LAUSR

Interspecific introgression lines are important resources for plant breeders to access novel alleles from exotic germplasm. The Pee Dee breeding program developed several extralong staple “Sealand” germplasm lines that presumably contain sea island cotton (Gossypium barbadense L.) chromatin introgressed into upland cotton (Gossypium hirsutum L.). The objectives of this study were to identify the G. barbadense chromatins in the Sealand lines, 542 and 883, and evaluate their effects on fiber quality. A total of 31 putative G. barbadense chromatins were detected, including 12 segments on seven chromosomes that were unique to Sealand 542 and 10 segments on five chromosomes that were unique to Sealand 883, and the remaining nine segments were common to both the Sealand lines. Sealand 542 and 883 mapping populations were created to identified 28 quantitative trait locus (QTL) regions associated with fiber quality traits, including six for elongation, four for fineness, five for short fiber content, five for strength, three for length, and five for fiber uniformity. At least 13 QTLs were detected on the G. barbadense introgressed chromosomal segments. Favorable alleles for 17 QTLs were contributed by the Sealand lines, and the genetic effects of five loci were stably expressed across environment and generation. Stable expression of G. barbadense fiber quality alleles in the Sealand lines and the absence of these alleles in upland germplasm make these introgression lines a valuable resource for fiber quality improvement. In particular, markerassisted introgression of the qFL-Chr25 locus from Sealand 883 should result in improved fiber length, whereas that of qMIC-Chr24 from Sealand 542 should result in finer fiber. P. Kumar, Cotton Molecular Breeding Lab., Univ. of Georgia, Tifton, GA 31793, current address, USDA-ARS, Crop Improvement and Protection Research Unit, Salinas, CA 93905; R. Singh, E.L. Lubbers, and P.W. Chee, Cotton Molecular Breeding Lab., Univ. of Georgia, Tifton, GA 31793; X. Shen, Cotton Molecular Breeding Lab., Univ. of Georgia, Tifton, GA 31793, current address, Biotechnology Institute, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China; A.H. Paterson, Plant Genome Mapping Lab., Univ. of Georgia, Athens, GA 30606; B.T. Campbell, USDA-ARS Coastal Plains Soil, Water and Plant Research Center, 2611 W. Lucas St., Florence, SC 29501; D.C. Jones, Cotton Incorporated, 6399 Weston Parkway, Cary, NC 27513. Received 12 Dec. 2018. Accepted 12 Feb. 2019. *Corresponding author ([email protected]). Assigned to Associate Editor Linghe Zeng. Abbreviations: GRIN, Germplasm Resources Information Network; LOD, logarithm of odds; PCR, polymerase chain reaction; PV%, percentage phenotypic variation; QTL, quantitative trait locus; SSR, simple sequence repeat. Published in Crop Sci. 59:1073–1084 (2019). doi: 10.2135/cropsci2018.12.0745 © 2019 The Author(s). Re-use requires permission from the publisher. Published May 16, 2019