Consequently, only seven breeding cycles in four years were required to develop new varieties exhibiting multiple resistance traits.
Multiple resistance traits in the commensal E. coli microbiota were apparently the rule, as they were detected in most study participants.
In contrast, growth efficiency-resistance tradeoffs may be a consequence of the direct physiological costs of bearing multiple resistance traits that limit population growth rates.
Since an agricultural landscape can be seen as a mosaic of crops with multiple cultivars carrying different resistance traits, both adaptation and gene flow processes are expected to shape the genetic structure of pathogen populations.
Inbreeding depression is known to affect multiple traits including lifespan and stress resistance traits in Drosophila [20] [22] and inbreeding per se can also result in changes in gene expression of hundreds of genes [13], [14], [23], [24].
By using a mapping approach it was possible to show that the complex Verticillium syndrome in A. thaliana is controlled by multiple genes which affect different disease and/or resistance traits separately.
In some scenarios, the net selective effect of multiple resistance alleles may be understood by considering how the trait effects of one allele can be influenced by the presence of another resistance allele.
The evolution of this multiple resistance may be constrained by the accumulation of fitness costs associated with each resistance trait, particularly where these costs are additive, or potentially even synergistic.
In Canada, where herbicide resistant varieties have been cultivated at large scale, volunteers as well as feral populations with multiple herbicide resistance occur, whose origin is attributed to pollen flow among cultivars with different resistance traits [ 5, 27].
Interestingly, in cases where multiple resistance alleles are present on the same genome, plasmid, or lineage of cells, their net trait effects and resultant selective effects in combination may deviate from what we would predict based on their independent effects.
We will use disease resistance traits to illustrate the extraction of useful germplasm from the 3,000 sequenced accessions and propose a breeding scheme to accumulate multiple favorable traits in a breeding-ready genetic background.
