A thrips vector of tomato spotted wilt virus responds to tomato acylsugar chemical diversity with reduced oviposition and virus inoculation.

There is increasing evidence that acylsugars deter insect pests and plant virus vectors, including the western flower thrips (WFT), Frankliniella occidentalis (Pergande), vector of tomato spotted wilt virus (TSWV). Acylsugars are sugar-polyesters composed of saturated, un-saturated, and variously branched short and long chain fatty acids (FAs) esterified to a glucose (acylglucose) or sucrose (acylsucrose) moiety. We sought to understand how acylsucrose amount and composition of associated FA profiles interacted to mediate resistance to WFT oviposition and TSWV inoculation on tomato leaves. Towards this goal, we examined WFT oviposition and TSWV inoculation behavior on tomato lines bred to exude varying amounts of acylsucrose in association with diverse FA profiles. Our data show that as acylsucrose amounts increased, WFT egg-laying (oviposition) decreased and TSWV inoculation was suppressed. Western flower thrips also responded to FA profiles that included iC4, iC11, nC12 and nC10 FA. These findings support improving acylsugar-mediated resistance against WFT by breeding tomatoes exuding greater amounts of acylsucrose associated with specific FA profiles. We show that increasing acylsucrose amount output by type IV trichomes and selecting for particular FA profiles through advanced breeding profoundly affects WFT behavior in ways that benefit management of WFT as direct pests and as TSWV vectors

Acylsugar backbone profile of entries.

Total accumulation amount of acylsugars of each entry averaged across samples and experiments. Acylsugars were determined to have either a sucrose (acylsucrose) or glucose (acylglucose) backbone. (TIF)</p

The average amounts of total acylsugars (AS) (± SEM) accumulated by each entry for each field trial season in umol g^-1 weight leaf tissue.

Measured acylsugar accumulation from each entry for each season was utilized to assign each entry to one of four categories ranging from “0” to “3”, with “0” indicating the standard tomato entry(s) with trace acylsugar accumulation, “1” indicating low, “2” indicating moderate and “3” indicating high acylsugar amount accumulation. Within each season, entries not connected by the same letter are significantly different (a = 0.05) Tukey HSD.</p

Absolute abundance of acylsugar fatty acids in profile of entries.

Acylsugar fatty acids that constitute more than 1% of the total fatty acid profile of at least one entry were included in the analysis. Amounts of acylsugar fatty acids are presented as umol g-1 dry leaf weight. (TIF)</p

Hierarchical clustering of included tomato entries by relative abundance of acylsugar fatty acids, where each fatty acid constitutes a percentage of the total fatty acid profile for a given entry.

Fatty acids included make up at least 1 percent of a given entries’ total fatty acid profile. Pearson correlation used to separate entries. Within a row, colors are standardized across columns, allowing comparisons of the relative proportion of an individual fatty acid across entries, but does not reveal the absolute amount of the acylsugar fatty acids (see S3 Fig for this information). Comparisons within a column are not relevant, because the colors do not convey relative proportion of each fatty acid within an entry (see S2 Fig for this information). Color represents the relative abundance of an acylsugar fatty acid for a given entry with red indicating higher accumulation compared to the other entries in the row, and blue indicating a lower relative percent accumulation of a fatty acid compared to the other entries. Purple represents fatty acids that could not be detected for a given entry. Entries with the prefix "FA" have modified fatty acid profiles and entries with the prefix "ISX" are interspecific hybrids with modified fatty acid profiles; these two groups displayed the most unique fatty acid profiles and clustering patterns.</p

Pedigrees or category of all entries included in field trials.

Pedigrees or category of all entries included in field trials.</p

Whitefly egg counts per 10 leaflets across acylsugar amount groupings Fall 2014.

Number of whitefly eggs in Fall 2014 trial for each acylsugar amount grouping of entries. Four replicates pooled for each entry at each count date and averaged across entries within each acylsugar amount grouping at each count date. For each count date, acylsugar amount groupings of entries not connected by the same letter are significantly different (a = 0.05). Error bars represent one standard error of the mean. (TIF)</p

AIC independent variables selected to model abundance of whitefly nymphs.

AIC independent variables selected to model abundance of whitefly nymphs.</p

Number of whitefly nymphs per ten leaflets in Fall 2014 trial for each acylsugar amount grouping of entries.

Four replicates from 10 leaflet samples pooled for each entry at each count date and averaged across entries within each acylsugar amount grouping at each count date. For each count date, acylsugar amount groupings of entries not connected by the same letter are significantly different (a = 0.05). Error bars represent one standard error of the mean.</p

Practical Weed Science for the Field Scout: Corn and Soybean (2009)

This publication is intended to serve as a practical reference and educational tool to be used in scouting corn and soybean fields for the presence of weeds, identifying whether a rescue treatment is necessary, and determining crop response to herbicide activity. This publication consists of two main sections. The first section includes information on weed identification, scouting and mapping procedures, and a discussion of economic thresholds for weeds. An identification key and color photographs of weeds common to Missouri are also included. The second section includes information on diagnosing herbicide injury. It discusses the various causes and conditions contributing to herbicide injury. It also includes a key to help determine which herbicide family might have caused the injury symptoms, and color photos of herbicide injury caused by various herbicide families