Environmental and Genetical Effect on the Chromosomal Variation in Callus of Nicotiana species

Abstract

Effect of four types of media containing or not containing growth regulator on the chromosome numbers was studied by using haploid calluses induced by means of anther culture of Nicotialea tabacum (cv. Wisconsin 38). The occurrence of polyploid cells in the callus tissues was promoted by the media containing IAA alone or IAA and kinetin in combination. In addition, various kinds of aneuploid cells were observed, especially in the callus tissues cultured on the medium containing both IAA and kinetin. On the media containing' no growth regulator or kinetin alone, however, the haploidy of the callus tissues were m.aintained with the exception of a few aneuploid cells. Therefore, it was concluded that the chromosomal stability or instability in the callus tissues is greatly affected by the constituents of growth regulators in the medium. N.tabacule4. N.sylvestris and F₁ of their reciprocal crosses were compared with the attention on chromosomal stability of callus tissues. The callus tissues of N.tabacum showed a considerable stabilization of the original chromosome number, while a high frequency of the multiplicatian of chromosome numbers was fcund in the calluses of N.sylvestris. Furthermore, the calluses of N.tabacumXN.sylvestris showed considerable chromosomal stability, while a high frequency of chromosome multiplication was observed in the calluses of N.sylvestrisXN.tabacum. Therefore, it was suggested that the callus culture which is cytogenetically stable state depends upon the plant species and that the chromosomal stability or instability in the callus tissues may bp controlled by a factor or factors in the cytoplasm of the callus cells.