Diploid mint (M. longifolia) can produce spearmint type oil with a high yield potential

Mint oil is a key source of natural flavors for gum, candy, perfumes, cosmetics and health care products. Two unbalanced polyploid cultivars named Native (Mentha Spicata L) and Scotch (M. x gracilis Sole) are the main producers of spearmint type oil, which is characterized by high levels of the monoterpenes (-)-carvone and (-)-limonene. These cultivars have been the backbone of spearmint oil production for decades, while breeding and improvement remained largely unexplored, in part, due to sterility in cultivated lines. Here we show that sexual breeding at the diploid level can be leveraged to develop new clones that produce spearmint type oil, along with the improvement of other important traits. Using field trials, we identified a diploid accession that exhibited 89.5 % increase in oil yield, and another that produces spearmint type oil. Spearmint type oil was present at high frequency in a segregating F2 population (32/160) produced from these two accessions. Field-testing of ten lines from this population demonstrated segregation for oil yield, and confirmed production of spearmint-type profiles similar to the industry controls. Four of these lines presented an increase in oil yield, of up to 64.7 %, and two of them combined high yield and spearmint-type oil with acceptable analytic and sensory profiles. These results demonstrate that spearmint-type oil can be produced in a diploid background with high yield potential, providing a simpler genetic system for the development of improved spearmint varieties.