Discrimination of cultivation ages and cultivars of ginseng leaves using Fourier transform infrared spectroscopy combined with multivariate analysis

Abstract

To determine whether Fourier transform (FT)-IR spectral analysis combined with multivariate analysis of whole-cell extracts from ginseng leaves can be applied as a high-throughput discrimination system of cultivation ages and cultivars, a total of total 480 leaf samples belonging to 12 categories corresponding to four different cultivars (Yunpung, Kumpung, Chunpung, and an open-pollinated variety) and three different cultivation ages (1 yr, 2 yr, and 3 yr) were subjected to FT-IR. The spectral data were analyzed by principal component analysis and partial least squares-discriminant analysis. A dendrogram based on hierarchical clustering analysis of the FT-IR spectral data on ginseng leaves showed that leaf samples were initially segregated into three groups in a cultivation age-dependent manner. Then, within the same cultivation age group, leaf samples were clustered into four subgroups in a cultivar-dependent manner. The overall prediction accuracy for discrimination of cultivars and cultivation ages was 94.8% in a cross-validation test. These results clearly show that the FT-IR spectra combined with multivariate analysis from ginseng leaves can be applied as an alternative tool for discriminating of ginseng cultivars and cultivation ages. Therefore, we suggest that this result could be used as a rapid and reliable F1 hybrid seed-screening tool for accelerating the conventional breeding of ginseng.

Keywords: Fourier transform IR; Panax ginseng; cultivation age; ginseng cultivars; ginseng leaves.

Fig. 1

Representative leaf morphology of ginseng (Panax ginseng Meyer cv. Kumpung) grown on fields. (A) 1-yr-old ginseng leaves, (B) 2-yr-old ginseng leaves, and (C) 3-yr-old ginseng leaves. Scale bars represent 5 cm.

Fig. 2

Representative Fourier transform infrared (FT-IR) spectra from ginseng leaves of different cultivars and cultivation ages. (A) Each line represents the FT-IR spectra from four types of ginseng cultivars (Yunpung, Kumpung, Chunpung, and an open-pollinated variety) subjected to FT-IR spectroscopy analysis. (B) Each line represents FT-IR spectra from ginseng leaves of the open-pollinated variety of ginseng with different cultivation ages (1 yr, 2 yr, and 3 yr).

Fig. 3

Fourier transform infrared (FT-IR) spectra from ginseng leaves of different cultivars and cultivation ages. (A) Principal component (PC) analysis. Broken circles represent each cultivation age. Capital letters represent each cultivar (Y, Yunpung; K, Kumpung; C, Chunpung; N, open-pollinated variety), and numbers represent cultivation age. (B) PC-loading plots. Unbroken and broken lines represent loading values for PC 1 and PC 2, respectively.

Fig. 4

Partial least squares-discriminant analysis (PLS-DA) score plot and hierarchical clustering analysis dendrogram of Fourier transform infrared data from ginseng leaves. (A) Two-dimensional PLS-DA score plot of Fourier transform infrared data from ginseng leaves. Dotted circles represent each cultivation age. (B) A dendrogram based on hierarchical clustering analysis of PLS-DA data from ginseng leaves. Capital letters represent each cultivar (Y, Yunpung; K, Kumpung; C, Chunpung; N, open-pollinated variety), and numbers represent cultivation age.

Fig. 5

Partial least squares-discriminant analysis score plots from different cultivation ages. (A) 1 yr, (B) 2 yr, and (C) 3 yr. Capital letters and dotted circles represent each cultivar (Y, Yunpung; K, Kumpung; C, Chunpung; N, open-pollinated variety), and numbers represent cultivation age.