Coumarin variation in Iranian biennial Melilotus genetic resources and its relationship with agro-morphophenological traits

Abstract

Most of Melilotus Miller species, a forage legume, contain coumarin, an unfavorable component in their shoot. There is no information concerning coumarin on Iranian Melilotus germplasms. It is crucial for plant breeders to know the concentration of this component in the breeding materials, its relationship with other traits and with genotype geographic origin. In a two-year field study a total of 196 accessions of biennial Melilotus were planted in two replications in March 2014. Thirty-nine agro-morphobiochemical traits were recorded according to standard descriptors. Fluorescencemetery assay was applied to detect free, conjugated, and total coumarin concentrations in plant leaves. The data were subjected to correlation, path, regression, factor, and cluster analyses. Total coumarin concentration varied from 0.09 to 5.27% of leaf dry weight (LDW) with a mean of 1.63 ± 0.08% of LDW among accessions. In M. officinalis, correlation analysis showed no significant correlation between coumarin concentration and cotyledon, hypocotyl, and stem colors. Therefore, no early predicting trait was determined to estimate coumarin concentration in the early growth phases of the germplasms. A positive linear relationship between leaf area and total coumarin concentration was observed by path and regression analyses. Based on factor analysis and extracted bi-plot, the scatter of accessions with low coumarin and high forage yield was determined. Materials were divided into three groups by k-means cluster analysis. There was no clear pattern between coumarin concentration and genotype geographic origin. The findings could be utilized by Melilotus breeders to apply in their breeding programs.