Role of trichomes in defense against herbivores: comparison of herbivore response to woolly and hairless trichome mutants in tomato (Solanum lycopersicum)

Abstract

Trichomes contribute to plant resistance against herbivory by physical and chemical deterrents. To better understand their role in plant defense, we systemically studied trichome morphology, chemical composition and the response of the insect herbivores Helicoverpa zea and Leptinotarsa decemlineata (Colorado potato beetle = CPB) on the tomato hairless (hl), hairy (woolly) mutants and wild-type Rutgers (RU) and Alisa Craig (AC) plants. Hairless mutants showed reduced number of twisted glandular trichomes (types I, IV, VI and VII) on leaf and stem compared to wild-type Rutgers (RU), while woolly mutants showed high density of non-glandular trichomes (types II, III and V) but only on the leaf. In both mutants, trichome numbers were increased by methyl jasmonate (MeJA), but the types of trichomes present were not affected by MeJA treatment. Glandular trichomes contained high levels of monoterpenes and sesquiterpenes. A similar pattern of transcript accumulation was observed for monoterpene MTS1 (=TPS5) and sesquiterpene synthase SST1 (=TPS9) genes in trichomes. While high density of non-glandular trichome on leaves negatively influenced CPB feeding behavior and growth, it stimulated H. zea growth. High glandular trichome density impaired H. zea growth, but had no effect on CPB. Quantitative real-time polymerase chain reaction (qRT-PCR) showed that glandular trichomes highly express protein inhibitors (PIN2), polyphenol oxidase (PPOF) and hydroperoxide lyase (HPL) when compared to non-glandular trichomes. The SlCycB2 gene, which participates in woolly trichome formation, was highly expressed in the woolly mutant trichomes. PIN2 in trichomes was highly induced by insect feeding in both mutant and wild-type plants. Thus, both the densities of trichomes and the chemical defenses residing in the trichomes are inducible.

Jasmonic Acid and Its Precursor 12-Oxophytodienoic Acid Control Different Aspects of Constitutive and Induced Herbivore Defenses in Tomato

“…These findings indicate that JA/JA-Ile is the relevant signal that acts through JAI1/COI1 to control trichome development and terpene synthesis. Consistent with this conclusion, trichome formation and terpene biosynthesis are both known to be induced in response to methyl jasmonate treatment in wild-type plants (Boughton et al, 2005;van Schie et al, 2007;Peiffer et al, 2009;Tian et al, 2012), but not in jai1 mutants (Li et al, 2004) or COI1-silenced transgenic coyote tobacco (Heiling et al, 2010) mutants.…”

Influence of plant resistance traits in selectiveness and species strength in a tropical plant‐herbivore network

“…For example, leaf toughness is a physical barrier ( Lucas et al, 2000 ;Read and Stokes, 2006 ;Peeters, 2007 ) that is highly correlated with herbivore damage ( Coley, 1983 ) and offers effective resistance against herbivores ( Summerville and Crist, 2003 ;Hanley et al, 2007 ;Clissold et al, 2009 ;Carmona et al, 2011 ). Trichomes constrain the movement of herbivores and aff ect larval consumption and survival ( Zalucki et al, 2002 ;Handley et al, 2005 ;Tian et al, 2012 ) and oft en exudate toxic chemicals ( Lin et al, 1987 ). Phenolic compounds, and in particular tannins, are the most abundant specialized metabolites in plants ( Barbehenn and Constabel, 2011 ).…”

Resistência à Helicoverpa armigera em genótipos de tomateiro obtidos do cruzamento de Solanum lycopersicum com Solanum galapagense

“…Nos orifícios feitos pelas lagartas, desenvolvem-se microrganismos que causam a podridão mole. Nesta fase, os prejuízos à cultura podem chegar a até 55% de perda da produção (Usman et al, 2013).…”

“…Nessas espécies, os principais fatores de resistência são os tricomas glandulares e aleloquímicos, produzidos e exsudados pelos tricomas. Esses compostos têm sido associados aos mecanismos de resistência de antibiose e antixenose (Maluf et al, 2010;Tian et al, 2012;Dias et al, 2016).…”