Effect of Bacillus amyloliquefaciens and Bacillus subtilis on fermentation, dynamics of bacterial community and their functional shifts of whole-plant corn silage

Background Bacillus amyloliquefaciens (BA) and Bacillus subtilis (BS) are usually used as feed supplements directly or bacterial inoculants in biological feeds for animals. However, few research have reported the effects of BA and BS on fermentation characteristics and bacterial community successions of whole-plant corn silage during ensiling. If the BA and BS inoculants have positive effects on silages, then they could not only improve fermentation characteristics, but also deliver BA or BS viable cells to ruminants, which would play its probiotic effect. Therefore, the objectives of this study were to investigate the effects of BA and BS on the fermentation, chemical characteristics, bacterial community and their metabolic pathway of whole-plant corn silage. Results Freshly chopped whole-plant corn was inoculated without or with BA and BS, respectively, and ensiled for 1, 3, 7, 14 and 60 d. Results showed that BA and BS inoculations increased lactic acid concentrations of whole-plant corn silages compared with control, and BA inoculation decreased acetic acid concentrations, whereas BS inoculation decreased fiber contents and increased crude protein (CP) content. Higher water-soluble carbohydrate contents and lower starch contents were observed in BA- and BS-inoculated silages compared with that in control. The decreased CP content and increased non-protein nitrogen content were observed in BA-inoculated silage, which was consistent with the higher amino acid metabolism abundances observed in BA-inoculated silage. In addition, it was noteworthy that BA and BS inoculations increased the metabolism of cofactors and vitamins, and decreased the relative abundances of drug resistance: antimicrobial pathways. We also found that the bacterial metabolism pathways were clearly separated into three clusters based on the ensiling times of whole-plant corn silage in the present study. There were no significant differences in bacterial community compositions among the three groups during ensiling. However, BA and BS inoculations decreased the relative abundances of undesirable bacteria such as Acetobacter and Acinetobacter. Conclusion Our findings suggested that the BS strain was more suitable as silage inoculants than the BA strain in whole-plant corn silage in this study.

Exogenous putrescine attenuates the negative impact of drought stress by modulating physio-biochemical traits and gene expression in sugar beet (Beta vulgaris L.)

Drought tolerance is a complex trait controlled by many metabolic pathways and genes and identifying a solution to increase the resilience of plants to drought stress is one of the grand challenges in plant biology. This study provided compelling evidence of increased drought stress tolerance in two sugar beet genotypes when treated with exogenous putrescine (Put) at the seedling stage. Morpho-physiological and biochemical traits and gene expression were assessed in thirty-day-old sugar beet seedlings subjected to drought stress with or without Put (0.3, 0.6, and 0.9 mM) application. Sugar beet plants exposed to drought stress exhibited a significant decline in growth and development as evidenced by root and shoot growth characteristics, photosynthetic pigments, antioxidant enzyme activities, and gene expression. Drought stress resulted in a sharp increase in hydrogen peroxide (H2O2) (89.4 and 118% in SBT-010 and BSRI Sugar beet 2, respectively) and malondialdehyde (MDA) (35.6 and 27.1% in SBT-010 and BSRI Sugar beet 2, respectively). These changes were strongly linked to growth retardation as evidenced by principal component analysis (PCA) and heatmap clustering. Importantly, Put-sprayed plants suffered from less oxidative stress as indicated by lower H2O2 and MDA accumulation. They better regulated the physiological processes supporting growth, dry matter accumulation, photosynthetic pigmentation and gas exchange, relative water content; modulated biochemical changes including proline, total soluble carbohydrate, total soluble sugar, and ascorbic acid; and enhanced the activities of antioxidant enzymes and gene expression. PCA results strongly suggested that Put conferred drought tolerance mostly by enhancing antioxidant enzymes activities that regulated homeostasis of reactive oxygen species. These findings collectively provide an important illustration of the use of Put in modulating drought tolerance in sugar beet plants.

Improving Grain Yield via Promotion of Kernel Weight in High Yielding Winter Wheat Genotypes

Improving plant net photosynthetic rates and accelerating water-soluble carbohydrate accumulation play an important role in increasing the carbon sources for yield formation of wheat (Triticum aestivum L.). Understanding and quantify the contribution of these traits to grain yield can provide a pathway towards increasing the yield potential of wheat. The objective of this study was to identify kernel weight gap for improving grain yield in 15 winter wheat genotypes grown in Shandong Province, China. A cluster analysis was conducted to classify the 15 wheat genotypes into high yielding (HY) and low yielding (LY) groups based on their performance in grain yield, harvest index, photosynthetic rate, kernels per square meter, and spikes per square meter from two years of field testing. While the grain yield was significantly higher in the HY group, its thousand kernel weight (TKW) was 8.8% lower than that of the LY group (p < 0.05). A structural equation model revealed that 83% of the total variation in grain yield for the HY group could be mainly explained by TKW, the flag leaf photosynthesis rate at the grain filling stage (Pn75), and flag leaf water-soluble carbohydrate content (WSC) at grain filling stage. Their effect values on yield were 0.579, 0.759, and 0.444, respectively. Our results suggest that increase of flag leaf photosynthesis and WSC could improve the TKW, and thus benefit for developing high yielding wheat cultivars.

Isolation and Characterization of Levoglucosan Metabolizing Bacteria

Bacteria were isolated from wastewater and soil containing charred wood remnants based on their ability to use levoglucosan as a sole carbon source and on their levoglucosan dehydrogenase (LGDH) activity. On the basis of their 16S rRNA gene sequences, these bacteria represented diverse genera of Microbacterium, Paenibacillus , Shinella , and Klebsiella . Genomic sequencing of the isolates verified that two isolates represented novel species, Paenibacillus athensensis MEC069 T and Shinella sumterensis MEC087 T , while the remaining isolates were closely related to either Microbacterium lacusdiani or Klebsiella pneumoniae . The genetic sequence of LGDH, lgdA , was found in the genomes of these four isolates as well as Pseudarthrobacter phenanthrenivorans Sphe3. The identity of the P. phenanthrenivorans LGDH was experimentally verified following recombinant expression in E. coli . Comparison of the putative genes surrounding lgdA in the isolate genomes indicated that several other gene products facilitate the bacterial catabolism of levoglucosan, including a putative sugar isomerase and several transport proteins. Importance Levoglucosan is the most prevalent soluble carbohydrate remaining after high temperature pyrolysis of lignocellulosic biomass, but it is not fermented by typical production microbes such as Escherichia coli and Saccharomyces cerevisiae . A few fungi metabolize levoglucosan via the enzyme levoglucosan kinase, while several bacteria metabolize levoglucosan via levoglucosan dehydrogenase. This study describes the isolation and characterization of four bacterial species which degrade levoglucosan. Each isolate is shown to contain several genes within an operon involved in levoglucosan degradation, furthering our understanding of bacteria which metabolize levoglucosan.

Evaluation of Cadmium Bioaccumulation-Related Physiological Effects in Salvinia biloba: An Insight towards Its Use as Pollutant Bioindicator in Water Reservoirs

Free-living macrophytes play an important role in the health of aquatic ecosystems. Therefore, the use of aquatic plants as metal biomonitors may be a suitable tool for the management of freshwater reservoirs. Hence, in this study, we assessed the effects of cadmium (Cd) in Salvinia biloba specimens collected from the Middle Paraná River during a 10-day experiment employing artificially contaminated water (100 μM Cd). S. biloba demonstrated a great ability for Cd bioaccumulation in both the root-like modified fronds (named “roots”) and the aerial leaf-like fronds (named “leaves”) of the plants. Additionally, Cd toxicity was determined by the quantification of photosynthetic pigments (chlorophylls a and b, and carotenoids), flavonoids, and soluble carbohydrate contents in S. biloba over time (1, 3, 5, 7, and 10 days). In general, deterioration was more pronounced in leaves than in roots, suggesting a greater implication of the former in long-term Cd sequestration in S. biloba. Deleterious effects in the appraised parameters were well correlated with the total amount of Cd accumulated in the leaves, and with the qualitative changes observed in the plants’ phenotype during the 10-day metal exposure assay. The flavonoids and carotenoids in leaves were highly affected by low Cd levels followed by root carbohydrates. In contrast, chlorophylls and root flavonoids were the least impacted physiological parameters. Therefore, our results demonstrate that S. biloba displays dissimilar organ-linked physiological responses to counteract Cd phytotoxicity and that these responses are also time-dependent. Though further research is needed, our work suggests that easy-handled physiological data obtained from autochthonous free-floating S. biloba specimens may be used as a valuable tool for metal-polluted water biomonitoring.

BIOMASS AND CHEMICAL RESPONSES OF Desmanthus spp. ACCESSIONS SUBMITTED TO WATER DEPRIVATION1

ABSTRACT Due to the predictions of climate change, there is a need to identify forage plants that can keep their productivity and nutritive value under hydric stress. The objective of this study was to evaluate the biomass and chemical responses of three Desmanthus spp. accessions under two water deprivation regimens (7 and 21-day). The experimental design used was randomized blocks in a 3 × 2 factorial arrangement (access and water deprivation) with four replications. There were reductions in the biomasses of leaf and stem fractions of 64% and 51%, respectively. The 43F accession showed greater leaf (1.86 g.plant-1) and stem (1.97 g.plant-1) biomasses under a total water restriction of 21 days, compared to the 89F and AusT accessions. In accessions 43F and 89F, there were carbohydrate accumulations in the leaves of 28% and 51%, respectively, under the 21-day water restriction, while AusT decreased 38% within a 7-day interval. Water deprivation affected the chemical characteristics of the accessions. Free proline was similar among accessions and accumulated 463% more in the leaves of plants submitted to 21-day water deprivation (90.22 mg.kg-1) compared to those subjected to water deprivation for 7 days (16.03 mg.kg-1). Proline and total soluble carbohydrate accumulation in 43F and 89F were insufficient to regulate crude protein, C content, and C:N ratios. These results demonstrate the variability in drought tolerance among accessions. Accessions 43F and 89F were more susceptible to 21-day water deprivation, while AusT showed greater drought tolerance.

Enhancement of Growth, Flowering and Corm Freesia Hybrida Plant via Rice Organic Residue Application and Chelated Zinc Spray

A pot trial was conducted to identify the effect of adding rice organic residues (ROR) to the potting soil and spraying chelated zinc (CZn) on the growth, flowering, and corm characteristics of the Freesia hybrida plant. An RCBD experiment was adopted with two factors and three replicates. ROR comprised three levels (0, 4, and 8%), and CZn included three concentrations (0, 20, and 40) mg.L−1. The findings revealed that applying ROR at 8% and spraying CZn at 20 mg.L−1 significantly increased leaf number, shoot dry weight, total chlorophyll content in fresh leaves, and total soluble carbohydrate content in dry leaves (6.66 leaves. plant−1, 8.76 g DW, 48.79 mg.100 g−1 FW, and 1.50 g DW) respectively. Also, the same treatment combination realized significant results for the number of florets per inflorescence, floret diameter, floret vase life, number of corms per plant, and corm diameter by (12.85 florets. inflorescence−1, 7.03 cm, 8 days, 3.66 corms. plant−1, and 2.33 cm) consecutively. Further, adding ROR at 8% and spraying CZn at 40 mg.L−1 significantly increased the number of inflorescences (5.33 inflorescences. plant−1) and inflorescence length (39.10 cm).

The Effect of Foliar Thiamine and Roselle Extract on NPK Content and Some Chemical Parameters inof Mathiola Plant

The experiment was conducted in the Directorate of Agriculture in Najaf during the agricultural season 2020-2021 to know the effect of Foliar application of thiamine and Roselle extract on the chemical parameters of the Mathiola plant(Matthiola incana L).The experiment included two factors, the first is thiamine at four concentrations (90,60,30,0) mg.L-1. The second is Roselle extract at four concentrations (0,2,4,6) g.L-1, a factorial experiment was conducted consisting of three replicates, the experiment was conducted based on the Randomized Complete Block Design (R.C.B.D) 4×4×3=48, The results can be summarized that thiamine at a concentration of 90 mg.L-1 with Roselle extract at a concentration of 6.4 g.L-1 when sprayed on the plant led to a significant increase in the study parameters as the leaves content of total chlorophyll and nitrogen phosphorous potassium, boron and the total soluble carbohydrate content of the leaves and the anthocyanin content of the flowers were increased reached to 57.27 mg.100 g-1 and 2.45% and 0.29% and 2.96% and 13.72 mg.kg-1 and 18.10 mg.g-1 respectively.