Tolerance to Imidazolinone Herbicides in Wheat

Abstract

An imidazolinone-tolerant wheat (Triticum aestivum L. em Thell) mutant in the winter wheat cultivar Fidel has been identified and characterized. The mutant was isolated from a population derived through seed mutagenesis of the variety with an aqueous solution containing sodium azide. Imidazolinone-tolerant wheat seedlings were selected from the M2 generation of the population in the presence of imazethapyr herbicide and identified as herbicideinsensitive individuals. The trait is inherited as a single semidominant gene and confers high levels of tolerance to imazethapyr. Acetohydroxyacid synthase activity in extracts from imidazolinonetolerant plants was less inhibited by imazethapyr than the enzyme from the wild type. The herbicide-tolerant plants have a completely normal phenotype and display no negative effects on growth and yield in either the absence or presence of imazethapyr.find imidazolinone-tolerant wheat (Triticum aestivum L. em Thell) through seed mutagenesis and selection with an M2 seedling screen. MATERIALS AND METHODS Seed MutagenesisFive thousand seeds of the French winter wheat (Triticum aestivum L. em Thell cv Fidel) were mutagenized by the procedure of Kueh and Bright (9). Wheat seeds were soaked in water for 18 h at 50C. Air was then bubbled through the seeds for 6 h at 200C. Following imbibition, seeds were soaked in 1 mm sodium azide (pH 3) for 2 h. The seeds were rinsed for 30 min, dried on paper towels, and planted in the field. The plants arising from these seeds were Ml generation plants. M2 seeds were harvested from these plants at maturity.The imidazolinone class of herbicides has been demonstrated to have a broad spectrum of weed control activity, flexibility in timing of application, low usage rates, and low mammalian toxicity. These herbicides inhibit the enzymic activity of AHAS2 (EC 4.1.3.18) (15), the first enzyme in the pathway for the synthesis of the branched chain amino acids valine, leucine, and isoleucine. This same enzyme has been shown to be the site of action for the sulfonylurea and triazolopyrimidine herbicides (4,19). The basis for crop selectivity of the imidazolinones has been shown to be the result of a difference in the nature or rate of metabolism of the herbicide (2,3,16 882Screening Procedure M2 seeds were surface disinfected in 70% ethanol for 30 s. This was followed by a disinfection in a solution of 2.6% sodium hypochlorite for 30 min under vacuum with gentle agitation. Two drops of the nonionic surfactant Tween 20 were used per 100 mL of the sodium hypochlorite solution to aid the disinfestation procedure. Subsequently, seeds were rinsed three times in sterile distilled water and placed into sterile plastic 10-x 1.5-cm Petri dishes at 250 seeds/dish. Twenty-five milliliters of 1 M imazethapyr was placed in each dish. After 3 d in the imazethapyr solution, the seeds were drained and blotted dry. The seeds were planted at a 1-to 2-cm depth in 15-x 20-cm peat flats containing Metromix 350 (W.R. Grace Co.) at the rate of 1000 seeds/flat. These flats...

Single nucleotide mutation in the barley acetohydroxy acid synthase ( AHAS ) gene confers resistance to imidazolinone herbicides

“…The plants from these seeds, the M 1 generation, were selfed, and M 2 seeds were bulk harvested at maturity. The M 2 seeds were screened for imidazolinone resistance using a modified procedure developed by Newhouse et al (33). About 250 seeds were placed on a sterile 10 × 1.5-cm Petri dish and soaked in 25 mL imazethapyr solution [1,120.3 μM; 48.06 g active ingredient (ai)·ha After screening more than 2 million M 2 seeds, one line was confirmed to show imidazolinone resistance, because all 72 M 4 plants derived from this line survived with little symptoms after herbicide application (Fig.…”

Current Status and Perspective of Weed Management in Herbicide-Resistant Crops

“…Imidazolinone 저항성 밀은 1992년에 돌연변이 유발에 의하여 품종(Clearfield)이 처음으로 육성되었고 (Newhouse, 1992), 2007년에는 단일유전자를 가진 AGS CL7 품종이 육성되었다 (Johnson, 2010). Imidazolinone 저항성 벼는 1993 년에 종자돌연변이 유발에 의하여 비형질전환방법으로 개 발되었으며 (Croughan, 1994), imazethapyr는 벼에서 파종 전 혹은 발아 전 토양처리제와 경엽처리제로 개발되어 사 용되고 있다.…”

Tolerância de trigo (Triticum aestivum) e aveia (Avena sp.) a herbicidas inibidores da enzima acetolactato sintase (ALS)

“…Em algumas espé-cies de importância agrícola (milho, canola, beterraba, arroz, trigo e soja) foram desenvolvidas constituições genéticas para tolerância aos inibidores da ALS por meio de seleção de células somáticas, melhoramento por mutação, transformação genética e cruzamento interespecífico (Anderson & Georgeson, 1989;McHughen, 1989;Swanson et al, 1989;D'Halluin et al, 1992;Newhouse et al, 1992;Silva & Silva, 2007).…”