Positive selection with other modes of action

BASF Plant Science GmbH and SweTree Technologies AB jointly own an European patent on methods for selecting transformed plants with D-amino acids.

Technology overview

Among the amino acids used as building blocks for proteins, all but one (glycine) can be found in two isomeric forms which are distinguished by their ability to rotate polarised light. The form found in largest quantities in nature rotates light to the left and is termed L- or levorotatory, while the less common form is termed D- or dextrorotatory.

Whilst D-amino acids are found in nature, they are present only at very low concentrations and only in specific compounds as cell wall proteins in bacteria. Although plant amino acid transporters mediate transport of both D- and L-forms of amino acids, plants lack the necessary enzymes to convert D-amino acids into nitrogen forms that can be used in synthetic reactions inside the plant. Normal plants cannot therefore use D-amino acids as a source of nitrogen.

Generally, only a single D-amino acid metabolising enzyme is needed to convert the D-amino acid into compounds that can participate in the usual plant pathways of nitrogen metabolism. Therefore, by introducing a bacterial gene, such as the gene coding for the enzyme D-serine dehydratase or the gene coding for D-amino acid oxidases, into plant cells, nitrogen that is otherwise inaccessibly bound in D-amino acids can thus be converted enzymatically into forms that can be readily utilised by the transgenic plant.

Specific Patent information

Patent/Application Number Title, Independent Claims and Summary Assignee
US 2005/76409

  • Earliest priority – 17 Jan 2002 (UK)
  • Filed – 30 Jun 2004
  • Granted – Pending
  • Expected expiry – N/A
Title – Selective plant growth using d-amino acids

Claim 1
An isolated nucleic acid comprising a nucleotide sequence encoding a polypeptide which has a D-amino acid metabolizing activity, wherein the nucleotide sequence is operably linked to a heterologous plant specific regulatory element.
Claim 14
A composition having herbicide activity and comprising one or more D-amino acids.
Claim 16
A method of stimulating stress tolerance of a plant comprising: expressing in said plant a polypeptide which oxidizes a D-amino acid substrate; and treating said plant with said D-amino acid substrate.
Claim 17
A method of inhibiting growth of a transgenic plant that expresses a polypeptide which oxidizes a D-amino acid substrate, the method comprising: allowing the polypeptide to accumulate in cytosol of the plant; and treating the plant with the D-amino acid substrate.
Claim 19
A method for selective growth of plant cells that have a D-amino acid metabolizing activity comprising treating said plant cells with a fertilizer that contains D-amino acids.

BASF Plant Science GmbH & SweTree Technologies AB

EP 1468096 B1

  • Earliest priority – 17 Jan 2002 (UK)
  • Filed – 13 Jan 2003
  • Granted – 26 Apr 2006
  • Expected expiry – 13 Jan 2023
Title – Selective plant growth using d-amino acids

Claim 1
An isolated nucleic acid comprising a nucleotide sequence encoding a polypeptide which has a D-amino acid metabolising activity, the sequence being operably linked to a plant specific regulatory element heterologous to the gene encoding the D-amino acid metabolizing enzyme.


Patent applications were also filed in Australia (AU 2003235629), Canada (CA 2471517 AA), New Zealand (NZ 534469), China (CN 1620506 A), Japan (JP 2005514069) and Israel (IL 162644 A0). The PCT application is WO 2003/060133.

Search strategy

Search details
Date of search 09/06/2006
Database searched Patent Lens
Type of search Expert, stemming off
Collections searched AU-B, US-A, US-B, EP-B, WO
Search terms (growth near/5 support) AND (plant near/5 growth) AND ((transformed near/2 cell) in claims)
Results 56 hits
Comments The following new doc is relevant to positive selection:

US 2005/76409: Selective plant growth using d-amino acids; by BASF