Reveal perturbations in genetic networks and gene expression associated with
naturally-occurring variation in fiber phenotypes using the introgression
Here we combine the phenotypically selected, near-isogenic lines generated
under component 1 with the novel,
custom microarray developed under component 2.
The combination of QTL mapping and arraying is an especially powerful
approach to discovering genes underlying traits of interest. As demonstrated in
tomato, this strategy is particularly effective using NILs, which effectively
isolate and thereby permit the study of the effects of small chromosomal
segments on phenotypes and genetic networks. Recalling that we will tile the
genome using four different populations of NILs, representing two parallel
domestications and reciprocal interspecific NILs between advanced cultivars of G.
barbadense and G. hirsutum, lines will be phenotypically
evaluated as described above. To demonstrate the power of this combined
mapping/arraying approach, we will select 10-15 lines (representing 10-15
chromosomal segments) from each of the four populations for further study.
While it is not possible to describe the morphology of these 40-60 NILs a
priori, we will focus on those that show striking differences from the
recurrent parent in key fiber quality components (e.g., length, fineness),
giving preference to introgressed segments of minimal genomic length. We also
will endeavor to select reciprocally introgressant lines in at least two cases
for the Maxxa/Pima and Pima/Maxxa NILs, and two parallel chromosomal regions
for the wild vs. cultivated NILs in both species. The former will allow a novel
test of homoeology equivalence, and the latter will provide an exciting
evaluation of parallel domestication.