Seed Biopriming with Salt-Tolerant Endophytic Pseudomonas geniculata-Modulated Biochemical Responses Provide Ecological Fitness in Maize (Zea mays L.) Grown in Saline Sodic Soil

Abstract

Under changing climate, soil salinity and sodicity is a limiting factor to crop production and are considered a threat to sustainability in agriculture. A number of attempts are being made to develop microbe-based technologies for alleviation of toxic effects of salts. However, the mechanisms of salt tolerance in agriculturally important crops are not fully understood and still require in-depth study in the backdrop of emerging concepts in biological systems. The present investigation was aimed to decipher the microbe-mediated mechanisms of salt tolerance in maize. Endophytic Pseudomonas geniculate MF-84 was isolated from maize rhizosphere and tagged with green fluorescent protein for localization in the plant system. Confocal microphotographs clearly indicate that MF-84 was localized in the epidermal cells, cortical tissues, endodermis and vascular bundles including proto-xylem, meta-xylem, phloem and bundle sheath. The role of P. geniculate MF-84 in induction and bioaccumulation of soluble sugar, proline and natural antioxidants enzymes in maize plant was investigated which lead not only to growth promotion but also provide protection from salt stress in maize. Results suggested that application of P. geniculate MF-84 reduces the uptake of Na+ and increases uptake of K+ and Ca2+ in maize roots indicative of the role of MF-84 in maintaining ionic balance/homeostasis in the plant roots under higher salt conditions. It not only helps in alleviation of toxic effects of salt but also increases plant growth along with reduction in crop losses due to salinity and sodicity.

Seed Biopriming with Microbial Inoculant Triggers Local and Systemic Defense Responses against Rhizoctonia solani Causing Banded Leaf and Sheath Blight in Maize (Zea mays L.)

“…During the course of examination under the confocal microscope, the signal of GFP-tagged MF-30 was observed in the coleoptiles at 15 days of inoculation (data not shown). In our previous study, it was reported that P. geniculata significantly colonized the epidermis, cortical region, endodermis, and vascular tissues, including xylem, phloem, and bundle sheath [70].…”

“…A recent study on the structure and function of the plant microbiome have focused on the host-mediated recruitment and shaping of their rhizosphere microbiome [42]. These microorganisms play a key role in the plant establishment in a wide range of environmental conditions [38,39,70]. In this, the role of endophytic microorganisms on the plant health is well documented [33].…”

“…Further, maize seeds were bio-primed with GFP-tagged P. aeruginosa MF-30 and sown in the pot containing sterile sand-soil mixture (sand:soil:vermiculite in 1:1:1 ratio). Fifteen days after sowing, plants were up-rooted gently, washed in running tap water and microscopy was done as per the methods described by Singh et al [70]. Briefly, confocal imaging was done using 488 and 543 nm channels under a confocal scanning laser microscope (Nikon Eclipse Confocal A1, Japan).…”

Diving Into Reef Ecosystems for Land-Agriculture Solutions: Coral Microbiota Can Alleviate Salt Stress During Germination and Photosynthesis in Terrestrial Plants

“…50%) as well as antioxidant enzyme activity (c.a. 150%; Singh et al, 2020). Recently, IAA has been shown to specifically up-regulate chlorophyll content via Auxin response factor 6A (Yuan et al, 2019), which may account for the mild positive effect on the photosynthetic performance of N. attenuata plants treated with A. brasilense under conditions of saline stress.…”

A Simplified Protocol for Reversing Phenotypic Conversion of Ralstonia solanacearum during Experimentation

“…R. solanacearum NAIMCC-B-01630 was tagged with gfp by triparental mating with Escherichia coli S17-1 containing Tn5 gus A gfp cassette and E. coli HB101 containing pRK2013 [ 23 ]. Briefly, transconjugants were selected on Luria Bertani (LB) agar plates containing nalidixic acid and kanamycin.…”