Effect of Oryzalin on the Gravitropic Response and Ethylene Production in Maize Roots

Abstract

Oryzalin is a dinitroaniline herbicide, which disrupts the arrangement of microtubules. Microtubules and microfilaments are cytoskeletal components that are thought to play a role in the sedimentation of statoliths and the formation of cell walls. Statoliths regulate the perception of gravity by columella cells in the root tip. To determine the effect of oryzalin on the gravitropic response, ethylene production in primary roots of maize was investigated. Treatment with 10 -4 M oryzalin to the root tip inhibited the growth and gravitropic response of the roots. However, the treatment had no effect on the elongation zone of the roots. An application of 10 -4 M oryzalin for 15 hr to the root tip caused root tip swelling. The application of 1-aminocycopropane-1-carboxylic acid (ACC), a precursor of ethylene, to the root tip also inhibited the gravitropic response. To understand the role of oryzalin in the regulation of the growth and gravitropic response of roots, ethylene production in the primary roots of maize was measured following treatment with oryzalin. Oryzalin stimulated ethylene production via the activation of ACC oxidase (ACO) and ACC synthase (ACS), and it increased the expression of ACO and ACS genes. Indole-3-acetic acid (IAA) played a key role in the asymmetric elongation rates observed during gravitropism. The results suggest that oryzalin alters the gravitropic response of maize roots through modification of the arrangement of microtubules. This might reduce the distribution of IAA in the upper and lower sides of the elongation zone and increase ethylene production, thereby inhibiting growth and gravitropic responses.

Morphological and Anatomical Comparison between Tetraploid Stevia rebaudiana (Bertoni) Bertoni and its Parental Diploid

“…The induction of polyploidy using colchicine in various concentrations also decreased plant survival and the growth of axillary buds and shoots of in vitro Trachyspermum ammi (Noori et al 2017). Colchicine also inhibited the growth of Arabidopsis roots (Kim et al 2018).…”

Oryzalin delays germination and induces putative polyploidy plants in local North Sumatra garlic (Allium sativum L.)

“…At high concentrations, oryzalin inhibits cell division at the metaphase stage causing no increase in cell number, eventually inhibiting the development of roots and shoots, and embryos failing to develop into plants [9]. Oryzalin also inhibited maize root formation when it was exposure in 10 -4 M oryzalin [10]. In another study it was reported that oryzalin also inhibited shoot growth of tomato seeds of Tymoti and Permata varieties.…”