The ethylene response factor Pti5 contributes to potato aphid resistance in tomato independent of ethylene signalling.
Bottom Line: Ethylene response factors (ERFs) comprise a large family of transcription factors that regulate numerous biological processes including growth, development, and response to environmental stresses.Virus-induced gene silencing of Pti5 enhanced aphid population growth on tomato, both on an aphid-susceptible cultivar and on a near-isogenic genotype that carried the Mi-1.2 resistance (R) gene.Furthermore, experiments with inhibitors of ethylene synthesis revealed that Pti5 and ethylene have distinctly different roles in plant responses to aphids.
Affiliation: Department of Entomology, University of Arkansas, Fayetteville, AR 72701, USA.Show MeSH
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Mentions: To investigate if Pti5 influenced plant defences against aphids, VIGS was performed to suppress Pti5 expression in the aphid-susceptible tomato ‘Moneymaker’ and the near-isogenic resistant line ‘Motelle’ carrying the Mi-1.2 gene. Plants were infiltrated either with a construct designed to silence Pti5 (TRV-Pti5) or with a control vector of comparable size (TRV-CV). Compared with plants that received the vector control, plants infiltrated with TRV-Pti5 had significantly lower abundance of Pti5 transcripts in the foliage (Fig. 2A; P=0.0013), and the efficacy of silencing was similar in the two genotypes. To measure antibiosis, plants were inoculated with caged adult aphids in a no-choice test, and insect survivorship and reproduction was monitored at 4 and 7 DAI. The aphid-susceptible cultivar ‘MoneyMaker’ had higher numbers of live adults (Fig. 2B; P=0.0098) and offspring (Fig. 2C; P<0.0001) than the aphid-resistant genotype ‘Motelle’ at 4 DAI. Regardless of the genotype tested, plants treated with TRV-Pti5 also supported higher numbers of surviving adults (Fig. 2B; P=0.0033) and live offspring (Fig. 2C; P=0.0063) than the TRV-CV-treated plants. The percentage increase in surviving adults (35% on ‘MoneyMaker’ and 35% on ‘Motelle’) and offspring (37% on ‘MoneyMaker’ and 40% on ‘Motelle’) that resulted from silencing of Pti5 was similar on the two genotypes, and there was no statistically significant interaction between VIGS treatment and plant genotype (P>0.1). This suggested that the effects of silencing by TRV-Pti5 was similar in the two genetic backgrounds. The same patterns of aphid population growth observed at 4- DAI persisted at 7 DAI (Fig. 2D, E), indicating that the effect of Pti5 silencing on aphid population growth remained stable for the time period tested.
Affiliation: Department of Entomology, University of Arkansas, Fayetteville, AR 72701, USA.