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. 2012 Aug 17;7(8):e43607. doi: 10.1371/journal.pone.0043607

Figure 3. Projection to Latent Structures Discriminant Analysis (PLS-DA) on the volatile compounds emitted by egg-infested B. nigra.

Figure 3

HR+ (+) or HR− (−) plants were infested by eggs of Pieris brassicae (PB) or Mamestra brassicae (MB) sampled 24 or 72 h after oviposition. (A) Score plot visualizing the grouping pattern of the samples according to the first two PLS components with the explained variance in brackets. The ellipse defines Hotelling’s T2 confidence region (95%). (B) Loading plot of the first two principal components shows the contribution of each of the compounds to the two PLS-DA components. Markers of the 5 different treatments shown in the score plot are given. Hypersensitive response type, (−): no necrotic zone observed, (+): with necrotic zone. Compound numbers: (1) 2-Methylpropanal, (2) 2-methyl-2-Propenal, (3) Ethyl acetate, (4) 2-Methyl-1-propanol, (5) Tetrahydrofuran, (6) 2-Butenal, (7) 3-Methylbutanal, (8) 2-Methylbutanal, (9) 1-Methoxy-2-propanol, (10) 1-Pentene-3-ol, (11) 2-Pentanone, (12) 3-Pentanone, (13) Methylcyclohexane, (14) Pyrazine, (15) 4-Methyl-2-pentanone (16) 1,2-Dimethyldisulfide, (17) (E)-2-Pentenal, (18) 2,4-Pentanedione, (19) 4-Methyl-3-pentene-2-one, (20) (Z)-3-Hexen-1-ol, (21) Allyl isothiocyanate, (22) α-Pinene, (23) 6-Methyl-2-heptanone, (24) (Z)-3-Hexen-1-yl acetate, (25) 3-Carene, (26) (S)-Limonene, (27) α-Phellandrene, (28) Methyl-2-ethylhexanoate, (29) (E)-β-Ocimene, (30) o-Cresol, (31) 2,2,6-Trimethyl-4-methylene-2H-pyran, (32) p-Mentha-1,5,8-triene, (33) 2-Phenylacetonitrile, (34) Isopulegon, (35) p-Menthan-3-one, (36) Isomenthone, (37) Menthol, (38) Undecan-2-one, (39) 7-α-H-Silphiperfol-5-ene, (40) Presilphiperfol-7-ene, (41) 7-β-H-Silphiperfol-5-ene, (42) 4-(3-cyclohexen-1-yl)-3-Buten-2-one, (43) Silphiperfol-6-ene, (44) α-Funebrene, (45) Longifolen, (46) 2-Phenylethyl isothiocyanate, (47) Lilial, (48) Guaiazulene, (49) 2-Ethylhexyl salicylate, (50) Cembrene. Significantly increased terpenoids in volatile blends of P. brassicae egg-infested plants compared to uninfested plants are in bold (*P<0.05, Mann-Whitney U-test).