Jasmonates: An Emerging Approach in Biotic and Abiotic Stress Tolerance

*Shivani Lalotra, Akhouri Hemantaranjan, Bhudeo Rana Yashu, Rupanshee Srivastava and Sandeep Kumar*

## **Abstract**

Plant hormones acts as key signaling compounds in plant stress responses and development under biotic and abiotic stresses. The potential roles of phytohormones had been considered so far and copious investigation is going on in finding the impending role of phytohormones in abiotic and biotic stresses. In the list of known classical plant hormones, Jasmonates, [jasmonic acid and its methyl ester (methyl Jasmonates)] have been recently added and shown as potential tool in enhancing tolerance of plants against various physiological processes. These are oxidized lipids (oxylipins) mainly derived from α-linolenic acids (α-LAs), play an active role in senescence through signaling, flower nectar secretion, Gprotein signaling, physiological activities and development in plants. Exogenous application of jasmonates on different plant parts have proved effective in improving plant abiotic stress tolerance particularly salinity, drought, and temperature (low/high) conditions and also in biotic stress tolerance like pathogen attack or wounding by production of defensive secondary metabolites, through the stimulation of phenyl-propanoid metabolism resulted from accumulation of JA in plant cells or tissues. Based on this prolific role of Jasmonates and its derivatives in different fields of biological sciences these phytohormones have opened new vistas and increasing interest in future Agricultural, Biotechnological and Physiological researches.

**Keywords:** biotic and abiotic stress, phytohormones, jasmonates and its derivatives, biosynthesis, emerging roles, signal transduction etc.

### **1. Introduction**

The total geographical area of India is 328.7 million hectares [1], and its economy is chiefly dependent on agriculture sector. About 54.6% of the Indian population is affianced in agriculture and allied activities [2], and about 141.4 million hectares is the reported net sown area, and 200.9 million hectares is the gross cropped area with a cropping intensity of 142%. Moreover, the human population is rapidly increasing and needs a substantial increase in agricultural productivity worldwide. There has been a continuous decline in the share of agriculture and allied sector due to the changing climatic scenario, exploding population, and stressful environment which made it unfeasible for proper operation of gross cropped area. Therefore, exploiting recent and innovative strategies, tools, approaches, chemicals, and

technologies is the only solution to increase productivity for the ever-increasing population. Given the importance of agriculture sector, steps have been taken to improve productivity on a sustainable basis by agronomic, biotechnological, genetical, and physiological approaches. Stressful environments are now being recognized as a potential agricultural threat for the sustainable agriculture. The commencement of environmental stresses results in plant defense responses, e.g., expression of stress-responsive genes and production of many defensive proteins and nonprotein compounds through various signaling pathways [3]. Plants produce various volatile or nonvolatile endogenous compounds and also certain mechanisms developed and deployed by plants to counteract environmental stress. Such endogenous compounds are called phytohormones.

## **2. Phytohormones**

Phytohormones are the chemical compounds produced endogenously in very low concentrations that play significant role in the regulation and expression of gene encoding proteins. They are the diverse group of signaling molecules that result in a variety of cellular and developmental processes, signaling networks in plants under biotic and abiotic stress. They work as chemical messengers to communicate cellular activities and act either at their site of synthesis or elsewhere in plants following their transport in higher plants [4, 5]. Different phytohormones interact with each other and show synergetic or antagonist interactions that might be helpful in tolerance mechanisms. A large number of phytohormones are studied to date; among them jasmonates are the emerging players in environmental stress tolerance.

#### **3. Jasmonate: a potent phytohormone**

Jasmonates [jasmonic acid (**Figure 2**) and its methyl ester methyl jasmonate (**Figure 1**)] the cyclopentanone phytohormones are a class of oxidized lipids (oxylipins) derived from α-linolenic acids (α-LAs) through lipoxygenase-dependent manner. [6] first isolated JA from culture filtrate of the fungus *Lasiodiplodia (Botryodiplodia) theobromae,* a plant pathogen, was identified as a plant growth inhibitor, whereas its derivative methyl jasmonate was first isolated from *Jasminum grandiflorum* (jasmine) petal extract [7]. (+)-7-iso-Jasmonoyl-L-isoleucine (JA-Ile) is the best-described bioactive JA [7] till date, but other JAs like *cis*-jasmone, jasmonoyl ACC (JA-ACC), and jasmonoyl isoleucine (JA-Ile) are also studied by scientists with multiple biological functions [9–12]. Various developmental and environmental factors are responsible for the production of JA in membranes and resulted in expression of stress tolerant genes (**Figure 3**). JA is ubiquitously found in the plant kingdom and results in the expression of genes at the transcriptional and post transcriptional levels [13, 14]. An imperative role of jasmonate (when applied exogenously in low concentrations) is reported in enhanced pathogen resistance.

Cross talks of jasmonates with signaling pathways generated by various phytohormones like ABA, salicylic acid, ethylene, etc. result in diverse developmental processes like seed germination, seedling growth, pollen fertility, fruit ripening, senescence and tolerance. However, its extent of effectiveness entirely depends on the type of plant species tested or its concentration. MeJA is more volatile than JA, so exposure to it either in solution or in the gaseous phase can elicit plant responses. Apart from its significant role in plants, derivatives of jasmonates, e.g., methyl jasmonate are used as a fragrant constituent in many aromatic mixtures [15**]**.

**49**

**Figure 3.**

*stressful environment. Source: Ahmad et al., [16].*

*Jasmonates: An Emerging Approach in Biotic and Abiotic Stress Tolerance*

*Chemical structure of methyl jasmonate [3-oxo-2-(2-pentenyl)-, methyl ester].*

*Chemical structure of Jasmonic acid [3-oxo-2-(2-pentenyl) cyclopentaneacetic acid].*

*Various developmental and environmental factors are shown that signals membrane for the production of endogenous jasmonates which further results in the regulation of certain genes and defense mechanisms against* 

*DOI: http://dx.doi.org/10.5772/intechopen.84608*

**Figure 1.**

**Figure 2.**

*Jasmonates: An Emerging Approach in Biotic and Abiotic Stress Tolerance DOI: http://dx.doi.org/10.5772/intechopen.84608*

*Plant Science - Structure, Anatomy and Physiology in Plants Cultured in Vivo and in Vitro*

enous compounds are called phytohormones.

**3. Jasmonate: a potent phytohormone**

trations) is reported in enhanced pathogen resistance.

**2. Phytohormones**

technologies is the only solution to increase productivity for the ever-increasing population. Given the importance of agriculture sector, steps have been taken to improve productivity on a sustainable basis by agronomic, biotechnological, genetical, and physiological approaches. Stressful environments are now being recognized as a potential agricultural threat for the sustainable agriculture. The commencement of environmental stresses results in plant defense responses, e.g., expression of stress-responsive genes and production of many defensive proteins and nonprotein compounds through various signaling pathways [3]. Plants produce various volatile or nonvolatile endogenous compounds and also certain mechanisms developed and deployed by plants to counteract environmental stress. Such endog-

Phytohormones are the chemical compounds produced endogenously in very low concentrations that play significant role in the regulation and expression of gene encoding proteins. They are the diverse group of signaling molecules that result in a variety of cellular and developmental processes, signaling networks in plants under biotic and abiotic stress. They work as chemical messengers to communicate cellular activities and act either at their site of synthesis or elsewhere in plants following their transport in higher plants [4, 5]. Different phytohormones interact with each other and show synergetic or antagonist interactions that might be helpful in tolerance mechanisms. A large number of phytohormones are studied to date; among them

jasmonates are the emerging players in environmental stress tolerance.

Jasmonates [jasmonic acid (**Figure 2**) and its methyl ester methyl jasmonate (**Figure 1**)] the cyclopentanone phytohormones are a class of oxidized lipids (oxylipins) derived from α-linolenic acids (α-LAs) through lipoxygenase-dependent manner. [6] first isolated JA from culture filtrate of the fungus *Lasiodiplodia (Botryodiplodia) theobromae,* a plant pathogen, was identified as a plant growth inhibitor, whereas its derivative methyl jasmonate was first isolated from *Jasminum grandiflorum* (jasmine) petal extract [7]. (+)-7-iso-Jasmonoyl-L-isoleucine (JA-Ile) is the best-described bioactive JA [7] till date, but other JAs like *cis*-jasmone, jasmonoyl ACC (JA-ACC), and jasmonoyl isoleucine (JA-Ile) are also studied by scientists with multiple biological functions [9–12]. Various developmental and environmental factors are responsible for the production of JA in membranes and resulted in expression of stress tolerant genes (**Figure 3**). JA is ubiquitously found in the plant kingdom and results in the expression of genes at the transcriptional and post transcriptional levels [13, 14]. An imperative role of jasmonate (when applied exogenously in low concen-

Cross talks of jasmonates with signaling pathways generated by various phytohormones like ABA, salicylic acid, ethylene, etc. result in diverse developmental processes like seed germination, seedling growth, pollen fertility, fruit ripening, senescence and tolerance. However, its extent of effectiveness entirely depends on the type of plant species tested or its concentration. MeJA is more volatile than JA, so exposure to it either in solution or in the gaseous phase can elicit plant responses. Apart from its significant role in plants, derivatives of jasmonates, e.g., methyl jasmonate are used as a fragrant constituent in many

**48**

aromatic mixtures [15**]**.

*Chemical structure of Jasmonic acid [3-oxo-2-(2-pentenyl) cyclopentaneacetic acid].*

#### **Figure 3.**

*Various developmental and environmental factors are shown that signals membrane for the production of endogenous jasmonates which further results in the regulation of certain genes and defense mechanisms against stressful environment. Source: Ahmad et al., [16].*
