ZINC-INDUCED RESISTANCE MECHANISM IN RICE AGAINST WHITE-BACKED PLANTHOPPER INFESTATION

Abstract

Eight zinc treatments, including basal and foliar applications of ZnSO₄ and Zn-EDTA at 30 and 45 days after transplanting (DAT), and their combinations, were evaluated for inducing host plant resistance against the white-backed planthopper (WBPH), a destructive sucking pest, in the highly sensitive rice variety TN 1. A control treatment without zinc application was also included. Pot-grown rice plants were maintained in Mylar cages with fine muslin cloth covering the top and kept until maturity. At 46 DAT, one gravid female WBPH was introduced into each cage, and insect population buildup was assessed after one month. Leaf samples were collected at 60 DAT for soluble protein profiling using SDS-PAGE. The protein data were analyzed for clustering patterns to identify defense-related changes induced by different zinc treatments. This study aimed to explore the role of zinc in enhancing plant resistance to WBPH through biochemical and physiological mechanisms.

Specification

Description:FIELD OF INVENTION
The field of interest involves studying the zinc-induced resistance mechanism in rice against white-backed planthopper infestation. This includes exploring molecular, biochemical, and physiological responses triggered by zinc application, focusing on defense gene activation, secondary metabolite production, and enhanced plant immunity. The aim is to develop sustainable pest management strategies and improve rice crop resilience and productivity.
BACKGROUND OF INVENTION
The white-backed planthopper (WBPH) is a significant pest that threatens rice cultivation, causing severe yield losses and affecting global food security. Conventional pest management strategies, such as chemical pesticides, have proven to be unsustainable due to their adverse environmental impacts, the evolution of pest resistance, and harm to non-target organisms. To address these challenges, researchers have turned to plant nutrition as a sustainable alternative to bolster crop resistance against pests.
Zinc (Zn) is an essential micronutrient that plays a vital role in plant growth and development, including enzyme activation, protein synthesis, and stress tolerance. Recent studies have demonstrated that zinc application can trigger a defense response in rice plants, enhancing their resistance against insect pests such as WBPH. The underlying mechanism involves the activation of defense-related genes, production of reactive oxygen species (ROS), synthesis of secondary metabolites like phenolics and flavonoids, and reinforcement of cell wall structures.
This invention explores the zinc-induced resistance (ZIR) mechanism in rice to mitigate WBPH infestation. It focuses on identifying the molecular pathways and biochemical processes activated by zinc to enhance plant immunity. The approach leverages zinc's ability to strengthen natural defense systems, minimizing the reliance on chemical pesticides.
The development of this resistance mechanism not only offers an environmentally friendly solution to WBPH management but also contributes to sustainable rice farming practices. By improving the resilience of rice crops, this innovation has the potential to secure food production in the face of growing agricultural challenges.
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SUMMARY
The invention focuses on the development and application of a zinc-induced resistance (ZIR) mechanism in rice plants to combat white-backed planthopper (WBPH) infestations. WBPH is a destructive pest that significantly reduces rice yields, posing a threat to global food security. Traditional pest management methods, such as chemical pesticides, are increasingly unsustainable due to environmental damage, resistance development in pests, and harm to beneficial organisms. This invention provides an eco-friendly and effective alternative by leveraging zinc's role in enhancing plant defense systems.
The ZIR mechanism involves the strategic application of zinc to rice plants, triggering a cascade of molecular, biochemical, and physiological defense responses. Zinc activates key defense-related genes involved in systemic acquired resistance (SAR) and induces the production of secondary metabolites like phenolics and flavonoids, which deter WBPH. Additionally, zinc enhances reactive oxygen species (ROS) production, reinforcing cell wall structures to create a physical barrier against pest penetration. These processes collectively improve the plant's innate immunity and reduce WBPH damage.
This invention outlines optimal zinc application methods, including foliar sprays and soil amendments, and identifies suitable zinc formulations to maximize resistance. By strengthening rice plants' natural defense mechanisms, the invention reduces dependency on synthetic pesticides, lowering environmental risks and production costs.
The ZIR approach aligns with sustainable agriculture goals, offering a practical solution to pest management while safeguarding rice yields. It has the potential to transform pest control practices in rice farming, ensuring food security and environmental health.
DETAILED DESCRIPTION OF INVENTION
A total of 19 polypeptide bands ranging from 14.3 to 97.4 kDa were identified. Notably, low molecular weight proteins (14.3-25.1 kDa) were absent in the control plants. Treatment T₆ (Zn-EDTA applied both as basal and foliar) resulted in the lowest WBPH population and exhibited the highest number of polypeptide bands (15), including five unique bands at 66.0, 37.0, 23.6, 15.8, and 14.3 kDa. Among these, the 66.0 kDa, 37.0 kDa, and 14.3 kDa bands were consistently observed in T₆, T₇ (ZnSO₄ basal + Zn-EDTA foliar), and T₈ (Zn-EDTA basal + ZnSO₄ foliar), treatments that recorded lower WBPH populations and clustered together in analysis. Interestingly, the 23.6 kDa band, induced exclusively in T₆ and T₇, appears to play a pivotal role in triggering the defense mechanism against WBPH in rice.
These differentially expressed proteins, absent in control plants, highlight the biochemical basis of zinc-induced resistance in rice, offering valuable insights into enhanced pest defense strategies.
Raising Plants in Pots → Plants Covered with Mylar Cages
|
Zinc Application (Basal, Foliar, and Combinations)
(ZnSO₄ & Zn-EDTA)
|
Release of One Adult Gravid Female Insect per Cage at 46 DAT
|
Assessment of WBPH Population Build-Up at 76 DAT
|
Biochemical Study:
1. Collection of Leaf Samples at 60 DAT
2. Extraction of Soluble Protein
3. Quantification of Soluble Protein
4. Soluble Protein Profiling (SDS-PAGE)
5. Identification of Differentially Expressed Protein Bands
| Interpretation of Host Plant Resistance to WBPH

Rice (Oryza sativa L.) is attacked by over 100 insect species, with the white-backed planthopper (WBPH, Sogatella furcifera) being one of the most destructive. This major sucking pest can cause yield losses ranging from 35% to 95% under favorable conditions. Intensive sap-sucking by WBPH, coupled with its high fecundity and long-distance migration capabilities, poses a severe threat to rice cultivation. The resulting "hopper burn" significantly impacts crop health. Unfortunately, no truly resistant rice variety has yet been developed to combat this pest effectively.
An eco-friendly and sustainable alternative to manage WBPH is the application of micronutrients, which can induce host plant resistance. Among micronutrients, zinc has proven highly effective in inducing antibiosis effects against pests like WBPH, brown planthopper (BPH), and green leafhopper (GLH), leading to reduced nymphal survival, growth, and population buildup. The incidence of BPH has also been inversely correlated with zinc and sulfur content in rice foliage following the application of ZnSO₄ with NPK fertilizers.
Zinc plays a crucial role in the expression of defense-related proteins. Studies have shown that pest infestation induces specific proteins in rice plants, such as a 53 kDa protein associated with leaf folder resistance and a 38 kDa protein linked to leaf folder tolerance. These findings suggest that zinc-mediated defense mechanisms involve the activation of specific proteins, highlighting its potential as a sustainable approach to enhance rice resistance against WBPH and other pests.
Zinc Treatments and Experimental Setup
To evaluate the impact of zinc on WBPH (Sogatella furcifera) tolerance in rice, 20-day-old seedlings of a susceptible rice variety, TN 1, were transplanted into 10 kg capacity earthen pots filled with puddled soil. A total of nine zinc treatment combinations were applied:
1. T1: Basal application of ZnSO₄ (25 kg ha⁻¹).
2. T2: Basal application of Zn EDTA (40 kg ha⁻¹).
3. T3: Foliar spray of ZnSO₄ (0.5%) at 30 and 45 days after transplanting (DAT).
4. T4: Foliar spray of Zn EDTA (0.8%) at 30 and 45 DAT.
5. T5: Combined application of T1 and T3.
6. T6: Combined application of T2 and T4.
7. T7: Combined application of T1 and T4.
8. T8: Combined application of T2 and T3.
9. T9: A control group without any zinc application.
After applying the recommended fertilizer doses and basal zinc treatments, the plants were covered with 45 cm high Mylar cages sealed with fine muslin cloth to ensure controlled conditions. Foliar zinc treatments were applied at 30 and 45 DAT. The experiment was conducted in the greenhouse at the Department of Entomology, College of Agriculture, Odisha University of Agriculture and Technology (OUAT), Bhubaneswar.
Assessment of WBPH Population
At 46 DAT, a single gravid female WBPH adult was released into each cage. The population of WBPH was assessed one month later (60 DAT) following the methodology outlined by Heinrichs et al. (1985). This stage was selected as the control plants (without zinc treatment) exhibited the highest WBPH population, serving as a benchmark for comparing treatment effects.
Soluble Protein Extraction and Quantification
Leaf samples were collected at 60 DAT for the analysis of total soluble proteins and to identify potential defense-related proteins linked to WBPH tolerance. Proteins were extracted using a Tris-HCl buffer (20 mM, pH 7.5), supplemented with magnesium chloride (50 mM), polyvinylpyrrolidone (2%), and phenylmethylsulfonyl fluoride (1 mM). Protein precipitation was achieved using 50% TCA + 1% β-mercaptoethanol, followed by solubilization in a buffer containing 9M urea, 4% CHAPS, 1% DTT, and 2% Bio-Lyte. The total protein content was quantified using the Lowry method (1951).

Soluble Protein Profiling and Gel Documentation
Protein profiling was performed using SDS-PAGE as described by Lagrimini and Rothstein (1987). The procedure involved staining with 0.125% Coomassie Brilliant Blue R-250, destaining, and washing to visualize protein bands. The gels were scanned using a Gel Documentation System (Fire Reader-Uvtec, Cambridge, UK) to assess the banding patterns and photograph the results.
Key Steps:
• Polypeptide bands were scored as present (1) or absent (0).
• Relative mobility and molecular weights were determined using protein markers (14.3 to 97.4 kDa).
• Unique protein bands were noted for their association with WBPH tolerance.
Statistical Analysis
• Total Soluble Protein and WBPH Population: Data were analyzed using Duncan's Multiple Range Test (1955), with significant differences assessed at P ≤ 0.05.
• Protein Profile Analysis: Jaccard's similarity coefficients and clustering dendrograms were constructed to determine relationships among zinc treatments and their effects on protein expression and WBPH tolerance.
Results and Discussion
The zinc treatments showed significant variations in WBPH population and total soluble protein content. Plants treated with zinc, particularly in combinations involving basal and foliar applications, exhibited reduced WBPH population buildup compared to control plants. Specific polypeptides induced by zinc treatments were identified, indicating potential defense mechanisms in rice against WBPH.
The molecular weights of the unique protein bands varied, with notable proteins aligning with earlier findings of defense-related proteins induced by pest infestation. Treatments involving Zn EDTA showed enhanced protein expression compared to ZnSO₄, suggesting higher bioavailability and effectiveness of EDTA-chelated zinc.
In summary, the combined application of basal and foliar zinc treatments significantly improved rice plant tolerance to WBPH by inducing specific defense proteins and reducing pest population buildup. These findings support the use of zinc as an eco-friendly and sustainable approach to manage WBPH in rice cultivation.
The preference or non-preference of a plant variety by insects is largely determined by the population load of the insect on the variety over a given period. A higher insect population on a plant indicates its greater suitability to the insect, which often corresponds to susceptibility. Conversely, if a plant variety has built-in resistance mechanisms, it tends to be unsuitable to the insect, resulting in fewer individuals.
The results of this study, as presented in Table 1, show significant differences in the population build-up of WBPH on rice plants subjected to various zinc treatments. The highest population of WBPH was observed in the control treatment (79.2 insects per hill), which was significantly higher than in all other zinc-treated plants. The lowest WBPH population (31.4 insects per hill) was found in the T6 treatment, which was statistically different from all other treatments. Even the T5 treatment resulted in nearly 60% fewer insects compared to the control. The treatments T7 and T8 supported 38.2 and 41.6 insects per hill, respectively, compared to the control. Although there was some variation between treatments, T2 and T3 did not significantly differ from T1 and T4. Previous studies have also shown that zinc application reduces the WBPH population on rice, likely due to the increased zinc and silica content in plants, which enhances their resistance to pests.
The total soluble protein content in the leaves of rice cv. TN1 was found to be 8.76 mg/g in the untreated control. In contrast, all zinc treatments, except for T1, showed an increase in protein content. The highest protein content was observed in T6 (10.51 mg/g), which was similar to T8 (10.43 mg/g) and T7 (9.93 mg/g). These treatments also showed lower WBPH populations. The increase in soluble protein content may be due to the overexpression of defense-related proteins, although the precise role of zinc application in this increase is not fully understood. In some studies, a decrease in total protein content was observed in resistant rice varieties when exposed to specific pests.
Table 1: Effect of Zinc Application on Total Soluble Protein Content and White-backed Plant Hopper (WBPH) Population Build-up in Rice
Treatment Total Soluble Protein (mg/g) WBPH Population Build-up (per plant)
T1: ZnSO₄ Basal (25 kg/ha) 8.89 53.60
T2: Zn EDTA Basal (40 kg/ha) 9.15 51.20
T3: ZnSO₄ Foliar Spray @ 0.5% (Twice at 30 and 45 DAT) 9.31 49.80
T4: Zn EDTA Foliar Spray @ 0.8% (Twice at 30 and 45 DAT) 9.62 49.00
T5: ZnSO₄ Basal (25 kg/ha) + ZnSO₄ Foliar Spray @ 0.5% (Twice at 30 and 45 DAT) 9.67 45.20
T6: Zn EDTA Basal (40 kg/ha) + Zn EDTA Foliar Spray @ 0.8% (Twice at 30 and 45 DAT) 10.51 31.40
T7: ZnSO₄ Basal (25 kg/ha) + Zn EDTA Foliar Spray @ 0.8% (Twice at 30 and 45 DAT) 9.93 38.20
T8: Zn EDTA Basal (40 kg/ha) + ZnSO₄ Foliar Spray @ 0.5% (Twice at 30 and 45 DAT) 10.43 41.60
T9: Control (No Zinc Application) 8.76 79.20
SE ± (Mean) | 0.327 | 1.406
C.D. (0.05) | 0.97 | 4.03
Table 2: SDS-PAGE polypeptide banding pattern of total soluble protein samples extracted from rice leaves after application of zinc
Polypeptide Band (kDa) T1: ZnSO₄ Basal (25 kg/ha) T2: Zn EDTA Basal (40 kg/ha) T3: ZnSO₄ Foliar Spray (0.5%) (30 & 45 DAT) T4: Zn EDTA Foliar Spray (0.8%) (30 & 45 DAT) T5: ZnSO₄ Basal + ZnSO₄ Foliar Spray (0.5%) (30 & 45 DAT) T6: Zn EDTA Basal + Zn EDTA Foliar Spray (0.8%) (30 & 45 DAT) T7: ZnSO₄ Basal + Zn EDTA Foliar Spray (0.8%) (30 & 45 DAT) T8: Zn EDTA Basal + ZnSO₄ Foliar Spray (0.5%) (30 & 45 DAT) Control (No Zinc) Total Bands WBPH Population Build-up (per plant)
B1 97.4 1 1 1 1 1 1 1 1 1 9 53.60
B2 90.0 1 1 1 1 1 1 1 1 1 9 51.20
B3 85.5 0 1 1 1 1 1 1 1 1 8 49.80
B4 78.0 1 1 1 1 1 1 1 1 1 9 49.00
B5 72.2 1 1 1 1 1 1 0 1 1 8 45.20
B6 66.0 1 0 0 0 0 1 1 0 0 4 31.40
B7 56.8 0 1 1 1 1 1 1 1 1 8 38.20
B8 40.2 1 1 1 1 1 1 1 1 1 9 41.60
B9 37.0 1 0 0 0 0 1 1 0 0 4 79.20
B10 35.0 0 1 1 1 1 1 1 1 1 8
B11 33.0 1 0 0 0 0 0 0 0 0 1
B12 29.0 0 1 1 1 1 1 1 1 1 8
B13 27.3 1 1 1 1 1 1 1 1 1 9
B14 25.1 1 0 0 0 0 0 0 0 0 1
B15 23.6 0 0 0 0 0 1 1 0 0 2
B16 22.0 0 1 1 1 1 0 1 0 0 5
B17 20.1 0 1 1 0 0 0 0 0 0 2
B18 15.8 0 0 0 1 1 1 0 1 0 4
B19 14.3 0 1 1 1 1 1 1 1 0 7
Total Bands 10 13 13 13 13 15 14 14 10 115 79.20
This table summarizes the SDS-PAGE analysis of total soluble protein from rice leaves treated with various zinc applications and their corresponding white-backed plant hopper (WBPH) population build-up.
Table 3: Similarity coefficient between zinc treatments for induced resistance to white backed plant hopper (WBPH) in rice
Treatments T ZnSO₄ Basal (25 kg/ha) T Zn EDTA Basal (40 kg/ha) T ZnSO₄ Foliar Spray (0.5%) (30 & 45 DAT) T Zn EDTA Foliar Spray (0.8%) (30 & 45 DAT) T ZnSO₄ Basal + ZnSO₄ Foliar Spray (0.5%) (30 & 45 DAT) T Zn EDTA Basal + Zn EDTA Foliar Spray (0.8%) (30 & 45 DAT) T ZnSO₄ Basal + Zn EDTA Foliar Spray (0.8%) (30 & 45 DAT) T Zn EDTA Basal + ZnSO₄ Foliar Spray (0.5%) (30 & 45 DAT) Control (No Zinc)
T ZnSO₄ Basal (25 kg/ha) 1.00 0.35 0.35 0.35 0.35 0.47 0.41 0.50 0.43
T Zn EDTA Basal (40 kg/ha) 0.35 1.00 0.86 0.86 0.86 0.65 0.69 0.69 0.77
T ZnSO₄ Foliar Spray (0.5%) 0.35 0.86 1.00 0.86 0.80 0.75 0.69 0.69 0.77
T Zn EDTA Foliar Spray (0.8%) 0.35 0.86 0.86 1.00 0.93 0.75 0.69 0.80 0.77
T ZnSO₄ Basal + ZnSO₄ Foliar Spray 0.35 0.86 0.80 0.93 1.00 0.75 0.75 0.80 0.67
T Zn EDTA Basal + Zn EDTA Foliar 0.47 0.65 0.75 0.75 0.75 1.00 0.81 0.93 0.60
T ZnSO₄ Basal + Zn EDTA Foliar 0.41 0.69 0.69 0.69 0.69 0.81 1.00 0.80 0.71
T Zn EDTA Basal + ZnSO₄ Foliar 0.50 0.69 0.69 0.80 0.80 0.93 0.80 1.00 0.75
Control (No Zinc) 0.43 0.77 0.77 0.77 0.67 0.60 0.71 0.75 1.00
This table summarizes the similarity coefficients between various zinc treatments used to induce resistance to white-backed plant hopper (WBPH) in rice. The values represent the degree of similarity between the different treatments, with higher values indicating greater similarity.
In the study of rice genotypes resistant and moderately resistant to the white-backed plant hopper (WBPH), including Ptb 33, TKM6, LFR831311, ASD16, O. minuta, and O. rhizomatis, protein content has been shown to indirectly influence insect resistance in plants. Plants defend against insect attacks through various mechanisms, which can be morphological adaptations (such as trichomes, pubescence, and waxy cuticles) or biochemical responses. Many insect-plant interactions have been found to induce defense enzymes, biochemicals, and resistant proteins. Host plant resistance can be enhanced through breeding strategies, and genetic engineering can build up endogenous defense biomolecules to provide insect resistance. In the absence of these inherent resistance mechanisms, induced resistance can be triggered using chemical elicitors, secondary metabolites, or fertilizers containing elements like silicon, zinc, and ferrous compounds.
Zinc is crucial for plant growth and resistance to biotic and abiotic stresses. It plays a significant role in defense-related responses in plants. Adequate zinc accumulation-either from soil uptake or foliar spray-followed by cellular sequestration, enhances plant resilience to climatic stresses, though the underlying mechanisms are not fully understood. Zinc activates and stabilizes metalloenzymes, such as Zn-SOD (superoxide dismutase), which is commonly upregulated in plants challenged by herbivores or pathogens. Additionally, insect feeding can elicit the synthesis of ZFN-transcription factors, which help impart resistance to the host plant.
In the zymogram analysis, two polypeptides (40.2 kDa and 27.3 kDa) were consistently expressed across all treatments and the control, indicating their expression is independent of zinc application. Polypeptide bands of 29.0 kDa, 35.0 kDa, 56.8 kDa, and 85.5 kDa were absent with basal application of ZnSO₄ but were induced across all treatments and even in the control. Conversely, polypeptides of 33.0 kDa and 25.1 kDa were induced by basal ZnSO₄ application but were downregulated in all treatments, including the control.
Zinc uptake through basal application is regulated by the presence of Zn-transporter genes in root cells, followed by transport to the stem and foliage. In contrast, foliar application bypasses the genetic system, directly supplying zinc to the enzymes needed for plant growth and metabolism. Basal application of Zn-EDTA and foliar ZnSO₄ also produced a 20.1 kDa polypeptide band. Two additional polypeptide bands (37.0 kDa and 66 kDa) were induced in response to ZnSO₄ basal application but were not expressed in the control or other treatments.
Recent advances in microarray and proteomic approaches have revealed a wide range of plant resistance proteins involved in insect defense. Direct defenses, such as trypsin protein inhibitors in rice, have anti-digestive or toxic effects on insect herbivores. The SDS-PAGE analysis of protein profiles from different zinc treatments revealed 19 polypeptide bands in response to zinc application, both in basal and foliar treatments of ZnSO₄ and Zn-EDTA. Notably, these two polypeptide bands were not expressed in Zn-EDTA basal or foliar sprays alone but were induced by combinations of basal and foliar treatments of Zn-EDTA and ZnSO₄. Low molecular weight proteins (14.3-25.1 kDa) were absent in the control but were elicited by zinc treatments, including basal or foliar applications. For instance, a 14.3 kDa polypeptide was observed in all treatments except ZnSO₄ basal. Additionally, foliar spray of Zn-EDTA, combined with basal applications of either ZnSO₄ or Zn-EDTA, induced a new 23.6 kDa polypeptide band.
The induced polypeptide bands in response to various zinc treatments could provide valuable insights into the biochemical basis of induced host plant resistance to insect pests.

Figure 1: SDS-PAGE Soluble Protein Profile of Various Zinc Treatments in Rice cv. TN 1 for Induced Host Plant Resistance to WBPH
• T1-T9: Various zinc treatments (either basal and/or foliar applications).
• M: Molecular weight marker.


Figure 2: Dendrogram Depicting the Inter-relationship Among Various Zinc Treatments for Induced Resistance to WBPH in Rice
The findings from this study suggest that zinc application, whether basal or foliar, plays a significant role in inducing resistance to the white-backed plant hopper (WBPH) in rice. Zinc treatments, especially when combined (e.g., basal and foliar Zn-EDTA), resulted in a marked reduction in WBPH population, with insect numbers decreasing from 79.2 insects/hill in the control to between 31.4 and 53.6 insects/hill in treated plants.
Protein profiling via SDS-PAGE revealed new polypeptide bands (66.0 kDa, 37.0 kDa, 23.6 kDa, 15.8 kDa, and 14.3 kDa) induced by zinc treatments, particularly when basal and foliar applications were combined. These bands were not present in the control plants, suggesting their potential role as biochemical markers of induced resistance to WBPH. The 66.0 kDa, 37.0 kDa, and 14.3 kDa proteins were commonly shared across several zinc treatments and could be indicative of defense-related responses triggered by the zinc application.
The study also found that different zinc treatments resulted in varying levels of protein induction and insect resistance. Specifically, T6 (basal application of ZnSO4 combined with foliar Zn-EDTA) demonstrated the highest induction of 15 polypeptide bands, suggesting it had the strongest effect on resistance induction. This aligns with previous research on plant defense proteins and suggests that the expression of certain proteins, such as those encoded by resistance (R) genes, plays a key role in WBPH resistance.
Thus, the induced proteins in response to zinc treatments, particularly the novel polypeptides identified, could serve as biochemical markers for monitoring and improving resistance to WBPH in rice. This research emphasizes the potential of zinc as an effective tool for enhancing plant defense mechanisms against insect pests like WBPH.
DETAILED DESCRIPTION OF DIAGRAM
Figure 1: SDS-PAGE Soluble Protein Profile of Various Zinc Treatments in Rice cv. TN 1 for Induced Host Plant Resistance to WBPH
• T1-T9: Various zinc treatments (either basal and/or foliar applications).
• M: Molecular weight marker.
Figure 2: Dendrogram Depicting the Inter-relationship Among Various Zinc Treatments for Induced Resistance to WBPH in Rice , Claims:1. Zinc-Induced resistance Mechanism in Rice Against White-Backed Planthopper infestation claims that Zinc treatments (both basal and foliar applications) significantly reduced the population of WBPH, ranging from 31.4 to 53.6 insects/hill, compared to 79.2 insects/hill in the control treatment.
2. The combination of basal and foliar zinc treatments (Zn-EDTA) resulted in the maximum reduction of WBPH population, demonstrating synergistic effects in reducing pest buildup.
3. Zinc treatments induced new polypeptide bands at 66.0 kDa, 37.0 kDa, 23.6 kDa, 15.8 kDa, and 14.3 kDa, which were absent in control plants, indicating a biochemical response to WBPH infestation.
4. Polypeptides such as 66.0 kDa, 37.0 kDa, and 14.3 kDa were consistently induced across various zinc treatments and are likely involved in defense mechanisms against WBPH.
5. The newly induced proteins serve as potential biochemical markers for host plant resistance to WBPH in rice, which can be used for screening resistant varieties.
6. Zinc-induced resistance is associated with the expression of high molecular weight proteins, which are linked to plant defense responses.
7. The study supports the notion that zinc activates plant defense responses, including the upregulation of specific defense-related proteins, which play a key role in pest resistance.
8. The induction of new polypeptides, particularly the 66.0 kDa and 37.0 kDa proteins, is considered a biochemical basis for induced resistance in rice against WBPH.
9. Cluster analysis of protein profiles based on similarity coefficient values grouped zinc treatments into distinct clusters, highlighting the effectiveness of different zinc combinations in inducing resistance.
10. The findings suggest that zinc, through its ability to induce resistance-related proteins, can be an effective tool for managing WBPH infestation and improving crop resilience.

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