Genetic variants in progeny of regenerated maize plants

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Abstract
Tissue culture has been shown to be a method of generating genetic variation in regenerated plants and their progeny for several maize (Zea mays L.) genotypes. The objectives of this study were to (i) estimate the frequency and types of variants arising from maize tissue cultures, (ii) investigate the effect of culture age on the frequency of variants per regenerated plant, and (iii) estimate the frequency of sectoring among regenerated plants of an F3 from Oh43/A188 genetic background that had not been examined previously for genetic stability in culture. Organogenic callus cultures were initiated from immature F3 embryos for several Oh43ms isoline × A188 crosses. Plants were regenerated either 3 to 4 or 8 to 9 months after culture initiation. Progenies of 248 plants regenerated from 74 cultures were scored for kernel, seedling, and other sporophytic variants following one or two generations of self-pollination. The frequency of variants per regenerated plants increased from 0.5 after 3 to 4 months of culture to 1.3 after 8 to 9 months. A total of 44 variant phenotypes were observed. Defective kernels were the most frequent variant. Most variants were inherited as single-gene recessives. Segregation patterns suggested that the ear and tassel of several (40 of 80) self-pollinated, regenerated plants were genetically discordant. Key words: Zea mays L., tissue culture, somaclonal variation, chimera, qualitative variation.