Herbicide-resistant weeds pose significant challenges to sustainable weed management, with both short- and long-term implications. These include limited herbicide rotation options, threats to soil conservation gains due to a potential shift back to intensive tillage, and diminished effectiveness of existing weed control programs.

The evolution of herbicide resistance in weeds arises through two primary mechanisms:

1. Alterations at the herbicide target site and
2. Reduced herbicide availability or activity at the target site due to enhanced metabolic detoxification or decreased uptake/translocation of herbicides.

Research employing advanced physiological, molecular, and genomics approaches has unveiled fascinating and complex mechanisms underlying herbicide resistance. Notably, metabolism-based resistance to multiple herbicides within a single Palmer amaranth (Amaranthus palmeri) population was documented (Shyam et al., 2021; Nakka et al., 2017).

A groundbreaking discovery revealed the role of extrachromosomal circular DNA (eccDNA) in conferring glyphosate resistance, representing a novel and adaptive genomic mechanism (Koo et al., 2018). Additionally, single nucleotide polymorphisms (SNPs) associated with resistance to photosystem II (PSII) and acetolactate synthase (ALS)-inhibiting herbicides have been identified (Nakka et al., 2017; Adari et al., 2024).

Innovative RNA interference (RNAi)-based strategies for managing herbicide-resistant weed populationsRANi in weed science have also been explored, offering a promising alternative to conventional control methods (Kumam et al., 2023; Francis et al., 2024).

Understanding the molecular and genetic mechanisms underlying herbicide resistance is crucial for assessing the prevalence, frequency, and spread of resistant alleles in weed populations. This knowledge will ultimately inform the development of more effective and sustainable weed management strategies.

Physiology of herbicide resistance

Genomics of herbicide resistance

Weed molecular cytogenetics

RANi in weed science

Temperature stress plays a critical role in influencing herbicide efficacy, ultimately impacting the success of weed management programs. Variations in temperature can affect herbicide absorption, translocation, metabolism, and overall performance, leading to inconsistent weed control outcomes.

Our research findings indicate that the efficacy of several commonly used herbicides—such as lactofen, glyphosate, dicamba, and 2,4-D—can be significantly enhanced when applied under cooler temperature conditions. This improvement in control was found in problematic weed species like kochia (Bassia scoparia), lambsquarters (Chenopodium album), Palmer amaranth, and common waterhemp (Amaranthus tuberculatus) (Shyam et al., 2019; Ou et al., 2016; Rudell et al., 2023).

In addition, our research extends to understanding the effects of temperature stress on herbicide efficacy in crop species.

This work is crucial for balancing effective weed control with maintaining crop safety and productivity. Furthermore, physiological, biochemical, and molecular mechanisms underlying the differential efficacy of herbicides under varying temperature conditions also investigated.

The outcomes of this research will provide valuable insights into optimizing herbicide application timing and conditions, ultimately improving weed control efficiency and minimizing the risk of herbicide resistance evolution. This knowledge will guide more effective, climate-resilient weed management strategies.

The program’s research also focuses on the identification of sources of tolerance to herbicides in crop species including rice. Developing herbicide-tolerant crops is a crucial advancement in modern agriculture, offering multiple benefits such as more effective weed control options, the ability to use diverse herbicide modes of action, and the promotion of conservation practices like reduced or no-till farming, which helps preserve soil health and prevent erosion.

Previous studies have successfully identified and characterized herbicide tolerance in several crop species, including sorghum (Sorghum bicolor), canola (Brassica napus), and wheat (Triticum aestivum) (Pandian et al., 2021, 2022; Sudhakar et al., 2023; Dillon et al., 2016). These discoveries provide a foundation for developing commercial herbicide-tolerant cultivars and expanding integrated weed management strategies.

Our research not only focuses on identifying tolerant germplasm but also on understanding the underlying physiological, biochemical, and molecular mechanisms that confer herbicide tolerance.

Identifying novel sources of herbicide tolerance is critical for developing herbicide-tolerant crop technologies, which enable the adoption of diverse herbicide programs and reduce the risk of herbicide-resistant weed evolution.