The Effect of Various Forms of Sulfur on Soil Organic Matter Fractions and Microorganisms in a Pot Experiment with Perennial Ryegrass (Lolium perenne L.).

This article focuses on the agronomic evaluation of the supplementation of mineral NPKMg fertilizers with elemental sulfur, magnesium, potassium, or ammonium sulfates in pot experiments with ryegrass growing in a sandy Arenosol with very low sulfur content. A benefit evaluation was carried out on the basis of biomass production, crop nutritional status, and changes in the content of soil organic matter fractions. Furthermore, the total number of bacteria, nitrogen-fixing bacteria, and fungi was estimated using the qPCR technique in soil samples after 60 days of ryegrass growth. The combined application of NPKMg and sulfur or sulfate fertilizers significantly increased the summary yield of three cuttings of fresh ryegrass biomass in the range of 32.3% to 82.7%. The application, especially in the form of sulfates, significantly decreased the content of free phenolic acids. Furthermore, compared to the control, i.e., soil with NPKMg applied alone, an increase in the content of glomalin-related proteins and a decrease in the amount of water-soluble organic carbon compounds were observed. Neither the number of DNA marker copy numbers of the total bacterial community nor the nitrogen-fixing bacteria were noticeably different. In turn, the total number of genetic markers for fungi was significantly higher in soils with potassium or ammonium sulfates compared to the control soil. The general results suggest that the application of sulfur fertilizers with NPKMg mineral fertilizer can benefit crops and support soil fertility due to the stabilization of aggregates and the decrease in water-soluble organic compounds.

Monitoring of changes in 5-n-alkylresorcinols during wheat seedling development.

For seven days of wheat growth, caryopsis remained the main source of 5-n-alkylresorcinols with C19 and/or C21 homolog as a main compound. Shoot contained small amount of these phenolic lipids; their average content was 3.23% of level obtained in the whole seedling. Moreover, 41.38% of resorcinolic lipids of seven-day-old shoot was accumulated in part of leaf covered by coleoptile. Interestingly, a removal of 1.07% of the primary pool of kernel alkylresorcinols by short-term washing (10 s) of wheat seed with acetone before planting decreased their level only in seed of seven-day old seedling. Compared to the respective controls, this treatment did not affect the amount of these lipids in the green part of seedling that proved that de novo synthesis of 5-n-alkylresorcinols takes place in shoots. The very similar homolog profiles of these lipids in four- and seven-day-old shoots turned out to be markedly less diversified than those found in respective seed samples. Compared to the mature wheat caryopsis, the rise in the content of very-long-chain homologs was observed only in the oldest shoot. Their increased accumulation was probably connected with formation of cuticular layer providing the defensive barrier against various phytopathogens.

Biodegradation of the cross-linked copolymer of acrylamide and potassium acrylate by soil bacteria.

Chemical cross-linking and the high molecular weight of superabsorbent copolymers (SAPs) are the two main causes of their resistance to biodegradation. However, SAP particles are colonized by microorganisms. For the purposes of this study, the dry technical copolymer of acrylamide and potassium acrylate containing 5.28 % of unpolymerized monomers was wrapped in a geotextile and incubated in unsterile Haplic Luvisol soil as a water absorbing geocomposite. The highest number of soil bacteria that colonized the hydrated SAP and utilized it as the sole carbon and energy source was found after the first month of incubation in soil. It was equal to 7.21-7.49 log10 cfu g(-1) of water absorbed by the SAP and decreased by 1.35-1.61 log10 units within the next 8 months. During this time, the initial SAP water holding capacity of 1665.8 g has decreased by 24.40 %. Moreover, the 5 g of SAP dry mass has declined by 31.70 %. Two bacteria, Rhizobium radiobacter 28SG and Bacillus aryabhattai 31SG isolated from the watered SAP were found to be able to biodegrade this SAP in pure cultures. They destroyed 25.07 and 41.85 mg of 300 mg of the technical SAP during the 60-day growth in mineral Burk's salt medium, and biodegradation activity was equal to 2.95 and 6.72 µg of SAP µg(-1) of protein, respectively. B. aryabhattai 31SG and R. radiobacter 28SG were also able to degrade 9.99 and 29.70 mg of 82 mg of the ultra-pure SAP in synthetic root exudate medium during the 30-day growth, respectively.

Dynamics of alkylresorcinols during rye caryopsis germination and early seedling growth.

Among secondary metabolites, alkylresorcinols are considered particularly important for the antimicrobial defense system in cereal grains. Dry rye caryopses and young seedlings contain detectable quantities of resorcinolic lipids. Overall, 11 distinct alkylresorcinol homologues were identified, which showed variable profiles during rye germination and early seedling development, especially with reference to the production of very long homologues and to side chain saturation. Additionally, changes in the alkylresorcinol composition during rye seedling growth are presented for the first time.

Various effects of fluorescent bacteria of the genus Pseudomonas containing ACC deaminase on wheat seedling growth.

The study evaluates the effect of rhizobacteria having 1-aminocyclopropane-1-carboxylate deaminase (ACCd) on the development of wheat seedlings. This enzyme has been proposed to play a key role in microbe-plant association. Three fluorescent pseudomonads containing this deaminase were selected from 70 strains of pseudomonads isolated from rhizosphere of wheat (Triticum aestivum L.) and rape (Brassica napus L.). These bacteria, varied significantly in the ability to both biosynthesize auxins and hydrolyze ACC. Among them, Pseudomonas brassicacearum subsp. brassicacearum strain RZ310 presented the highest activities of ACC deaminase during 96h of growth in liquid Dworkin and Foster (DF) salt medium. Additionally, this rape rhizosphere strain did not produce indoles. Two other isolates, Pseudomonas sp. PO283 and Pseudomonas sp. PO366, secreted auxins only in the presence of their precursor. Phylogenetic analysis of the 16S rRNA gene and four other protein-encoding genes indicated that these wheat rhizosphere isolates belonged to the fluorescent Pseudomonas group. Moreover, the effects of these strains on wheat seedling growth under in vitro conditions were markedly dependent on both their cell suspensions used to grain inoculation and nutrient conditions. Strains tested had beneficial influence on wheat seedlings mainly at low cell densities. In addition, access to nutrients markedly changed bacteria action on cereal growth. Their presence generally favored the positive effects of pseudomonads on length and the estimated biomasses of wheat coleoptiles. Despite these general rules, impacts of each isolate on the growth parameters of cereal seedlings were unique.

Various effects of the photosystem II--inhibiting herbicides on 5-n-alkylresorcinol accumulation in rye seedlings.

The effect of three PSII-inhibiting herbicides, lenacil, linuron, and pyrazon, on the accumulation of 5-n-alkylresorcinols in rye seedlings (Secale cereale L.) grown under various light and thermal conditions was studied. All used chemicals increased resorcinolic lipid content in both green and etiolated plants grown at 29 °C. At 22 °C pyrazon and lenacil decreased the content of alkylresorcinols in plants kept in the darkness and increased their amount in the light-grown seedlings. In turn, level of resorcinolic lipids was decreased by linuron in both etiolated and green plants. At the lowest tested temperature lenacil enhanced production of alkylresorcinols only in etiolated rye seedlings, whereas the light-independent stimulatory action of pyrazon on alkylresorcinol accumulation in rye grown at 15 °C was observed. Additionally, only the latter did not exert a negative effect on rye seedling growth under any of tested conditions. Compared with respective controls, the herbicides used also markedly modified the qualitative pattern of resorcinolic homologs. Interestingly, the observed changes generally favored the enhanced antifungal activity of these compounds. Our study provides novel information on the influence of PSII inhibitors on alkylresorcinol metabolism in rye seedlings. The unquestionable achievement of this work is the observation that low dose of pyrazon mainly stimulated both growth and alkylresorcinol synthesis in rye seedlings, a non-target plant. Moreover, our experimental work showed unambiguously that the observed pyrazon-driven accumulation and homolog pattern modification of alkylresorcinols dramatically improved the resistance of winter rye to infections caused by Rhizoctonia cerealis.

Cycloate, an inhibitor of fatty acid elongase, modulates the metabolism of very-long-side-chain alkylresorcinols in rye seedlings.

BACKGROUND: Cycloate inhibits the biosynthesis of very-long-chain fatty acids, the essential constituents of plant waxes and suberin. Fatty acids also serve as precursors of aliphatic carbon chains in resorcinolic lipids, which play a fundamental role in the plant defence system against fungal pathogens. In this study, the effect of cycloate on the biosynthesis of 5-n-alkylresorcinols in rye seedlings (Secale cereale L.) grown under various light and thermal conditions was examined. RESULTS: The content of alkylresorcinols biosynthesised in rye was generally increased by the herbicide in both green and etiolated plants. The presence of cycloate also affected patterns of alkylresorcinol homologues in plants grown at 15 and 22 degrees C; very-long-side-chain compounds were less abundant, whereas both short-chain saturated and unsaturated homologues were generally accumulated. No cycloate-related effects caused by homologue pattern modifications were observed at elevated temperature. CONCLUSION: This study extends present understanding of the mode of action of thiocarbamate herbicides. Cycloate markedly affected the biosynthesis of very-long-side-chain resorcinolic lipids in rye seedlings, confirming the existence of parallels in both fatty acid and alkylresorcinol biosynthetic pathways. The observed cycloate-driven accumulation of 5-n-alkylresorcinols may improve the resistance of cereals to infections caused by microbial pathogens.

Effect of norflurazon on resorcinolic lipid metabolism in rye seedlings.

Norflurazon is a selective pyridazinone herbicide excessively employed in the control of many annual grasses and broad-leaved weeds. This chemical causes plant bleaching due to the inhibition of the carotenoid pigment biogenesis as well as induces irreparable changes to chloroplasts, which are considered the organelles where the biosynthesis of resorcinolic lipids takes place. Resorcinolic lipids, a group of phenolic compounds, constitute not only an essential part of the plant antifungal defense system, but also are an important component of the human cereal diet. The aim of this study was to investigate the effect of norflurazon on the biosynthesis of resorcinolic lipids in 5-day-old rye plants (Secale cereale L.) that were grown at three different temperatures under light or dark conditions. At all tested temperatures, norflurazon decreased the fresh biomass of light-grown rye seedlings and increased the weight of plants grown in darkness. Compared with respective controls, this herbicide caused an increase in total content of alkylresorcinols in both green and etiolated plants with the exception of dark-grown norflurazon-treated rye at 29 degrees C. The general level of saturated homologues was markedly decreased by norflurazon in all etiolated plants and in light-grown seedlings at 15 degrees C. Independent of thermal and light conditions, in all norflurazon-treated samples two alkylresorcinol derivatives predominated: 1,3-dihydroxy-5-n-heptadecylbenzene and 1,3-dihydroxy-5-n-nonadecylbenzene. Thus, our results suggest that norflurazon affected the metabolism of alkylresorcinols in rye seedlings and its action was dependent on external stimuli.