Assessment of Anthocyanin and Agronomic Trait Variation in Some Commonly Used Medicinal Legumes.

Several legumes including Canavalia ensiformis, Desmodium adscendens, Indigofera suffruticosa, Senna covesii, and S. occidentalis are currently used as medicinal plants. These species contain anthocyanins as well with potential to be used in the pharmaceutical markets. The USDA, ARS, Plant Genetic Resources Conservation Unit, Griffin, GA curates 74 accessions of these legumes. Anthocyanins are responsible for leaf, stem, flower, and seed colors, however recent research has shown that some anthocyanins can inhibit colon cancer cells.The objectives of this study were to 1) determine the amount of anthocyanin from leaves of these legumes using a modified CCM-200 meter and 2) characterize variability among regenerated legumes for anthocyanin indexes, plant height and width, days to maturity, seed number and 100 seed weight using principal component analysis. An Opti Sciences CCM-200 chlorophyll content meter was converted to an experimental hand-held anthocyanin meter. The 655 nm light emitting diode (LED) of the CCM was replaced with a 520 nm LED in order to measure absorbance near the wavelength at which free anthocyanin aglycones, cyanidin and pelargonidin monoglucosides absorb. Anthocyanin indexes were recorded from each of three leaves using this anthocyanin meter. Leaf anthocyanin indexes ranged from 6.7 – 29.2 in twelve accessions. Senna covesii (PI 288246), S. occidentalis (PI 200812) and I. suffruticosa (PI 206323) had significantly higher anthocyanin indexes (averaging 27). Leaf colors ranging from purple to bronze produced significantly higher anthocyanin indexes averaging 25. Overall anthocyanin index production for all species was highest during September and October, 2006. All agronomic traits and anthocyanin indexes contributed greatly to variation in I. suffruticosa and Senna spp.