Figure 7.

Aphid resistance conferred by loss of function of FAD7 is compromised by the NahG transgene. The spr2 and NahG tomato lines were crossed, the F1 progeny were self-pollinated, and the F₂ generation was screened by PCR for the presence or absence of the NahG transgene, the wild-type (WT) LeFAD7 allele, and the spr2 mutation in LeFAD7. Four phenotypic bulks were selected: (1) WT/NahG⁻ = plants carrying at least one copy of the wild-type LeFAD7 allele and lacking the NahG transgene; (2) WT/NahG⁺ = plants carrying the wild-type LeFAD7 allele and NahG; (3) spr2/NahG⁻ = plants homozygous for the spr2 mutation in LeFAD7 but lacking NahG; and (4) spr2/NahG⁺ = double mutant plants homozygous for the spr2 mutation and carrying NahG. All four bulks were inoculated with potato aphids (five aphids per cage; three cages per plant; 14–17 plants per bulk), and 6 d after inoculation, total offspring (dead and alive) were counted to measure adult fecundity (A) and offspring survival (B). One day after the aphids were counted, total, free, and bound SA content was measured in six randomly selected samples per bulk (C). The average number of total, dead, and living aphids per cage per plant was Box Cox transformed (Box and Cox, 1964) to stabilize variances, all values were analyzed by one-way ANOVA, and means were separated using Student’s t tests. Bars of the same pattern ± se with different letters differ significantly at α = 0.05. Uppercase letters above the bars in C denote significant differences in total (free + bound) SA content. FW, Fresh weight.