Introduction Effective weed management tools are crucial for maintaining the profitable production of snap bean (Phaseolus vulgaris L.). Preemergence herbicides help the crop to gain a size advantage over the weeds, but the few preemergence herbicides registered in snap bean have poor waterhemp (Amaranthus tuberculatus) control, a major pest in snap bean production. Waterhemp and other difficult-to-control weeds can be managed by flumioxazin, an herbicide that inhibits protoporphyrinogen oxidase (PPO). However, there is limited knowledge about crop tolerance to this herbicide. We aimed to quantify the degree of snap bean tolerance to flumioxazin and explore the underlying mechanisms. Methods We investigated the genetic basis of herbicide tolerance using genome-wide association mapping approach utilizing field-collected data from a snap bean diversity panel, combined with gene expression data of cultivars with contrasting response. The response to a preemergence application of flumioxazin was measured by assessing plant population density and shoot biomass variables. Results Snap bean tolerance to flumioxazin is associated with a single genomic location in chromosome 02. Tolerance is influenced by several factors, including those that are indirectly affected by seed size/weight and those that directly impact the herbicide's metabolism and protect the cell from reactive oxygen species-induced damage. Transcriptional profiling and co-expression network analysis identified biological pathways likely involved in flumioxazin tolerance, including oxidoreductase processes and programmed cell death. Transcriptional regulation of genes involved in those processes is possibly orchestrated by a transcription factor located in the region identified in the GWAS analysis. Several entries belonging to the Romano class, including Bush Romano 350, Roma II, and Romano Purpiat presented high levels of tolerance in this study. The alleles identified in the diversity panel that condition snap bean tolerance to flumioxazin shed light on a novel mechanism of herbicide tolerance and can be used in crop improvement.

Microorganisms associated with plant roots significantly impact the quality and quantity of plant defences. However, the bottom-up effects of soil microbes on the aboveground multitrophic interactions remain largely under studied. To address this gap, we investigated the chemicallymediated effects of nitrogen-fixing rhizobia on legume-herbivore-parasitoid multitrophic interactions. To address this, we initially examined the cascading effects of the rhizobia bean association on herbivore caterpillars, their parasitoids, and subsequently investigated how rhizobia influence on plant volatiles and extrafloral nectar. Our goal was to understand how these plantmediated effects can affect parasitoids. Lima bean plants (Phaseoulus lunatus) inoculated with rhizobia exhibited better growth, and the number of root nodules positively correlated with defensive cyanogenic compounds. Despite increase of these chemical defences, Spodoptera latifascia caterpillars preferred to feed and grew faster on rhizobia-inoculated plants. Moreover, the emission of plant volatiles after leaf damage showed distinct patterns between inoculation treatments, with inoculated plants producing more sesquiterpenes and benzyl nitrile than noninoculated plants. Despite these differences, Euplectrus platyhypenae parasitoid wasps were similarly attracted to rhizobia- or no rhizobia-treated plants. Yet, the oviposition and offspring development of E. platyhypenae was better on caterpillars fed with rhizobia-inoculated plants. We additionally show that rhizobia-inoculated common bean plants (Phaseolus vulgaris) produced more extrafloral nectar, with higher hydrocarbon concentration, than non-inoculated plants. Consequently, parasitoids performed better when fed with extrafloral nectar from rhizobiainoculated plants. While the overall effects of bean-rhizobia symbiosis on caterpillars were positive, rhizobia also indirectly benefited parasitoids through the caterpillar host, and directly through the improved production of high quality extrafloral nectar. This study underscores the importance of exploring diverse facets and chemical mechanisms that influence the dynamics between herbivores and predators. This knowledge is crucial for gaining a comprehensive understanding of the ecological implications of rhizobia symbiosis on these interactions.

Plant parasitic nematodes cause severe damage, reducing plant production. The ability of four various biocontrol agents was surveyed for effectiveness in inhibiting J 2 of Meloidogyne incognita in vitro . The study aims to explore the impact of different bio-agents ( Bacillus cereus 54-1, Streptomyces erythrogriesus sub sp. 2, Pleurotus ostreatus , and Spirulina platensis ) on the root-knot-nematode, M. incognita reproduction, and their influence on plant growth as well as physiological and biochemical parameters in Phaseolus vulgaris L. plants under greenhouse conditions. Effective inoculation of four bio-control agents on growth and physiobiochemical parameters of bean plants infected with root-knot-nematode was also investigated. After 48 hours of exposure to bioagents, mortality was caused by M. incognita J 2 s. Mortality ranged between 67.3 and 89%. Under experimental conditions, further validating the relative efficacy of different bioagents in control M. incognita on common bean in two successive seasons. All pageants were efficient in preventing nematode reproduction, but with varying efficacy. Oxamyl (Nematicide) was an extremely effective treatment for suppressing total nematode populations. Nevertheless, the second most effective treatment for reducing M. incognita in roots and soil was B. cereus . All treatments significantly enhanced growth as compared to the control. Treatments with four bioagents significantly reduced H 2 O 2 and malondialdehyde levels. While it significantly raised the activity of peroxidase, polyphenol-oxidase, and superoxide dismutase, in addition to raising the content of phenolics and flavonoids in the infected common bean. The tested bioagents were efficient in preventing nematode reproduction, but at various levels of efficacy. In addition, all treatments significantly enhanced common bean growth parameters and reduced the levels of both H 2 O 2 and MDA. While it raised the activity of POD, PPO, SOD, and contents of phenolics and flavonoids in the infected common bean. These results highlight the value of bioagents as a promising biocontrol technique to manage root-knot-nematodes in common beans.

Background: The interference caused by volunteer soybean plants from grains lost before or during harvest can cause economic losses to bean producers due to the competition they cause, especially for succeeding crops. Objective: Therefore, the objective of this work was to determine the competitive ability and economic damage level (EDL) of bean cultivars in the presence of different densities of soybean volunteer plants. Methods: The experiments were installed in completely randomized design, and replicated for two consecutive years, 2020/21 and 2021/22. Treatments consisted of the carioca bean cultivars BRS Tangar & aacute;, IAC 1850, and BRS Estilo and the black type IPR Uirapuru, IPR Urutau, and BRS Esteio, and 12 volunteer soybean densities established for each cultivar, ranging from 0 to a maximum of 66 plants m-2.-2 . Plant density, soil cover, leaf area, and shoot dry matter of volunteer soybean plants were determined 40 days after emergence. For bean, productivity, control cost, selling price, and control efficacy were determined. Results: Bean cultivars IPR Tangar & aacute;, BRS Estilo, IPR Uirapuru and BRS Esteio showed greater competitive ability in the presence of soybean. The highest EDL values ranged from 1.00 to 2.89 plants m-2 for BRS Estilo, IPR Uirapuru, IPR Urutau and BRS Esteio cultivars when competing with soybean. Conclusions: Bean cultivars have different competitive abilities, and EDL is directly influenced by these different genetic traits.