*2.6.1 Introduction*

Jasmonic acid (JA) is an organic compound found in several plants including jasmine. The molecule is a member of the jasmonate class of plant hormones. It is biosynthesized from linolenic acid by the octadecanoid pathway. It was first isolated in 1957 as the methyl ester of jasmonic acid by the Swiss chemist Edouard Demole and his colleagues.

Jasmonates are represented by jasmonic acid (JA) and its methyl ester. The plant hormone jasmonic acid (JA) and its derivative (jasmonoyl isoleucine: JA-Ile) are signalling molecules involved in the control of cellular defence and development in plants. Jasmonic acid plays a vital role in the various plant developmental processes including flowering, fruiting, senescence and secondary metabolism. These are known to be critically important in plant defence and abiotic stress response. Jasmonic acid stimulates the antioxidant system, induces amino acid and soluble sugar accumulation, and modulates stomatal opening and closing during abiotic stress [28].
