Chromosomal changes linked with the effect of high dose of aluminum on faba bean (Vicia faba L.) root tips

Abstract

In this work, we cytogenetically described the effects of different relatively high doses of aluminum (5, 15 and 25 mM AlCl₃) on mitotic activity and DNA integrity of faba bean (Misr 3 cultivar). Under Al stress, mitotic index (MI) decreased but total chromosomal abnormalities increased significantly compared to that of control. In addition, the detected chromosomal abnormalities in each mitotic phase increased significantly in comparison to that of control. All the used concentrations of Al enhanced micronuclei formation; no correlation could be detected between the size or number of micronuclei/cell and the applied conditions. Metaphase was the most sensitive stage to Al stress compared to the other stages of mitosis; C-metaphase was the common abnormalities and it increased strongly when the exposure time was more than 6 h. Under the influence of Al stress for 24 h, the appearance C-metaphase in high frequency decreased the frequency of appearance of other forms of abnormalities during metaphase or ana-telophase. The previous cytological events created alteration either at or between the primer binding sites which could be detected by RAPD and ISSR techniques. Application of ten RAPD primers resulted in amplification of 59 fragments including 20 monomorphic, seven unique and 32 polymorphic bands with polymorphism average of 60.09%. ISSR primers amplified 75 DNA fragments including 18 monomorphic, eight unique and 45 polymorphic bands with polymorphism average of 72.90%. These data indicated that faba bean cultivar suffered from harmful effect of Al on its genome when the duration of Al treatment was more than 6 hr. ISSR was better than RAPD to study genome stability of faba bean under abiotic stress agent.