Morphophysiogenetic characterization of wild poinsettia biotypes with low resistance to glyphosate

Abstract: The objective of this work was to compare wild poinsettia (Euphorbia heterophylla) biotypes as to their morphological characteristics, as well as to determine their genetic similarity in the state of Rio Grande do Sul, Brazil, and to confront the light compensation point of susceptible biotypes and of biotypes with low-resistance level to glyphosate. Besides the morphology analysis, the study included the genetic characterization, by AFLP, of susceptible (GR50= 58.65 g ha-1 a.e.) biotypes and of biotypes with low resistance (GR50= 310.36 g ha-1 a.e.) to glyphosate. The competitive ability of the biotypes was inferred according to their light compensation point. The observed morphological characteristics do not allow to differentiate biotypes as to their geographical location, or their resistance level to glyphosate. The genetic analysis identified low genetic diversity among the 15 tested biotypes, with a large amount of subgroups. The biotypes with low resistance formed an isolated group. The susceptible biotypes showed the lowest values of light compensation point and, possibly, they have a greater competitive ability under low-luminosity conditions. The evaluated characteristics do not enable to differentiate genotypes with different levels of glyphosate resistance.

摘要：本研究旨在对比巴西南里奥格兰德州野生猩猩木（Euphorbia heterophylla）不同生物型的形态特征，明确其遗传相似性，并比较敏感型生物型与低抗草甘膦生物型的光补偿点。除形态学分析外，本研究通过扩增片段长度多态性（AFLP）对敏感型（GR₅₀=58.65 g·ha⁻¹ 酸当量）生物型及低抗草甘膦生物型（GR₅₀=310.36 g·ha⁻¹ 酸当量）开展遗传特征鉴定。研究基于各生物型的光补偿点推断其竞争能力。结果显示，观测得到的形态特征无法依据地理来源或草甘膦抗性水平区分不同生物型。遗传分析表明，15个供试生物型间遗传多样性较低，且存在大量亚组；低抗草甘膦生物型单独形成一个孤立类群。敏感型生物型的光补偿点值最低，推测其在低光照条件下具备更强的竞争能力。本研究所评估的各项特征无法区分具有不同草甘膦抗性水平的基因型。