Use of micropeptides in order to stimulate mycorrhizal symbiosis

A method for promoting mycorrhizal symbiosis, in particular arbuscular mycorrhizal symbiosis, between a plant and a fungus, comprising a step of introducing exogenously a miPEP into the plant,

• said miPEP also being naturally present in said plant,
• said miPEP introduced exogenously being a peptide comprising, or consisting of, a sequence identical to that of said miPEP naturally present,
• said miPEP naturally present is a peptide of 3 to 100 amino acids the sequence of which is encoded by an open reading frame situated at 5′ on the primary transcript of a miRNA,
• said miPEP being capable of modulating the accumulation of said miRNA in said plant, which miRNA regulates the expression of at least one gene involved in the arbuscular mycorrhizal symbiosis in said plant,
• the sum of the quantity of said miPEP introduced exogenously and that of said miPEP naturally present being strictly greater than the quantity of said miPEP naturally present,
• in particular, said gene involved in the mycorrhizal symbiosis encoding a transcription factor of the GRAS family,
• in particular, said gene involved in the mycorrhizal symbiosis being selected from the group consisting of:
• HAM1 and HAM2.

A method for the production of a transgenic plant comprising:

• a) a step of introducing a nucleic acid encoding for a miPEP of 3 to 100 amino acids into a plant, or into at least one cell of said plant, under conditions allowing the expression of said miPEP,
• said miPEP also being naturally present in said plant, said miPEP naturally present is a peptide the sequence of which is encoded by an open reading frame situated at 5′ on the primary transcript of a miRNA, said miPEP being capable of modulating the accumulation of said miRNA in the plant, which miRNA regulates the expression of at least one gene involved in mycorrhizal symbiosis, in particular arbuscular mycorrhizal symbiosis, and
• b) a step of growing the plant, or at least one cell of said plant, obtained in step a) under conditions allowing a transgenic plant to be obtained,
• said gene involved in mycorrhizal symbiosis being in particular selected from the group consisting of:
• HAM1 and HAM2,
• said miRNA being in particular miR171b, said miR171b having in particular a nucleotide sequence consisting of SEQ ID NO:
• 1,
• said miPEP being in particular miPEP171b, said miPEP171b having in particular an amino acid sequence consisting of SEQ ID NO:
• 2,
• said miRNA being in particular slmiR171e, said slmiR171e having in particular a nucleotide sequence consisting of SEQ ID NO:
• 5,
• said miPEP being in particular slmiPEP171e, said slmiPEP171e having in particular an amino acid sequence consisting of SEQ ID NO:
• 6,
• said miRNA being in particular ljmiR171b, said ljmiR171b having in particular a nucleotide sequence consisting of SEQ ID NO:
• 9,
• said miPEP being in particular ljmiPEP171b, said ljmiPEP171b having in particular an amino acid sequence consisting of SEQ ID NO:
• 10, or
• said miRNA being in particular osmiR171i, said osmiR171i having in particular a nucleotide sequence consisting of SEQ ID NO:
• 13,
• said miPEP being in particular osmiPEP171i, said osmiPEP171i having in particular an amino acid sequence consisting of SEQ ID NO:
• 14.

A composition comprising:

• miPEP171b as the active ingredient, said miPEP171b preferably consisting of SEQ ID NO:
• 2, said miPEP171b being in particular at a concentration of 10−9 M to 10−4 M, in particular 10−9, 10−8, 10−7, 10−6, 10−5 or 10−4 M,
• slmiPEP171e as the active ingredient, said slmiPEP171e preferably consisting of SEQ ID NO:
• 6, said slmiPEP171e being in particular at a concentration of 10−9 M to 10−4 M, in particular 10−9, 10−8, 10−7, 10−6, 10−5 or 10−4 M,
• ljmiPEP171b as the active ingredient, said ljmiPEP171b preferably consisting of SEQ ID NO:
• 10, said ljmiPEP171b being in particular at a concentration of 10−9 M to 10−4 M, in particular 10−9, 10−8, 10−7, 10−6, 10−5 or 10−4 M, or
• osmiPEP171i as the active ingredient, said osmiPEP171i preferably consisting of SEQ ID NO:
• 14, said osmiPEP171i being in particular at a concentration of 109M to 10−4M, in particular 10−9, 10−8, 10−7, 10−6, 10−5 or 10−4 M,
• in particular, said composition also comprising an excipient, a diluent or a solvent,
• in particular, said composition being formulated so as to form a coating.