Involvement of Limonene Hydroperoxides Formed after Oil Gland Injury in the Induction of Defense Response against Penicillium digitatum in Lemon Fruit

Abstract

The effects of wounding oil glands of lemon [Citrus limon (L.) Burm.] fruit were investigated. Young mature-green lemons demonstrated significantly lower decay incidence than older yellow fruit when their oil glands were punctured in the presence of postharvest wound pathogen Penicillium digitatum Sacc. Contact with the released gland content on the green lemon surface reduced the viability of P. digitatum spores approximately twice. Wounding caused rapid production of limonene hydroperoxides that persisted for only a few minutes. The magnitude depended on the physiological maturity of the fruit; mature-green fruit produced much higher levels than did yellow lemons. Furthermore, wounding of the oil glands or injection of limonene hydroperoxides into the lemon peel elicited the production of the citrus fruit phytoalexins, scoparone and scopoletin, to levels known to be effective in reducing decay caused by P. digitatum. The mature-green fruit produced about twice as much of these phytoalexins as the older yellow fruit. This induced defensive elicitation of phytoalexin production, as well as the direct effects of these antifungal compounds, markedly inhibited the pathogen in mature-green fruits but was ineffective in older yellow ones.

Involvement of an extracellular fungus laccase in the flavonoid metabolism in Citrus fruits inoculated with Alternaria alternata

“…All the above suggests that scoparone may be involved as a phytoalexin in the defence mechanisms of this species against A. alternata, which would agree with the results of other authors for different pathogenic fungi (Afek et al, 1986;Kim et al, 1991;P erez et al, 1994), although the possible involvement of other compounds cannot be discarded (Ben-Yehoshua et al, 2008).…”

The rice terpene synthase gene OsTPS19 functions as an (S)‐limonene synthase in planta, and its overexpression leads to enhanced resistance to the blast fungus Magnaporthe oryzae

“…The spore germination of M. oryzae was inhibited by the presence of monoterpene ( S )‐limonene (Figure ). Additionally, limonene might be oxidized to limonene hydroperoxide, which acts as an active oxygen species to initiate wide defence responses (Ben‐Yehoshua et al ., ). Some nontarget pathways and products of metabolites (Pasoreck et al ., ) may also be involved in the increased resistance against rice blast fungus in OsTPS19 overexpression rice plants.…”

Genomic Analysis of Terpene Synthase Family and Functional Characterization of Seven Sesquiterpene Synthases from Citrus sinensis

“…Different citrus genotypes, including oranges, mandarins, lemons, citrons, and grapefruits, also emit high levels of D-limonene and linalool from flowers (Azam et al, 2013b ) and leaves (Azam et al, 2013a ). Additionally, both compounds have been reported as involved in citrus resistance to different pest and pathogens (Ben-Yehoshua et al, 2008 ; Rodríguez et al, 2011 , 2014 , 2015 ; Shimada et al, 2014 ; Rodrigues Marques et al, 2015 ). The existence of different genes with a common origin encoding redundant proteins could indicate that diversification, in addition to sequence level, has occurred at the level of gene expression patterns.…”