Discrimination of Cultivated Regions of Soybeans (Glycine max) Based on Multivariate Data Analysis of Volatile Metabolite Profiles

Abstract

Soybean (Glycine max) is a major crop cultivated in various regions and consumed globally. The formation of volatile compounds in soybeans is influenced by the cultivar as well as environmental factors, such as the climate and soil in the cultivation areas. This study used gas chromatography-mass spectrometry (GC-MS) combined by headspace solid-phase microextraction (HS-SPME) to analyze the volatile compounds of soybeans cultivated in Korea, China, and North America. The multivariate data analysis of partial least square-discriminant analysis (PLS-DA), and hierarchical clustering analysis (HCA) were then applied to GC-MS data sets. The soybeans could be clearly discriminated according to their geographical origins on the PLS-DA score plot. In particular, 25 volatile compounds, including terpenes (limonene, myrcene), esters (ethyl hexanoate, butyl butanoate, butyl prop-2-enoate, butyl acetate, butyl propanoate), aldehydes (nonanal, heptanal, (E)-hex-2-enal, (E)-hept-2-enal, acetaldehyde) were main contributors to the discrimination of soybeans cultivated in China from those cultivated in other regions in the PLS-DA score plot. On the other hand, 15 volatile compounds, such as 2-ethylhexan-1-ol, 2,5-dimethylhexan-2-ol, octanal, and heptanal, were related to Korean soybeans located on the negative PLS 2 axis, whereas 12 volatile compounds, such as oct-1-en-3-ol, heptan-4-ol, butyl butanoate, and butyl acetate, were responsible for North American soybeans. However, the multivariate statistical analysis (PLS-DA) was not able to clearly distinguish soybeans cultivated in Korea, except for those from the Gyeonggi and Kyeongsangbuk provinces.

Soybean Cyst Nematodes Influence Aboveground Plant Volatile Signals Prior to Symptom Development

“…Our findings also provide additional insight into the spectrum of VOCs produced by soybean plants, with fatty acid derivatives, phenylpropanoids and benzenoids, and terpenes being the most abundant metabolic sources. Several of the volatiles found in our study correlate with previous volatile studies of soybean plants (Kim et al, 2020 ). In our studies, the most abundant class of VOCs were fatty acid derivatives.…”

“…Styrene (CPV11), a phenylpropanoid and benzenoid derivative, an important monomer for commercial products such as plastics, synthetic rubbers and paints, does occur naturally (Miller et al, 1994 ). Styrene and derivatives have been found in plants, including soybean and as a by-product of fungal and microbial metabolism (Shirai and Hisatsuka, 1979 ; Arpaia et al, 2011 ; Kim et al, 2020 ). Styrene produced by Bacillus mycoides in the rhizosphere of tomato plants exhibited high nematocidal activity against M. incognita (Luo et al, 2018 ).…”

“…In our studies, the most abundant were Decanal (CPV52), Nonanal (CPV42), and (E)-2-hexenal (CPV56), consecutively. Both Nonanal (CPV42) and (E)-2-hexenal (CPV56) have been identified from soybeans, as well as have been shown to be potent antifungal volatiles against Aspergillus flavus (Cleveland et al, 2009 ; Kim et al, 2020 ). Decanal (CPV52) and to a lesser extent Nonanal (CPV42), produced by insect damaged potato tubers, have been shown to serve as powerful attractants to entomopathogenic nematodes (Laznik and Trdan, 2016 ).…”

“…Compounds associated with this group have been shown to be involved in plant growth, light response, and are key mediators of organismal interactions (Biała and Jasiński, 2018 ). In addition to Butylated Hydroxytoluene (CPV76) and its oxidized derivative 2,6-Di-T-butyl-4-methylene-2,5-cyclohexadiene-1-one (CPV74) mentioned above, Toluene (CPV4) was abundantly detected from soybeans (Kim et al, 2020 ). Although a common petroleum-derived product, Toluene was originally discovered in pine oil.…”

“…It is an oily VOC emitted by many plants, particularly in oils of citronella, lemon-grass and palmarosa and is a powerful mosquito pheromone (Logan et al, 2010 ; Dekel et al, 2019 ). α-Pinene (CPV17), and β-Pinene (CPV24) are isomers of pinene and are the main compounds released by forest trees and have been detected to be produced by soybeans (Kim et al, 2020 ). Both volatiles have a woody and pine scent and are most often generated together in plants (Geron et al, 2000 ).…”