<div style="text-align: justify;">Pesticide resistance and environment threat due to injudicious use of chemical pesticides for disease management employs the alteration in management practices. Chitosan, a deacetylated chitin derivative, behaves like a general elicitor, inducing a non-host resistance, and prime the plants for systemic acquired resistance in addition to this Chitosan has high antimicrobial activity against a wide &nbsp;range of pathogenic and spoilage microorganisms, including fungi and bacteria. The use of chitosan in agriculture and in food systems should be based on sufficient knowledge of the complex mechanisms of its elicitor and antimicrobial mode of action. In this article we a number of studies on the investigation of chitosan antimicrobial and resistance inducing properties and application of them in agriculture sector have been summarized.</div>

<div>Chitosan: An elicitor and antimicrobial Bio-resource in plant protection</div>

<div>Background: Plant defense against the pathogens can be induced by using different defense inducers. Plants can be treated with elicitors for fast and more intense mobilization of defense responses which can enhance the resistance against biotic or abiotic stresses. 
 
Methods: The present study has been undertaken to evaluate the synergistic effect of different plant defense inducing chemical (Salicylic acid, Isonicotinic acid, Oxalic acid and Chitosan) and biological (Trichoderma harzianum and Pseudomonas fluorescens) elicitors. Enzyme activity was expressed as the increase in absorbance using spectrophotometer. 
 
Result: Among all the treatments the maximum PAL activity (35.58 mg/g of fresh weight) was found in case of oxalic acid but after 48 hrs its activity reduced drastically. Next to oxalic acid Pseudomonas fluorescens (31.38 mg/g of fresh weight), chitosan + Trichoderma harzianum (29.38 mg/g of fresh weight) and chitosan + Pseudomonas fluorescens (27.89 mg/g of fresh weight) showed the maximum enzyme activity. The PPO activity reached the highest at 96 hr after challenge inoculation in case of chitosan + Trichoderma harzianum (9.74 &micro;mol/min/mg/protein) treated plants followed by Trichoderma harzianum (3.53 &micro;mol/min/mg/protein) alone. the maximum PO activity (49.12 &micro;mol/min/mg/protein) was found in case of chitosan + Pseudomonas fluorescens treated plants followed by chitosan (42.48 &micro;mol/min/mg/protein) after 72 hrs. the maximum phenolics (27.53 mg/gm of fresh weight) was found in case of chitosan + Pseudomonas fluorescens after 48 hrs of treatment.</div>

Synergistic Effect of Plant Defense Elicitors and Biocontrol Agents on Induction of Defense Enzymes in Pea against Downy Mildew

<div style="text-align: justify;">The study investigated the effect of different elicitors on two varieties of Triticum aestivum (10 days old seedlings) under drought stress. The growth of plants along with various biochemical and antioxidant parameters was determined on 5th, 10th and 15th day of drought stress. Six varieties of wheat viz. RAJ-4120, RAJ-4079, RAJ-3077, RAJ-4238, RAJ-4037 and RAJ-3765 were treated with different elicitors i.e. sodium nitroprusside (0.5mM), salicylic acid (10mM) and silver nitrate (10mM) for six hours before sowing and exposed to drought stress. Chemically primed seeds were sown in pots containing soil along with hydro primed seeds which were not pretreated with any chemical and were used as control. The results indicated that in all the control plants, growth of the seedlings increased with time. In drought stressed seedlings the growth was less than the control plants. Seedlings pretreated with sodium nitroprusside showed the highest growth, biochemical and antioxidant activity. Under drought stress also these parameters were higher in sodium nitroprusside pretreated plants when compared to stressed plants having no pretreatment.</div>

<div style="text-align: justify;">Effect of elicitors on growth, biochemical and antioxidant activity in two varieties of wheat (Triticum aestivum L.) under drought</div>

Background: In the presented work, we studied the effect of foliar spray of elicitors namely chitosan, phenylalanine and salicylic acid sans any stress treatment on physiological and quality parameters in turmeric genotypes.&nbsp; 
 
Methods: Feld experiment was undertaken under rainfed condition using four genotypes. The elicitors were sprayed at rhizome development stage and various measurements namely chlorophylls, carotenoids content and gas exchange parameters were done at different time intervals. The harvested rhizomes were analysed for its curcuminoids content. 
 
Result: The results showed that elicitor treatment increased the leaf chlorophyll and carotenoids content in statistically significant manner. The highest increase in total chlorophyll content (36%) was observed in chitosan treated plants. Likewise, the highest increase in total carotenoids content (33%) was found in phenylalanine treatment. The highest photosynthetic rate increase (76%) was obtained in salicylic acid treatment. The total curcuminoids showed significant increase in only Pragati (16%) and Rajapuri (20%) genotypes. Results suggested that foliar spray of chitosan and salicylic acid at rhizome development stage could be employed to elicit the physiological response and improve the quality of turmeric grown under rainfed condition.

​Foliar Spray of Elicitors on Physiology and Quality Responses in Turmeric (Curcuma longa L.)

<div>Background: Solanaceae plants have the potential to be a source of food, medicine, industrial materials and antioxidants.&nbsp;Antioxidants are compounds that can delay or prevent oxidation caused by free radicals significantly. Metabolomic analysis is a method used to study metabolite profiles. It is necessary to use elicitors to optimize the synthesis of metabolomic compounds and antioxidant potential: methyl jasmonate and salicylic acid as elicitors. 
 
Methods: This research aims to analyze the Solanaceae plant&rsquo;s metabolomic compounds and antioxidant potential using GCMS after the elicitors methyl jasmonate and salicylic acid induction. Experimental method research with stages: 1) Observation, collection and identification of Solanaceae plants, 2) Preparation of experimental land, 3) Planting of plant collections, 4) Application of elicitor methyl jasmonate 60 ppm and salicylic acid 0.45 g/L, 5) Metabolomic and antioxidant analysis on fresh extracts of samples. Testing antioxidant activity using a spectrophotometer with DPPH solution. Metabolomic profile analysis using GCMS. 
 
Result: The results of the non-targeted metabolomic analysis with GCMS and antioxidant activity with IC50&nbsp;in the Solanum genus, namely Solanum betaceum, Solanum melongena, Solanum torvum, Solanum Lycopersicum and Solanum tuberosum, respectively identified 18, 16, 14, 13 and 20 compounds. The IC50&nbsp;values&nbsp;&nbsp; were 51.32 mg/L (strong category), 56.64 mg/L (strong category), 65.86 mg/L (strong category), 113.60 mg/L (medium category), 102.71 mg/L (medium category), respectively. In the Capsicum genus, namely Capsicum frutescens and Capsicum annuum, 21 and 37 compounds were identified, respectively, with IC50&nbsp;values&nbsp; of 124.76 mg/L (medium category) and 63.23 mg/L (strong category). In Physalis angulata, 19 compounds were identified, IC50&nbsp;was 44.04 mg/L (very strong category), six compounds were identified in&nbsp; Nicotiana tabacum and IC50&nbsp;was 67.55 mg/L (strong category).&nbsp; Solanaceae plants have moderate to very strong antioxidant potential. 
&nbsp;</div>

<div>Analysis of Metabolomic Compounds and Antioxidant Potential of Solanaceae Family Plants using Gcms after Elicitor Induction Methyl Jasmonate and Salicylic Acid</div>

Background: Genetic diversity also determines a population&rsquo;s success in adapting to changing environments. Genetic diversity and kinship relationships can be analysed through morphological character markers, which help avoid duplication and germplasm collection. To optimise the genetic expression of a plant, including morphological characters, methyl jasmonate and salicylic acid elicitors can be used to induce the process. 
&nbsp; 
Methods: The objectives of this research are 1) to describe the morphological characteristics of sweet potato varieties cultivated by farmers in Tomohon City, 2) to analyse the genetic diversity and kinship relationships of sweet potato plants based on morphological characters after induction of the elicitors methyl jasmonate and salicylic acid. Research stages: 1) Sweet potato collection, 2) Planting sweet potato tubers and cuttings, 3) Making beds and fertilising Petroganik, 4) Application of elicitor methyl jasmonate 60 ppm and salicylic acid 0.45 g/L carried out at 15 days after planting (DAP) and 30 DAP and observed morphological characters at 50 DAP. Qualitative and quantitative morphological data were analysed for kinship relationships using SPSS version 25. The stages of cluster analysis are: 1) Scoring qualitative morphological data, 2) Determining the minimum and maximum number of clusters, 3) Cluster analysis using the intergroup relationship method produces a dendogram, 4) Interpreting the analysis results. 
&nbsp; 
Result: The results of research in Tomohon City obtained seven varieties of sweet potato, namely the Local purple variety (UJ1),&nbsp; Local white variety (UJ2), Cilembu variety (UJ3), Antin 1 variety (UJ4), Sarwentar variety (UJ5), Dungkul variety (UJ6) and Sari variety (UJ7). The results of kinship analysis based on qualitative morphological characters in the form of a dendrogram formed two main groups. Two clusters were formed, namely cluster 1 consisting of UJ1, UJ2 and UJ3 and cluster 2 consisting of UJ4, UJ5, UJ6 and UJ7. Two clusters of quantitative morphological characters were formed: cluster 1, comprising UJ1, UJ2, UJ3, UJ4 and UJ6 and cluster 2 comprising UJ5 and UJ7.

Analysis of Genetic Diversity and Relationships of Ipomoea batatas L. based on Morphological Characters after Induction of the Elicitors Methyl Jasmonate and Salicylic Acid

<div>Background: Climate change, abiotic and biotic stress pressure are forcing breeders and farmers to find alternative ways to improve and extend food production. Even though there are multiple ways to cope with stress conditions, alleviation of the stress by enhancing plant responses is one of the cheapest, environmentally safest and most direct ways. This study aimed to evaluate the effects of two common plant defense elicitors, 2,4-dichloro-6-{(E)-[(3-methoxyphenyl) imino] methyl} phenol (DPMP) and salicylic acid (SA) on plant growth and seedling vigor with forage pea [Pisum sativum (L.) arvense] as a model plant. 
 
Methods: Two different chemicals, 100 &micro;M SA and 10 &micro;M DPMP were evaluated in response to Polyethylene glycol 8000 (PEG) treatment in a semi-hydroponic growth system. Root architecture and shoot growth parameters were evaluated. The experiment was designed according to completely randomized design with three replications and ten plants per replication. 
 
Result: The effects of SA and DPMP foliar applications were significant on tap, lateral and total root lengths, number of lateral roots and root fresh weight. For most of the traits, SA and DPMP did not inhibit plant growth compared to control under treated and untreated conditions. Average lateral root length (aLatRL) was the noteworthy trait with significantly higher values in DPMP + unstressed conditions. Plants sprayed with DPMP had significantly higher (5.57 cm plant-1) aLatRL values compared to SA (4.53 cm plant-1) and control (3.01 cm plant-1). The results of the current study suggest that SA and DPMP foliar spraying can be beneficial to reduce the effects of abiotic stresses at optimal doses defined for each species. DPMP can be a candidate as a sustainable pesticide alternative and growth-enhancing agent, similar to SA.</div>

Trade-offs in Root and Shoot Growth in Forage Pea [Pisum sativum (L.) arvense] with Foliar Applications of Synthetic Elicitor DPMP (2,4-Dichloro-6-{(E)-[(3-Methoxyphenyl) Imino] Methyl} Phenol) and SA (Salicylic Acid)

<div style="text-align: justify;">Hypersensitivity is a natural defense for plants in response to a variety of pathogens such as viruses, bacteria, fungi and is characterized by a programmed cell death (PCD) accompanied by an accumulation of toxic compounds within the dead cell. Hypersensitive response (HR) is considered a biochemical reaction rather than a structural defense mechanism but can be seen with the naked eye or with a microscope. There are two types of hypersensitive responses: structural and induced. PCD is seen in both structural as well as in induced hypersensitive response. PCD is extreme resistance shown by the plants in which it kills its cells (suicidal death), upon a perception of the pathogen to deprive it of nutritional supply and stops its growth. Cell death plays a central role in innate immune responses in both plants and animals. Apoptosis and autophagy are physiological processes and two forms of biochemical PCD. Induced hypersensitive response comes out when the plant recognizes specific pathogen-produced signal molecules known as elicitors. Recognition of elicitors by the host plants activates an army of biochemical reactions. These reactions include an oxidative burst of reactive oxygen species (ROS), alterations in plant cell wall also including cell wall immunity (CWI) and damage-associated molecular patterns (DAMPs), induction of phytoalexins and synthesis of PR proteins. These all, are comprised under the first line of defense of plants which come into action after recognition of conserved molecules characteristic of many microbes. These are called elicitors and are known as microbeassociated or pathogen-associated molecular patterns (MAMPs or PAMPs). The second line of defense of plants is the recognition of effectors through plant resistance gene products known as R genes, which result in effector-triggered immunity (ETI). This is supported by the gene for gene hypothesis. Avirulence gene encodes a protein which is specifically recognized by genotypes of the host plant harboring the matching resistance genes.</div>

Hypersensitive Responses in Plants

Background: Ehretia asperula Zollinger et Moritzi is a medicinal tree abundant in rosmarinic acid, the primary phenolic component, with numerous beneficial biological properties, including antioxidant, antibacterial, antiviral, anti-allergy, anti-arthritis, asthma and anti-cancer. 
 
Methods: The cell suspension cultures of E. asperula Zollinger et Moritzi derived from the leaf in vitro callus were established in liquid B5 medium added with 0.4 mg/L NAA, 0.1 mg/L BA and 45 g/L glucose. After four weeks, 50 mg/L of chitosan was given to the cell suspension cultures to stimulate rosmarinic acid (RA) production after a 48-hour treatment period. RA content was analyzed using the HPLC and spectrophotometry method after four weeks and 48 hours of chitosan treatment. In addition, the antioxidant capacity of the extracts from E. asperula Zollinger et Moritzi was also tested using DPPH free radical scavenging assay. 
 
Result: The RA content and antioxidant capacity of E. asperula Zollinger et Moritzi&rsquo; extracts from the leaf in vitro &gt; callus derived from the leaf in vitro &gt; field-grown leaf &gt; biomass of cell suspension cultures. These results suggested a strong correlation between RA concentration and antioxidant capacity. The use of E. asperula Zollinger et Moritzi cell suspension cultures with chitosan as an elicitor for RA production and evaluation of antioxidant activity is presented in this study for the first time. Our results suggest that cell suspension cultures and others may be a good source of RA, an antioxidant compound.

Rosmarinic Acid Content and Antioxidant Activity in Ehretia asperula Zollinger et Moritzi Cell Suspension Cultures

<div>Background: Therapeutic horticulture (TH), as an adjuvant for mental health, attracts health care specialists to evidence-based therapy approaches. However, the effectiveness of plants as elicitors and in improving patient outcomes is still uncertain in practice. Hence, the study was conducted to evaluate the feasibility of different therapeutic approaches for shift work disorder amongst securities with poor sleep quality. 
 
Methods: Sixty securities working in night shifts were selected for the study and 30 participants were assigned to the intervention group and 30 to the control group through pre-test post-test control design. The intervention and the control groups were tested for the Perceived Stress Scale (PSS), the Inclusion of nature self scale (INS), the Pittsburg Sleep Quality Index (PSQI), Physical (Blood pressure, Heart rate), personal and psychological well-being.&nbsp;The horticulture interventions through combination of virtual reality, gardening, potpourri making, chamomile tea intake, aromatherapy and pot painting were provided for the experimental group. 
 
Result: The therapy has brought fascinating results in decreasing stress, improving the sleep and better well being of the subjects. The pre-test value for the Pittsburg sleep quality index indicated a sleep deprivation score of 13.27&plusmn;2.38 during the pre-test and it has improved the sleep level with a post-test value of 6.10&plusmn;2.23. The drop in blood pressure for the systolic/diastolic blood pressure from 138.30&plusmn;21.02/85.13&plusmn;12.59 (Pre-test) to 127.93&plusmn;14.80/81.90&plusmn;11.07 (Post-test) has been a good sign of therapeutic approaches at p&lt;0.001. The values are also significant for personal and psychological well being and the subjective feedback results shows, among the therapies the virtual reality garden viewing followed by potpourri and pot painting showed higher rankings. Therapeutic horticulture being benign and non-threatening will undoubtedly expand and can take upon as one of the sustainable approaches in kindling the senses and improving daytime sleep for night shift workers.</div>