Contents - Faperta

Mechanisms and Inheritance of Resistance to Insect Pests 141
Fruits
Resistance in fruits to several species of aphids is controlled by a single dominant gene, for
example, rosy apple aphid, Dysaphis plantaginea Pass., and rosy leaf-curling aphid, Dysaphis
devecta Walk., in apple (Alston and Briggs, 1977). In raspberry, Rubus phoenicolasius Maxim.,
two dominant genes control resistance to the raspberry aphid, Amphorophora idaei Bomer
(Daubeny, 1966; Jones, McGavin, and Birch, 2000). Monet and Massonie (1994) identifi ed a
single gene in peach, Prunus persica (L.), (Batsch.) that controls resistance to peach potato
aphid, M. persicae.
Conclusions
Sources of resistance to insect pests have been identifi ed in different crops. However, the
identifi ed sources of resistance have not been used widely because of low heritability or
linkage drag. The progress in developing crop cultivars with resistance to insects has been
quite slow because of lack of information on the mechanisms that contribute to insect
resistance, the number of genes involved, and the nature of gene action. Levels of resistance
to insect pests in most of the varieties released for cultivation are low to moderate
and, therefore, there is a need to diversify the bases of resistance through gene pyramiding
from cultivated germplasm and closely related wild relatives of crops. Resistance to insects
is largely due to antixenosis, antibiosis, and tolerance, and is controlled by many genes.
Resistance may be dominant or recessive. Pedigree and backcross approaches can be
used to transfer insect resistance genes into the cultivars with desirable agronomic backgrounds,
while recurrent selection is useful for gene pyramiding for the same or different
insect pests. Cytoplasmic male-sterility can be exploited for developing insect-resistant
hybrids, and resistance is needed in both the parents to produce insect-resistant hybrids.
Information on mechanisms and inheritance of resistance will be useful for marker-
assisted introgression of resistance genes into high yielding cultivars.
References
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