Interaction of novel Dobzhansky-Muller type genes for the induction of hybrid lethality between Gossypium hirsutum and G-barbadense cv. Coastland R4-4

Hybrid lethality was identified in interspecific hybrids between two cotton species, Gossypium hirsutum and G. barbadense cv. Coastland R4-4 (R4-4). Genetic analysis indicated that the lethal symptom was controlled by two dominant complementary genes, one from G. hirsutum and another from R4-4. Microsatellite mapping identified the location of the causal gene in G. hirsutum as chromosome D8, while the R4-4 gene was placed on chromosome D11. Our data indicate that these genes conform to the Dobzhansky-Muller model, and are novel for the induction of hybrid lethality in Gossypium. Following the genetic nomenclature, we propose that the two novel Dobzhansky-Muller genes from G. hirsutum and from R4-4 be named Le (3) and Le (4) , respectively. Given what we know about their inheritance patterns, their genotypes should be Le (3) Le (3) le (4) le (4) in G. hirsutum, and le (3) le (3) Le (4) Le (4) in R4-4. Data from this study supported previous information in that expression of the lethal symptom might be affected by the dosage of causal alleles and the environment in which plants are growing.