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:
We crossed 18 chromosome substitution from barbadense (CS-B) lines with FM966, SG747, and PSC 355. The CS-B lines were CS-B 01, 02, 04, 06, 07, 10, 16, 17, 18, 25, 5sh, 11sh, 12sh, 14sh, 15sh, 22sh, 22Lo, and 26Lo. F1 of these crosses were planted in Mexico in the winter nursery (2008-09) and the F1 plants were randomly intercrossed using bulk pollen. This was Cycle 0. We made the C1 generation of random mating in the summer of 2009 and sent these to the winter nursery in the fall of 2009 and made the C2 generation. C2 seed were returned in the first quarter and planted in the second quarter of 2010. We made the C3 generation of random mating in the third quarter of 2010 in Mississippi. We also grew a replicated experiment with the 18 CS-B parents, the 3 cultivars, and the 18 random mated (RM) C0F2 and 18 RMC1F2 lines in 2010. Yield and fiber data are currently being analyzed. We are keeping the half-sib families of the 18 CS-B lines individually as we make the RM crosses. Cycle 3 of the random mating was made in the third quarter of 2010. Bolls were harvested and seed of C3 were sent to winter nursery in Mexico for Cycle 4 of the random mating. We also sent seed C3 and parental seed to winter nursery to produce C3 F2 and parental seed for testing in the summer of 2011. We made the C5 generation of random mating in 2011. Cycle 4 of the random mating was made in the winter nursery and seed returned. 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 the winter nursery for selfing. Cycle 4 S1 seed was released in 2012. We will also start with the Cycle 4 S1 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.