fatty acid composition, vitamins, minerals, as well as the anti-nutritional compounds phytic acid and trypsin inhibitor.
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This record was last modified on Friday, March 26, 2010