Impact of hydroxylated and non-hydroxylated aliphatic glucosinolates in Arabidopsis thaliana crosses on plant resistance against a generalist and a specialist herbivore

Abstract

Glucosinolates (GSs) are part of a two-component defence system, characteristic for the Brassicales, including the model species Arabidopsis thaliana (L.) Heynh. The defence activity of GSs is associated with different side chain structures. The AOP genes are central in side-chain modification. AOP2 mediates formation of alkenyl GS from a methylsulfinyl precursor, whereas AOP3 catalyzes production of hydroxy-alkyl GSs from the same precursor. Although several studies have assessed the role of GSs in plant defence, the function of specific aliphatic GSs in plant defence is still not clarified. Structural different GSs may influence insect herbivores differentially. We created a set of plant lines derived of a cross between two A. thaliana accessions, Gie-0 9 Sap-0, which dominantly accumulate either 3-methylsulfinylpropyl GS or 3-hydroxypropyl GS. The generalist Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) and the crucifer-specialist Pieris brassicae (L.) (Lepidoptera: Pieridae) were used as model insects, to study effects of individual aliphatic GSs on lepidopteran herbivores with a different feeding specialization. However, the experiments revealed that weight gain of S. exigua and P. brassicae third and fourth-larval instars was similar on both chemotypes. But leaf consumption of the generalist was higher on 3-methylsulfinylpropyl-producing lines with low GS levels (23.2 lmol g -1 ) than on 3-hydroxypropylproducing lines that contained a more than twofold higher amount of GSs (60 lmol g -1 ). In contrast, no differential effects of non-hydroxylated and hydroxylated GSs were found on the specialist P. brassicae. Our study indicates that there is no simple relationship between GS content and insect responses.

Induced Production of 1-Methoxy-indol-3-ylmethyl Glucosinolate by Jasmonic Acid and Methyl Jasmonate in Sprouts and Leaves of Pak Choi (Brassica rapa ssp. chinensis)

“…Less attention has been paid to biosynthesis of indole glucosinolates, although these glucosinolates are induced by insect or pathogen attacks [12–15] and also influence the oviposition of crucifer specialist insects [16]. Indole glucosinolates were most prominent in roots and also found in leaves [17], therefore Brassicaceae providing breakdown products of glucosinolates are a good source for plant based manure and biofumigation, respectively [18].…”

Host-plant resistance to western flower thrips in Arabidopsis

“…Only a relatively small degree of such variation is contained in cultivated crop populations , but wild populations provide ample opportunities for discovering novel mechanisms responsible for resistance to insects. A wide range of resistance mechanisms against herbivorous insects has been described (Panda andKhush 1995, Schoonhoven, van Loon et al 2005), and the impact of mechanisms depends on the characteristics of the herbivore, such as insect diet breadth (Mewis, Tokuhisa et al 2006, Rohr, Ulrichs et al 2011. Although specialist insects, feeding on one or a few plant species within one family, are considered to be resistant to toxic compounds of their host (Karban and Agrawal 2002), generalist insects are thought to thrive on a wider range of hosts with relatively low levels of allelochemicals (Loxdale, Lushai et al 2011, Price, Denno et al 2011.…”

“…This has likely influenced the evolution of signaling pathways in Arabidopsis, because the main biotic stresses likely comprise pathogens such as oomycetes, bacteria and fungi. Still, Arabidopsis is of great interest for studying insect resistance, since many insect defense mechanisms have been evolved within the Brassicaceae family, such as glucosinolates (Mewis, Appel et al 2005, Mewis, Tokuhisa et al 2006, Rohr, Ulrichs et al 2011, and, many defense mechanisms against pathogens are also effective against herbivorous insects. Leaf toughness is for example effective against both microbial pathogens and insects (Schoonhoven, van Loon et al 2005), and salicylic acid-, jasmonic acid-and ethylene-regulated defenses are involved in defenses against both pathogen and insect infestations (De Vos, Van Oosten et al 2005, Mewis, Tokuhisa et al 2006, Pieterse, Leon-Reyes et al 2009, Verhage, Vlaardingerbroek et al 2011.…”

“…So far, only few GWA studies have been reported that deal explicitly with plant-defense mechanisms against herbivorous insects (see for an example on aphids). One such study on glucosinolates (GSLs)secondary defense metabolites within the Brassicaceae family involved in resistance 2 against herbivorous insects (Mewis, Appel et al 2005, Mewis, Tokuhisa et al 2006, Rohr, Ulrichs et al 2011 was conducted using 96 Arabidopsis accessions exhibiting 43 distinct GSL phenotypes and 230.000 SNPs (Chan, Rowe et al 2010). In this study, GWA analysis successfully identified two major polymorphic loci controlling GSL variation in natural populations, but variation in resistance to specialist and generalist insects remains to be investigated for these accessions.…”

The role of food nutrition: effects on foraging behavior, dealing with plant secondary metabolites and parasites in Helicoverpa armigera larvae

“…The adverse effect of isothiocyanates (ITCs) on insects has been noted in previous research (Li et al 2000, Ratzka et al 2002, Burow et al 2006, Mumm et al 2008, Rohr et al 2011, however, due to the characteristics of these chemicals, ITCs are mostly volatile, which makes it difficult to address this topic directly. The use of microencapsulated AITC was first introduced by Agrawal and Kurashige (2003) to investigate the interaction in Pieris rapae (Linnaeus) (Lepidoptera: Pieridae).…”