Development and characterization of synthetic amphiploids of Oryza sativa and Oryza latifolia

Oryza sativa and Oryza latifolia belong to the AA and CCDD genomes of Oryza, respectively. In this study, amphiploids were obtained from the tube seedlings of O. sativa × O. latifolia F1 hybrids by treatment with colchicine, an agent for chromosome doubling. Subsequently, amphiploids were investigated using the methods of morphology, genomic in situ hybridization, and molecular markers. Amphiploids were characterized by a shorter plant height, larger diameter of stem, longer and wider leaves, darker leaf color, decreased spikelets per panicle and panicle length, and larger spikelets and anthers than the original F1 hybrid. Based on the mitotic metaphase chromosome number of the investigated root tips, the somatic chromosome number of the amphiploid is 2n = 72. Additionally, the amphiploid is an allohexaploid, and its genomic constitution is AACCDD by genomic in situ hybridization analysis. Finally, the amphiploids were identified to be true using 37 polymorphic markers at the DNA level.