Identification and characterization of autoallododecaploid barnyard grass (Echinochloa crus-galli L.) induced by in vitro colchicine treatment

A protocol for in vitro induction of autoallododecaploid Echinochloa crus-galli with colchicine treatment was established. Colchicine concentration and exposure time had significant effects on the callus survival rate, shoot differentiation rate, and chromosome doubling rate. With the increase of colchicine concentration and the extension of treatment time, the callus survival rate and shoot differentiation rate both decreased. Treatment with 0.05% colchicine for 48 hr was the most effective condition for polyploidization, yielding 42.99% dodecaploids. The authenticity of the induced dodecaploid was confirmed by nuclear DNA content, chromosome number, and stomatal and morphological characteristics. Dodecaploid plants showed the obvious "giant" effects of polyploid organs, as well as significantly reduced seed set rate. The concentrations of calcium, iron, most free amino acids, and total free amino acids in dodecaploid plants were significantly higher than those in hexaploid plants. The results showed that the chromosome of allohexaploid E. crus-galli could be redoubled. The dodecaploid E. crus-galli could still grow normally and showed advantages associated with polyploidization, such as enlarged organs and increased nutrient concentrations. The study enriched the germplasm resources of barnyard grass and laid a foundation for the utilization and theoretical research of E. crus-galli in the future.