# US 2019/0169630 A1 · Improvement of photosynthetic organisms through the modulation of guanosine tetraphosphate homeostatis > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0169630 A1 - Document ID: US20190169630A1 - Status: Published application - Kind: A1 - Application number: 16/076,303 - Filed: 2017-02-07 - Published: 2019-06-06 - Earliest claimed: 2016-02-08 - Assignees: Centre National de la Recherche Scientifique (CNRS); Universite De La Mediterranee Aix-Marseille II - Applicants: Centre National De La Recherche Scientifique (Cnrs); Universite De La Mediterranee (Aix-Marseille II) - Inventors: Benjamin FIELD; Matteo SUGLIANI; Christophe ROBAGLIA; Hela ABDELKEFI - Web page: https://patentgrep.com/patent/US20190169630A1 ## CPC - C12N 15/8266: {Abscission; Dehiscence; Senescence} - C12N 15/00: Mutation or genetic engineering; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification; Use of hosts therefor (mutants or genetically engineered microorganisms, per se C12N1/00, C12N5/00, C12N7/00; new plants per se A01H; plant reproduction by tissue culture techniques A01H4/00; new animals per se A01K67/00; use of medicinal preparations containing genetic material which is inserted into cells of the living body to treat genetic diseases, gene therapy A61K48/00) - C12N 15/8261: {with agronomic (input) traits, e.g. crop yield} - C12N 15/8269: {Photosynthesis} - Y02A 40/146: Genetically Modified [GMO] plants, e.g. transgenic plants - C12N: MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA (microbiological testing media C12Q1/00) - Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE ## Abstract The present invention concerns methods and approaches for modifying guanosine tetraphosphate (ppGpp) homeostasis in photosynthetic eukaryotes, in particular plants or algae, in order to modulate senescence for the remobilisation of nitrogen and other nutrients from the chloroplast, and modified photosynthetic eukaryotes thus produced. ## Claims ### Claim 1 A modified photosynthetic eukaryote having a modified level of guanosine tetraphosphate (ppGpp) capable of altering nitrogen remobilization and/or causing senescence in a photosynthetic eukaryote, compared to that of a non-modified photosynthetic eukaryote, wherein said modified photosynthetic eukaryote displays a delayed or accelerated nitrogen remobilization and/or senescence relative to a non-modified photosynthetic eukaryote. ### Claim 2 (depends on 1) The modified photosynthetic eukaryote of claim 1, wherein said modified photosynthetic eukaryote displaying a delayed nitrogen remobilization and/or senescence is transformed with a nucleic acid molecule effective in reducing levels of ppGpp. ### Claim 3 (depends on 2) The modified photosynthetic eukaryote of claim 2, wherein said nucleic acid molecule encodes RSH1 and/or MESH hydrolase, or comprises an antisense form of a nucleic acid molecule encoding RSH2 and/or RSH3 synthase. ### Claim 4 (depends on 1) The modified photosynthetic eukaryote of claim 1, wherein modified photosynthetic eukaryote displaying an accelerated nitrogen remobilization and/or senescence is transformed with a nucleic acid molecule effective in increasing expression of ppGpp. ### Claim 5 (depends on 4) The modified photosynthetic eukaryote of claim 4, wherein said nucleic acid molecule encodes RSH2, RSH3 and/or the bacterial ReIA (SYN) synthase, or comprises an antisense form of a nucleic acid molecule encoding RSH1 hydrolase. ### Claim 6 (depends on 4) A seed with modified senescence characteristics produced from the modified photosynthetic eukaryote according claim 4, wherein said seed comprises the nucleic acid molecule. ### Claim 7 A seed with modified senescence characteristics, wherein said seed is transformed with a nucleic acid molecule effective in increasing expression of ppGpp. ### Claim 8 (depends on 7) The seed of claim 7, wherein the nucleic acid molecule encodes RSH2, RSH3 and/or the bacterial ReIA (SYN) synthase, or comprises an antisense form of a nucleic acid molecule encoding RSH1 hydrolase. ### Claim 9 (depends on 2) A method for delaying nitrogen remobilization and/or senescence in a photosynthetic eukaryote said method comprising providing a photosynthetic eukaryote as defined in claim 2. ### Claim 10 (depends on 4) A method for accelerating nitrogen remobilization and/or senescence in a photosynthetic eukaryote, said method comprising providing a photosynthetic eukaryote as defined in claim 4. ### Claim 11 A method for producing a photosynthetic eukaryote with modified nitrogen remobilization and/or senescence characteristics which comprises transformation of a photosynthetic eukaryote with a DNA construct adapted to modify ppGpp homeostatis, and subsequent selection of the modified photosynthetic eukaryote in which the senescence is either delayed or accelerated. ### Claim 12 (depends on 11) The method of claim 11 for producing a photosynthetic eukaryote with delayed nitrogen and/or senescence, wherein the DNA construct encodes RSH1 and/or MESH hydrolase, or comprises an antisense form of a nucleic acid molecule encoding RSH2 and/or RSH3 synthase. ### Claim 13 (depends on 11) The method of claim 11 for producing a photosynthetic eukaryote with accelerated nitrogen remobilization and/or senescence, wherein the DNA construct encodes RSH2, RSH3 and/or the bacterial ReIA (SYN) synthase, or comprises an antisense form of a nucleic acid molecule encoding RSH1 hydrolase. ### Claim 14 (depends on 5) A seed with modified senescence characteristics produced from the modified photosynthetic eukaryote according to claim 5, wherein said seed comprises the nucleic acid molecule. ### Claim 15 (depends on 3) A method for delaying nitrogen remobilization and/or senescence in a photosynthetic eukaryote said method comprising providing a photosynthetic eukaryote as defined in claim 3. ### Claim 16 (depends on 5) A method for accelerating nitrogen remobilization and/or senescence in a photosynthetic eukaryote, said method comprising providing a photosynthetic eukaryote as defined in claim 5.