Tissue-specific expression and hybrid plant production
Inventors
Kumar, Sandeep • German, Marcelo Ariel • CORAM, TRISTAN E • Wright, Terry R.
Assignees
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Publication Number
US-12649925-B2
Publication Date
2026-06-09
Expiration Date
Abstract
This disclosure concerns the use of endogenous plant RNAi machinery to preferentially or specifically reduce transgene expression. In some embodiments, the disclosure concerns specific reduction of transgene expression in male plant tissues, for example, to provide an economical male sterility system of hybrid seed production.
Core Innovation
The disclosure describes tissue-specific transgene knockdown in plants using endogenous small RNAs (miRNAs/siRNAs) by engineering an internal sRNA target site into a transgene. The sRNA target site is linked to a nucleotide sequence encoding an AAD-1 protein, so that sRNA expression in specific tissues reduces transgene mRNA and protein accumulation in those tissues while leaving other tissues tolerant.
In the plant examples, the transgene encodes AAD-1 (aryloxyalkanoate dioxygenase), which enzymatically degrades a phenoxy auxin herbicide and an (R)-aryloxyphenoxypropionate herbicide. Herbicide tolerance is maintained in tolerant tissues while tissue-preferred sRNA activity reduces AAD-1 accumulation in selected male/tassel tissues, and the resulting male phenotype enables herbicide-triggered male sterility as an alternative to manual detasseling for hybrid seed production.
The disclosure includes example target-site constructs using maize miR156 and miR529 target sites, including mutated forms, and describes modified tsh4 target sites using specified SEQ ID NOs. It specifically reports reduced AAD1 protein in tassel tissues and male tissue elimination upon herbicide application in SCBV: AAD1 plants while maintaining vegetative tolerance.
Claims Coverage
The independent claims contain two core inventive elements: a transgenic plant cell with an AAD-1 protein that degrades specified herbicides via aryloxyalkanoate dioxygenase activity, and an sRNA target site (SEQ ID NO:7 or SEQ ID NO:8) linked to a defined region of the nucleotide sequence encoding the AAD-1 protein (base pairs 1-888 of SEQ ID NO:5).
Herbicide-degrading AAD-1 transgenic plant cell
A transgenic plant cell comprising a recombinant polynucleotide that encodes an AAD-1 protein that exhibits aryloxyalkanoate dioxygenase activity, wherein said activity enzymatically degrades a phenoxy auxin herbicide and an (R)-aryloxyphenoxypropionate herbicide.
sRNA target site linked to AAD-1 coding sequence region
An sRNA target site comprising SEQ ID NO:7, or SEQ ID NO:8 is operably linked to the nucleotide sequence encoding the protein encoded by base pairs 1-888 of SEQ ID NO:5.
Transgenic plant tolerance to an aryloxyalkanoate herbicide
Expression of said polynucleotide renders said plant tolerant to an aryloxyalkanoate herbicide.
Tissue-context reduction or elimination of AAD-1 expression
Expression of the AAD-1 protein is reduced or eliminated in tissue-specific or tissue-preferred manner as compared to plants producing AAD-1 mRNA with no target site.
Seeds comprising the transgenic plant cells
A seed that comprises a plurality of the plant cells recited in claim 1.
Overall, the claims cover a transgenic plant cell and plant that combine an AAD-1 herbicide-degrading function with an operably linked sRNA target site connected to a defined region of the AAD-1 coding sequence, with dependent claims further specifying herbicide tolerance, tissue-specific or tissue-preferred reduction or elimination of AAD-1 expression, and seed coverage for the specified transgenic cells.
Stated Advantages
Allows herbicide-triggered male sterility in selected tissues by tissue-preferred transgene knockdown while maintaining vegetative tolerance.
Enables hybrid seed production by replacing manual detasseling with herbicide-induced male sterility.
Maintains tolerance to herbicides in tolerant tissues while reducing AAD-1 accumulation in target male/tassel tissues.
Documented Applications
Hybrid seed production using herbicide-triggered male sterility as an alternative to manual detasseling.
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