METHOD FOR DIRECTING NUCLEIC ACIDS TO PLASTIDS
The invention relates to nucleic acid sequences naturally imported into a plant cell plastid, and use thereof for directing an RNA sequence of interest to a plastid, which permits, in particular, the directed expression of a protein of interest in a plant cell plastid.
1 . A method for targeting an RNA of interest to a plastid of a plant cell, said method comprising the transformation of a plant cell with a nucleic acid of interest linked to a targeting nucleic acid, the transcribed sequence of which is that of an mRNA of a nuclear gene, said mRNA being detectable in a plastid.
2 . The method as claimed in claim 1 , in which the targeting nucleic acid has, as transcribed sequence, that of an mRNA of an endogenous nuclear gene.
3 . The method as claimed in claim 1 , in which said plastid is selected from the group consisting of a chloroplast, an amyloplast, a chromoplast and a proplastid.
4 . The method as claimed in claim 1 , in which said mRNA is characterized by a concentration in a plastid which is greater than its cytoplasmic concentration.
5 . The method as claimed in claim 4 , in which said mRNA is characterized by a concentration in a plastid that is at least twice its cytoplasmic concentration.
6 . The method as claimed in claim 1 , in which said targeting nucleic acid has a transcribed sequence which is that of an mRNA of a gene selected from the group consisting of the genes having, as coding sequence, SEQ ID No.1, SEQ ID No.3, SEQ ID No.5, SEQ ID No.7, SEQ ID No.9, SEQ ID No.11, SEQ ID No.13, SEQ ID No.15, SEQ ID No.17, SEQ ID No.19, SEQ ID No.21, SEQ ID No.23, SEQ ID No.25, SEQ ID No.27, SEQ ID No.29, SEQ ID No.31, SEQ ID No.33, SEQ ID No.35, SEQ ID No.37, SEQ ID No.39 and SEQ ID No.41.
7 . The method as claimed in claim 1 , in which said targeting nucleic acid has a transcribed sequence which is that of an mRNA of a gene encoding the eukaryotic translation initiation factor eIF4E.
8 . The method as claimed in claim 1 , in which said nucleic acid of interest is a DNA.
9 . The method as claimed in claim 1 , in which said nucleic acid of interest is an RNA.
10 . The method as claimed in claim 1 , in which said targeting nucleic acid is a DNA.
11 . The method as claimed in claim 1 , in which said targeting nucleic acid is an RNA.
12 . The method as claimed in claim 1 , in which said nucleic acid of interest encodes a heterologous protein.
13 . A nucleic acid construct comprising a nucleic acid of interest linked to a targeting nucleic acid, the transcribed sequence of which is that of an mRNA of a nuclear gene selected from the group consisting of the genes having, as coding sequence, SEQ ID No.1, SEQ ID No.3, SEQ ID No.5, SEQ ID No.7, SEQ ID No.9, SEQ ID No.11, SEQ ID No.13, SEQ ID No.15, SEQ ID No.17, SEQ ID No.19, SEQ ID No.21, SEQ ID No.23, SEQ ID No.25, SEQ ID No.27, SEQ ID No.29, SEQ ID No.31, SEQ ID No.33, SEQ ID No.35, SEQ ID No.37, SEQ ID No.39 and SEQ ID No.41.
14 . A plant cell transformed with a nucleic acid of interest linked to a targeting nucleic acid, the transcribed sequence of which is that of an mRNA of a nuclear gene selected from the group consisting of the genes having, as coding sequence, SEQ ID No.1, SEQ ID No.3, SEQ ID No.5, SEQ ID No.7, SEQ ID No.9, SEQ ID No.11, SEQ ID No.13, SEQ ID No.15, SEQ ID No.17, SEQ ID No.19, SEQ ID No.21, SEQ ID No.23, SEQ ID No.25, SEQ ID No.27, SEQ ID No.29, SEQ ID No.31, SEQ ID No.33, SEQ ID No.35, SEQ ID No.37, SEQ ID No.39 and SEQ ID No.41.
15 . A transgenic plant that can be regenerated from the transformed plant cell as claimed in claim 14 .
16 . A method for producing at least one protein of interest in a plastid of a plant cell, the method comprising the steps consisting in:
a) transforming a plant cell with a nucleic acid encoding a protein of interest linked to a targeting nucleic acid, the transcribed sequence of said targeting nucleic acid being that of an mRNA of a nuclear gene, said mRNA being detectable in a plastid of a plant cell; and
b) expressing said nucleic acid encoding a protein of interest.
17 . The method as claimed in claim 16 , in which the transcribed sequence of said targeting nucleic acid is that of an mRNA of a nuclear gene, said mRNA being characterized by a concentration in a plastid that is greater than its cytoplasmic concentration.
18 . A method for identifying an RNA capable of targeting an RNA of interest to a plastid of a plant cell, in which the concentration of a candidate RNA in a plastid and in the cytoplasm of a plant cell is determined, and where an RNA, the concentration of which in the plastid is greater than its concentration in the cytoplasm, is identified as RNA capable of targeting an RNA of interest to a plastid of a plant cell.
19 . The method as claimed in claim 18 , in which an RNA, the concentration of which in the plastid is at least twice its concentration in the cytoplasm, is identified as RNA capable of targeting an RNA of interest to a plastid of a plant cell.