Mapping of flumioxazin tolerance in a snap bean diversity panel leads to the discovery of a master genomic region controlling multiple stress resistance genes

Authors: SABALLOS, ANA - Oak Ridge Institute For Science And Education (ORISE); Brooks, Matthew; TRANEL, PAT - University Of Illinois; Williams, Martin

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/12/2024
Publication Date: 7/1/2024
Citation: Saballos, A.I., Brooks, M.D., Tranel, P.J., Williams II, M.M. 2024. Mapping of flumioxazin tolerance in a snap bean diversity panel leads to the discovery of a master genomic region controlling multiple stress resistance genes. Frontiers in Plant Science. 15:1404889. https://doi.org/10.3389/fpls.2024.1404889.
DOI: https://doi.org/10.3389/fpls.2024.1404889

Interpretive Summary: We found that snap bean's ability to survive an application of the herbicide flumioxazin is due to multiple physiological pathways that are controlled by a master element located in chromosome 2. The existence of a single element able to regulate the expression of a large number of genes involved in stress tolerance is of high interest for basic science and applied crop breeding. Conceivably, excessive reliance on flumioxazin or related herbicides for weed control could select for phenotypes of weed species that are enriched in tolerance mechanisms identified in this research.

Technical Abstract: The availability of effective weed management tools against waterhemp (Amaranthus tuberculatus) is crucial to maintain profitable production of snap bean (Phaseolus vulgaris L.). Preemergence herbicides enable the crop to gain a size advantage over the weed, but the few preemergence herbicides registered in snap bean have poor waterhemp control. Flumioxazin, a protoporphyrinogen oxidase (PPO)-inhibiting herbicide, controls waterhemp and other problematic weeds; however, crop tolerance to the herbicide is poorly known. To quantify snap bean tolerance to flumioxazin and investigate the underlying tolerance mechanism(s), a genome-wide association mapping study was conducted using field-collected data on a snap bean diversity panel. Response to a preemergence application of flumioxazin was measured using plant population density and shoot biomass variables. High levels of crop tolerance were found in several entries belonging to the Romano class, including Bush Romano 350, Roma II, and Romano Purpiat. Snap bean tolerance to flumioxazin is associated with a single genomic region. Seed size is partially responsible for the tolerance, thus the genetic factors conditioning flumioxazin tolerance are likely a combination of those driven indirectly by seed size/weight and those acting directly on the metabolism of the herbicide or ameliorating its damage. Biological pathways likely involved in flumioxazin tolerance include oxidoreductase processes. Upregulation of genes involved in those processes is possibly orchestrated by a transcription regulator located in the chromosome 2 region identified in the GWAS analysis. Alleles conditioning snap bean tolerance to flumioxazin identified in the diversity panel shed light on novel mechanisms of herbicide tolerance and could be used in crop improvement.