A Jasmonate-Inducible Defense Trait Transferred from Wild into Cultivated Tomato Establishes Increased Whitefly Resistance and Reduced Viral Disease Incidence

Abstract

Whiteflies damage tomatoes mostly via the viruses they transmit. Cultivated tomatoes lack many of the resistances of their wild relatives. In order to increase protection to its major pest, the whitefly Bemisia tabaci and its transmitted Tomato Yellow Leaf Curl Virus (TYLCV), we introgressed a trichome-based resistance trait from the wild tomato Solanum pimpinellifolium into cultivated tomato, Solanum lycopersicum. The tomato backcross line BC5S2 contains acylsucrose-producing type-IV trichomes, unlike cultivated tomatoes, and exhibits increased, yet limited protection to whiteflies at early development stages. Treatment of young plants with methyl jasmonate (MeJA) resulted in a 60% increase in type-IV trichome density, acylsucrose production, and enhanced resistance to whiteflies, leading to 50% decrease in the virus disease incidence compared to cultivated tomato. Using transcriptomics, metabolite analysis, and insect bioassays we established the basis of this inducible resistance. We found that MeJA activated the expression of the genes involved in the biosynthesis of the defensive acylsugars in young BC5S2 plants leading to enhanced chemical defenses in their acquired type-IV trichomes. Our results show that not only constitutive but also these inducible defenses can be transferred from wild into cultivated crops to aid sustainable protection, suggesting that conventional breeding strategies provide a feasible alternative to increase pest resistance in tomato.

Genome-wide analyses of cassava Pathogenesis-related (PR) gene families reveal core transcriptome responses to whitefly infestation, salicylic acid and jasmonic acid

“…One day prior to hormone treatments, three-month-old COL2246 plants were moved from the glasshouse into growth chambers with a 16-h light/ 8-h dark cycle and a 24-28°C temperature range. Cassava leaves were sprayed to saturation with salicylic acid (200 μM SA, 0.1% EtOH, 0.01% Tween 20) and methyl jasmonate (7.5 mM MeJA, 0.1% EtOH, 0.01% Tween 20) [74,75]. Treatments were performed in growth chambers in different rooms.…”

The drought-tolerant Solanum pennellii regulates leaf water loss and induces genes involved in amino acid and ethylene/jasmonate metabolism under dehydration

“…Despite the economic importance of tomato, the mechanisms that govern responses to water stress in this horticultural species are not well characterized, and only a small number of genes playing a role in tomato tolerance to drought have been identified 15 , 16 . Moreover, despite the wealth of sources of variation for drought tolerance in accessions of tomato wild related species 17 , we still do not know the key genes controlling the tolerance. The wild species Solanum pennellii is a drought-adapted species and it constitutes an ideal experimental model to advance in our understanding of the underlying molecular mechanisms of drought adaptation and tolerance in tomato 18 .…”

Leaf trichomes affect caterpillar feeding in an instar-specific manner

“…Trichomes are commonly considered a first line of defense [4–6] and come in two distinct forms: glandular and non-glandular. Glandular trichomes act in defense by producing toxic secondary metabolites to impede or kill herbivores and/or by serving as triggers for the activation of jasmonic acid (JA) mediated defenses [7,8]. In Solanum lycopersicum , for example, herbivore movement ruptures glandular trichomes and elicits the expression of JA-mediated defense genes even prior to leaf damage [7].…”