Segregation in New Allopolyploids of Gossypium. Iv. Segregation in New World × Asiatic and New World × Wild American Hexaploids

P hillips , L yle L. (North Carolina State Coll., Raleigh.) Segregation in new allopolyploids of Gossypium. IV. Segregation in New World × Asiatic and New World × wild American hexaploids. Amer. Jour. Bot. 49(1): 51–57. 1962.—The New World tetraploid cottons, G. hirsutum and G. barbadense , are natural amphidiploids (genome formula, 2 [AD]) combining species of the cultivated Asiatic (2A) and wild American (2D) groups of diploid cottons. Genetic segregation for marker alleles in New World × Asiatic and New World × wild American synthetic hexaploids have been determined. Average segregation for several loci in New World × Asiatic hexaploids is close to the autoploid 5:1 ratio, ranging from 5.1 to 6.8:1. Average segregation for 3 loci ( L, Rd , and R 1 ) common to a series of New World × wild American hexaploids is: New World × G. raimondii , 9.3:1;–× G. harknessii , 16.4:1;–× G. armourianum , 17.4:1;–× G. aridum , 20.3:1;–× G. lobatum , 21.4:1–× G. thurberi , 32.9:1;–× G. gossypioides , 66.5:1. These data are discussed, and the method by which they were derived is compared with other cytogenetical means of discerning phylelic interrelationships among Gossypium species.