Avoiding prolonged exposure to which PGR reduces somaclonal variation?
Among auxins, 2,4-dichlorophenoxyacetic acid stands out for strong callus inducing activity but also high genotoxicity. At 1 to 3 mg per liter it stimulates rapid cell division through auxin response factors ARF activation, yet its stable structure persists intracellularly, generating reactive intermediates interfering with mitotic spindle assembly and DNA repair. Long-term exposure triggers hypermethylation of cytosine in CCGG sites, reactivation of dormant transposable elements like Tos17, and increased incidence of aneuploidy and polyploidy observed in barley and rice cultures. Habituação a
Ref: Evans Amer J Bot 1984 2,4-D genotoxic; Phillips Theor Appl Genet 1994; NCBI NBK153356 auxin toxicity; PubMed 24254045 epigenetic instability; Taylor & Francis tissue culture variation.
