Acetolactate Synthase–Inhibitor–Resistant Yellow Nutsedge (Cyperus esculentus): I—Phenotypic Differences

Abstract

Acetolactate synthase (ALS) -inhibitor resistance has been recently documented in a yellow nutsedge biotype in Arkansas rice production, with a target-site mutation resulting in an amino acid substitution from Trp574 to Leu. Preliminary observations have indicated that the resistant biotype showed distinct phenotypic characteristics. Two greenhouse experiments were conducted on the resistant biotype in comparison with three susceptible standards (1) to understand differential growth habit and spatial distribution, and (2) to characterize shoot emergence pattern and seedling vigor. The resistant biotype exhibited a drastically different growth habit with secondary and tertiary basal bulbs emerging away from the parent shoot, resulting in a wider spatial distribution and ground coverage compared to the very compact growth habit of susceptible biotypes. Unlike the susceptible biotypes, the rhizomes developing into tubers were not often connected to the primary basal bulb, but were originating randomly from daughter shoots. The resistant biotype produced an extensive subterranean network of rhizomes and basal bulbs, with wider root spread and distribution compared to the susceptible biotypes. The growth habit of the resistant biotype appeared to be intermediate between yellow and purple nutsedges. Further, the resistant biotype showed a considerably delayed emergence pattern with relatively high levels of tuber dormancy. Although the resistant plants exhibited low early-growth seedling vigor and biomass production compared to the susceptible biotypes (perhaps because of smaller tubers), final aboveground biomass production was greater than that of susceptible biotypes. The overall growth habit and phenotype of the resistant biotype may provide a competitive advantage over adjacent species through the ability to occupy niches and gain improved access to critical resources. The distinct growth pattern may also mean that tillage should not be relied upon for control because it can assist further spread by disconnecting and displacing the chains of rhizomes. Nomenclature: Yellow nutsedge, Cyperus esculentus L.; purple nutsedge, Cyperus rotundus L.; rice, Oryza sativa L.

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

“…Flowering and Seed Production. Similar to previous observations (Bagavathiannan et al 2015), the Res biotype flowered during the 12-wk period under each of the photoperiod treatments. When Sus plants from each biotype were harvested, no floral structures were observed and none of these plants formed involucral leaves and axillary inflorescence.…”

“…This can be due to a tendency for the Res biotype to produce longer rhizomes and more tertiary daughter plants to aggressively colonize habitats. Bagavathiannan et al (2015) showed greater overall production of biomass in the Res biotype under ample space and greater potential for rapid spread relative to Sus biotypes.…”

“…Hetroplasmy in the mitochondrial transcriptional unit (e.g., nad3-orfa56) of wheat (Triticum aestivum L.) 3 cereal rye (Secale cereale L.) hybrid progeny demonstrated potential paternal transmission of the mtDNA molecule (Hattori et al 2002). Given the distinct genetic grouping of the Res biotype based on nuclear and cytoplasmic DNA, coupled with its intermediary growth habit between yellow and purple nutsedge (Bagavathiannan et al 2015), it is most likely that the Res biotype results from hybridization between yellow and purple nutsedge. Interspecific natural hybridization within the genus Cyperus has been reported worldwide (Koyama 1961;Manhart 1989).…”

“…It was unclear whether the Res biotype was a hybrid between yellow and purple nutsedge. Moreover, the Res biotype flowered uniformly under greenhouse conditions (30/20 C day/night temperatures and 14-h photoperiod), whereas the susceptible standards failed to do so (Bagavathiannan et al 2015). It appears that the photoperiodic requirements for reproduction in the Res biotype is different from the Sus biotypes, and the influence of photoperiod on differences in flowering, tuber production, and seed viability between the Res and Sus yellow nutsedge biotypes is not well understood.…”

“…Previous work revealed drastic differences in growth habit between the ALS-resistant yellow nutsedge (Res) biotype originating from eastern Arkansas and the susceptible (Sus) biotypes (Bagavathiannan et al 2015). In particular, the growth and phenological characteristics of the Res biotype appeared to be intermediate between yellow and purple nutsedge, with chain-like network of rhizomes and basal bulbs as in purple nutsedge, and formation of solitary, terminal tubers and golden yellow-colored inflorescence (and other morphological characteristics) resembling yellow nutsedge.…”