Departamento de Biotecnología, Nidera S.A, Casilla de Correo 6, CP.: 2600, Venado Tuerto, Santa Fe, Argentina.
Theor Appl Genet. 2012 Feb;124(2):385-96. doi: 10.1007/s00122-011-1713-6. Epub 2011 Oct 2.
Imisun and CLPlus are two imidazolinone (IMI) tolerance traits in sunflower (Helianthus annuus L.) determined by the expression of different alleles at the same locus, Ahasl1-1 and Ahasl1-3, respectively. This paper reports the level of tolerance expressed by plants containing both alleles in a homozygous, heterozygous and in a heterozygous stacked state to increasing doses of IMI at the enzyme and whole plant levels. Six genotypes of the Ahasl1 gene were compared with each other in three different genetic backgrounds. These materials were treated at the V2-V4 stage with increasing doses of imazapyr (from 0 to 480 g a.i. ha(-1)) followed by an assessment of the aboveground biomass and herbicide phytotoxicity. The estimated dose of imazapyr required to reduce biomass accumulation by 50% (GR(50)) differed statistically for the six genotypes of the Ahasl1 gene. Homozygous CLPlus (Ahasl1-3/Ahasl1-3) genotypes and materials containing a combination of both tolerant alleles (Imisun/CLPlus heterozygous stack, Ahasl1-1/Ahasl1-3) showed the highest values of GR(50), 300 times higher than the susceptible genotypes and more than 2.5 times higher than homozygous Imisun materials (Ahasl1-1/Ahasl1-1). In vitro AHAS enzyme activity assays using increasing doses of herbicide (from 0 to 100 μM) showed similar trends, where homozygous CLPlus materials and those containing heterozygous stacks of Imisun/CLPlus were statistically similar and showed the least level of inhibition of enzyme activity to increasing doses of herbicide. The degree of dominance for the accumulation of biomass after herbicide application calculated for the Ahasl1-1 allele indicated that it is co-dominant to recessive depending on the imazapyr dose used. By the contrary, the Ahasl1-3 allele showed dominance to semi dominance according to the applied dose. This last allele is dominant over Ahasl1-1 over the entire range of herbicide rates tested. At the level of enzymatic activity, however, both alleles showed recessivity to semi-recessivity with respect to the wild-type allele, even though the Ahasl1-3 allele is dominant over Ahasl1-1 at all the herbicides rates used.
Imisun 和 CLPlus 是向日葵（Helianthus annuus L.）中的两种咪唑啉酮（IMI）耐受特性，分别由同一基因座 Ahasl1-1 和 Ahasl1-3 上不同等位基因的表达决定。本文报告了在酶和整株水平上，含有这两个等位基因的纯合子、杂合子和杂合子叠加状态的植物对不断增加的 IMI 剂量的耐受水平。在三个不同的遗传背景下，比较了 Ahasl1 基因的六个基因型。在 V2-V4 阶段，用不断增加的咪草烟剂量（从 0 到 480 g a.i. ha(-1)) 处理这些材料，然后评估地上生物量和除草剂的植物毒性。估计的咪草烟剂量，使生物量积累减少 50%（GR(50)），在 Ahasl1 基因的六个基因型之间存在统计学差异。纯合 CLPlus（Ahasl1-3/Ahasl1-3）基因型和含有两种耐受等位基因的组合材料（Imisun/CLPlus 杂合子叠加，Ahasl1-1/Ahasl1-3）表现出最高的 GR(50)值，比敏感基因型高 300 倍，比纯合 Imisun 材料高 2.5 倍以上（Ahasl1-1/Ahasl1-1）。使用不断增加的除草剂剂量（从 0 到 100 μM）进行的体外 AHAS 酶活性测定也显示出相似的趋势，其中纯合 CLPlus 材料和含有 Imisun/CLPlus 杂合子叠加的材料在统计学上相似，对不断增加的除草剂剂量表现出最低水平的酶活性抑制。根据应用的咪草烟剂量，计算出 Ahasl1-1 等位基因对除草剂处理后生物量积累的显性程度表明，它是共显性的，取决于隐性。相反，Ahasl1-3 等位基因表现出显性到半显性，根据应用的剂量。在测试的整个除草剂浓度范围内，最后一个等位基因对 Ahasl1-1 是显性的。然而，在酶活性水平上，两个等位基因相对于野生型等位基因都表现出隐性到半隐性，尽管在所有使用的除草剂浓度下，Ahasl1-3 等位基因对 Ahasl1-1 都是显性的。
