Induction, identification, and characterization of autoallo-dodecaploid barnyard grass (Echinochloa crus-galli L.) using in vitro colchicine treatment

Abstract

Polyploidization is a major trend in plant evolution that has many advantages over diploid. Barnyard grass (Echinochloa crusgalli L.) has many good characteristics, but has not been fully utilized until now. In this study, we report for the first time the in vitro induction of autoallo-dodecaploid E. crus-galli by colchicine treatment. Calli derived from young panicles were transferred to liquid medium containing different concentrations of colchicine (0.01, 0.05, or 0.1% w/v) and incubated for 24, 48, or 72 h. Treatment with 0.05% colchicine for 48 h was the most effective condition for producing polyploid plants, yielding 42.9% dodecaploids. The relative DNA content of the induced dodecaploids was twice that of wild-type hexaploids. The chromosome number of dodecaploids was 2n = 12x = 108, whereas that of hexaploids was 2n = 6x = 54. Compared with the hexaploids, the dodecaploids had larger individual stomata, but a lower stomatal density. There were significant differences between dodecaploid and hexaploid plants in terms of morphological variables, such as plant height, leaf length, panicle length, and grain size. Dodecaploid plants showed the obvious “gigas” effects of polyploid organs, as well as significantly reduced seed set. The nutritional concentrations of crude protein, crude fat, crude ash, and nitrogen-free extract in the dodecaploid were higher than those in the hexaploid, whereas the concentration of crude fiber in the dodecaploid was lower. Compared with the hexaploid, the concentrations of calcium, iron and some free amino acids in dodecaploid plants were significantly higher than in hexaploids. The dodecaploid E. crus-galli had been obtained successfully by treating calli with colchicine. And E. crus-galli has the potential to be developed as a new type of high quality forage crop for cultivation under stress conditions, especially the dodecaploid with its greater nutritional value.