Interação de proteínas Cry1 e Vip3A de Bacillus thuringiensis para controle de lepidópteros‑praga

The objective of this work was to evaluate the susceptibility of Anticarsia gemmatalis (Lepidoptera: Erebidae) and Chrysodeixis includens (Lepidoptera: Noctuidae) caterpillars to Cry1 and Vip3A proteins, as well as to determine if there is any interaction between these proteins on the control of the two species. Bioassays with both isolated and combined proteins were carried out, and lethal concentrations LC50 and LC90 were estimated for each condition. Cry1Aa, Cry1Ac, and Vip3Af were the more effective proteins for the control of A. gemmatalis, while Cry1Ac, Vip3Aa, and Vip3Af were more effective for the control of C. includens. Cry1Ac and Cry1Ca proteins caused the highest inhibition to the development of larvae that survived the LC50 dose in both species. Different combinations of Vip3A and Cry1 have synergistic effect in the control of both species, and the combination Vip3Aa + Cry1Ea showed an outstanding control of A. gemmatalis and C. includens. These proteins are promising for building pyramided plants for the simultaneous control of the pests.O objetivo deste trabalho foi avaliar a suscetibilidade das lagartas Anticarsia gemmatalis (Lepidoptera: Erebidae) e Chrysodeixis includens (Lepidoptera: Noctuidae) às proteínas Cry1 e Vip3A, bem como determinar se há a interação entre essas proteínas no controle das duas espécies. Bioensaios com as proteínas isoladas e em combinações foram realizados, e as concentrações letais CL50 e CL90 foram estimadas para cada condição. As proteínas Cry1Aa, Cry1Ac e Vip3Af foram as mais efetivas no controle de A. gemmatalis, enquanto Cry1Ac, Vip3Aa e Vip3Af foram mais efetivas no de C. includens. As proteínas Cry1Ac e Cry1Ca causaram maior inibição do desenvolvimento das larvas sobreviventes à CL50, em ambas as espécies. Combinações entre Vip3A e Cry1 apresentam efeito sinérgico no controle das espécies e a combinação Vip3Aa+Cry1Ea destaca-se no controle de A. gemmatalis e C. includens. Essas proteínas combinadas são promissoras na construção de plantas piramidadas, para o controle simultâneo das pragas

Interaction of Cry1 and Vip3A proteins of Bacillus thuringiensis for the control of lepidopteran insect pests

O objetivo deste trabalho foi avaliar a suscetibilidade das lagartas Anticarsia gemmatalis (Lepidoptera: Erebidae) e Chrysodeixis includens (Lepidoptera: Noctuidae) às proteínas Cry1 e Vip3A, bem como determinar se há a interação entre essas proteínas no controle das duas espécies. Bioensaios com as proteínas isoladas e em combinações foram realizados, e as concentrações letais CL50 e CL90 foram estimadas para cada condição. As proteínas Cry1Aa, Cry1Ac e Vip3Af foram as mais efetivas no controle de A. gemmatalis, enquanto Cry1Ac, Vip3Aa e Vip3Af foram mais efetivas no de C. includens. As proteínas Cry1Ac e Cry1Ca causaram maior inibição do desenvolvimento das larvas sobreviventes à CL50, em ambas as espécies. Combinações entre Vip3A e Cry1 apresentam efeito sinérgico no controle das espécies e a combinação Vip3Aa+Cry1Ea destaca-se no controle de A. gemmatalis e C. includens. Essas proteínas combinadas são promissoras na construção de plantas piramidadas, para o controle simultâneo das pragas.The objective of this work was to evaluate the susceptibility of Anticarsia gemmatalis (Lepidoptera: Erebidae) and Chrysodeixis includens (Lepidoptera: Noctuidae) caterpillars to Cry1 and Vip3A proteins, as well as to determine if there is any interaction between these proteins on the control of the two species. Bioassays with both isolated and combined proteins were carried out, and lethal concentrations LC50 and LC90 were estimated for each condition. Cry1Aa, Cry1Ac, and Vip3Af were the more effective proteins for the control of A. gemmatalis, while Cry1Ac, Vip3Aa, and Vip3Af were more effective for the control of C. includens. Cry1Ac and Cry1Ca proteins caused the highest inhibition to the development of larvae that survived the LC50 dose in both species. Different combinations of Vip3A and Cry1 have synergistic effect in the control of both species, and the combination Vip3Aa + Cry1Ea showed an outstanding control of A. gemmatalis and C. includens. These proteins are promising for building pyramided plants for the simultaneous control of the pests

Synergism and Antagonism between Bacillus thuringiensis Vip3A and Cry1 Proteins in Heliothis virescens, Diatraea saccharalis and Spodoptera frugiperda

Second generation Bt crops (insect resistant crops carrying Bacillus thuringiensis genes) combine more than one gene that codes for insecticidal proteins in the same plant to provide better control of agricultural pests. Some of the new combinations involve co-expression of cry and vip genes. Because Cry and Vip proteins have different midgut targets and possibly different mechanisms of toxicity, it is important to evaluate possible synergistic or antagonistic interactions between these two classes of toxins. Three members of the Cry1 class of proteins and three from the Vip3A class were tested against Heliothis virescens for possible interactions. At the level of LC50, Cry1Ac was the most active protein, whereas the rest of proteins tested were similarly active. However, at the level of LC90, Cry1Aa and Cry1Ca were the least active proteins, and Cry1Ac and Vip3A proteins were not significantly different. Under the experimental conditions used in this study, we found an antagonistic effect of Cry1Ca with the three Vip3A proteins. The interaction between Cry1Ca and Vip3Aa was also tested on two other species of Lepidoptera. Whereas antagonism was observed in Spodoptera frugiperda, synergism was found in Diatraea saccharalis. In all cases, the interaction between Vip3A and Cry1 proteins was more evident at the LC90 level than at the LC50 level. The fact that the same combination of proteins may result in a synergistic or an antagonistic interaction may be an indication that there are different types of interactions within the host, depending on the insect species tested.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Evaluation of antagonism, at the LC₅₀ and LC₉₀ level, of combinations of Vip3A and Cry1 protoxins to <i>H. virescens</i> neonate larvae.

a<p>Each data point was obtained from three replicates of 16 larvae per replicate (n = 48).</p>b<p>Proportions of proteins were chosen approximately to match those of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0107196#pone-0107196-t002" target="_blank">Table 2</a>.</p>c<p>Slope ± standard error.</p>d<p>FL₉₅: 95% fiducial limits.</p>e<p>Expected mortality considering simple similar action.</p>f<p>AF: Antagonism factor, calculated as the ratio of the observed LC₅₀ over the expected LC₅₀. NS = not significant.</p><p>Evaluation of antagonism, at the LC₅₀ and LC₉₀ level, of combinations of Vip3A and Cry1 protoxins to <i>H. virescens</i> neonate larvae.</p

Susceptibility of <i>D. saccharalis</i> and <i>Spodoptera frugiperda</i> neonate larvae to Vip3Aa and Cry1Ca protoxins and their 1: 2 combination.

a<p>Slope ± standard error.</p>b<p>Each data point was obtained from three replicates of 16 larvae per replicate (n = 48).</p>c<p>FL₉₅: 95% fiducial limits.</p>d<p>Expected mortality considering simple similar action.</p>e<p>AF: Antagonism factor.</p><p>Susceptibility of <i>D. saccharalis</i> and <i>Spodoptera frugiperda</i> neonate larvae to Vip3Aa and Cry1Ca protoxins and their 1: 2 combination.</p

Susceptibility of <i>H. virescens</i> neonate larvae to Cry1 and Vip3A protoxins.^a

a<p>Values represent the mean from three replicates of 16 larvae per replicate (n = 48).</p>b<p>Slope ± standard error.</p>c<p>Values are expressed as µg/cm² with 95% fiducial limits (at 5 days).</p><p>Susceptibility of <i>H. virescens</i> neonate larvae to Cry1 and Vip3A protoxins.^{<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0107196#nt101" target="_blank">a</a>}</p

SDS-PAGE of <i>Escherichia coli</i> lysates.

<p>MM, Molecular Mass Marker “Spectra TM Multicolor Broad Range Protein Ladder” (Fermentas); lane 1, Vip3A not induced with IPTG; lane 2, Vip3Aa; lane 3, Vip3Ae; lane 4, Vip3Af lane 5, Cry1Aa; lane 6, Cry1Ac; lane 7, Cry1Ca.</p

Susceptibility of <i>H. virescens</i> neonate larvae to combinations of Vip3A and Cry1 protoxins.

a<p>Concentrations of proteins were chosen such as to equal their respective LC₅₀ values. Values are expressed as µg/cm².</p>b<p>Each value represents the mean from three replicates of 16 larvae per replicate (n = 48).</p>c<p>Expected mortality considering simple independent action.</p>d<p>Asterisks indicate significant differences at P<0.05, and two asterisks at P<0.001.</p>e<p>Chi-square and P values.</p><p>Susceptibility of <i>H. virescens</i> neonate larvae to combinations of Vip3A and Cry1 protoxins.</p