Production of an auxinic herbicide-resistant microspore-derived doubled haploid wild mustard (Sinapis arvensis L.) plant

The genetic basis for auxinic herbicide resistance of a wild mustard biotype is unknown, although the physiological basis of its resistance is well characterized. Since the auxinic herbicide-resistant (R) biotype and normally susceptible (S) wild mustard plants are genetically diverse, development of completely homozygous R and S lines is a prerequisite for isolation and subsequent characterization of the resistance gene. Completely homozygous lines can be produced using either in vitro microspore culture or by conventional breeding methods (i.e., several generations of selfing); the former being a less time consuming method. With this in mind, microspore culture was used to produce homozygous wild mustard plants. However, despite altering many variables, only a few cotyledonary stage embryos and haploid plantlets could be produced. Upon transfer to soil only one doubled haploid plant established. This plant was self-sterile, cross compatible and resistant to auxinic herbicides. This is the first report describing production of a microspore-derived doubled haploid of wild mustard. However, because only one R doubled haploid plant could be produced, conventional breeding methods (i.e., repeated selfing) will be required for production of both R and S wild mustard plants that are completely homozygous.