Colchicine induced polyploidy from thallus segments of Kappaphycus alvarezii (Doty) for genetic improvement

Regeneration of polyploidy from young thallus segments of Kappaphycus alvarezii was optimized for genetic improvement. Kappaphycus thallus segment cultured on sterile sea water supplemented with various combina-tions of Indole acetic acid, Kinetin and Acardian Marine Plant Extract Powder revealed differential response on callus proliferation and development of new thallus. Presence of Acardian Marine Plant Extract Powder (3 mg/l) in combination with Indole acetic acid and Kinetin (0.01 mg/l each) had induced the longest emerging thallus. Exposure of thallus to colchicine at 0.01% with above combination was optimal to induce high frequency regeneration of polyploidy mostly from the meristematic cells. Anatomical study of colchicine induced poly-ploidy revealed larger cortical cells with irregular thickening of epidermal layer. Phase contrast and Scanning Electron Microscopic study revealed increase in cell size in cortical region with significantly larger number of spherical shaped carrageenan globules in colchicine induced polyploidy than normal thallus. Single cells isolated using enzymatic treatments from colchicine induced polyploidy, shown chromosome number with a ploidy status of 4n approximate to 40. Whereas in normal thallus, only half the number of chromosomes (2n approximate to 20) were observed. Poly-ploidy were successfully acclimatized gradually using raft method for further evaluation. This is the first report reveals the induction and regeneration of polyploidy in Kappaphycus. The possible application of this finding in genetic improvement of Kappaphycus is discussed.

Automated summary

This study optimized the regeneration of polyploidy from young thallus segments of Kappaphycus alvarezii for genetic improvement. The results showed differential response in callus proliferation and development of new thallus when Kappaphycus thallus segments were cultured on sterile sea water supplemented with different combinations of Indole acetic acid, Kinetin, and Acardian Marine Plant Extract Powder. The combination of Acardian Marine Plant Extract Powder, Indole acetic acid, and Kinetin, along with exposure to colchicine, induced the highest frequency of polyploidy regeneration from meristematic cells. Anatomical and microscopic studies provided further insights into the characteristics of colchicine-induced polyploidy.