DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Continued Examination Under 37 CFR 1.114
1. A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on May 26, 2026 has been entered.
Claim Status
2. Claims 1-16 and 21-23 are pending and under examination on the merits.
Claims 18-20 are withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected invention, there being no allowable generic or linking claim. Election was made without traverse in the reply filed on May 26, 2026.
Claim 17 is cancelled.
Response to Arguments – Objections to the Specification
3. Applicant’s amendments filed May 26, 2026 have overcome the objections of record.
Response to Arguments – Claim Objections
4. Applicant’s amendments filed May 26, 2026 have overcome the objections of record. Claim 17 has been cancelled; therefore, any objections and/or rejections to the claims have been rendered moot.
Claim Rejections - 35 USC § 112(a)
5. The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
Written Description
6. Claims 1-16 and 21-23 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention.
Claim 1 is drawn to a method of introducing a DNA construct into a plant plastid genome to silence an endogenous nuclear-encoded gene within the same plant to impart a beneficial trait to the plant. The claim places no limitations on and provides no structure defining the DNA construct. Thus, the claim is broad and encompasses any and all nuclear genes endogenous to the recited plant and any and all DNA constructs that can be introduced into a plant plastid genome silence said gene(s). The claim places no limitation on the plants encompassed. Thus, the claim is broad and encompasses any and all plant species. The limitations encompassing any and all nuclear genes, any and all DNA constructs, and any and all plant species lack adequate written description for the following reasons.
Applicant describes the construction of plasmid vectors (i.e., DNA constructs) containing a sense and/or antisense fragment of the phytoene desaturase gene (PDS)[0053-0054], [0080-0084], the transformation and selection of transgenic Nicotiana tabacum comprising transplastomic PDS DNA constructs resulting in a bleaching phenotype in immature plants[0055-0057], [0085-0087], [0090], [0092], the maternal inheritance of transplastomic PDS-induced bleaching[0088-0089], [0091], confirmation of PDS gene silencing and the presence of small plastid-encoded PDS transcripts in plastid-transformed lines[0096], [00100-00102], the presence of 21-nucleotide RNAs in the cytosol resulting from the plastid-expressed PDS dsRNA construct[00103-00109], the processing of plastid-encoded transgene polycistronic transcripts into small RNAs[00113-00121], and a failure to induce bleaching in plants expressing an antisense PDS construct[00138].
Applicant does not describe the insertion of any DNA constructs into plastids to produce nuclear gene silencing besides the aforementioned PDS constructs. Applicant does not describe the transformation of any plant species besides the aforementioned tobacco species.
Issue #1: Applicant has not disclosed a representative number of plant species transformed to comprise a plastid-encoded DNA construct which induces silencing of an endogenous nuclear gene to convey possession of the claimed invention commensurate with the scope of encompassed plant species.
As stated above, the claim 1 places no limitations on the scope of the encompassed plants, however, Applicant describes the plastid transformation of only tobacco plants.
The state of the art (Yu et al., Int J Mol Sci. 2020; 21, 4854 (U)) indicates that plastid transformation is more challenging and less understood than nuclear transformation and that major issues limiting plastid transformation include the method of DNA delivery, the efficiency of homologous recombination, and the selection and regeneration of transformants (p. 02, final paragraph). The art (Narra et al., Frontier Plant Sci. 2025; 16:1526578 (V)) also teaches that while plastid transformation has been successfully achieved in several dicotyledonous crop plants (p. 03, Table 1; pp. 20-21, “4.1 Limited range of target plant species”), no transplastomic crop has been commercialized (Abstract), transplastomic crops are mostly restricted to model species in laboratory settings (Abstract), and there are many “significant obstacles” to applying reliable chloroplast transformation systems in monocot crops (Abstract; p. 02, first paragraph). Furthermore, Yu teaches that the application of plastid transformation is largely restricted to crops that have a well-developed tissue culture system and high regeneration potential (p. 05, first paragraph). In fact, for the 23 crops for which plastid transformation has been reported, Narra discloses rice as the only monocot crop successfully transformed and regenerated (p. 03, Table 1). Collectively, the state of the art indicates that plastid transformation methods are nonstandard, that some species are recalcitrant and nonamenable to current plastid transformation techniques, and that plastid transformation is limited to species with high potential for regeneration and/or those for which well-developed tissue culture systems have been established.
MPEP § 2163 states that the written description requirement for a claimed genus may be satisfied through sufficient description of a representative number of species by actual reduction to practice, or by disclosure of relevant, identifying characteristics, i.e., structure or other physical and/or chemical properties, by functional characteristics coupled with a known or disclosed correlation between function and structure, or by a combination of such identifying characteristics, sufficient to show the applicant was in possession of the claimed genus. A “representative number of species” means that the species which are adequately described are representative of the entire genus. See, e.g., AbbVie Deutschland GMBH v. Janssen Biotech, 759 F.3d 1285, 111 USPQ2d 1780 (Fed. Cir. 2014). When there is substantial variation within a genus, as here in which the genus comprises over 300,000 known plant species (Christenhusz and Byng, Phytotaxa. 2016; 261(3):201–217 (W); Abstract) and wherein only 23 of those species are known in the art to be amenable to plastid transformation, one must describe the transformation of plastids in a sufficient variety of species to reflect the variation within the genus. While one skilled in the art at the time of filing could reasonably transform the plastids of any plant known in the art to be amenable to plastid transformation, successful plastid transformations appear to require specific conditions and/or techniques for different plant species. Accordingly, one of ordinary skill in the art could not predictably determine, with a reasonable expectation of success, which plants are amenable to plastid transformation and regeneration besides those demonstrated by the Applicant and the state of the art. Therefore, the plastid transformation of tobacco alone does not provide adequate written description for all plant species or even all crop species and Applicant has not disclosed sufficient relevant identifying characteristics to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, had possession of the claimed invention at the time the application was filed. Accordingly, claim 1 lacks adequate written description.
Claims 2-16 and 21-23 do not address the deficiency regarding any all and all plants. Accordingly, claims 2-16 and 21-23 also lack adequate written description.
Issue #2: Applicant has not disclosed a representative number of nuclear genes silenced by a plastid-encoded DNA construct to convey possession of the claimed invention commensurate with the scope of encompassed nuclear genes.
Applicant has described the plastid transformation and resulting nuclear gene silencing of only a single gene in a single tobacco species expressing vector-based DNA constructs encoding fragments of the PDS gene. The state of the art teaches the presence of over 20,000 distinct gene loci in Arabidopsis, rice, and other plant species (Sterck et al., Curr Opin Plant Biol. 2007 Apr;10(2):199-203 (Z); Abstract) as well as the existence of over 300,000 known plant species (Christenhusz and Byng, Phytotaxa. 2016; 261(3):201–217 (W); Abstract). The state of the art (Pandey et al. Methods Mol Biol. 2015:1287:3-23 (Y)) teaches varying compatibilities and incompatibilities of distinct gene-silencing DNA constructs among distinct plant species (Abstract; p. 16, “3 Limitations of the Gene Silencing Methods”).
As stated above, the art is poorly developed with regard to the induction of nuclear gene silencing via the expression of RNA transgenes from the plastid genome; Applicant suggests that RNAi strategies currently known in the art cannot be expected to provide any expectation of success in plastids (Applicant’s Remarks dated 11/18/2025; p. 12, final paragraph); and Applicant asserts that the mechanism of the RNAi-based gene silencing of the instant invention (i.e., plastid-derived cytoplasmically-localized RNAs derived from dsRNA, antisense, or sense constructs) is well understood in the art to be fundamentally distinct from the mechanism of the RNAi-based gene silencing from plastid-expressed dsRNAs which are retained in the plastids and mechanism of the RNAi-based gene silencing from nuclear-expressed RNAi (Applicant Remarks dated 05/26/2026; p. 08, first and second full paragraphs). Accordingly, one of ordinary skill in the art could not predictably determine which nuclear genes, among the millions of genes encompassed by the claims, are amenable to silencing via the expression of a gene silencing construct from the plastids.
MPEP § 2163 states that the written description requirement for a claimed genus may be satisfied through sufficient description of a representative number of species by actual reduction to practice, or by disclosure of relevant, identifying characteristics, i.e., structure or other physical and/or chemical properties, by functional characteristics coupled with a known or disclosed correlation between function and structure, or by a combination of such identifying characteristics, sufficient to show the applicant was in possession of the claimed genus. When there is substantial variation within a genus, as here in which the genus comprises millions of distinct nuclear-encoded genes, one must describe a sufficient variety of species to reflect the variation within the genus. Two DNA constructs capable of silencing a single gene (i.e., PDS) in a single plant does not provide adequate written description for all genes in all plants. Therefore, Applicant has not disclosed sufficient relevant identifying characteristics to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, had possession of the claimed invention at the time the application was filed. Accordingly, claim 1 lacks adequate written description.
Claims 2-16 and 21-23 do not address the deficiency regarding any and all nuclear-encoded genes. Accordingly, claims 2-16 and 21-23 also lack adequate written description.
Enablement
7. Claims 1-16 and 21-23 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, because the specification, while being enabling for tobacco (Nicotiana tabacum), does not reasonably provide enablement for all plants. One of ordinary skill in the art could not predict, with a reasonable expectation of success and without any surprising or unexpected results which plant species would be amenable to the recited method of plastid transgene-mediated nuclear gene silencing besides the single species of N. tabacum disclosed in Applicant’s working examples. The instant specification does not enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to practice the invention commensurate in scope with these claims.
Claims 1-16 and 21-23 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, because the specification, while being enabling for DNA constructs encoding double strand RNA and sense-strand RNA constructs, does not reasonably provide enablement for all DNA constructs. One of ordinary skill in the art could not predict, with a reasonable expectation of success and without any surprising or unexpected results which features, structures, or sequences are required a the DNA construct to introduced into the plastid genome to allow the production of RNAs capable of silencing an endogenous nuclear gene of the plant expressing said RNAs and/or which features, structures, or sequences are required to allow said RNAs to escape the plastids. The instant specification does not enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to practice the invention commensurate in scope with these claims.
When determining whether a claimed invention complies with the enablement requirement, factors to consider include: “(1) the quantity of experimentation necessary, (2) the amount of direction or guidance presented, (3) the presence or absence of working examples, (4) the nature of the invention, (5) the state of the prior art, (6) the relative skill of those in the art, (7) the predictability or unpredictability of the art, and (8) the breadth of the claims.” Id.
The claimed invention is not enabled for the following reasons.
The breadth of the claims is found in claim 1 directed to a method of introducing a DNA construct into a plant plastid genome to silence an endogenous nuclear gene of the plant to impart a beneficial trait to the plant. The term “DNA constructs” is broad and encompasses any and all forms of DNA including single-stranded DNAs, double-stranded DNAs, linear DNAs, circular DNAs, viral DNAs, T-DNAs, and several other types of DNA. Claim 1 places no limitations on the scope of the encompassed plants or DNA constructs.
The nature of the invention comprises the silencing of plant nuclear genes by plastid-encoded DNA constructs.
The level of ordinary skill in the art is high.
The state of the art is not well-developed with regard to the transformation of plant plastids and major limitations to plastid transformation include the method of DNA delivery, the efficiency of homologous recombination, and the selection and regeneration of transformants (Yu et al., Int J Mol Sci. 2020; 21, 4854 (U); p. 02, final paragraph). The art (Narra et al., Frontier Plant Sci. 2025; 16:1526578 (V)) also teaches that while plastid transformation has been successfully achieved in several dicotyledonous crop plants (p. 03, Table 1; pp. 20-21, “4.1 Limited range of target plant species”), no transplastomic crop has been commercialized (Abstract), transplastomic crops are mostly restricted to model species in laboratory settings (Abstract), and there are many “significant obstacles” to applying reliable chloroplast transformation systems in monocot crops (Abstract; p. 02, first paragraph). However, it is known in the art that plastid transformation requires that the DNA to be integrated into the plastid genome comprises a sequence that is identical to at least 121bp of the target integration site in the plastid genome, because plastid transformation is highly dependent upon the frequency of homologous recombination within the plastids (Yu et al.; p. 04, “2.2. Harnessing Homologous Recombination in Chloroplasts”).
The state of the art is poorly developed with regard to the induction of nuclear gene silencing via the expression of RNA transgenes from the plastid genome. In fact, the Examiner’s search uncovered only a single primary research article disclosing the silencing of a nuclear gene due the transformation and subsequent expression of plastid-encoded transgenes (Bélanger et al., The Plant Cell, Volume 35, Issue 9, September 2023, Pages 3398–3412 (Z)). Bélanger discloses the successful induction of nuclear gene silencing in tobacco plants expressing a PDS gene fragment flanked by either convergent or divergent plastid promoter sequences and an aadA spectinomycin resistance gene flanked by divergent plastid promoter sequences (Abstract; p. 3399, final paragraph; p. 3400, second full paragraph; p. 3401, Figure 1). Though Arabidopsis thaliana plastids are known to produce tRNA fragments that escape into the cytoplasm to impact nuclear gene expression, the structures, features, and/or sequences required for the functions of these tRNAs is not well understood (Park and Kim, Int J Mol Sci. 2018 Feb 8;19(2):518 (XX); Abstract; pp. 05-06, “4. tRFs Are Involved in Post-Transcriptional and Translational Gene Silencing”’ pp. 06-07, “5. Function of tRFs during Abiotic Stress Signal Transduction in Plants”; p. 07, “Conclusions”). Similarly, Bélanger discloses that intact plastid-encoded RNAs had not previously been observed outside of the organelle (p. 3399, second full paragraph) and that the mechanism by which plastid-encoded gene products escape the organelle is unknown (p. 3399, first full paragraph). Thus, the mechanism by which small RNAs are exported from the plastids to the cytosol are not well understood in the art. Accordingly, one of ordinary skill in the art could not determine how to design a plastid-encoded DNA construct capable of expressing small RNAs that can escape the plastids and/or effect nuclear gene silencing without either further guidance from Applicant or engaging in extensive experimentation.
The state of the art also teaches at least 4 distinct mechanisms of post-transcriptional gene silencing (pp. 04-08, “1.2 Posttranscriptional Gene Silencing (PTGS)”), at least 6 distinct mechanisms of transcriptional gene silencing (pp. 08-16, “1.3 miRNA Transcriptional Gene Silencing”), and that each of these mechanisms has various limitations, advantages, and disadvantages (p. 16, “3 Limitations of the Gene Silencing Methods”) in different plants (Pandey et al. Methods Mol Biol. 2015:1287:3-23 (Y)). Therefore, the success of any one particular mechanism of gene silencing is unpredictable and will vary based on both the plant and gene target. As such, gene silencing constructs, especially those intended to affect nuclear gene silencing from the plastids, are not predictably functional. For example, the instant specification discloses the failure of an antisense PDS transcript to produce gene silencing when expressed from plastids in comparison to the successful silencing induced by double strand and sense strand PDS transcripts[0096], [00100-00102], [00103-00109], [00138]. Concordantly, Applicant asserts that the mechanism of the RNAi-based gene silencing of the instant invention (i.e., plastid-derived cytoplasmically-localized RNAs derived from dsRNA, antisense, or sense constructs) is well understood in the art to be fundamentally distinct from the mechanism of the RNAi-based gene silencing from plastid-expressed dsRNAs which are retained in the plastids and mechanism of the RNAi-based gene silencing from nuclear-expressed RNAi (Applicant Remarks dated 05/26/2026; p. 08, first and second full paragraphs). Applicant also suggests that RNAi strategies currently known in the art cannot be expected to provide any expectation of success in plastids (Applicant’s Remarks dated 11/18/2025; p. 12, final paragraph). Therefore, the transformation of plastids for the expression of RNA-based silencing constructs from the plastid genome for the silencing of an endogenous nuclear gene is difficult, is not standard in the art, and is not well-understood in the art.
Collectively, the state of the art, Applicant’s remarks, and the instant specification indicate that plastid transformation methods are nonstandard, that many species are recalcitrant to known plastid transformation techniques, and that plastid transformation is limited to species with high potential for regeneration and/or those for which well-developed tissue culture systems have been established. While one skilled in the art could reasonably transform the plastids of any plant known in the art to be amenable to plastid transformation, successful plastid transformations require specific conditions and/or techniques for different plant species, and one of skill in the art could not reasonably determine the structure, features, or sequences required for functional plastid-based gene silencing constructs in any specific plant species besides those few described by Applicant and the prior art without engaging in extensive experimentation.
Applicant’s working examples describe the plastid transformation and silencing of a nuclear gene in only tobacco plants transformed with either of a dsRNA construct or a sense strand RNA construct (Figure 1A)[0096], [00100-00102], [00103-00109], [00138]. Applicant does not describe the transformation of any plant species besides Nicotiana tabacum. Though the instant specification indicates that each of the constructs described by Applicant comprises a PDS gene fragment flanked by either convergent or divergent plastid promoter sequences of approximately 1950 nucleotides and an aadA spectinomycin resistance gene flanked by divergent plastid promoter sequences of approximately 670 nucleotides[0053], neither Applicant nor the state of the art describe the features, structures, or sequences required in said DNA construct to allow the silencing an endogenous nuclear gene of the plant expressing RNAs encoded by said construct from its plastids and/or which features, structures, or sequences are required in the DNA construct to allow said RNAs to escape the plastids. Accordingly, there is insufficient guidance with regard to how to identify plant species and to design DNA constructs amenable to the instant invention without engaging in extensive experimentation.
Because neither Applicant nor the state of the art provide sufficient guidance as to how to identify plant species amenable to the plastid transformation, one of ordinary skill in the art could not predict which plants are amenable to plastid transformation besides the N. tabacum plant disclosed by Applicant and the 23 transplastomic species reported in the art (Narra et al.,; p. 03, Table 1) without engaging in extensive and undue experimentation.
Because neither Applicant nor the state of the art provide sufficient guidance as to the features, sequences, or structures required to allow the recited plastid-encoded DNA construct to produce functional RNAs capable of effecting nuclear gene silencing, one of ordinary skill in the art could not produce a DNA construct capable of silencing a plant nuclear gene when transformed into and expressed from the plastids of said plant, besides the dsRNA and sense strand RNA constructs described by both Applicant (instant Figure 1A) and the prior art (Bélanger et al.) without engaging in extensive and undue experimentation.
Given the separate unpredictability of gene silencing and plastid transformation, both of which are required by the instant invention, the nature of plastid-encoded nuclear gene silencing is highly unpredictable. One of ordinary skill in the art could not predict which of the 23 plant species disclosed by either Applicant or the art are amenable to the recited method of introducing a DNA construct into a plant plastid to induce silencing of a nuclear gene in said plant besides the N. tabacum plant disclosed by Applicant without engaging in extensive and undue experimentation.
Weighing all of the Wands factors based on the totality of the record as discussed above, the Office determines that it would require undue experimentation for a person of ordinary skill in the art to make and use the invention as claimed.
Claim 3-4, 6-7, 9, 11-13 do not address the deficiency regarding any and all plants and any and all DNA constructs. Claims 2, 5, 8, 10, 14-16, and 21-23 do not address the deficiency regarding any and all plants and do not limit the encompassed DNA constructs to those sufficiently represented by Applicant’s disclosure. Accordingly, claims 2-16 and 21-23 are also not enabled.
Response to Arguments – Claim Rejections - 35 USC § 103
8. Applicant’s remarks and amendments filed May 26, 2026 have overcome the rejections of record.
Claim 17 has been cancelled; therefore, any objections and/or rejections to the claims have been rendered moot.
Conclusion
9. No claim is allowed.
10. The closest prior art, He et al., (Journal of Experimental Botany. 2020; 71(9):2670-2677 (previously cited) teaches a method of introducing a DNA construct into a plant plastid genome to silence the nuclear-encoded β-actin gene of the Colorado potato beetle larvae to impart pathogen resistance to the plant (Abstract; p. 2672, “Potato plastid transformation”; p. 2672, “Effect of dsRNAs of different lengths on RNAi efficacy in Colorado potato beetle larvae”; p. 2673, “Generation and molecular characterization of transplastomic potato plants expressing dsACTs”). However, He does not teach silencing an endogenous nuclear-encoded gene of the plant expressing the plastid-encoded DNA construct.
Examiner’s Contact Information
11. Any inquiry concerning this communication or earlier communications from the examiner should be directed to DEQUANTARIUS J SPEED whose telephone number is (703)756-4779. The examiner can normally be reached M-F; 9AM-5PM ET.
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/DEQUANTARIUS JAVON SPEED/Junior Examiner, Art Unit 1663
/Amjad Abraham/SPE, Art Unit 1663
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