Phenotypic and molecular characterisation of novel Vicia faba germplasm with tolerance to acetohydroxyacid synthase‐inhibiting herbicides (AHAS) developed through mutagenesis techniques

Abstract

BACKGROUND Faba bean (Vicia faba L.) is an important crop in Australian farming systems, however, weed control is a major constraint due to a lack of in‐crop broadleaf herbicide options. To address this, we developed acetohydroxyacid synthase (AHAS) inhibitor herbicide tolerance in faba bean using mutagenesis techniques. Dose–response experiments, agronomic field evaluation and DNA sequencing of the AHAS gene were used to quantify and validate tolerance traits. RESULTS Four M2 faba bean single‐plant biotypes (IMI‐1, IMI‐2, IMI‐3 and IMI‐4) at a frequency of 3.63 × 10−6 were successfully recovered. Molecular characterisation of the AHAS gene identified two known target site mutations (resulting in protein substitutions Ala205Val and Ser653Asn) conferring tolerance. Phenotypic characterisation found that both mutations conferred high levels of tolerance to the imidazolinone herbicide imazapyr. However, although the Ala205Val substitution showed improved levels of cross‐tolerance to a range of sulfonylurea chemistries, the Ser653Asn substitution did not. In the field, IMI‐3 showed the highest level of agronomic tolerance across a range of imidazolinone herbicides. CONCLUSIONS Mutagenesis techniques were successful in the development of tolerance to AHAS inhibitor herbicides in faba bean, and could facilitate the first safe in‐crop broadleaf herbicide control option in Australian faba bean production. © 2019 Society of Chemical Industry

Evidence for the Application of Emerging Technologies to Accelerate Crop Improvement – A Collaborative Pipeline to Introgress Herbicide Tolerance Into Chickpea

“…In 2013, a sample of c. 100,000 seeds (M 0 ) of PBA HatTrick were treated at SARDI with ethyl methanesulfonate (EMS) following the method of Mao et al (2019) . All seed multiplication and herbicide selection trials were undertaken at a site near Paskeville, South Australia.…”

“…Plants were compared for their response to increasing rates of two AHAS-inhibitor herbicides imazapyr and chlorsulfuron, representing Group 2 families imidazolinone and sulfonylurea. Herbicide treatments were applied at the 4–5 node growth stage according to Mao et al (2019) . For each sample, above ground biomass was harvested 21 days after treatment (DAT), oven-dried at 60°C for 48 h, and dry weight was recorded.…”

“…For each sample, above ground biomass was harvested 21 days after treatment (DAT), oven-dried at 60°C for 48 h, and dry weight was recorded. Data were analyzed using non-linear log-logistic regression models with the DRC package 3.0–1 in R v3.2.2.27 ( R Core Team, 2020 ) as per Mao et al (2019) .…”

Conventional and Molecular Breeding Tools for Accelerating Genetic Gain in Faba Bean (Vicia Faba L.)

“…Bhatia et al (2001) has given a detailed description of 265 varieties developed through induced mutation on grain legumes including 13 in faba bean genotypes. A number of imazapyr resistance mutations through EMS were identified in South Australia (Mao et al, 2019) that resulted in the development of the first imidazolinone herbicide resistant variety, PBA Bendoc in Australia. Recently morphological diversity of faba bean mutant populations was explored (Nurmansyah et al, 2019(Nurmansyah et al, , 2020.…”

“…All elements are in place for straightforward foreground selection of low v-c genotypes, thereby bypassing the need for expensive, time-consuming and destructive biochemical analysis of seeds (Khazaei et al, 2019a;Tacke et al, 2021). The vc − marker and another marker for a herbicide (imidazolinone) tolerance (Mao et al, 2019) are being used routinely in faba bean breeding programs in Australia. Very recently, the biosynthetic pathway of v-c was uncovered (Björnsdotter et al, 2021).…”