Cell-Free Supernatant of Bacillus Strains can Improve Seed Vigor Index of Corn (Zea mays L.) Under Salinity Stress

Abstract

Currently, salinity is the second biggest challenge in the world after drought and affects all stages of plant growth. The use of environmentally friendly methods such as microorganisms and their derivatives can reduce the destructive effects of salinity stress. A growth chamber experiment was conducted to determine the effects of cell-free supernatant (CFS) from Bacillus strains on germination of corn under salinity stress. Corn seeds were subjected to three salinity levels (0, 100 and 150 mM of NaCl), cell-free supernatant of Bacillus strains (U35, U47, U48, U49, and U50) at two levels of dilution (1:50 and 1:250). Germination percentage and rate decreased with increasing salinity toward 150 mM NaCl all together leading to suppressed growth variables for corn seed seedlings including fresh and dry weight of radicle (47.71 and 52.63%, respectively), and shoot (49.52 and 49.25%, respectively), radicle and shoot lengths (39.90 and 66.07%, respectively). Seed vigor index also decreased by 63.04% at 150 mM NaCl. Contrary to salinity, the CFSs of Bacillus strains increased all the growth traits of corn seeds and reduced the negative effects of salinity, especially severe salinity. Ratios of 1:50 and 1: 250 gave best performance for CFSs from U35 and U50, respectively. In general, the highest seed vigor index was obtained by application of 1: 250 CFS from U50. Most germination traits and seed vigor index correlated significantly positive; however, mean germination time was negatively and significantly correlated with the seed vigor index of corn. The results showed that cell-free supernatant use, may as well-helped in changing the ratios of phytohormones, ROS, the activity of antioxidant enzymes and osmotic proteins, hence reduce the negative effects of salinity and improve seed vigor index which eventually increases the ability of plant seedling establishment under saline conditions.

The Effect of Cultivation Conditions on Antifungal and Maize Seed Germination Activity of Bacillus-Based Biocontrol Agent

“…BioSol021 cultivation, which favors biomass growth, antimicrobial activity against aflatoxigenic A. flavus , and PGP traits in maize seeds. Similar results were observed by Yaghoubian et al [ 88 ] when treating maize seed with a cell-free supernatant of Bacillus cultivation broth, resulting in an improved germination percentage and rate at different levels of salinity stress, thus contributing to salinity stress alleviation. The possible mechanisms included in the Bacillus -related improvement in maize germination and seedling development include the improved activity of hydrolytic enzymes involved in seed germination [ 89 , 90 ], a shift in phytohormone ratios—increased amount of plant growth phytohormones compared with plant growth inhibitors [ 88 ]—and the prevention of ROS (reactive oxygen species) accumulation under stress conditions, thus improving antioxidant enzymes activity and preventing damage to seed-stored proteins [ 91 ].…”

Combination Effect of Temperature and Salinity Stress on Germination of Different Maize (Zea mays L.) Varieties

“…As the SVI is influenced by the germination percentage and the seedling length, reducing these parameters during the stress period caused the number to plummet. In maize, it was discovered that the presence of 150 mM salt stress could reduce the SVI by 63% [69]. A similar observation was found in various main crops, including sorghum and rice [70,71].…”

Secretome Analysis of the Plant Biostimulant Bacteria Strains Bacillus subtilis (EB2004S) and Lactobacillus helveticus (EL2006H) in Response to pH Changes

“…The total proteins were digested with trypsin and injected into an LC-MS/MS equipped with a Linear Trap Quadrupole Velos Orbitrap (Thermo Fisher, Waltham, MA, USA). The subsequent analysis for the protein identification was conducted following established methods [ 16 , 116 ]. The dataset obtained from the mass spectra were searched against Lactobacillus spp.…”