A Rapid Phenotyping Method for Imazamox Resistance in Wheat

ABSTRACT: The availability of imidazolinone (IMI) resistant cultivars has provided an effective option for weed control in wheat production systems. IMI herbicides control several weeds, including Avena fatua and Lolium multiflorum, which are the most frequent grass weeds in wheat crops of the Argentine Pampas. The aim of this study was to develop a soil-less method that allows rapid phenotyping of IMI resistance in wheat. Nine wheat cultivars differing in IMI resistance were evaluated through a between-paper germination method. Herbicide concentrations required to reduce shoot and root length by 50% for resistant cultivars were > 75 fold that of the susceptible cultivars. The response of resistant and susceptible commercial cultivars was assessed in the between-paper and top-paper methods at 100 mM imazamox as discriminating dose. The Z’-factor was calculated for evaluation of the quality of the screening methods. Both germination methods showed Z’-factors > 0 indicating that the assays were appropriate but the between-paper method allowed to save space in the growth chamber. The germination methods were useful for distinguishing between susceptible and resistant plants carrying at least one resistance gene. The rapid, simple and cost-effective method described in the present study could be a potential tool when selecting for IMI resistance in wheat in breeding programs.

摘要：抗咪唑啉酮类（imidazolinone, IMI）小麦品种的应用为小麦生产体系的杂草防控提供了有效手段。IMI除草剂可防控多种杂草，其中野燕麦（Avena fatua）与多花黑麦草（Lolium multiflorum）是阿根廷潘帕斯草原小麦田最为常见的禾本科杂草。本研究旨在开发一种无需土壤的方法，以实现小麦IMI抗性的快速表型鉴定。本研究采用纸间发芽法，对9个IMI抗性水平存在差异的小麦品种进行了评价。结果显示，抗性品种的芽长与根长降低50%所需的除草剂浓度为敏感品种的75倍以上。以100 mM甲氧咪草烟（imazamox）作为区分剂量，分别采用纸间发芽法与纸上发芽法，对抗性与敏感型商用小麦品种的响应特征进行了评估。通过计算Z’因子（Z’-factor）对两种筛选方法的检测质量进行评价，两种发芽法的Z’因子均大于0，表明检测方法均适用，且纸间发芽法可节省植物生长箱内的空间。该类发芽法可有效区分携带至少一个抗性基因的敏感与抗性植株。本研究开发的快速、简便且经济高效的检测方法，有望成为小麦育种程序中IMI抗性筛选的潜在实用工具。