Fig 1.
The effect of touching on potato mass fractions (SMF–Stem Mass Fraction, BMF–Branch Mass Fraction and LMF–Leaf Mass Fraction).
Significant differences between treatments (*P < 0.05; **P < 0.01; Tukey’s HSD test).
Table 1.
Effect of one minute of touching over a period of 17 days on morphological characteristics of potato plants.
Fig 2.
Potato non glandular trichomes obtained by SEM under magnification ×180 on leaf surface from A) touched terminal leaf, B) untouched terminal leaf. No tissue damage was observed on leaf samples.
Fig 3.
Mean number of: A) non-glandular trichomes per leaf sample on images obtained by light microscopy, B) glandular trichomes per image obtained by SEM. Significant differences in the number of trichomes (*P < 0.05; Tukey’s HSD test).
Fig 4.
Mean number of pavement cells per 0.06 mm2 on image obtained by SEM.
Significant differences in the number of trichomes (*P < 0.05; **P < 0.01; Tukey’s HSD test).
Fig 5.
Principal Component analysis (PCA) score plots for touched and control plants.
A) Plots PC1 vs PC2 compare total variation in volatile profile between treatments. B) Vectors on the loading plot based on the first two PC show the relative importance of each peak area in volatile compounds released that discriminate treatments (C1: (a)-pinene, C2: 6-methyl-5-hepten-2-one, C3: (E)-ocimene, C4: linalool, C5: DMNT, C6: methyl salicylate, C7: (-)-cyclosativene, C8: a-copaene, C9: (E)-caryophyllene, C10: unknown sesquiterpene 1, C11: unknown sesquiterpene 2, C12: cadinene, C13: (E)-nerolidol, C14: TMTT, C15: germacrene D 4-ol, C16: hexahydrofarnesyl acetone).
Table 2.
Volatile compounds released by treated and control plants (p values from T-test).
TMTT: (E,E)-4,8,12-Trimethyl-1,3,7,11-tridecatetraene, DMNT: (E)-4,8-dimethyl-1,3,7-nonatriene.
Fig 6.
Olfactory preferences of: A) M. euphorbiae and B) M. persicae for volatiles released from touched and untouched potato plants. Significant differences in aphid olfactory preference (*P < 0.05, **P < 0.01; Wilcoxon’s mean pairs test).