A comparison of APM-induced micronucleation and influence of some factors in various genotypes of potato and Nicotiana

Abstract

The results of a comparative study on the induction of micronuclei by the spindle toxin amiprophos-methyl (APM) in nine cell lines of potato and one of Nicotiana plumbaginifolia transformed by single and binary vectors of Agrobacterium are reported. These cell lines contained various T-DNA introduced genetic markers (hairy root phenotype, hormone autotrophy (HA), opine production, kanamycin resistance (KR), β-glucuronidase (GUS) activity), to be used for selection and gene localization. Cytological observations revealed differences between potato and N. plumbaginifolia with respect to the APM-induced micronucleation process and detection of micronucleated cells. The frequency of micronucleation differed among the various cell lines. The percentage of micronucleated cells was significantly increased by alteration of subculture period at the time of APM treatment. Also seedling root meristems showed high frequencies of metaphases and micronucleated cells after APM treatment, thus revealing the efficiency of APM for treatment of tissue cells, especially to obtain a high metaphase index for karyotype analysis of materials which have low mitotic index as well as to induce micronuclei directly in root meristems of hairy root clones. Analysis of the effect of two other chemicals (cytochalasin-B and hydroxy urea (HU)) showed that addition of cytochalasin-B as a sequential treatment to APM resulted in an enhancement of micronucleation in both species, whereas pretreatment with HU gave no increase in the frequencies of metaphases or micronucleated cells in potato. The factors influencing micronucleation of cells are discussed.