Potential Use of a Serpin from Arabidopsis for Pest Control

Abstract

Although genetically modified (GM) plants expressing toxins from Bacillus thuringiensis (Bt) protect agricultural crops against lepidopteran and coleopteran pests, field-evolved resistance to Bt toxins has been reported for populations of several lepidopteran species. Moreover, some important agricultural pests, like phloem-feeding insects, are not susceptible to Bt crops. Complementary pest control strategies are therefore necessary to assure that the benefits provided by those insect-resistant transgenic plants are not compromised and to target those pests that are not susceptible. Experimental GM plants producing plant protease inhibitors have been shown to confer resistance against a wide range of agricultural pests. In this study we assessed the potential of AtSerpin1, a serpin from Arabidopsis thaliana (L). Heynh., for pest control. In vitro assays were conducted with a wide range of pests that rely mainly on either serine or cysteine proteases for digestion and also with three non-target organisms occurring in agricultural crops. AtSerpin1 inhibited proteases from all pest and non-target species assayed. Subsequently, the cotton leafworm Spodoptera littoralis Boisduval and the pea aphid Acyrthosiphon pisum (Harris) were fed on artificial diets containing AtSerpin1, and S. littoralis was also fed on transgenic Arabidopsis plants overproducing AtSerpin1. AtSerpin1 supplied in the artificial diet or by transgenic plants reduced the growth of S. littoralis larvae by 65% and 38%, respectively, relative to controls. Nymphs of A. pisum exposed to diets containing AtSerpin1 suffered high mortality levels (LC50 = 637 µg ml−1). The results indicate that AtSerpin1 is a good candidate for exploitation in pest control.

Set‐point control of RD21 protease activity by AtSerpin1 controls cell death in Arabidopsis

“…AtSerpin1 was also shown to inhibit the activity of Arabidopsis AtMC9, a type‐2 metacaspase of unknown function (Vercammen et al ., ). However, other roles for AtSerpin1 have been suggested that are related to its ability to directly inhibit the proteases of herbivorous insects (Roberts and Hejgaard, ; Alvarez‐Alfageme et al ., ). Thus, the biological significance of protease inhibition by plant serpins remains to be established.…”

Juggling jobs: roles and mechanisms of multifunctional protease inhibitors in plants

“…The biological role(s) of serpins remains somewhat unclear, although there are hints in two directions. First, artificial diets containing serpins impair growth and fertility of insect pests, indicating a potential role in defence and highlighting the potential serpins hold for crop improvement (Thomas et al, 1994(Thomas et al, , 1995Yoo et al, 2000;Alvarez-Alfageme et al, 2011). Second, two putative plant target proteases of A. thaliana serpin 1 (AtSerpin1) are involved in programmed cell death (PCD), suggesting that AtSerpin1 could have a prosurvival function.…”

Resistance to sap-sucking insects in modern-day agriculture

“…Hence, if GM strategies are to be used, these insect pests require other GM resistance strategies. GM approaches using plant-derived lectins, agglutinin, and protease inhibitors have been shown to provide high levels of resistance to aphids and other phloem-feeding insect species (Fitches et al, 2008; Alvarez-Alfageme et al, 2011; Carrillo et al, 2011). In addition, in planta expression of RNAi-vectors that target physiologically important insect transcripts for degradation, have been shown to result in crop protection against a number of insect pests, including phloem-feeding aphids (Price and Gatehouse, 2008; Upadhyay et al, 2011; Zha et al, 2011).…”