Taxonomy, morphology and breeding of menthol mints (review)

Vegetative plant parts of menthol mint varieties contain up to 2-3%, and the inflorescences - up to 6% of essential oil, the main component of which (45-92 %) is menthol. A peppermint - M. x piperita L. is the most widespread and has an economic importance in the world. Mint garden (M. spicata L.), field mint (M. arvensis L.), water mint (M. aquatica L.), horse mint (M. longifolia (L.) Huds.), apple mint (M. suaveolens Ehrh. = M. rotundifolia Aust.) are also cultivated in the world. Besides them it is known at least 11 mint interspecific hybrids. All species of mints are perennial herbs. Elementary species of mints are reproduced by seeds and fragments of shoots, rhizomes, sometimes leaves. Peppermint and other interspecific hybrids are multiply with the horizontal rhizomes. The essential oil glands of 80-100 microns in diameter are located in all the aboveground parts of the peppermint plants. The essential oil content in the dry leaves varies from 1 to 3.5%. Breeding of menthol mints is conducted to improve the yield of essential oil and menthol. This is achieved by increasing of the yield of a vegetative mass and an increase in the content of the essential oil in the leaves and inflorescences. All created varieties must be resistant to pests, diseases and winter hardiness. A scheme of a mint breeding process includes a nursery of parental germplasm, control nursery, preliminary and competitive varieties trials. The basic method of varieties’ creation is interspecific hybridization, sometimes with the use of polyploidy. Also methods of clonal selection and mutagenesis are used. In 2011 ten varieties of mint are admitted for cultivation in Russia, three varieties of them: Vesna, Mechta and Raduga, are developed at Voznesensky affiliate of VNIIMK.