Catalyzes the methylation of jasmonate into methyljasmonate, a plant volatile that acts as an important cellular regulator mediating diverse developmental processes and defense responses. jasmonate + S-adenosyl-L-methionine = methyl (-)-jasmonate + S-adenosyl-L-homocysteine Binds 1 Mg(2+) ion per subunit. Lipid metabolism; oxylipin biosynthesis. Predominantly cytoplasmic (PubMed:10809010). Partially nuclear (PubMed:10809010). Specifically expressed to the flower base. Localizes specifically to both the lateral and median nectaries of flowers (at protein level). Increases with flower development, especially during nectary development, but decreases abruptly with the opening of the flower. Belongs to the methyltransferase superfamily. Type-7 methyltransferase family.