PeaT1 and PeBC1 Microbial Protein Elicitors Enhanced Resistance against Myzus persicae Sulzer in Chili Capsicum annum L

Abstract

The green peach aphid (Myzus persicae Sulzer), a major and harmful chili aphid usually managed using chemical pesticides, is responsible for massive annual agricultural losses. The efficacy of two protein elicitors, PeaT1 and PeBC1, to stimulate a defensive response against M. persicae in chili was studied in this study. When compared to positive (water) and negative (buffer, 50 mM Tris-HCl, pH 8.0) controls, the rates of population growth (intrinsic rate of increase) of M. persicae (second and third generations) were lower with PeaT1- and PeBC1-treated chilli seedlings. M. persicae demonstrated a preference for colonizing control (12.18 ± 0.06) plants over PeaT1- (7.60 ± 0.11) and PeBC1 (6.82 ± 0.09) treated chilli seedlings in a host selection assay. Moreover, PeaT1- and PeBC1-treated chilli seedlings, the nymphal development period of the M. persicae was extended. Similarly, fecundity was lowered in the PeaT1- and PeBC1-treated chilli seedlings, with fewer offspring produced compared to the positive (water) and negative controls (50 mM Tris-HCl, pH 8.0). The trichomes and wax production on the PeaT1 and PeBC1-treated chilli leaves created a disadvantageous surface environment for M. persicae. Compared to control (30.17 ± 0.16 mm^-2), PeaT1 (56.23 ± 0.42 mm^-2) and PeBC1 (52.14 ± 0.34 mm^-2) had more trichomes. The levels of jasmonic acid (JA), salicylic acid (SA), and ethylene (ET) were significantly higher in the PeaT1- and PeBC1-treated chili seedlings, indicating considerable accumulation. PeaT1 and PeBC1 significantly affected the height of the chili plant and the surface structure of the leaves, reducing M. persicae reproduction and preventing colonization, according to the data. The activation of pathways was also part of the defensive response (JA, SA, and ET). This present research findings established an evidence of biocontrol for the utilization of PeaT1 and PeBC1 in the defence of chili plants against M. persicae.

Keywords: EPG; M. persicae; PeBC1; PeaT1; defense pathways; induced plant resistance against aphids.

Figure 1

M. persicae feeding preferences (A) M. persicae preferred feeding on control plants in PeaT1; (B) M. persicae feeding on PeBC1-treated and control-treated chilli seedlings 24 h after infestation colonization (mean ± SD). SPSS 18.0 was used to compare data using one-way analysis of variance (ANOVA) and the least significant difference (LSD). Lower style alphabet letters show significant variations across all treatments. (p = 0.05).

Figure 2

In PeaT1- and PeBC1-treated (A,B) and control seedlings of chili, developmental time, reproductive capacity, and growth of the intrinsic rate of M. persicae are reported as mean ± SD. Td stands for development period, nymphs per day stands for average reproduction ability, and r_m stands for intrinsic rate rise. To compare data, SPSS 18.0 was utilized with one-way analysis of variance (ANOVA) and the least significant difference (LSD) (p = 0.05).

Figure 3

Mean developmental time, (±SE) of different nymphal instars of M. persicae on chili plants by PeaT1 elicitor protein at different concentrations and different temperature (23, 25, 27 °C) regimes (n = 10). Different alphabets above bar tops specify significant differences between treatments (factorial analysis one way ANOVA; LSD at α = 0.05).

Figure 4

Mean developmental time (±SE) of different nymphal instars of M. persicae on chili plants by PeBC1 elicitor protein at different concentrations and different temperature (23, 25, 27 °C) regimes (n = 10). Different alphabets above bar tops specify significant differences between treatments (factorial analysis one way ANOVA; LSD at α = 0.05).

Figure 5

Average fecundity with (±SE) of aphids (M. persicae) on chili plants with various PeaT1 elicitor protein changed concentrations at different altered temperature regimes (n = 10); alphabet letters on each bar’s top show inequalities between treatments (factorial analysis one-way ANOVA; LSD at α = 0.05). Fecundity was reduced in PeaT1-treated seedlings.

Figure 6

Average fecundity with (±SE) of aphids (M. persicae) on chili plants with various PeBC1 elicitor protein changed concentrations at different altered temperature regimes (n = 10); alphabet letters on each bar’s top show inequalities between treatments (factorial analysis one-way ANOVA; LSD at α = 0.05). Fecundity was reduced in PeBC1-treated seedlings.

Figure 7

Influence of PeaT1 and PeBC1 on the growth of treated chili seedlings (A,B). Average growth parameters with (±SE) of chili plants in PeaT1, PeBC1, buffer, and control-treated seedlings (n = 10). Statistically, data were compared by the least significant difference (LSD), one-way analysis of variance (ANOVA), and Levene’s test in SPSS 18.0. Different lower style alphabets letters indicate a significant difference in different treatment patterns (p = 0.05).

Figure 8

Chili seedlings’ jasmonic acid (JA), salicylic acid (SA), and ethylene (ET) levels (mean ± SD). (A,B), respectively. One day after spraying, data on PeaT1 and PeBC1 treatment was collected. The aphids were inoculated one day after seedlings were sprayed in both treatments, and samples were collected one day later. The LSD, ANOVA, and Leven’s test were used to compare data statistically. Version 8.1 of Statistix. Lower-case letters indicate significant differences between various treatments in JA, SA, or ET (p = 0.05).

Figure 9

Treatment with PeaT1-elicitor, PeaT1 with aphid, and aphid infestation alone revealed relative expression of the JA, SA, and ET pathway genes. One day after spraying, PeaT1 treatment was carried out. The aphids were inoculated one day after the seedlings were sprayed in both treatments, and the samples were collected one day later. Using SPSS 18.0, data were compared using LSD, one-way ANOVA, and Levene’s test. The fold expression of treated chilli seedlings is represented by bars. Controls were given a relative fold expression of 0.54.

Figure 10

Treatment with PeBC1-elicitor, PeBC1 with aphid, and aphid infestation alone revealed relative expression of the JA, SA, and ET pathway genes. One day after spraying, PeaT1 treatment was carried out. The aphids were inoculated one day after the seedlings were sprayed in both treatments, and the samples were collected one day later. Using SPSS 18.0, data were compared using LSD, one-way ANOVA, and Levene’s test. The fold expression of treated chilli seedlings is represented by bars. Controls were given a relative fold expression of 0.54.