Coexpression of I. variabilis-EPSPS* and WBceGO-B3S1 Genes Contributes to High Glyphosate Tolerance and Low Glyphosate Residues in Transgenic Rice

A Critical Review of Conventional and Modern Approaches to Develop Herbicide-Resistance in Rice

Together with rice, weeds strive for nutrients and space in farmland, resulting in reduced rice yield and quality. Planting herbicide-resistant rice varieties is one of the effective ways to control weeds. In recent years, a series of breakthroughs have been made to generate herbicide-resistant germplasm, especially the emergence of biotechnological tools such as gene editing, which provides an inherent advantage for the knock-out or knock-in of the desired genes. In order to develop herbicide-resistant rice germplasm resources, gene manipulation has been conducted to enhance the herbicide tolerance of rice varieties through the utilization of techniques such as physical and chemical mutagenesis, as well as genome editing. Based on the current research and persisting problems in rice paddy fields, research on the generation of herbicide-resistant rice still needs to explore genetic mechanisms, stacking multiple resistant genes in a single genotype, and transgene-free genome editing using the CRISPR system. Current rapidly developing gene editing technologies can be used to mutate herbicide target genes, enabling targeted genes to maintain their biological functions, and reducing the binding ability of target gene encoded proteins to corresponding herbicides, ultimately resulting in herbicide-resistant crops. In this review article, we have summarized the utilization of conventional and modern approaches to develop herbicide-resistant cultivars in rice as an effective strategy for weed control in paddy fields, and discussed the technology and research directions for creating herbicide-resistant rice in the future.

Herbicides may threaten advances in biological control of diseases and pests

Advances in agriculture include integrated methods of controlling pests, diseases, and weeds with biocontrollers, which are constantly increasing, along with herbicides. The objective is to present a systematic review of the main reports of herbicide effects on non-target organisms used in applied biological control and those naturally occurring in the ecosystems controlling pests. The categories were divided into predatory and parasitoid arthropods. Three hundred and fifty reports were analyzed, being 58.3% with parasitoids and 41.7% with predators. Lethal or sublethal effects of herbicides on reproduction, predation, genotoxicity, and abundance of biological control organisms have been reported. Two hundred and four reports of the impact of herbicides on parasitoids were analyzed. The largest number of reports was with parasitoids of the genus Trichogramma, with wide use in managing pests of the herbicide-tolerant transgenic plants. Most tests evaluating effects on parasitism, emergence, and mortality of natural enemies subjected to herbicides are with parasitoids of Lepidoptera eggs with a high diversity and use in managing these pests in different crops. Additive and synergistic effects of molecules increase the risks of herbicide mixtures. Herbicide use for weed management must integrate other control methods, as the chemical can impact natural enemies, reducing the biological control of pests.

Comparison of Glyphosate-Degradation Ability of Aldo-Keto Reductase (AKR4) Proteins in Maize, Soybean and Rice

Genes that participate in the degradation or isolation of glyphosate in plants are promising, for they endow crops with herbicide tolerance with a low glyphosate residue. Recently, the aldo-keto reductase (AKR4) gene in Echinochloa colona (EcAKR4) was identified as a naturally evolved glyphosate-metabolism enzyme. Here, we compared the glyphosate-degradation ability of theAKR4 proteins from maize, soybean and rice, which belong to a clade containing EcAKR4 in the phylogenetic tree, by incubation of glyphosate with AKR proteins both in vivo and in vitro. The results indicated that, except for OsALR1, the other proteins were characterized as glyphosate-metabolism enzymes, with ZmAKR4 ranked the highest activity, and OsAKR4-1 and OsAKR4-2 exhibiting the highest activity among the AKR4 family in rice. Moreover, OsAKR4-1 was confirmed to endow glyphosate-tolerance at the plant level. Our study provides information on the mechanism underlying the glyphosate-degradation ability of AKR proteins in crops, which enables the development of glyphosate-resistant crops with a low glyphosate residue, mediated by AKRs.