Table 2: List of elicitors used and their effects on different plant species.

S. No.PlantType of elicitor usedEffectsReferences

1Brassica napus Methyl jasmonateAccumulation of indolyl glucosinolates in the leaves. The predominant components of the response were 3-indolylmethyl- and 1-methoxy-3-indolylmethylglucosinolates, which together comprised 90% of the total glucosinolates in treated leaves.[23]

2Oryza sativa BenzothiadiazoleBTH protected wheat systemically against powdery mildew infection by affecting multiple steps in the life cycle of the pathogen. The onset of resistance was accompanied by the induction of a number of wheat chemically induced (WCI) genes, including genes encoding a lipoxygenase and a sulfur-rich protein. [24]

3Lycopersicon esculentum Salicylic acidDiminished susceptibleness to pathogens harm and abiotic stress.[25]

4Beta vulgaris BenzothiadiazoleInduced synthesis of chitinase and β-1,3-glucanase isozymes providing resistance against tobacco necrosis virus.[26]

5Brassica oleracea (var. Botrytis)BenzothiadiazoleBTH induced downy mildew (caused by P. parasitica) resistance in both cauliflower seedlings and 30-day old plants.[27]

6Lycopersicon esculentum, Commelina communis Oligogalacturonic acid (OGA) and chitosanThese elicitors reduced the size of the stomatal aperture. OGA not only inhibited light-induced stomatal opening, but also accelerated stomatal closing in both species; chitosan inhibited light-induced stomatal opening in tomato epidermis.[28]

7Musa acuminata Salicylic acidDelayed ripening of banana fruit.[29]

8Lycopersicon esculentum Salicylic acidInduced the synthesis of some stress proteins, such as PR proteins, which leads to increased chilling tolerance and resistance to pathogens, thereby decreasing the incidence of decay.[30]

9Lilium Benzoic acidModified the growth, stress tolerance, anatomy and morphology of eatable and ornamental species.[31]

10Helianthus annuus BenzothiadiazolePrevented infestation by the parasitic weed Orobanche cumana. Root exudates revealed synthesis of the phytoalexin scopoletin, PR-protein chitinase and H2O2.[32]

11Avena sativa, Oryza sativa, Raphanus sativus, Arachis hypogea, Nicotiana tabacum, Pisum sativumChitosanAct as a stress tolerance inductor when directly applied to plant tissues, unchaining a hypersensitive reaction and lignifications, and promoting the activation of defenses against pathogens.[33]

12Lycopersicum esculentum ChitosanProduced a higher resistance against Fusarium oxysporum and Phytophthora capsici. [34]

13Lycopersicon esculentum (var. Castlemart)Salicylic acidUpregulation of transcription of PR1 and BGL2 genes (marker genes of SA pathway), increased endogenous H2O2 level involved in resistance against Helicoverpa armigera. [35]

14Pisum sativum Salicylic acid and 4-aminobutyric acidIncreased activity of phenol metabolizing enzymes viz., POD, PPO, PAL providing resistance against Erysiphe. polygony in pea.[36]

15Brassica juncea BenzothiadiazoleIncreased phenolics and extracellular proteins act as markers of induced resistance. [37]

16Lycopersicon esculentum Chitosan and salicylic acidIncreased level of catalase and peroxidase enzymes activity.[38]

17Citrus sinensis β-amino butyric acidInhibited Penicillium italicum spore germination and germ tube elongation in vitro. Involved in the induced resistance against Penicillium italicum. [39]

18Glycine max BenzothiadiazoleDecreased incidence of soybean stem vascular discoloration, increased germination, photosynthetic pigments, lignin, phenolics, and flavonoids. Increased activities of phenylalanine ammonia lyase, peroxidase, and polyphenoloxidase. Decreased catalase activity was observed.[40]

19BhendiSalicylic acidAccumulation of phenolics and increased activity of enzyme PAL leading to resistance against Erysiphe cichoracearum. [41]

20Brassica speciesSalicylic acidRecovery from heat stress, increased seedling length, reduced electrolyte leakage, and enhanced membrane protection. Increased level of total soluble sugars, fresh/dry weight, and enzymatic activities of invertase, catalase, and peroxidase conferred thermotolerance. Enhanced expression of some new proteins including heat shock proteins (HSPs) was also observed.[42]

21Brassica napus Salicylic acid and nitric oxideIncreased the activities of the antioxidant enzymes in leaves of Ni-stressed plants, improved the chlorophyll content and decreased the level of lipid peroxidation, and H2O2 and proline accumulation in leaves.[43]

22Solanum melongena Salicylic acid, chitosan, methyl salicylate, and methyl jasmonateIncreased lignin deposition in cell walls of roots, accumulation of phenolics, increase in the activity of enzymes PAL, POD, polyphenol oxidase, cinnamyl alcohol dehydrogenase, and catalase. Provided resistance against Ralstonia solanacearum. [44]

23Brassica juncea (var. Rlm619)Benzothiadiazole and salicylic acidInduction of defense related enzymes, namely, peroxidase, phenylalanine ammonia lyase, and superoxide dismutase; increase in oil content and yield. Prevention of invasion of Alternaria brassicae.[45]

24Phaseolus vulgaris Salicylic acid and Methyl jasmonateControlled spider mite infestation, improved plant growth and bean yield.[46]

25Brassica oleracea (var. Italica)Methionine, tryptophan, chitosan, salicylic acid, and methyl jasmonateSalicylic acid and chitosan induced increase in vitamin C content. Flavonoid concentration increased after MeJA and SA treatments. Methionine or tryptophan solutions did not positively affect the vitamin C or the phenolic compounds. Methionine increased the levels of aliphatic glucosinolates. However, indole glucosinolates presented a significant response to the induction with tryptophan, SA, or MeJA treatments. [47]

26Glycine max Benzothiadiazole and humic acidReduced damping-off and wilt diseases and increased growth parameters. BTH and HA in combination showed the highest activities of oxidative enzymes followed by BTH and HA alone.[48]

27Soybean, rice, and wheatβ-glucans and chitin oligomers from Phytophthora and Pythium Produced phytoalexins in soybean and rice plants. Lignification in wheat leaves.[49]

28Arabidopsis, tomato Oligogalacturonides from bacteria and fungiSynthesis of protein inhibitors and activation of defense genes.[50]

29Tobacco, tomatoViral coat protein harpin from TMV Activation of hypersensitive response.[49]

30TomatoAvr gene products, for example, AVR4 and AVR9 from Cladosporium fulvum Activation of hypersensitive response.[51]

31Arabidopsis Flagellin, flg 15 from gram negative bacteriaDeposition of callose and activation of defense genes in Arabidopsis.[52]

32OatProtein or peptide toxin, victorin from Helminthosporium victoriae (rust)Programmed cell death in oat.[53]

33ParsleyGlycoprotein from Phytophthora sojae Synthesis of phytoalexin and activation of defense genes in parsley.[49]

34SoybeanSyringolids from Pseudomonas syringae Activation of hypersensitive response.[49]

35TobaccoFatty acid amino acid conjugates from LepidopteransSynthesis of monoterpenes leading to activation of indirect defense in tobacco.[49]

36Arabidopsis Bacterial toxin, for example, coronatine from Pseudomonas syringae Acivation of defense genes in Arabidopsis.[54]

37Arabidopsis, tomato Sphinganine analogue mycotoxins from Fusarium moniliforme Programmed cell death and activation of defense genes in Arabidopsis and tomato.[49]