Acetolactate Synthase–Inhibitor Resistance in Yellow Nutsedge (Cyperus esculentus): II—Physiognomy and Photoperiodic Response

Abstract

Yellow nutsedge is one of the most problematic weedy sedges in rice-soybean systems of the Mississippi Delta region. An acetolactate synthase (ALS)-inhibiting, herbicide-resistant (Res) yellow nutsedge biotype was recently documented in eastern Arkansas, which showed intermediary growth habit between yellow nutsedge and purple nutsedge and also exhibited differential photoperiodic sensitivity to flowering. The objectives of this study were to: (a) determine variation in reproductive characteristics of the Res biotype and three susceptible (Sus) yellow nutsedge biotypes, (b) understand the influence of photoperiod on growth and reproduction, (c) understand the potential role of seeds in population establishment, and (d) elucidate the phylogenetic relationships between the Res yellow nutsedge biotype and purple nutsedge. Tuber production per plant and tuber weight of the Res biotype were less than that of the Sus biotypes. Differences in quantitative traits, such as shoot and tuber production existed between the Res and Sus biotypes for photoperiods ranging from 12 to 16 h. Generally, photoperiods greater than 12 h increased shoot development in all yellow nutsedge biotypes, with differential responses among the biotypes. Number of tubers reached the maximum for the Res biotype at a 14-h photoperiod. Over a 90-d period, inflorescence formation was only observed in the Res biotype with maximum flowering and seed production in the 14-h photoperiod. Subsequent tests revealed up to 18% seed germination, suggesting that seed could also play a role (in addition to tubers) in the persistence and spread of the Res yellow nutsedge. Phylogenetic analysis based on ribosomal DNA internal transcribed spacer (ITS) regions and mitochondrial nad4 gene intergenic spacer sequences indicated that the Res biotype was more closely associated with Sus yellow nutsedge biotypes. Nevertheless, 100% similarity for the nad4 gene sequences between the Res yellow nutsedge biotype and a reference purple nutsedge suggests that the Res biotype is likely a result of hybridization between yellow and purple nutsedges, which perhaps explains the intermediary growth characteristics observed in the Res biotype. Nomenclature: Purple nutsedge, Cyperus rotundus L.; yellow nutsedge, Cyperus esculentus L.; rice, Oryza sativa L.; soybean, Glycine max (L.) Merr.

The Evidence for Reduced Glyphosate Efficacy on Acetolactate Synthase–Inhibiting Herbicide-Resistant Yellow Nutsedge (Cyperus esculentus)

“…Dose-response assay by determining the GR 50 value is a classical approach to differentiating weed populations and natural variability of species in response to herbicides (Burgos et al 2013). Overall, these results indicate genetic differences in the response of yellow nutsedge biotypes to glyphosate, which are comparable to the findings of our previous experimentations regarding the phenological variations of yellow nutsedge biotypes under different photoperiodic regimes (Tehranchian et al 2015). Furthermore, similar responses of the Res and purple nutsedge plants to glyphosate may parallel their phylogenetic relationships and growth habit similarities that were exhibited in previous studies (Bagavathiannan et al 2015;.…”

“…Plant Propagation and Growth Conditions. Tubers of the Res and susceptible (Sus1, Sus2, and Sus3) yellow nutsedge biotypes were used (see Tehranchian et al 2015 for the history of these populations). Tubers of purple nutsedge were provided by Azlin Seed Company in Leland, MS. Tubers were initially sprouted in plastic flats (52.5 by 26.5 by 5.5 cm 3 ) filled with LC1 potting mix (Sun Gro Horticulture, Seba Beach, AB, Canada) in the greenhouse under a 14-h photoperiod at 35/25 C day/night temperatures.…”

“…Further investigations revealed the Res biotype had similarities to purple nutsedge based on growth characteristics such as a chain-like network of basal bulbs (Bagavathiannan et al 2015). Phylogenetic analysis based on internal transcribed spacer and mitochondrial nad4 gene intergenic spacer sequencing also suggested that the Res biotype is likely the result of natural hybridization between yellow and purple nutsedges (Tehranchian et al 2015).…”

Gene expression and target-site mutations are associated with resistance to ALS inhibitors in annual sedge (Cyperus compressus) biotypes from Georgia

“…Previous research demonstrated that Pro-197 and Trp-574 are common amino acid substitution sites that confer a high-level resistance to sulfonylureas (Corbett and François 2006;Heap 2015). It was reported that these amino acid substitutions in the ALS gene conferred resistance in C. difformis (Tehranchian et al 2015b), C. esculentus (Tehranchian et al 2014(Tehranchian et al , 2015a, and C. iria (Riar et al 2015). Our data revealed a mutation (CCC-TCC) in the ALS enzymes resulting in a Pro-197-Ser amino acid substitution codon in all R biotypes.…”

“…There are presently six Cyperus species, annual sedge (Cyperus compressus L.), fragrant flatsedge (Cyperus odoratus L.), rice flatsedge (Cyperus iria L.), smallflower umbrella sedge (Cyperus difformis L.), shortleaf spike sedge (Kyllinga brevifolia Rottb. ), and yellow nutsedge (Cyperus esculentus L.), that have developed resistance to ALS-inhibiting herbicides (Busi et al 2006;Heap 2015;Kuk et al 2004;McCullough et al 2016a;Merotto et al 2010;Ortiz et al 2015;Riar et al 2015;Tehranchian et al 2015aTehranchian et al , 2015b. Among these Cyperus species, C. compressus, C. odoratus, C. iria, and C. difformis are annuals, while the others are perennials.…”