Does the compositional change of soil organic matter in the rhizosphere and bulk soil of tea plants induced by tea polyphenols correlate with Pb bioavailability?

Purpose

Soil organic matter (SOM) plays a vital role in controlling metal bioavailability. However, the relationship between SOM and its fractions, including water-soluble substances (WSS), fulvic acid (FA), humic acid (HA), and soil microbial biomass (SMB), to metal bioavailability in plants has not been thoroughly investigated. This study examined the compositional change of SOM after tea polyphenols (TPs) were added to the soil and its correlation with Pb bioavailability.

Materials and methods

Ultisol samples were collected from Fuyang, spiked with two levels (0 and 300 mg kg^?1 DW) of Pb, and aged for 30 days. Four uniform seedlings were transplanted to each plastic pot, which were filled with 3 kg of air-dried soil. After successful transplantation, three levels (0, 300, and 600 mg kg^?1 DW) of TPs were amended as irrigation solution for the pots. The Pb concentrations in different tissues of the tea plants were determined after 6 months. SOM, WSS, FA, HA, and SMB were extracted and quantified using a Multi N/C Total Organic Carbon Analyser.

Results and discussion

Adding TPs to Pb-polluted soils alleviated Pb toxicity to microorganisms and increased SMB and the rhizosphere effect. The rhizosphere SOM was lower than bulk SOM in Pb-unspiked soils, while the opposite results were observed in Pb-spiked soils. A similar inconsistency for HA in the rhizosphere and bulk soil between Pb-unspiked and Pb-spiked soils might explain the difference in SOM. FA increased with the addition of TPs in both the rhizosphere and bulk soils, which might be the result of TP transformation. Positive correlations are present between the compositions of rhizosphere SOM and Pb in different tissues of the tea plant. SMB correlated negatively with Pb in young leaves and stems. Compared to rhizosphere soil, SOM components in bulk soil were less strongly correlated with Pb in tea plants.

Conclusions

Addition of TPs to soil changes the components of SOM and Pb bioavailability. SOM and its fractions, including WSS, FA, HA, and SMB, show a close relationship to Pb in different tissues of the tea plants.     

Nutritional Effect of Flaxseeds on Cholesterol Profile and Fatty Acid Composition in Egg Yolk

This experiment investigated the effect of a supplementary dietary source (flaxseed) on egg yolk cholesterol contents and fatty acid profile. Flaxseeds at three different levels (5, 10, and 15%) were supplemented to 84 Rhode Island Red × Fayoumi cross layers during 21–24 weeks of age. The birds were divided randomly into four groups. Flaxseeds were supplemented in the diet at the level of 5% (FS‐5), 10% (FS‐10), and 15% (FS‐15), and one group served as the control (FS‐0). Cholesterol content of eggs was not significantly affected by flaxseed. The amount of monounsaturated fatty acids was significantly decreased with the increase in the flaxseed level, and the highest reduction was observed in FS‐15. The highest total polyunsaturated fatty acid (PUFA) and total omega‐3 PUFA were recorded in FS‐15. These findings reflect that unsaturated healthy fatty acid content in poultry eggs can be increased with dietary supplementation of flaxseed.     

Fat-tailed sheep production systems in the Khyber Pakhtunkhwa Province of Pakistan

Balkhi, Michni and Hashtnagri populations are the three fat-tailed phenotypes native to Khyber Pakhtunkhwa Province of Pakistan, harbouring the central valley. Their distribution, breeding trend and performances were evaluated through a survey using a pre-tested questionnaire during August, 2008. Out of the total populations, 70.7% were mixed flocks and 5.8%, 3.1% and 9.2% were purebred flocks belonging to Balkhi, Hashtnagri and Michni populations, respectively. Sheep flocks were reared under three different production systems, i.e. sedentary, transhumant and nomadic. Nomads keep Balkhi and are sole responsible for their development as a mutton breed. They practise autumn breeding only, for which they select the heaviest ram/s available within the community. Sedentary and transhumant shepherds had mixed flock, who were constantly replacing their native breed stock, i.e. Michni and Hashtnagri through outcrossing with Balkhi. The size of Balkhi and Michni populations warrants no immediate threat to their existence and diversity. However, in case of increased popularity of crossbreeding, Michni could pose threats of extinction. Hashtnagri on the other hand can be declared as breed at risk. Age at first lambing was significantly lower in Hashtnagri ewes, followed by Michni, crossbred and Balkhi. Hashtnagri ewes outperformed other populations in lambing twice per annum.     

Vanadate inhibition of fungal PhyA and bacterial AppA2 histidine acid phosphatases

The fungal PhyA protein, which was first identified as an acid optimum phosphomonoesterase (EC 3.1.3.8), could also serve as a vanadate haloperoxidase (EC 1.11.1.10) provided the acid phosphatase activity is shut down by vanadate. To understand how vanadate inhibits both phytate and pNPP degrading activities of fungal PhyA phytase and bacterial AppA2 phytase, kinetic experiments were performed in the presence and absence of orthovanadate and metavanadate under various acidic pHs. Orthovanadate was found to be a potent inhibitor at pH 2.5 to 3.0. A 50% activity of fungal phytase was inhibited at 0.56 μM by orthovanadate. However, metavanadate preferentially inhibited the bacterial AppA2 phytase (50% inhibition at 8 μM) over the fungal phytase (50% inhibition at 40 μM). While in bacterial phytase the K(m) was not affected by ortho- or metavanadate, the V(max) was reduced. In fungal phytase, both the K(m) and V(max) was lowered. The vanadate exists as an anion at pH 3.0 and possibly binds to the active center of phytases that has a cluster of positively charged Arg, Lys, and His residues below the enzymes' isoelectric point (pI). The active site fold of haloperoxidase was shown to be very similar to fungal phytase. The vanadate anions binding to cationic residues in the active site at acidic pH thus serve as a molecular switch to turn off phytase activity while turning on the haloperoxidase activity. The fungal PhyA phytase's active site housing two distinct reactive centers, one for phosphomonoesterase and the other for haloperoxidase, is a unique example of how one protein could catalyze two dissimilar reactions controlled by vanadate.     

Two new antioxidant bergenin derivatives from the stem of Rivea hypocrateriformis

Two new bergenin derivatives, named rivebergenin A and B (1, and 2), together with two known compounds, bergenin (3) and norbergenin (4) were isolated from the stem of Rivea hypocrateriformis (Desr.) Choisy. The structures of the new compound have been assigned from ¹H and ¹³C NMR spectra, DEPT, and by 2D COSY, HMQC, and HMBC experiments. Compounds 1-4 showed the strong antioxidant activity.     

FOLIAR APPLICATION OF ZINC INFLUENCES THE LEAF MINERAL STATUS,VEGETATIVE AND REPRODUCTIVE GROWTH,YIELD AND FRUIT QUALITY OF ‘KINNOW’ MANDARIN

Deficiency of zinc (Zn) is widespread in many citrus orchards of Pakistan, consequently hampering fruit yield. Effects of foliar applications of zinc sulfate on tree nutrition, growth, productivity and fruit quality were studied on ‘Kinnow’ mandarin. Leaf nitrogen (N), calcium (Ca), and manganese (Mn) were highest for trees sprayed with 0.2% zinc sulfate, while phosphorus (P) and iron (Fe) were highest with 0.6% zinc sulfate and potassium (K) and Zn were highest with 0.8% Zn sulfate applications. Trees sprayed with 0.6% zinc sulfate exhibited highest increase in height, crown width and stem girth, fruit diameter, fruit weight, ascorbic acid contents, and total phenolics compared to all other treatments. Pre-harvest fruit drop was lowest and total number and weight of fruit per tree was highest at harvest with 0.4% zinc sulfate application. In conclusion, foliar application of zinc sulfate up to 0.6% improved tree mineral nutrients, growth, and productivity with better fruit quality in ‘Kinnow’ mandarin.     

Exploring Agrobiodiversity on Farm: A Case from Middle–Hills of Nepal

A survey was conducted to examine agrobiodiversity status of farms in the Pokhare Khola watershed of Dhading district in the Middle-Hills of Nepal. A total of 53 farmland tree and one crop species from 22 families were documented. The most commonly found species were fruit and fodder species (on over 60 % farms) including banana (Musa paradisiaca), khasrato (Ficus hispida) and khanayo (Ficus semicordata). Tree density was highest (226/ha) on marginal farms (farm area ≤0.25 ha) and lowest (165/ha) on small farms (farm area 0.26–0.5 ha). For the study area as a whole, the Shannon-Wiener species diversity index was 3.26 and the species evenness index 1.89. Large farms (farm area >1 ha) had the greatest tree species diversity (4.47 ± 0.52) and marginal farms the lowest (2.18 ± 0.37), indicating the positive relationship between farm size and species diversity. A total of six types of cereals and 18 types of vegetable crops were grown in the study area. The major livestock component of each household was chickens (average 8/household) and goats (6/household). The mean value of livestock in the large farm category was estimated as $2235, significantly higher than that of the other three categories. A significant relationship was found between agrobiodiversity and livelihoods, irrespective of annual production, and the critical role of the farmed landscape in agrobiodiversity conservation was apparent.     

Decolorization of Azo,Triphenylmethane and Anthraquinone Dyes by Laccase of a Newly Isolated <Emphasis Type="Italic">Armillaria</Emphasis> sp. F022

A newly isolated white-rot fungus, Armillaria sp. strain F022, was isolated from the decayed wood in a tropical rain forest. Strain F022 was capable of decolorizing a variety of synthetic dyes, including azo, triphenylmethane, and anthraquinone dyes, with an optimal efficiency of decolorization obtained when dyes added after 96 h of culture, with the exception of Brilliant Green. All of the tested dyes were decolorized by the purified laccase in the absence of any redox mediators, but only a few were completely removed, while others were not completely removed even when decolorization time was increased. The laccase, with possible contributions from unknown enzymes, played a role in the decolorization process carried out by Armillaria sp. F022 cultures, and this biosorption contributed a negligible part to the decolorization by cultures. The effect of dye to fungal growth was also investigated. When dyes were added at 0 h of culture, the maximum dry mycelium weight (DMW) values in the medium containing Brilliant Green were 1/6 of that achieved by the control group. For other dyes, the DMW was similar with control. The toxic tolerance of dye for the cell beads was excellent at least up to a concentration of 500 mg/l. The optimum conditions for decolorization of three synthetic dyes are at pH 4 and 40°C.     

Gibberellic Acid and Boron Enhance Antioxidant Activity,Phenolic Content,and Yield Quality in Pyrus Communis L.

Gesunde Pflanzen - Foliar application of micronutrients and plant growth regulators (PGRs) is one of the strategies of plant-feeding direct through leaves to allow rapid uptake irrespective of soil...     

Mechanism of disease development caused by a multihost plant bacterium, Pseudomonas cichorii, and its virulence diversity

Pseudomonas cichorii causes rot on lettuce leaves, distinct from the necrotic spots of infected eggplant leaves. On lettuce leaves, P. cichorii invades intercellular spaces through stomata and grows vigorously, causing rot on the leaves. Surprisingly, P. cichorii does not produce pectate lyase, the most important enzyme for degrading plant cell walls. Alternatively, infection with P. cichorii causes heterochromatin condensation and DNA laddering in lettuce cells, followed by induced cell death, which results in disease symptoms. Thus, apoptotic programmed cell death (PCD) is associated with the symptoms on lettuce leaves. Although PCD in P. cichorii-infected eggplant leaves is also associated with necrotic spots caused by the bacteria, there are differences in the responses of the two hosts. P. cichorii harbors the N-acetyltransferase family gene (pat) and the hrp genes (hrp) encoding a type III secretion system, adjacent to an aldehyde dehydrogenase gene (aldH). The virulence of P. cichorii is hrp-dependent in eggplant, but not in lettuce. Furthermore, hrp, pat and aldH are implicated in the diversity of P. cichorii virulence on susceptible Asteraceae species. The involvement of hrp, aldH and pat in bacterial virulence on the respective species has no relationship with the phylogeny of the plants species. When these results are considered together, P. cichorii has multiple virulence determinants. The involvement of not only hrp but also aldH and pat in P. cichorii virulence arose after species diversification of host plants. Host responses implicated in symptom development have been responsible for the development of virulence determinants of P. cichorii.