Chinese farmers face worsening problems with goat grass (Aegilops tauschii) – close to wheat – growing on their wheat fields.
Currently, mezosulfuron is the only herbicide used on the list, registered on wheat, which provides control of goat grass in China, but often damages wheat. Non-transgenic wheat varieties resistant to imidazolinone herbicides (IMI) can address these problems by allowing IMI to control goat grass. However, IMI herbicides persist in the soil and seriously damage sensitive crops planted months or even years later. Therefore, nontransgenic crops with tolerance to herbicides combined with low-risk herbicides are badly needed for millions of farmers cultivating many plants in the fight against weeds.
Recently, the research team headed by prof. GAO Caixia and LI Jiayang at the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences (IGDB, CAS), together with Associate Prof. JIANG Linjianem from China Agricultural University (CAU), generated several herbicide-tolerant wheat strains using the basic edition to facilitate weed control on wheat fields.
Researchers generated wheat germplasm carrying herbicide tolerance mutations that confer tolerance to sulfonylurea, imidazolinone and aryloxyphenoxypropionate herbicides by editing the acetyl lactate carboxylate (ALS) and acetylcenzyme A genes of Kenong wheat commercial99.
The mutations in the P174 ALS codon (TAALS-P174) give tolerance to nicosulfuron, a sulfonylurea herbicide with relatively low risk for later crops, indicating high application value in field production.
Mutations in both TaalS-P174 and TaALS-G631 positions gave tolerance to Imazapik, IMI herbicide, three times, and even five-fold relative to the recommended field. Researchers also obtained quisofoil-tolerant wheat by editing TaACCase-A1992.
In addition, they found that the basic edition of TaalS-P174 wheat with sufficient resistance to nicosulfuronic herbicide in the MS growth medium allows selection. When the TaALS-P174 editor was linked to the editors for other interesting targets, the co-edification occurred in plants resistant to nicosulfuron, and the selection for resistance in growth medium enriched the frequency of the conjugate targets by several times. Because TaALS-P174 is conserved in all plant species, similar co-edited selection systems can easily be established to facilitate base editing in other plant species.
The article entitled "Generating herbicide tolerance traits and a new selection marker in wheat using a basic edition" will be published online in Plants of Nature April 15, 2019
The work was supported by subsidies from the National Key Program for Research and Development of China, the National Foundation for Natural Sciences of China, the Chinese Academy of Sciences and Beijing Municipal Science and Technology.
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