Target Site Resistance to Acetolactate Synthase Inhibitors in Diplotaxis erucoides and Erucaria hispanica–Mechanism of Resistance and Response to Alternative Herbicides

Maor Matzrafi,Ofri Gerson,Baruch Rubin,M Sibony

doi:10.3390/agronomy10040471

Maor Matzrafi, Ofri Gerson + Show 2 more

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https://doi.org/10.3390/agronomy10040471

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Abstract

Diplotaxis erucoides and Erucaria hispanica are common weeds of the Mediterranean region; they infest various habitats including cultivated fields and roadsides. In several fields across Israel, farmers have reported on poor control of D. erucoides and E. hispanica plants using acetolactate synthase (ALS) inhibitors. Greenhouse experiments were conducted to determine the effect of various ALS inhibitors on plants from two potentially resistant D. erucoides and E. hispanica populations. Additionally, alternative management strategies using auxinic herbicides were studied. Plants from both populations exhibited resistance to all tested ALS inhibitors, up to 20-fold the label field rate, as compared with ALS sensitive populations of D. erucoides and E. hispanica. Sequencing of the ALS gene revealed Trp574 to Leu substitution in ALS-resistant D. erucoides plants, whereas a Pro197 to Ser substitution was detected in ALS-resistant E. hispanica plants. Although high levels of resistance were observed in individuals from both putative resistant populations, sensitive individuals were also detected, suggesting the evolution of resistance in these two populations is still in progress. Auxinic herbicides, 2,4-D, and mecoprop-P, provided excellent control of plants from both ALS-resistant populations. This study documents and confirms the first case of evolution of resistance to ALS inhibitors in D. erucoides and E. hispanica populations.

Highlights

Diplotaxis erucoides and Erucaria hispanica (Spanish pink mustard) are common weeds of the Brassicaceae family spread across the Mediterranean region [1]
They are very common in the Mediterranean region, apart from this case, herbicide resistance has never before been reported for both D. erucoides or E. hispanica [9]
No significant reduction in fresh weight (FW) and survival percentage of EHR plants was recorded in response to tribenuron-methyl; the ED50 and LD50 values have exceeded the highest applied rate (60 g ha−1 ), which eventually resulted in failure to fit a correct model to describe this treatment (Figure 2a)

Summary

Introduction

Diplotaxis erucoides (white wall-rocket) and Erucaria hispanica (Spanish pink mustard) are common weeds of the Brassicaceae family spread across the Mediterranean region [1]. These species are frequently found as native weeds mostly in Portugal, Spain, Italy, Cyprus, Greece, Turkey, and Israel; recently, they had invaded as alien species other countries, such as Romania, Norway, Switzerland, and Slovakia [2]. Both species have high seed fecundity with reproduction mechanisms that prevent self-pollination [5,6] These species can germinate in several flushes in a season, enabling them to better compete with crop seedlings, dominate the entire field, and cause high yield losses (B Rubin, personal communication). The fact that these weed species are exogamous (i.e., they rely mainly on outcross-pollination) may enhance the spread of beneficial adaptive traits, especially if they are inherited as a single dominant gene, such as in the case of target-site resistance [7]

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