Herbicide-resistant weeds result from rare genetic mutations that increase in frequency through selection by herbicides. The ability of scientists to make specific edits in weed genomes including the genes for herbicide resistance is becoming feasible. The value of such work is that studying changes in herbicide response due to specific gene edits would greatly further our understanding of potential solutions to the growing herbicide resistance problem. Gene editing processes could also one day be introduced into weed populations to facilitate control of herbicide-resistant weeds. To develop genetic biocontrol strategies for herbicide-resistant weeds weeds, laboratory studies need to be done using weed tissues that do not have the capacity to escape laboratory containment through the production of seed and pollen. Plants grown in tissue culture as undifferentiated cells do not have such capacity, yet still maintain most of the physiological processes that are targeted by herbicides. We previously developed waterhemp and Palmer amaranth cell suspension cultures, which are undifferentiated cells suspended in liquid media. The waterhemp cultures were used to obtain protoplasts (cells without cell walls), but transforming these protoplasts by introducing DNA carrying gene(s) of interest has been problematic. Stress induced by the removal of cell walls has been identified as a likely reason why waterhemp protoplast transformation has been difficult, and research is ongoing to address this problem. However, alternative transformation procedures should be explored. The current proposal looks to initiate research to develop an Agrobacterium-based transformation system using existing waterhemp and Palmer amaranth cell suspension cultures.

A) Establish Agrobacterium transformation of waterhemp suspension cell cultures.
B) Establish Agrobacterium transformation of Palmer amaranth cell suspension cultures.

1) Ability to perform waterhemp and Palmer amaranth genetic research in a laboratory where escape of seeds and pollen is not a concern.
2) Ability to develop and assess emerging genetic biocontrol methods for herbicide-resistant waterhemp and Palmer amaranth in North Dakota.

Herbicide-resistant weeds such as waterhemp and Palmer amaranth are decreasing the effectiveness of existing herbicides for soybean production. Alternative weed control strategies need to be explored, including the potential of emerging genetic biocontrol technologies. As this research progresses, it is important that: 1) problems experienced by soybean farmers are included among the priorities, 2) research is performed in a manner that does not risk negative impacts on agriculture through unintentional weed escapes. The proposed research is a necessary step toward these goals.