Heterologous expression of Aspen PTM3, a MADS box gene in cotton

The PTM3 gene of Aspen was ectopically expressed in cotton to explore the opportunity to introduce desirable agronomic traits with the potential to improve yield and modify the duration of the parent cotton variety. Sixty-seven transgenic cotton lines expressing Aspen PTM3 (MADS box) gene were developed. The transgenic cotton lines expressing PTM3 gene showed earliness of 4-15 days variations in flowering and maturity. The transgenic lines were confirmed by kanamycin leaf paint assay, GUS assay and PCR. Among 67 transgenic lines, the event-10 showed profuse branching, event-24 showed abnormal growth and the remaining events exhibited single erect phenotype. In addition, the event-24 produced no flower and this might be due to the positional effect of PTM3 gene integration. Southern blot analysis performed for event-10, 24 and 48 showed distinct single copy integrations of PTM3 gene cassette. GUS assay performed using various plant parts of event-10 showed constitutive expression of the transgene. In view of cotton breeding, among all the events, the event-10 was found to be phenotypically significant with earliness of 12 days in flowering and 15 days in maturity and yield enhancement of 27%. In addition, the event-10 showed no square dropping and allowed the plants to bear more number of bolls. Based on these results, event-10 was chosen to carry out the inheritance study of expressed characters in the progeny.