C. Mollema et Ra. Cole, LOW AROMATIC AMINO-ACID-CONCENTRATIONS IN LEAF PROTEINS DETERMINE RESISTANCE TO FRANKLINIELLA-OCCIDENTALIS IN 4 VEGETABLE CROPS, Entomologia experimentalis et applicata, 78(3), 1996, pp. 325-333
Analysis of total aromatic amino acid (free and bound) in some cucumbe
r accessions selected previously for resistance to western flower thri
ps, Frankliniella occidentalis (Pergande) [Thysanoptera: Thripidae], i
ndicated that low concentrations of these essential nutrients, relativ
e to total leaf protein, were correlated with a reduction in damage by
the insect. Further analysis of samples of four important horticultur
al crops (lettuce, tomato, pepper and cucumber) with unknown levels of
resistance to thrips showed a significant genotypic variation in the
concentrations of total aromatic amino acids relative to the total lea
f protein. Accessions from each crop with low or high concentrations o
f aromatic amino acids in proteins were exposed to thrips larvae. Regr
ession analysis showed a highly significant positive correlation betwe
en aromatic amino acid concentration in leaf protein and thrips damage
, regardless of crop species. It is concluded that higher concentratio
ns of aromatic amino acids in plant proteins are important for success
ful thrips development. These results provide plant breeders with a pr
omising tool for indirect selection without using undesirable insect b
ioassays.