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Food waste is recognized as a valuable source for potential agricultural applications to supply organic matter and nutrients to arable soil. However, the information on the combined application of food waste and the plant growth-promoting bacterial strain, Chlorella, related to plant metabolic features and sodium chloride content in arable soil is limited. The present study was conducted to investigate the exogenous application of food waste along with Chlorella, which improved the physio-morphological features of red pepper. Our results revealed that this combination enhanced the organic matter in the soil, ultimately improving the fertility rate of the soil, and the physio-morphological features, such as chlorophyll a content (24.5 ± 0.7), root (7.8 ± 0.7) cm and shoot length (12.1 ± 0.7) cm, fresh weight (2.1 ± 0.05) g, dry weight (0.19 ± 0.05) g, mineral contents, and hormonal concentration (ABA by up to 2 folds). The combined treatment also minimized free radicals via the activation of the intrinsic antioxidant series cascade and electrolyte leakage. Our findings showed that adding Chlorella and food wastes improved growth characteristics and can be used as a green bio-fertilizer for sustainable agriculture. [ABSTRACT FROM AUTHOR]

Plants are adapted to defend themselves through programming, reprogramming, and stress tolerance against numerous environmental stresses, including heavy metal toxicity. Heavy metal stress is a kind of abiotic stress that continuously reduces various crops' productivity, including soybeans. Beneficial microbes play an essential role in improving plant productivity as well as mitigating abiotic stress. The simultaneous effect of abiotic stress from heavy metals on soybeans is rarely explored. Moreover, reducing metal contamination in soybean seeds through a sustainable approach is extremely needed. The present article describes the initiation of heavy metal tolerance mediated by plant inoculation with endophytes and plant growth-promoting rhizobacteria, the identification of plant transduction pathways via sensing annotation, and contemporary changes from molecular to genomics. The results suggest that the inoculation of beneficial microbes plays a significant role in rescuing soybeans under heavy metal stress. They create a dynamic, complex interaction with plants via a cascade called plant-microbial interaction. It enhances stress metal tolerance via the production of phytohormones, gene expression, and secondary metabolites. Overall, microbial inoculation is essential in mediating plant protection responses to heavy metal stress produced by a fluctuating climate. [ABSTRACT FROM AUTHOR]

Wheat is one of the major cereal crop grown food worldwide and, therefore, plays has a key role in alleviating the global hunger crisis. The effects of drought stress can reduces crop yields by up to 50% globally. The use of drought-tolerant bacteria for biopriming can improve crop yields by countering the negative effects of drought stress on crop plants. Seed biopriming can reinforce the cellular defense responses to stresses via the stress memory mechanism, that its activates the antioxidant system and induces phytohormone production. In the present study, bacterial strains were isolated from rhizospheric soil taken from around the Artemisia plant at Pohang Beach, located near Daegu, in the South Korea Republic of Korea. Seventy-three isolates were screened for their growth-promoting attributes and biochemical characteristics. Among them, the bacterial strain SH-8 was selected preferred based on its plant growth-promoting bacterial traits, which are as follows: abscisic acid (ABA) concentration = 1.08 ± 0.05 ng/mL, phosphate-solubilizing index = 4.14 ± 0.30, and sucrose production = 0.61 ± 0.13 mg/mL. The novel strain SH-8 demonstrated high tolerance oxidative stress. The antioxidant analysis also showed that SH-8 contained significantly higher levels of catalase (CAT), superoxide dismutase (SOD), and ascorbic peroxidase (APX). The present study also quantified and determined the effects of biopriming wheat (Triticum aestivum) seeds with the novel strain SH-8. SH-8 was highly effective in enhancing the drought tolerance of bioprimed seeds; their drought tolerance and germination potential (GP) were increased by up to 20% and 60%, respectively, compared with those in the control group. The lowest level of impact caused by drought stress and the highest germination potential, seed vigor index (SVI), and germination energy (GE) (90%, 2160, and 80%, respectively), were recorded for seeds bioprimed with with SH-8. These results show that SH-8 enhances drought stress tolerance by up to 20%. Our study suggests that the novel rhizospheric bacterium SH-8 (gene accession number OM535901) is a valuable biostimulant that improves drought stress tolerance in wheat plants and has the potential to be used as a biofertilizer under drought conditions. [ABSTRACT FROM AUTHOR]

Salinity stress is one of the most serious environmental stress that inhibits plant growth. In this study, we adopted an environment friendly technique and screened different plant growth-promoting fungi for different plant growth promoting (PGP) traits and salinity stress. Among those isolates, Bipolaris sp. CSL-1 was selected based on plant growth-promoting characteristics, such as producing indole-3-acetic acid (IAA), gibberellins (GAs), organic acids and resistance to sodium chloride (NaCl) stress. Here, we found that inoculating soybean with isolate CSL-1 significantly increased shoot and root length, shoot and root fresh and dry weight and chlorophyll content under NaCl stress (200 mM). Endogenous abscisic acid (ABA) levels were significantly decreased, whereas salicylic acid (SA) levels were increased in CSL-1-inoculated plants under NaCl stress. NaCl-treated noninoculated plants showed higher levels of antioxidants and oxidative stress such as peroxidase, polyphenol oxidase (PPO), malondialdehyde (MDA) and superoxide anion (SOA). Furthermore, CSL-1 inoculation improved soybean resistance to NaCl stress, and there was a significant decrease in GmFDL19, GmNARK, and GmSIN1 expression levels. As a result, the fungal isolate CSL-1 mitigates the effect of salt stress and enhance soybean growth and might be used as a valuable ecofriendly microorganism resource in salt-affected areas. [ABSTRACT FROM AUTHOR]

Drought and ultraviolet radiation (UV radiation) are the coexisting environmental factors that negatively affect plant growth and development via oxidative damage. Flavonoids are reactive, scavenging oxygen species (ROS) and UV radiation-absorbing compounds generated under stress conditions. We investigated the biosynthesis of kaempferol and quercetin in wild and flavanone 3-hydroxylase (F3H) overexpresser rice plants when drought and UV radiation stress were imposed individually and together. Phenotypic variation indicated that both kinds of stress highly reduced rice plant growth parameters in wild plants as compared to transgenic plants. When combined, the stressors adversely affected rice plant growth parameters more than when they were imposed individually. Overaccumulation of kaempferol and quercetin in transgenic plants demonstrated that both flavonoids were crucial for enhanced tolerance to such stresses. Oxidative activity assays showed that kaempferol and quercetin overaccumulation with strong non-enzymatic antioxidant activity mitigated the accumulation of ROS under drought and UV radiation stress. Lower contents of salicylic acid (SA) in transgenic plants indicated that flavonoid accumulation reduced stress, which led to the accumulation of low levels of SA. Transcriptional regulation of the dehydrin (DHN) and ultraviolet-B resistance 8 (UVR8) genes showed significant increases in transgenic plants compared to wild plants under stress. Taken together, these results confirm the usefulness of kaempferol and quercetin in enhancing tolerance to both drought and UV radiation stress. [ABSTRACT FROM AUTHOR]

Abiotic stresses, such as salt and heat stress, coexist in some regions of the world and can have a significant impact on agricultural plant biomass and production. Rice is a valuable crop that is susceptible to salt and high temperatures. Here, we studied the role of flavanol 3-hydroxylase in response to combined salt and heat stress with the aim of better understanding the defensive mechanism of rice. We found that, compared with wild-type plants, the growth and development of transgenic plants were improved due to higher biosynthesis of kaempferol and quercetin. Furthermore, we observed that oxidative stress was decreased in transgenic plants compared with that in wild-type plants due to the reactive oxygen species scavenging activity of kaempferol and quercetin as well as the modulation of glutathione peroxidase and lipid peroxidase activity. The expression of high-affinity potassium transporter (HKT) and salt overly sensitive (SOS) genes was significantly increased in transgenic plants compared with in control plants after 12 and 24 h, whereas sodium-hydrogen exchanger (NHX) gene expression was significantly reduced in transgenic plants compared with in control plants. The expression of heat stress transcription factors (HSFs) and heat shock proteins (HSPs) in the transgenic line increased significantly after 6 and 12 h, although our understanding of the mechanisms by which the F3H gene regulates HKT , SOS , NHX , HSF , and HSP genes is limited. In addition, transgenic plants showed higher levels of abscisic acid (ABA) and lower levels of salicylic acid (SA) than were found in control plants. However, antagonistic cross talk was identified between these hormones when the duration of stress increased; SA accumulation increased, whereas ABA levels decreased. Although transgenic lines showed significantly increased Na+ ion accumulation, K+ ion accumulation was similar in transgenic and control plants, suggesting that increased flavonoid accumulation is crucial for balancing Na+/K+ ions. Overall, this study suggests that flavonoid accumulation increases the tolerance of rice plants to combined salt and heat stress by regulating physiological, biochemical, and molecular mechanisms. [ABSTRACT FROM AUTHOR]