Salt-Tolerant Compatible Microbial Inoculants Modulate Physio-Biochemical Responses Enhance Plant Growth, Zn Biofortification and Yield of Wheat Grown in Saline-Sodic Soil

Abstract

A wide range of root-associated mutualistic microorganisms have been successfully applied and documented in the past for growth promotion, biofertilization, biofortification and biotic and abiotic stress amelioration in major crops. These microorganisms include nitrogen fixers, nutrient mobilizers, bio-remediators and bio-control agents. The present study aimed to demonstrate the impact of salt-tolerant compatible microbial inoculants on plant growth; Zn biofortification and yield of wheat (Triticum aestivum L.) crops grown in saline-sodic soil and insight of the mechanisms involved therein are being shared through this paper. Field experiments were conducted to evaluate the effects of Trichoderma harzianum UBSTH-501 and Bacillus amyloliquefaciens B-16 on wheat grown in saline-sodic soil at Research Farm, ICAR-Indian Institute of Seed Sciences, Kushmaur, India. The population of rhizosphere-associated microorganisms changed dramatically upon inoculation of the test microbes in the wheat rhizosphere. The co-inoculation induced a significant accumulation of proline and total soluble sugar in wheat at 30, 60, 90 and 120 days after sowing as compared to the uninoculated control. Upon quantitative estimation of organic solutes and antioxidant enzymes, these were found to have increased significantly in co-inoculated plants under salt-stressed conditions. The application of microbial inoculants enhanced the salt tolerance level significantly in wheat plants grown in saline-sodic soil. A significant increase in the uptake and translocation of potassium (K+) and calcium (Ca2+) was observed in wheat co-inoculated with the microbial inoculants, while a significant reduction in sodium (Na+) content was recorded in plants treated with both the bio-agents when compared with the respective uninoculated control plants. Results clearly indicated that significantly higher expression of TaHKT-1 and TaNHX1 in the roots enhances salt tolerance effectively by maintaining the Na+/K+ balance in the plant tissue. It was also observed that co-inoculation of the test inoculants increased the expression of ZIP transporters (2–3.5-folds) which ultimately led to increased biofortification of Zn in wheat grown in saline-sodic soil. Results suggested that co-inoculation of T. harzianum UBSTH-501 and B. amyloliquefaciens B-16 not only increased plant growth but also improved total grain yield along with a reduction in seedling mortality in the early stages of crop growth. In general, the present investigation demonstrated the feasibility of using salt-tolerant rhizosphere microbes for plant growth promotion and provides insights into plant-microbe interactions to ameliorate salt stress and increase Zn bio-fortification in wheat.

Alpha Tocopherol-Induced Modulations in the Morphophysiological Attributes of Okra Under Saline Conditions

“…All these findings recommend the salinity mitigation role of α-tocopherol as a shielding agent by protecting chlorophyll pigments from photoinhibition. Agricultural crops suffer severe nutritional disorders due to competition among Na + , Ca 2+ , and K + ions ( Singh et al, 2021 ). In this study, higher concentrations of Na + were observed in the leaf and root tissues of okra plants under saline regimes.…”

Cross Talk Between Zinc-Solubilizing Bacteria and Plants: A Short Tale of Bacterial-Assisted Zinc Biofortification

“…The gene expression analysis, which has been proven from recent studies, clearly showed that Zn-solubilizing microbial inoculants and other plant growth-stimulating microbes modulate the expression patterns of some of the genes from the Zn-regulated transporter family and thus played an important role in the transmission of Zn in the different parts of plants (143,159). The co-inoculation of Trichoderma harzianum (UBSTH-501) and Bacillus amyloliquefaciens (B-16) augmented the expression level of the ZIP transporters genes ("TaZIP-1, " "TaZIP-3, " "TaZIP-5, " "TaZIP-6, " "TaZIP-7, " "TaZIP-10, " and "TaZIP-13") by 2.76-4.96-folds, which eventually led to increased Zn translocation in wheat cultivated in saline-sodic soil (159). Besides ZSB, mycorrhizal fungi also showed their contribution in biofortification (160).…”

Contemplating the role of zinc-solubilizing bacteria in crop biofortification: An approach for sustainable bioeconomy

“…In recent research, gene expression analysis was used to demonstrate that Znsolubilizing microbial biostimulants, along with other plant growth-stimulating microbes, influence the expression profiles of some of the Zn-regulated transporter family genes and, as a result, play a key role in the transport of zinc to the various plant parts (Krithika and Balachandar, 2016;Upadhayay et al, 2022a). The co-inoculation of Trichoderma harzianum and Bacillus amyloliquefaciens led to a 2.76-4.96-fold increase in the expression of the ZIP transporter gene in wheat, which resulted in enhanced zinc transport (Singh et al, 2021). In addition to addressing zinc deficiency, Zn-solubilizing microorganisms can also be used to enhance the productivity of food crops.…”