Bensulfuron-Methyl, Terbutylazine, and 2,4-D Butylate Disturb Plant Growth and Resistance by Deteriorating Rhizosphere Environment and Plant Secondary Metabolism in Wheat Seedlings

Abstract

Frequent and improper use of herbicides disrupts a plant's metabolism, causing oxidative stress that degrades crop quality. However, few studies have examined the inhibitory effects of herbicides on plant growth and defense mechanisms in terms of their impact on soil quality and crop rhizosphere. Therefore, the current study investigated the detrimental impacts of six typical and multilevel herbicides on the microbial community and signal molecules in the soil as well as on the levels of hormones and secondary metabolites in wheat seedlings. Interestingly, bensulfuron-methyl, terbutylazine (TBA), and 2,4-D butylate significantly induced oxidative damage while reducing the number of phytohormones (salicylic acid and jasmonic acid) and secondary metabolites (tricin, quercetin, and caffeic acid) in the roots and leaves compared with the controls, isoproturon, fenoxaprop-p-ethyl, and pretilachlor. At twice the recommended levels (2×), they also decreased the microbial α diversity and, in particular, the abundance of Gammaproteobacteria, Alphaproteobacteria, Actinobacteria, Bacteroidia, Verrucomicrobia, Bacilli, Acidimicrobiia, Deltaproteobacteria, and Gemmatimonadetes by disrupting the level of enzymes (e.g., urease and sucrase) and metabolites (indole-3-acetic acid, salicylic acid, apigenin, 4-hydroxybenzoic acid, DIMBOA, and melatonin) in the rhizosphere soil. Overall, significant exposure to herbicides may inhibit wheat growth by disturbing the microbial composition in the rhizosphere soil and the distribution of secondary metabolites in wheat seedlings.

Novel Finding on How Melatonin and Nanoselenium Alleviate 2,4-D Butylate Stress in Wheat Plants

“…Based on our previous research, a method for detecting DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one) and MT has been established. 4 Analysis of Flavonoids and Phenolic Acid Compounds. Leaves, roots, and rhizosphere soil samples (100 mg) were extracted using 1 mL of water (60% ethanol).…”

“…The QuECHhERS method was used to analyze the 2,4-D butylate herbicide residue. 4 A 10 mL portion of acetonitrile in a 50 mL centrifuge tube extracted 2.0 ± 0.1 g of soil and wheat tissues (leaves and roots). Before adding 3 g of MgSO 4 and 1 g of NaCl, the compounds were vigorously agitated for 5 min.…”

“…The high-throughput sequencing technology was used to analyze soil microorganisms with different treatments (Baimaike Biological Company, Beijing, China). 4 Using a PowerSoil DNA Isolation Kit (MoBio Laboratories, CA), we isolated bacterial DNA from fresh soil (0.5 g) following the specification provided by the manufacturer. Before the V3−V4 section of the bacterial 16S rRNA gene was generated using PCR (primer combination 338F/806R), the DNA was first analyzed on Agarose plates at a concentration of 1% to determine its level of purity and quality.…”

“…In recent years, extensive research has been conducted on assessing the deleterious effects of pesticide application on crops. 4 Phenoxyacetic herbicides, as the most representative plant growth regulators, were produced in large quantities and extensively used globally due to their strong polarity and good solubility. 5 Low concentrations of 2,4-butyl ester can prevent weeds' average growth and maturation (<0.01, www.chemicalbook.…”

“…The excessive accumulation of pesticide residues inhibits plant growth and diminishes crop quality. In recent years, extensive research has been conducted on assessing the deleterious effects of pesticide application on crops . Phenoxyacetic herbicides, as the most representative plant growth regulators, were produced in large quantities and extensively used globally due to their strong polarity and good solubility .…”