Ameliorative effects of endogenous and exogenous indole-3-acetic acid on atrazine stressed paddy field cyanobacterial biofertilizer Cylindrospermum stagnale

Abstract

Across the world, paddy fields naturally harbour cyanobacteria that function as biofertilizers and secrete various compounds like Indole-3-acetic acid (IAA) that help organisms in regulating their growth. Also, paddy field farming utilizes large amounts of pesticides (e.g. atrazine); but their continued application in the agricultural field causes toxicity in non-target cyanobacterial species that hinder their performance as a biofertilizer. Hence, the current study is an attempt to ameliorate the atrazine stress in cyanobacterium Cylindrospermum stagnale by addition of IAA (1 mM each) under different atrazine levels (0, 60, 80, 100, 120, 140 µg/l). Atrazine toxicity affected C. stagnale in a dose-dependent manner further experiments revealed that both the exogenous and endogenous IAA mitigated the detrimental effects of atrazine. It reduced MDA content and simultaneously increased chlorophyll content, total protein content, and multiple antioxidant enzyme activities [superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX)] at 140 µg/l. A molecular docking study revealed that the pesticide binds to the D1 protein of the photoelectric chain in photosynthesis. Hence, the application of IAA or cyanobacterial biofertilizer that secretes a sufficient amount of IAA may assist sustainable agriculture in counteracting the atrazine toxicity.

Assessing the role of temperature as an elicitor for indole-3-acetic acid production in cyanobacterial species

“…Previously, it has been reported that among many compounds that cyanobacteria produce, IAA promotes growth and prevents organisms from environmental stress such as desiccation, osmotic, cold shock, and heat shock. Further, IAA activates the antioxidant activity in the cell by inducing the expression of antioxidant enzymes such as CAT, SOD, and peroxidase [45]. A similar results have also been obtained in the present study which corroborates with the cited literature.…”

“…IAA isolated from yeast has been known to inhibit the growth of weeds and therefore can be used as a herbicide and replace the chemical herbicides [48]. Similarly, it has been observed that usage of IAA or cyanobacterial biofertilizer ameliorates the atrazine toxicity in paddy crops [45]. Role of cyanobacteria as biofertilizers and soil stabilizers in agriculture has been well proved where it promotes cell division and plant elongation [49].…”

Exploring Exogenous Indole-3-acetic Acid’s Effect on the Growth and Biochemical Profiles of Synechocystis sp. PAK13 and Chlorella variabilis

“…Interestingly, cyanobacteria can produce IAA, which promotes growth under normal conditions and provides protection against various stressors [ 33 ]. Studies that have examined the growth yield after adding exogenous IAA in quantities critical for hormone production have long established the fact that IAA aids cyanobacteria in growing [ 34 ].…”