Role of Elicitors in Inducing Resistance in Plants against Pathogen Infection: A Review

Table 2

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

S. No.	Plant	Type of elicitor used	Effects	References
1	Brassica napus	Methyl jasmonate	Accumulation 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]
2	Oryza sativa	Benzothiadiazole	BTH 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]
3	Lycopersicon esculentum	Salicylic acid	Diminished susceptibleness to pathogens harm and abiotic stress.	[25]
4	Beta vulgaris	Benzothiadiazole	Induced synthesis of chitinase and β-1,3-glucanase isozymes providing resistance against tobacco necrosis virus.	[26]
5	Brassica oleracea (var. Botrytis)	Benzothiadiazole	BTH induced downy mildew (caused by P. parasitica) resistance in both cauliflower seedlings and 30-day old plants.	[27]
6	Lycopersicon esculentum, Commelina communis	Oligogalacturonic acid (OGA) and chitosan	These 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]
7	Musa acuminata	Salicylic acid	Delayed ripening of banana fruit.	[29]
8	Lycopersicon esculentum	Salicylic acid	Induced 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]
9	Lilium	Benzoic acid	Modified the growth, stress tolerance, anatomy and morphology of eatable and ornamental species.	[31]
10	Helianthus annuus	Benzothiadiazole	Prevented infestation by the parasitic weed Orobanche cumana. Root exudates revealed synthesis of the phytoalexin scopoletin, PR-protein chitinase and H2O2.	[32]
11	Avena sativa, Oryza sativa, Raphanus sativus, Arachis hypogea, Nicotiana tabacum, Pisum sativum	Chitosan	Act 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]
12	Lycopersicum esculentum	Chitosan	Produced a higher resistance against Fusarium oxysporum and Phytophthora capsici.	[34]
13	Lycopersicon esculentum (var. Castlemart)	Salicylic acid	Upregulation of transcription of PR1 and BGL2 genes (marker genes of SA pathway), increased endogenous H2O2 level involved in resistance against Helicoverpa armigera.	[35]
14	Pisum sativum	Salicylic acid and 4-aminobutyric acid	Increased activity of phenol metabolizing enzymes viz., POD, PPO, PAL providing resistance against Erysiphe. polygony in pea.	[36]
15	Brassica juncea	Benzothiadiazole	Increased phenolics and extracellular proteins act as markers of induced resistance.	[37]
16	Lycopersicon esculentum	Chitosan and salicylic acid	Increased level of catalase and peroxidase enzymes activity.	[38]
17	Citrus sinensis	β-amino butyric acid	Inhibited Penicillium italicum spore germination and germ tube elongation in vitro. Involved in the induced resistance against Penicillium italicum.	[39]
18	Glycine max	Benzothiadiazole	Decreased 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]
19	Bhendi	Salicylic acid	Accumulation of phenolics and increased activity of enzyme PAL leading to resistance against Erysiphe cichoracearum.	[41]
20	Brassica species	Salicylic acid	Recovery 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]
21	Brassica napus	Salicylic acid and nitric oxide	Increased 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]
22	Solanum melongena	Salicylic acid, chitosan, methyl salicylate, and methyl jasmonate	Increased 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]
23	Brassica juncea (var. Rlm619)	Benzothiadiazole and salicylic acid	Induction 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]
24	Phaseolus vulgaris	Salicylic acid and Methyl jasmonate	Controlled spider mite infestation, improved plant growth and bean yield.	[46]
25	Brassica oleracea (var. Italica)	Methionine, tryptophan, chitosan, salicylic acid, and methyl jasmonate	Salicylic 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]
26	Glycine max	Benzothiadiazole and humic acid	Reduced 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]
27	Soybean, rice, and wheat	β-glucans and chitin oligomers from Phytophthora and Pythium	Produced phytoalexins in soybean and rice plants. Lignification in wheat leaves.	[49]
28	Arabidopsis, tomato	Oligogalacturonides from bacteria and fungi	Synthesis of protein inhibitors and activation of defense genes.	[50]
29	Tobacco, tomato	Viral coat protein harpin from TMV	Activation of hypersensitive response.	[49]
30	Tomato	Avr gene products, for example, AVR4 and AVR9 from Cladosporium fulvum	Activation of hypersensitive response.	[51]
31	Arabidopsis	Flagellin, flg 15 from gram negative bacteria	Deposition of callose and activation of defense genes in Arabidopsis.	[52]
32	Oat	Protein or peptide toxin, victorin from Helminthosporium victoriae (rust)	Programmed cell death in oat.	[53]
33	Parsley	Glycoprotein from Phytophthora sojae	Synthesis of phytoalexin and activation of defense genes in parsley.	[49]
34	Soybean	Syringolids from Pseudomonas syringae	Activation of hypersensitive response.	[49]
35	Tobacco	Fatty acid amino acid conjugates from Lepidopterans	Synthesis of monoterpenes leading to activation of indirect defense in tobacco.	[49]
36	Arabidopsis	Bacterial toxin, for example, coronatine from Pseudomonas syringae	Acivation of defense genes in Arabidopsis.	[54]
37	Arabidopsis, tomato	Sphinganine analogue mycotoxins from Fusarium moniliforme	Programmed cell death and activation of defense genes in Arabidopsis and tomato.	[49]