Premium
Stability of S Alleles in a Doublecross Hybrid of Red Clover 1
Author(s) -
Taylor Norman L.
Publication year - 1982
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1982.0011183x002200060032x
Subject(s) - biology , allele , aphis , population , red clover , genetics , botany , gene , demography , aphid , sociology
The S‐allele system used for controlling crossing in doublecross hybrid red clover ( Trifolium pratense L.) is expected in theory to produce four heterozygous allelic types arbitrarily designated S 1 S 5 , S 1 S 7 , S 3 S 5 , and S 3 S 7 . This study was undertaken to ascertain if this theoretical segregation is achieved in a doublecross produced under field cages where crosses are made with honey bees ( Aphis mellifera L.). S‐alleles of doublecross hybrid plants were identified by presence or absence of seed produced from crosses to four homozygous I 1 parents, and from chain crosses. Among 77 plants examined, 16 had S 1 S 5 , 11 had S 1 S 7 , 14 had S 3 S 5 , 11 had S 3 S 7 , 12 had one unknown allele, and 10 had two unknown alleles. Three exceptional plants were found that appeared to be S 5 S 7 but set seed when intra‐crossed suggesting an unusual genetic control. No S 1 S 3 or S 1 S 7 plants other than the three plants described above, were found. About 68% of the population conformed to theoretical expectations. The remainder apparently resulted from generation of new S‐specificities, contamination, or both. Either possibility would have serious consequences for control of crossing by the S‐allele system.