Mitotic Disrupter Herbicides

Abstract

Approximately one-quarter of all herbicides that have been marketed affect mitosis as a primary mechanism of action. All of these herbicides appear to interact directly or indirectly with the microtubule. Dinitroaniline and phosphoric amide herbicides inhibit microtubule polymerization from free tubulin subunits. Because of the loss of spindle and kinetochore microtubules, chromosomes cannot move to the poles during mitosis, resulting in cells exhibiting an arrested prometaphase configuration. Nuclear membranes re-form around the chromosomal masses to form lobed nuclei. Cortical microtubules, which influence cell shape, are also absent, and, as a result, the cell expands isodiametrically. In root tips and other structures that are normally elongated, these herbicides induce a characteristic club-shaped swelling. Pronamide and MON 7200 induce similar effects, except that tufts of microtubules remain at the kinetochore region of the chromosomes. The carbamate herbicides barban, propham, and chlorpropham alter the organization of the spindle microtubules so that multiple spindles are formed. Chromosomes move to many poles and multiple nuclei result. Abnormal branched cell walls partly separate the nuclei. Terbutol induces “star anaphase” chromosome configurations in which the chromosomes are drawn into an area at the poles in a star-like aggregation. DCPA's most dramatic effect is on phragmoplast microtubule arrays. Multiple, branched, and curved phragmoplasts are found after herbicide treatment. These disrupters should prove to be useful tools in investigations of the proteins and structures required for a successful cell division.

The sprout inhibitors chlorpropham and 1,4-dimethylnaphthalene elicit different transcriptional profiles and do not suppress growth through a prolongation of the dormant state

“…Chlorpropham (isopropyl 3-chlorophenylcarbamate; CIPC) and 1,4-Dimethylnaphthalene (DMN) are compounds that inhibit sprouting in potato tubers following loss of endodormancy. CIPC is a synthetic compound that modifies spindle formation, inhibits mitosis, and prevents sprouting (Vaughn and Lehnen 1991). DMN is a natural product found in potato tissues that also inhibits sprout growth.…”

Occurrence of viable unreduced pollen in a Begonia collection

“…In plant breeding, the traditional chromosome duplication is performed through the use of harmful mitosis inhibitors like colchicine, oryzalin and trifluraline (Vaughn and Lehnen 1991;Hancock 1997). The major drawback of this technique is that it largely disables the recombination between chromosomes of different parents in allopolyploids (Lim et al 2000;Ramanna and Jacobsen 2003).…”

The influence of chlorsulfuron and metsulfuron methyl on root growth and on the ultrastructure of root tips of germinating maize seeds

“…Abnormal nuclear morphology has been observed in different plant cells treated with anti-microtubular herbicides (Vaughn and Lehnen, 1991). It cannot be excluded that chlorsulfuron and metsulfuron methyl, although not being typical anti-microtubular agents, would indirectly affect the cytoskeleton via inhibition of amino acid synthesis and thereby disturb the maintenance of the nuclear shape.…”