Maize somatic chromosome preparation: pretreatments and genotypes for obtention of high index of metaphase accumulation

The present paper reports the results of experiments aiming to optimize procedures for maize somatic chromosome preparation, by selecting maize genotypes yielding high mitotic index in root tips, and evaluating metaphase and prometaphase accumulation by 8-hydroxiquinoline and a combination of this mitotic fuse inhibitor with cycloheximide, a protein synthesis inhibitor. Two tropical inbred lines and their hybrid were used. The values of mitotic index ranged from 6.44 to 7.80 % in the lines and 9.24 % in the hybrid, a value higher than references in the literature. The combination of 8-hydroxiquinoline at 300 ppm and cycloheximide at 12.5 ppm for 2.5 hours was effective for the three genotypes investigated, resulting in a high index of metaphase and prometaphase cells per preparation showing chromosomes suitable for identification of cytological markers, in the hybrid genotype. The hybrid selected and the treatments employed represent interesting parameters for maize cytogenetic research.