Physiological and molecular insight of microbial biostimulants for sustainable agriculture

Abstract

Increased food production to cater the need of growing population is one of the major global challenges. Currently, agro-productivity is under threat due to shrinking arable land, increased anthropogenic activities and changes in the climate leading to frequent flash floods, prolonged droughts and sudden fluctuation of temperature. Further, warm climatic conditions increase disease and pest incidences, ultimately reducing crop yield. Hence, collaborated global efforts are required to adopt environmentally safe and sustainable agro practices to boost crop growth and productivity. Biostimulants appear as a promising means to improve growth of plants even under stressful conditions. Among various categories of biostimulants, microbial biostimulants are composed of microorganisms such as plant growth-promoting rhizobacteria (PGPR) and/or microbes which stimulate nutrient uptake, produce secondary metabolites, siderophores, hormones and organic acids, participate in nitrogen fixation, imparts stress tolerance, enhance crop quality and yield when applied to the plants. Though numerous studies convincingly elucidate the positive effects of PGPR-based biostimulants on plants, yet information is meagre regarding the mechanism of action and the key signaling pathways (plant hormone modulations, expression of pathogenesis-related proteins, antioxidants, osmolytes etc.) triggered by these biostimulants in plants. Hence, the present review focuses on the molecular pathways activated by PGPR based biostimulants in plants facing abiotic and biotic challenges. The review also analyses the common mechanisms modulated by these biostimulants in plants to combat abiotic and biotic stresses. Further, the review highlights the traits that have been modified through transgenic approach leading to physiological responses akin to the application of PGPR in the target plants.

Morphological, metabolomic and genomic evidences on drought stress protective functioning of endophyte Bacillus safensis Ni7, offering its application as probiotic to plant drought

“…These genes produce protective compounds, such as osmoprotectants and antioxidants, which help the plants combat with the adverse effects of drought (Paul et al, 2022). Treating plants with surfactin compounds has also been described to activate pathways responsible for the enhanced production of polyamines and heat shock proteins which enable the plant to endure the stress under drought conditions (Kaushal et al, 2023). Surfactin producing endophytes has already been tried as a bioinoculant for crops and those were found to improve the water uptake efficiency of the crop.…”

Can Foliar Application of Natural Biostimulants Reduce Nitrate and Fiber Content in Fresh Green Bean under Soil Nutrient Deficiency?

“…3). This role of biostimulants in mitigating the effects of stressful conditions on crop productivity for sustainable agriculture (Kaushal et al 2023).…”

<em>Solicoccozyma aeria</em> YCPUC79 Promotes Tomato Seedling Root Growth by Volatile Organic Compounds Emission

“…Within the group of hydrocarbons, the only compound present in both Sa and TSa treatments was 6-methyloctadecane. There are no reports of this VOC as a biostimulant, however, it has been described that hydrocarbons can participate as elicitors of systemic defense and growth responses in plants, leading to the activation of salicylic acid pathways or the synthesis of IAA [29,30]. Then it is interesting to note the inhibition in the release of hydrocarbons compounds such as 2,6,10trimethyldodecane, 3E-6-methyl-3-undecene, butylhydroxytoluene, heptadecane and hexane from tomato plants once exposed to the same environment than S. aeria.…”