Effect of Elicitors and Precursors on Azadirachtin Production in Hairy Root Culture of Azadirachta indica

Abstract

The present study involved strategies for enhancement in in vitro azadirachtin (commercially used biopesticide) production by hairy root cultivation of Azadirachta indica. Improvement in the azadirachtin production via triggering its biosynthetic pathway in plant cells was carried out by the exogenous addition of precursors and elicitors in the growth medium. Among the different abiotic stress inducers (Ag(+), Hg(+2), Co(+2), Cu(+2)) and signal molecules (methyl jasmonate and salicylic acid) tested, salicylic acid at 15 mg l(-1) of concentration was found to enhance the azadirachtin yield in the hairy roots to the maximum (up to 4.95 mg g(-1)). Similarly, among the different biotic elicitors tested (filter-sterilized fungal culture filtrates of Phoma herbarium, Alternaria alternata, Myrothecium sp., Fusarium solani, Curvularia lunata, and Sclerotium rolfsii; yeast extract; and yeast extract carbohydrate fraction), addition of filter-sterilized fungal culture filtrate of C. lunata (1 % v/v) resulted in maximum azadirachtin yield enhancement in hairy root biomass (up to 7.1 mg g(-1)) with respect to the control (3.3 mg g(-1)). Among all the biosynthetic precursors studied (sodium acetate, cholesterol, squalene, isopentynyl pyrophosphate, mavalonic acid lactone, and geranyl pyrophosphate), the overall azadirachtin production (70.42 mg l(-1) in 25 days) was found to be the highest with cholesterol (50 mg l(-1)) addition as an indirect precursor in the medium.

In vitro plant tissue culture: means for production of biological active compounds

“…Several types of elicitors can increase the secondary metabolite production, including pectin and cellulose (plant cell wall constituents), chitin and glucan (from microorganisms) and salicylic acid and methyl jasmonate (plant immune signaling molecules) (Namdeo 2007;Shilpa et al 2010;Sharma et al 2011;Ochoa-Villarreal et al 2016). Srivastava and Srivastava (2014) used different fungal culture filtrates as biotic elicitors in root cultures of Azadirachta indica to promote the production of Azadirachtin. Filtrates of Curvularia lunata yielded the highest production of the target compound compared to control.…”

“…When searching for appropriate precursors it is important to look at the entire biosynthetic pathway and include several molecules involved in different steps of the process, incorporating some examples that affect the production of the target compound in indirect ways. Srivastava and Srivastava (2014) studied the use of precursors to enhance production of azadirachtin including sodium acetate, cholesterol, squalene, isopentenyl pyrophosphate, and others. They found the best results using cholesterol as an indirect precursor.…”

Ephedrine production from suspension cultures of Ephedra alata L. callus

“…Nadeem et al (2018) also reported enhanced biosynthesis of secoisolariciresinol diglucoside, lariciresinol diglucoside, and dehydrodiconiferyl alcohol glucoside in Linum usitatissimum cell cultures, when yeast extract was used as an elicitor. It is assumed that the effect of yeast extract as an elicitor may be associated with the presence of some cations in it, such as Zn, Ca, and Co, which act as abiotic elicitors (Srivastava and Srivastava, 2014). On the other hand, the presence of amino acids, vitamins, and minerals in the yeast extract complex may play a role in the regulation of enzyme activity in the pathway of ephedrine biosynthesis (Srivastava and Srivastava, 2014).…”

Production of biopesticide azadirachtin using plant cell and hairy root cultures

“…A. indica is known to function against the plant pathogen C. lunata that possibly triggered the azadirachtin biosynthesis (7.1 mg/g DW) sufficiently higher than in the seed kernels . The same authors on supplementation of cholesterol as an indirect precursor in hairy root cultures showed the azadirachtin production of 70.42 mg/L (3.1 mg/g DW), again comparable to the content in the seed (2–6 mg/g DW) . As per these investigators, the sterol biosynthetic pathway generally diverts the precursor from the azadirachtin production.…”