Evaluation of genotoxic and cytologic effects of environmental stress in wheat species with different ploidy levels

Abstract

Drought and salinity induce biochemical, physiological, morphological, and genetic responses in plants. To understand the damage to different wheat species caused by these stresses, we investigated root-shoot growth, cell division, chromosomal aberrations, and nucleolus organizer regions (AgNORs) in root tip cells. Inhibition of root and shoot growth were observed in diploid, tetraploid, and hexaploid wheat genotypes after salt and drought stresses. Both stresses had adverse effects on dividing cells in root tips of all wheat species and caused a decrease in mitotic index values. Salt and drought lead to the induction of chromosome aberrations and repression of interphase AgNOR parameters. Both treatments produced different mitotic abnormalities including chromosomal stickiness, c-mitosis, and micronuclei formation, which indicated their action on the mitotic spindle. Reduction in AgNOR parameters showed that salt and drought may decrease the level of ribosomal biogenesis and reduce the length of the cell cycle. Because of the toxicity of Na ions, salinity inhibited all parameters at a higher degree than drought in all Triticum species. Cytotoxic effects of salinity and drought were mainly observed in meristematic cells in all wheat species. This comprehensive analysis may provide valuable information for understanding the effects of salt and drought stresses on cytogenetics of wheat species.