Project Summaries

04-524TX  Project Manager: D. C. Jones


David M. Stelly, Texas AgriLife Research

The goal of this project is to increase the genetic diversity among USA-adapted cottons. It is well known that the rates and ranges of genetic gain from selection and breeding depend on genetic diversity. Genetic diversity among US cottons is extremely low by every measure. In fact, it is low in the entire species (Gossypium hirsutum). In this project, we are diversifying US cotton by introducing 100,000s of alternative genes (alleles). 

We are using several complementary breeding strategies to transfer chromosomes, segments and genes, identify their trait-specific effects, as well as achieve recombination to identify and selectively retain beneficial genes. One method, "chromosome substitution" (CS), is leading to a powerful new platform of wide utility to many cotton researchers for cotton germplasm usage, genomic research and genetic improvement. It will establish a powerful foundation for long-term genetic improvement of cotton.

We are introgressing germplasm of 5 species.  G. barbadense (New World), G. tomentosum (Hawaii) and G. mustelinum (Brazil) of the "Primary Gene Pool",and G. longicalyx (Africa) and G. armourianum (Mexico). Deliverables from this project will enhance US cotton improvement. They include [1] diversified elite cotton germplasm, [2] new and improved tools, resources and methods for interspecific introgression and breeding, and [3] well-trained cotton geneticist-breeders. Equally important, if not more, is that maturation of this project entails community involvement in follow-through germplasm development, increases and evaluations, data resource development, and implementing marker-assisted analyses and selection. The US cotton research community is already beginning to benefit from a new research/breeding platform that includes new germplasm, data and genomic tools that facilitate and expedite its usage for US cotton improvement.

We conducted multiple modified backcross-inbred breeding programs in parallel, one for each chromosome-specific CS line for G. barbadense (CS-B), G. tomentosum (CS-T) and G. mustelinum (CS-M) series. Generations of backcrossing vary widely among the various chromosome-specific CS lines. Advanced lines (BC5F1) were inbred to recover disomic BC5S1 substitutions; disomics were identified by phenotype, cytogenetic type and molecular markers. Euploid CS-B, -T and -M lines (52) were increased as BC5Sn seed by open-pollination in a low-outcrossing environment.
For previously developed CS lines, we collaboratively tested agronomic performance, fiber traits, and other traits of CS lines, topcrosses and CS line intercrosses.  We collaboratively began testing 49 CS-B17RILs. We continued expanding collaborations with USDA-ARS-Mississippi State, USDA-SC, -TX-LBB, TX AgriLife, and prospectively others.

Available CS lines were intercrossed to produce F1 hybrids between homeologues, homologous and non-hom(e)ologous pairwise combinations within and across series (CS-B, -T and -M). We grew remant G. tomentosum and G. mustelinum BC1 introgression seed and harvested seed from seed-bearing plants.
These were grown and male-fertile plants were used for intermatings within each sub-population. After completing statistical analyses on 2011 fiber quality data, we selected about 400 IPS for progeny row testing, but later retained only about 100 rows, plowing under the others because they were in a field ill-suited for cotton growth. We conducted a small yield-trial (4 reps, RCBD) of previous selections.


Project Year: 2012

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