1a. Objectives (from AD-416)
To improve the utility of G. barbadense chromosome substitution lines for G. hirsutum breeding. To develop and release to the public a random mated population(s) that has unique combinations of alleles from the two species. To develop a breeding scheme that facilitiates the recombination of alleles from G. barbadense and G. hirsutum.
1b. Approach (from AD-416)
Seventeen CS-B lines have been crossesd to five elite cultivars from different commercial breeding programs in the U.S. ('DP 90', 'SureGrow 747', 'PSC 355', ST474, and FM 966). The CS-B lines ae CS-B01, CS-B02, CS-B04, CS-B06, CS-B07, CS-B16, CS-B17, CS-B18, CS-B25, CS-B05sh, CS-B11sh, CS-B12sh, CS-B14sh, CS-B15sh, CS-0B22sh, CS-B22Lo, and CS-B26Lo. The designations sh and Lo indicate that only the short or the long arm of a chromosome from G. barbadense is in the CS-B line. We will begin the random mating with two or three F1 hybrids from each of these 17 CS-B lines with two or three of the five cultivars. We will use the bulk pollen methodology of Miravalle to accomplish random mating, thus we will have 51 familes many of which will be half-sibs. The F1 hybrids will have one of five elite cultivars as one parent and a particular CS-B line as the other parent. From the cultivar parents we expect to gain adaptability, yield, and other necessary properties. From the CS-B parent we expect to gain alleles from particular chromosomes or chromosome arms from G. barbadense. These chromosome or chromosome arms should contain many alleles for fiber quality because of the very high fiber quality of the G. barbadense parent.
3. Progress Report
Cycle 4 of the random mating was made in the winter nursery and seed returned. We decided not to make cycle 5, but to stop the random mating after cycle 4 to save on expense and to speed up the germplasm release. Our simulation data also showed that after 4 cycles there was not much improvement in making the 5th cycle. In the second quarter of 2011 we planted selfed seed of C0, C1, C2, C3, and parents in randomized experiments for yield and fiber data. We will send Cycle 4 seed to winter nursery for selfing so we will have selfed seed following each cycle. Cycle 4 S1 seed is planned for a release in 2012. We will also start with the Cycle 4S1 seed and do single seed descent until F5 to develop recombinant inbred lines (RIL) from the random mating population. These RIL will then be used in an association mapping study to determine the extent of introgression of favorable alleles from Gossypium barbadense into the random mated population. This population will be compared with the upland random mated population RMUPC5S1 that we developed and released. Progress has been monitored by frequent contacts by phone and e-mail as well as a meeting each year among all cooperators and Cotton Incorporated. Quarterly reports were provided to Cotton Incorporated.