gm-alfalfa/report-2

Plant height and flowering were altered in alfalfa genetically engineered to reduce lignin content.

Manipulated Organism: Alfalfa (Medicago sativa)

Inserted Transgenes: Antisense sequences of genes involved in lignin synthesis (C3H, C4H, F5H, and HCT), taken either from alfalfa or a closely related species (M. truncatula). The gene construct included the bean promoter PAL2.

Goal: Improve the digestibility of alfalfa by reducing its lignin content or altering its lignin composition. Antisense sequences were used in an attempt to suppress enzyme expression.

Intended Effect: Genetically engineered (GE) lines were created with reduced enzyme activity and lowered lignin content.

Unintended Effects:

Many of the GE lines were only 25-50% as tall as the parent line.
Flowering was delayed in the GE lines, sometimes by as much as 20 days compared with the parent line.
In some GE lines the flowers were white instead of their normal purple-blue color.
The researchers even reported a different floral scent for one of the GE lines.

Source:

Reddy, M. S. S., F. Chen, G. Shadle, L. Jackson et al. (2005). "Targeted Down-regulation of Cytochrome P450 Enzymes for Forage Quality Improvement in Alfalfa (Medicago sativa L.)," Proceedings of the National Academy of Sciences vol. 102, pp. 16573-8.

Shadle, G., F. Chen, M. S. S. Reddy, L. Jackson et al. (2007). "Down-regulation of Hydroxycinnamoyl CoA: Shikimate Hydroxycinnamoyl Transferase in Transgenic Alfalfa Affects Lignification, Development and Forage Quality," Phytochemistry vol. 68, pp. 1521-9.

Author Affiliations: Samuel Roberts Noble Foundation, Ardmore, Oklahoma.

Funding: Forage Genetics International and the Samuel Roberts Noble Foundation.

Product Status: Not on the market as of April, 2009.

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Seth JordanAugust 11, 2020