Broad‐Spectrum Arthropod Resistance in Hybrids between High‐ and Low‐Acylsugar Tomato Lines

Abstract

Three elite tomato (Solanum lycopersicum L., syn. Lycopersicon esculentum Mill.) breeding lines (TOM‐687, TOM‐688, TOM‐689) with high foliar acylsugar (AS) contents were obtained, and used along with two low‐AS lines (TOM‐690, TOM‐684) in hybrid combinations, to obtain six hybrids between one low‐AS line × one high‐AS line (= hybrids with intermediate AS levels), one hybrid between two high‐AS lines (= high‐AS hybrid), and one hybrid between two low‐AS lines (= low‐AS hybrid). These genotypes were tested for resistance to three different tomato pests (spider mites [Tetranychus urticae Koch], silverleaf whitefly [Bemisia argentifolii Bellows & Perring], and the South American tomato pinworm [Tuta absoluta (Meyrick)]) along with hybrid TEX‐154 (low‐AS) and/or Solanum pennellii Correll ‘LA‐716’ (high‐AS wild accession). In all three instances, high‐AS genotypes showed higher levels of pest resistance than low‐AS genotypes. Hybrids with intermediate AS levels showed resistances that were just as high as those of high‐AS genotypes for Bemisia argentifolii and Tuta absoluta, and nearly as good as those for Tetranychus urticae. Acylsugars were confirmed as being a major component of the high levels of pest resistances found in S. pennellii—a component that was successfully introgressed into elite tomato breeding lines. Acylsugar‐mediated pest resistance is effective against a broad spectrum of tomato pests. Because high‐AS breeding lines are scarce, the deployment of hybrids between high‐AS line × low‐AS line would be a quick, viable alternative to obtain commercial pest‐resistant hybrids.

Role of allelochemicals and trichome density in the resistance of tomato to whitefly

“…glabratum PI 134417, and lines BPX-365F and BPX-367D were selected because they exhibited the highest glandular trichome (where 2-TD accumulates) density; presumably, the latter two lines also exhibit high 2-TD contents. TOM-687 is an AS-rich line with commercial characteristics that exhibits well-documented resistance to the mite Tetranychus spp., tomato leaf miner Tuta absoluta, and silverleaf whitefly B. tabaci biotype B (MALUF et al, 2010); for this reason, this line was used as the standard resistant line.…”

“…For the purpose of infestation by B. tabaci biotype B, as previously identified and used by Silva et al (2009) and Maluf et al (2010), silverleaf whiteflies were grown in a protected greenhouse with a 12-m 2 domed protective structure covered by transparent plastic. Adult insects were randomly collected at several tomato cv.…”

“…Maluf et al (2010) assessed the AS-mediated resistance of the tomato plant to arthropod pests and found that hybrids with intermediate AS contents exhibited satisfactory resistance to Bemisia tabaci biotype B and Tuta absoluta (Lepidoptera: Gelechiidae), similar to homozygous lines with high AS contents. Silva et al (2009) compared the degrees of resistance to B. tabaci biotype B and Tetranychus urticae (Thysanoptera: Tetranychidae) exhibited by tomato plant hybrids resulting from the crossing of lines with high ZGB and AS contents with those of the parental lines and commercial controls.…”

“…Alth ough correlat ions between the concentrations of foliar allelochemicals (2-TD, ZGB or AS) and the degree of pest resistance have been established (ARAGÃO; DANTAS; BENITES, 2000;MALUF et al, 2007;SILVA et al, 2009;GONÇALVES NETO et al, 2010;MALUF et al, 2010), few critical studies have compared the degree of pest resistance among lines rich in different allelochemicals.…”

In vitro reconstruction and analysis of evolutionary variation of the tomato acylsucrose metabolic network

“…Nicotiana attenuata acylsucroses are at the center of a multitrophic defense interaction where they are metabolized to volatile fatty acids by Manduca sexta larvae, and these airborne products attract predatory ants (6). Protective properties against herbivores have made increasing total acylsugars or altering acyl chain types a target for breeding insect-resistant cultivated tomatoes (Solanum lycopersicum) (16)(17)(18). In addition, synthetic sucrose esters mimicking natural acylsugars have been applied as safe, biodegradable insecticidal compounds (19)(20)(21) and also have commercial value in the food, cosmetic, and pharmaceutical industries (22,23).…”