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

Abstract

In Brazil, the tomato is cultivated in almost all geographic regions even though its yield is significantly reduced by pests and diseases. Among these pests and diseases, whitefly is a major problem that causes direct and indirect damage due to its role in transmission of geminiviruses. The aim of the present study was to compare the degree of resistance to the silverleaf whitefly of tomato plant lines rich in acyl sugars (AS), zingiberene (ZGB), and 2-tridecanone (2-TD) and to establish whether selection for strains with higher densities of glandular trichomes promotes sufficient resistance to this insect pest. The investigated lines were developed by performing back-crossings in tomato (Solanum lycopersicum) from the interspecific crossing of S. lycopersicum x S. habrochaites var. glabratum 'PI 134417'. Lines rich in AS, ZGB, and 2-TD were tested for their levels of resistance to B. tabaci biotype B. Two tomato plant lines (TOM-584 and TOM-679) with normal AS levels and one wild specimen (PI 134417) with high 2-TD content were used as controls. TOM-687, ZGB-703, and TOM-622 were less preferred by B. tabaci for oviposition, and nymphs exhibited a poorer survival rate on those plant lines than on the susceptible controls, TOM-584 and TOM-679. Allelochemicalrich lines exhibited pest resistance, whereas the controls did not, and the allelochemical-rich lines did not differ significantly from each other in the level of resistance. The results show that the development of tomato plant lines rich in 2-TD, ZGB and AS is an effective option for indirect selection for resistance to B. tabaci biotype B. All lines selected based on high trichome density except for BPX-365F-751-05-01-03 exhibited fewer nymphs than the susceptible controls, indicating that selection for more glandular trichomes was generally effective in promoting increased resistance to the silverleaf white flay.Index terms: Solanum lycopersicum, 2-tridecanone, zingiberene, acyl sugars, indirect selection. RESUMONo Brasil, o tomate é cultivado em praticamente todas as regiões, embora seu rendimento seja reduzido por pragas e doenças. A mosca-branca, comumente presente, causa danos diretos e indiretos, devido à transmissão de geminiviros. O objetivo do presente trabalho foi comparar o grau de resistência à mosca branca de linhagens de tomateiro ricas em acilaçúcares (AA), zingibereno (ZGB) e 2-tridecanona (2-TD) e verificar se a seleção de linhagens com base em tricomas glandulares é efetiva no sentido de promover níveis satisfatórios de resistência. Essas linhagens foram obtidas através de retrocruzamentos em tomateiro Solanum lycopersicum, a partir do cruzamento interespecífico S. lycopersicum x S. habrochaites var. glabratum 'PI 1344171'. Linhagens ricas em AA , ZGB e 2-TD foram testadas para níveis de resistência. Duas linhagens de tomateiro (TOM-584 e TOM-679), com nível normal de AA, e o acesso selvagem (PI 134417), alto teor de 2-TD, foram utilizados como testemunhas. TOM-687, ZGB-703 e TOM-622 mostraram diminuições na ovoposição e na contage...

Mini tomato genotypes resistant to the silverleaf whitefly and to two-spotted spider mites

“…Santa Clara (susceptible check treatment). These results corroborate with recent studies that were done with tomato plants of Santa Cruz type Maciel et al, 2011;Oliveira et al, 2012;Neiva et al, 2013). The genotypes UFU-22-F 2 BC 1 #9 and UFU-73-F 2 BC 1 #11 stood out and showed significant difference from the cv.…”

“…The result (18.0 nmol/cm 2 leaf area) obtained on "C2" (genotypes F 2 BC 1 versus S. pennellii) corroborates with the results obtained by Gonçalves et al (2007), in relation to the possibility of another factors controlling the presence of acylsugar in S. pennellii, but these factors do not prevent the obtaining of genotypes in advanced generations, with satisfactory levels of resistance to pests (Gonçalves et al, 2007;Gonçalves Neto et al, 2010;Maluf et al, 2010;Maciel et al, 2011;Oliveira et al, 2012;Neiva et al, 2013). This can be confirmed by analyzing the "C3" (genotypes F 2 BC 1 versus check treatments, cv.…”

“…In relation to the number of nymphs/cm 2 , the genotypes, UFU-22-F 2 BC 1 #9, UFU-22-F 2 BC 1 #10, and UFU-73-F 2 BC 1 #11, highlighted showing the lowest rates of preference (Table 1). In tomato genotypes, there is evidence of hybrids (Santa Cruz type) with satisfactory levels of resistance to the silverleaf whitefly (Maciel et al, 2011;, Neiva et al, 2013. Despite the existence of mini tomato genotypes with commercial potential (Maciel et al, 2016), nowadays, there are no mini tomato genotypes rich in acylsugar with satisfactory levels of resistance to the silverleaf whitefly.…”

“…During the tomato cropping, many species of arthropod pests affect the yield (Maciel et al, 2011;Oliveira et al, 2012;Czepak et al, 2013;Neiva et al, 2013;Maciel and Silva, 2014). The chemical control (insecticides and miticides) has been the most used method since the XX century (Sato et al, 2009;Silveira et al, 2011).…”

“…In breeding programs, specific methods have been successfully used (interespecific cross and backcross) in order to reduce the attack of the most common pests in the tomato crop (Maciel et al, 2009;Gonçalves Neto et al, 2010;Maluf et al, 2010;Oliveira et al, 2012;Neiva et al, 2013). The use of the wild accession, Solanum pennellii, allows obtaining lines (Maciel et al, 2009;Gonçalves Neto et al, 2010) and hybrids of tomato, with broad-spectrum resistance to pests Maciel et al, 2011;Oliveira et al, 2012;Neiva et al, 2013). The wild species, S. pennellii, has a secondary metabolite that acts as an allomone to arthropods, named acylsugar, which when combined with the presence of glandular trichomes, become the mainly responsible for induce pest's resistance on tomato plants.…”