The aim of this study was to determine if compounds involved in auxin biosynthesis, transport and signalling are able to synergise with 2,4-D and increase its ability to control 2,4-D-resistant R. raphanistrum populations.
Overexpression of the multiple herbicide-metabolizing genes could contribute to HPPD-inhibiting herbicide resistance in this wild radish population.
We report here the first case of field resistance to HPPD-inhibiting herbicides in R. raphanistrum (wild radish), caused by 12 years of continuous reliance on that mode of action.
This paper demonstrates that an early flowering time adaptation does not come at a growth cost when in competition with wheat. Flowering time however did result in an increasing number of flowers being located below the harvest cutting height. As the early flowering wild radish does not come at a competitive cost, it needs to be managed through diversity in both management tactic and timing.
Resistance to the synthetic auxin 2,4-dichlorophenoxyacetic acid (2,4-D) in wild radish (Raphanus raphanistrum) appears to be due to a complex, multifaceted mechanism possibly involving enhanced constitutive plant defence and alterations in auxin signalling. Based on a previous gene expression analysis highlighting the plasma membrane as being important for 2,4-D resistance, this study aimed to identify the components of the leaf plasma membrane proteome that contribute to resistance. Key results included: two receptor-like kinases of unknown function (L-type lectin domain-containing receptor kinase IV.1-like and At1g51820-like) and the ATP-binding cassette transporter ABCB19, an auxin efflux transporter, were identified as being associated with auxinic herbicide resistance.
Herbicides that inhibit HPPD have become very important. In North America, corn-selective HPPD herbicides have long been used and cases of HPPD herbicide-resistant weeds reported.
The paper “Non-target site resistance to PDS-inhibiting herbicides in a wild radish Raphanus raphanistrum population” is the work of AHRI PhD student Huan Lu.
This paper identifies multiple mechanisms: as well as psbA gene mutation there is a non-target site resistance mechanism of enhanced metabolism. Of course, we expect multiple mechanisms of herbicide resistance as evident here in both target site psbA gene mutation and non-target site enhanced metabolism resistance.
Wild radish (Raphanus raphanistrum) is a globally important weed of crops. Two atrazine-resistant wild radish populations (R1 and R2), collected from the Western Australia grain belt, were investigated for resistance to photosystem II (PSII) herbicides.
An overall finding of this study of auxinic herbicide resistance, at least in Raphanus R populations, is that conclusions on mechanisms cannot be made from studying just a few R populations. There are very clear differences between and within resistant populations. This research is ongoing in an attempt to reveal the important mechanisms that can endow resistance to 2,4-D and dicamba in plants.