Suppression of Jasmonic Acid-Dependent Defense in Cotton Plant by the Mealybug Phenacoccus solenopsis

Abstract

The solenopsis mealybug, Phenacoccus solenopsis, has been recently recognized as an aggressively invasive pest in China, and is now becoming a serious threat to the cotton industry in the country. Thus, it is necessary to investigate the molecular mechanisms employed by cotton for defending against P. solenopsis before the pest populations reach epidemic levels. Here, we examined the effects of exogenous jasmonic acid (JA), salicylic acid (SA), and herbivory treatments on feeding behavior and on development of female P. solenopsis. Further, we compared the volatile emissions of cotton plants upon JA, SA, and herbivory treatments, as well as the time-related changes in gossypol production and defense-related genes. Female adult P. solenopsis were repelled by leaves from JA-treated plant, but were not repelled by leaves from SA-treated plants. In contrast, females were attracted by leaves from plants pre-infested by P. solenopsis. The diverse feeding responses by P. solenopsis were due to the difference in volatile emission of plants from different treatments. Furthermore, we show that JA-treated plants slowed P. solenopsis development, but plants pre-infested by P. solenopsis accelerated its development. We also show that P. solenopsis feeding inhibited the JA-regulated gossypol production, and prevented the induction of JA-related genes. We conclude that P. solenopsis is able to prevent the activation of JA-dependent defenses associated with basal resistance to mealybugs.

Previous infestation of pea aphidsAcyrthosiphon pisumon broad bean plants resulted in the increased performance of conspecific nymphs on the plants

“…Taken together, our results showed that pea aphids manipulated JArelated defenses in broad bean plants, and exogenous JA treatment could recover the defense levels. Whitefly (Zarate et al 2007) and mealybug (Zhang et al 2011) were reported to increase the quality of host plants by suppressing the induction of JArelated defensive responses. Our study was the first to show that aphids suppressed the accumulation of JA.…”

“…Several studies have shown that sucking insects manipulate the nutritional factors in sieve-tube liquids and/or defeat plant defenses (Fisher 1987;Zarate et al 2007;Walling 2008;Sarmento et al 2011). Phloem-feeding silverleaf whitefly Bemisia tabaci (Zarate et al 2007) and mealybug Phenacoccus solenopsis (Zhang et al 2011) enhanced food-plant quality by manipulating the induction of JA-related defensive responses in plants. The performances of yellow sugarcane aphids (Sipha flava) on sorghum plants previously infested by conspecifics were higher than those on uninfested sorghum plants (Gonzales et al 2002).…”

Spodoptera exigua modulates gossypol biosynthesis in cotton Gossypium hirsutum

“…Gossypol is an important allelochemical produced by the subepidermal glands of some cotton varieties and exhibits antibiosis against some cotton pests (Wu et al 2010). High gossypol level expressed by some cotton varieties has been shown to affect feeding and development of certain insect pests (Du et al 2004;Mao et al 2007;Zhang et al 2011). Zhang et al (2011) demonstrated that exogenous application of jasmonic acid (JA) to cotton plants resulted in increased levels of gossypol, and nymphs of the mealybug Phenacoccus solenopsis that fed on JA-treated cotton plants showed reduced growth and development.…”

“…High gossypol level expressed by some cotton varieties has been shown to affect feeding and development of certain insect pests (Du et al 2004;Mao et al 2007;Zhang et al 2011). Zhang et al (2011) demonstrated that exogenous application of jasmonic acid (JA) to cotton plants resulted in increased levels of gossypol, and nymphs of the mealybug Phenacoccus solenopsis that fed on JA-treated cotton plants showed reduced growth and development. JA is a key phytohormone involved in plant defense against herbivores (War et al 2011), which is derived from linolenic acid through octadecanoid pathway and accumulates upon herbivory in plant tissues (Zhang et al 2008).…”

Do organic silicon and imidacloprid synergistically induce toxicity to the new invasive mealybug Phenacoccus solenopsis Tinsley on Portulaca grandiflora plants?

“…Like most of the scale insect species, P. solenopsis is an obligate phloem-feeding pest (Arif et al, 2009;Zhang et al, 2011;Huang F et al, 2012) and causes fruits, vegetables, and flower buds to drop off prematurely. In a bad infestation, their honeydew induces the development of sooty mold fungus (Saeed et al, 2007).…”