title: A New Synthetic Amphiploid (AADDAA) between Gossypium hirsutum and G. arboreum Lays the Foundation for Transferring Resistances to Verticillium and Drought.
abstract: Gossypium arboreum, a cultivated cotton species (2n = 26, AA) native to Asia, possesses invaluable characteristics unavailable in the tetraploid cultivated cotton gene pool, such as resistance to pests and diseases and tolerance to abiotic stresses. However, it is quite difficult to transfer favorable traits into Upland cotton through conventional methods due to the cross-incompatibility of G. hirsutum (2n = 52, AADD) and G. arboreum. Here, we improved an embryo rescue technique to overcome the cross-incompatibility between these two parents for transferring favorable genes from G. arboreum into G. hirsutum. Our results indicate that MSB2K supplemented with 0.5 mg l(-1) kinetin and 250 mg(-1) casein hydrolysate is an efficient initial medium for rescuing early (3 d after pollination) hybrid embryos. Eight putative hybrids were successfully obtained, which were further verified and characterized by cytology, molecular markers and morphological analysis. The putative hybrids were subsequently treated with different concentrations of colchicine solution to double their chromosomes. The results demonstrate that four putative hybrid plants were successfully chromosome-doubled by treatment with 0.1% colchicine for 24 h and become amphiploid, which were confirmed by cytological observation, self-fertilization and backcrossing. Preliminary assessments of resistance at seedling stage indicate that the synthetic amphiploid showed highly resistant to Verticillium and drought. The synthetic amphiploid between G. hirsutum × G. arboreum would lay the foundation for developing G. arboreum-introgressed lines with the uniform genetic background of G. hirsutum acc TM-1, which would greatly enhance and simplify the mining, isolation, characterization, cloning and use of G. arboreum-specific desirable genes in future cotton breeding programs.
authors.affiliation: State Key Laboratory of Crop Genetics & Germplasm Enhancement, MOE Hybrid Cotton R&D Engineering Research Center, Nanjing Agricultural University, Nanjing, People's Republic of China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Crop Genetics & Germplasm Enhancement, MOE Hybrid Cotton R&D Engineering Research Center, Nanjing Agricultural University, Nanjing, People's Republic of China.
authors.forename: Yingying
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Crop Genetics & Germplasm Enhancement, MOE Hybrid Cotton R&D Engineering Research Center, Nanjing Agricultural University, Nanjing, People's Republic of China.
authors.forename: Ting
authors.initials: T
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Crop Genetics & Germplasm Enhancement, MOE Hybrid Cotton R&D Engineering Research Center, Nanjing Agricultural University, Nanjing, People's Republic of China.
authors.forename: Jianwei
authors.initials: J
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Crop Genetics & Germplasm Enhancement, MOE Hybrid Cotton R&D Engineering Research Center, Nanjing Agricultural University, Nanjing, People's Republic of China.
authors.forename: Shouli
authors.initials: S
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Crop Genetics & Germplasm Enhancement, MOE Hybrid Cotton R&D Engineering Research Center, Nanjing Agricultural University, Nanjing, People's Republic of China.
authors.forename: Wajad
authors.initials: W
authors.lastname: Nazeer
authors.affiliation: State Key Laboratory of Crop Genetics & Germplasm Enhancement, MOE Hybrid Cotton R&D Engineering Research Center, Nanjing Agricultural University, Nanjing, People's Republic of China.
authors.forename: Tianzhen
authors.initials: T
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Crop Genetics & Germplasm Enhancement, MOE Hybrid Cotton R&D Engineering Research Center, Nanjing Agricultural University, Nanjing, People's Republic of China.
authors.forename: Baoliang
authors.initials: B
authors.lastname: Zhou
mesh_terms: D000220:Adaptation, Biological; D002678:Chimera / Q000235:genetics* / Q000254:growth & development; D060467:Disease Resistance; D055864:Droughts; D022761:Gene Transfer, Horizontal; D017343:Genes, Plant; D003368:Gossypium / Q000145:classification / Q000235:genetics* / Q000254:growth & development; D000069600:Plant Breeding / Q000379:methods*; D010935:Plant Diseases / Q000382:microbiology; D040641:Quantitative Trait Loci; D057945:Self-Fertilization; D057891:Tetraploidy; D020172:Verticillium / Q000502:physiology