Role of Saponins in Plant Defense against the Diamondback Moth, Plutella xylostella (L.)

Abstract

Abstract:The diamondback moth (DBM), Plutella xylostella L. (Lepidoptera: Plutellidae) is very destructive crucifers specialized pest that has resulted in significant crop losses worldwide. The pest is well attracted to glucosinolate-containing crucifers such as; Barbarea vulgaris (Brassicaceae), and generally to other plants in the genus Barbarea. B. vulgaris on their part, build up resistance against DBM and other herbivorous insects using glucosinolates; that are plant secondary metabolites used in plant defense-contained only in plants of the order Brassicales. Aside glucosinolates, plants in this genus Barbarea (Brassicaceae) also contain saponins; which is toxic to insects and act as feeding deterrents for plant herbivores, most importantly, DBM, as it was found to prevent the survival of DBM larvae on the plant. Saponins are plant secondary metabolites have been established in higher concentrations in younger in contrast to older leaves within the same plant. Previous studies have found a relationship between ontogenetical changes in the host plant's saponin content and attraction/resistance to P. xylostella. The younger leaves recorded higher concentrations of glucosinolates and saponins, which naturally attracts the plant herbivores. DBM was reported to have evolved mechanisms to avoid the toxicity of the former. The plant-herbivore had adapted glucosinolates for host plant recognition, feeding and oviposition stimulants. Despite the adaptation for oviposition by P. xylostella adults, larvae of the insect cannot survive on the same plant. An example is in some varieties of B. vulgaris. The triterpenoid saponins which act as feeding deterrents in larvae are responsible for this direct defense mechanism against P. xylostella. In the future, trials by plant breeders could aim at transferring this insect resistance to other crops. The previous trials had limited because of lack of knowledge on the biosynthetic pathways and regulatory networks of saponins. Herein, we discussed exclusively; saponins mediated plant defense mechanisms against the DBM.

The Arbuscular Mycorrhizal Fungus Rhizophagus irregularis MUCL 41833 Modulates Metabolites Production of Anchusa officinalis L. Under Semi-Hydroponic Cultivation

“…Wide diversity of chemical structures is reported in the plant kingdom on the basis of aglycone structure and the nature of glycosylation (Mugford and Osbourn, 2013 ). Their content is influenced by various biotic stimuli, such as herbivory and pest attack or related to plant-microorganism symbiosis (Hussain et al, 2017 ). Interestingly, the ability to produce these compounds has been already reported for Anchusa spp., specifically oleanane-type glycosidic derivatives mainly present in the foliar part of the plants (Koz et al, 2009 ; Chen et al, 2017 ).…”

Toxicity and Antifeedant Activity of Calotropis gigantea L. Leaf Extract Against Plutella xylostella L. (Lepidoptera: Plutellidae)

“…Saponins are toxic and antifeedant [35]. Some saponins form complexes with proteins [36] that inhibit proteinase and affect insect digestion [27]. Saponins indirectly affect the insect gut microbiome, several digesting enzymes, and mucous membranes.…”

The Metabolic Profile of Anchusa officinalis L. Differs According to Its Associated Arbuscular Mycorrhizal Fungi

“…In our analysis, and in contrast to the phenylpropanoids derivatives, these compounds were essentially affected/modulated in the shoots of A. officinalis . Saponins are involved in plant defense mechanisms against biotic constraints, such as pest or herbivores attack, and their content is strongly influenced by plant-AMF symbiosis [ 47 , 48 , 49 ]. Nine significantly modulated compounds from the different AMF treatments were tentatively identified.…”