In vitro induction and assessment of tetraploid plants from shoot cultures of diploid Niger (Guizotia abyssinica (L.f.) Cass.): a multipurpose oilseed crop

Abstract

Agronomic traits improvement in crop plant can be accomplished by induction of polyploidy. Niger (Guizotia abyssinica (L.f.) Cass.) is one of the important edible oil yielding diploid crop (2n = 30). In the present study, the tetraploidization in Niger plants was achieved by treating apical portion of in vitro raised shoots with colchicine and their con rmation by chromosome counting and ow cytometry. The in vitro shoots were raised from leaf explants on MS medium supplemented with 1.0 mg/l BAP (6benzylaminopurine). The survival and nature of growth of treated shoots was variable with colchicine concentration (0.0, 0.005, 0.01, 0.02, 0.03, and 0.04%) and exposure time (4, 8, 12, and 16 h). The maximum tetraploid induction ratio was recorded with 0.02% colchicine treatment for 8 h which yielded 38.4% tetraploids. The chromosome number in root cells of tetraploid plantlets was 2n=4x=60 and the DNA content in leaf cells was 10.34 pg which was double to the diploid plant (4.70 pg) cells. In addition, there was signi cant difference exist in leaf characteristics of diploid and tetraploid plantlets. Compared to diploid plantlets, the tetraploid plantlets showed larger leaves, larger stomatal size, low stomatal index, larger capitula, larger seeds, and a greater number of seeds per capitula. The oil content in seeds was higher and associated with altered fatty acid pro le. The results demonstrated that the tetraploid plantlets obtained in this study exhibited some superior agronomical traits (as mentioned above) compared to diploid. The developed protocol and produced tetraploid plantlets will open the new door in improvement of edible oil yielding crop Guizotia abyssinica (L.f.) Cass.