Screening of high biomass and phenolic producing clonal lines of Spearmintin tissue culture using Pseudomonas and azetidine-2 carboxylate.

Rosmarinic acid (RA) and related phenolics are natural antioxidants found a s secondary metabolites in spearmint (Mentha spicata). These phenolic-secon dary metabolites have diverse food processing and nutraceutical application s. Since natural cross-pollination results in plant to plant variation in t he level of phenolic metabolites, tissue culture-based techniques are essen tial to isolate elite antioxidant-producing clonal lines. The objective of this research is to develop tissue culture-based selection techniques to is olate high rosmarinic acid and phenolic-producing clonal lines from a heter ogenous bulk seed population of spearmint. Multiplied clonal shoots of each line were screened for tolerance to azetidine-2-carboxylate (A2C). Individ ual shoot apex of each line were also screened for Pseudomonas tolerance. R osmarinic acid and total phenolics were assayed in all treated clonal lines and compared to uninoculated/untreated shoot explants of corresponding lin e. The Pseudomonas and A2C treatment strategy allowed the rapid tissue cult ure-based screening of potentially high phenolic antioxidant-producing clon al lines of spearmint for future field and greenhouse evaluation. Targeted elite lines had combinations of Pseudomonas tolerance with no loss in bioma ss in response to the bacterium and enhanced levels of total phenolics and rosmarinic acid in response to A2C.