A plant growth-promoting pseudomonad is closely related to the Pseudomonas syringae complex of plant pathogens

Pseudomonas putida GR12-2 is well known as a plant growth-promoting rhizobacterium; however, phylogenetic analysis using the 16S rRNA gene and four housekeeping genes indicated that this strain forms a monophyletic group with the Pseudomonas syringae complex, which is composed of several species of plant pathogens. On the basis of these sequence analyses, we suggest that P. putida GR12-2 be redesignated as P. syringae GR12-2. To compare the ecological roles of P. syringae GR12-2 with its close relatives P. syringae pathovar (pv.) tomato DC3000 and P. syringae pv. syringae B728a, we investigated their ability to cause disease and promote plant growth. When introduced on tobacco or tomato leaves, P. syringae GR12-2 was unable to elicit a hypersensitive response or cause disease, which are characteristic responses of P. syringae DC3000 and B728a, nor were type III secretion system genes required for virulence detected in P. syringae GR12-2 by PCR or DNA hybridization. In contrast to P. syringae GR12-2, neither of the phytopathogens was able to promote root growth when inoculated onto canola seeds. Although commensals and nonpathogens have been reported among the strains of the P. syringae complex, P. syringae GR12-2 is a mutualist and a phytostimulator.

Comparative effect of integrated pest management and farmers' standard pest control practice for managing insect pests on cabbage (Brassica spp.)

BACKGROUND

Studies were conducted on experimental cabbage plantings in 2009 and on experimental and commercial plantings in 2010, comparing farmers' current chemical standard pesticide practices with an integrated pest management (IPM) program based on the use of neem (Aza-Direct) and DiPel (Bacillus thuringiensis). In experimental plantings, the IPM program used six or eight applications of neem and DiPel on a rotational basis. The standard-practice treatments consisted of six or eight applications of carbaryl and malathion or control treatment.

RESULTS

The IPM treatments reduced pest populations and damage, resulting in a better yield than with the standard chemical or control treatment. When IPM treatment included three applications of neem plus three applications of DiPel (on a rotational basis in experimental fields), it again reduced the pest population and damage and produced a better yield than the standard practice. The lower input costs of the IPM program resulted in better economic returns in both trials.

CONCLUSIONS

The IPM components neem and DiPel are suitable for use in an IPM program for managing insect pests on cabbage (Brassica spp.).

Characterization of alginase and elicitor-active oligosaccharides from Gracilibacillus A7 in alleviating salt stress for Brassica campestris L

Alginase was purified from Gracilibacillus A7 and evaluated for its ability to produce elicitor-active oligosaccharides. The optimum conditions for the alginase reaction are as follows: temperature, 40 °C; pH, 8.0; alginate content, 0.3-0.7%; and the presence of Na(+) and Mg(2+) metal ions. The degree of polymerization (DP) decreased as the reaction time of the alginase progressed, achieving values of 5.4 and 3.3 after 240 and 300 min, respectively. The relative root length (RRL) of the Brassica campestris L. increased with the addition of oligosaccharides with reduced DP values. The oligosaccharides with lower DP values are effective in reducing the effect of salt stress on the activity of the superoxide dismutase (SOD) and guaiacol peroxidase (POD), and oligosaccharides with moderate DP values can reduce the increase in lipid peroxidation activities (as malondialdehyde content) induced by salt stress. These results suggest that oligosaccharides may act as osmoprotective agents during the plant germination process.

[Silkworm excrement organic fertilizer: its nutrient properties and application effect]

In this paper, silkworm excrement was harmless-treated via controlled fermentation to prepare silkworm excrement organic fertilizer (SEOF). The nutrient properties of the SEOF were determined, and a pot experiment was conducted to examine the application effect of the fertilizer. After fermentation, the total N, P, and K contents in the SEOF had a significant increase, being 58.0%, 84.4% , and 29.7% higher than those in the raw material, respectively. The addition of microbial inoculants shortened the fermentation period, and decreased the carbon and nitrogen losses during fermentation. With the application of SEOF, the seed germination index of cabbage and tomato was higher than 80% , suggesting that the fertilizer had no inhibitory effect on the seed germination. The application of SEOF not only increased the Chinese cabbage yield and its nutrients and Vc contents, decreased the plant nitrate content, but also improved the soil pH value, and increased the soil available nutrients and organic matter contents and soil enzyme activities, with better effect than applying composted goat feces.

Functional analysis of the two Brassica AP3 genes involved in apetalous and stamen carpelloid phenotypes

The Arabidopsis homeotic genes APETALA3 (AP3) and PISTILLATA (PI) are B genes which encode MADS-box transcription factors and specify petal and stamen identities. In the current study, the stamen carpelloid (SC) mutants, HGMS and AMS, of B. rapa and B. napus were investigated and two types of AP3 genes, B.AP3.a and B.AP3.b, were functional characterized. B.AP3.a and B.AP3.b share high similarity in amino acid sequences except for 8 residues difference located at the C-terminus. Loss of this 8 residues in B.AP3.b led to the change of PI-derived motifs. Meanwhile, B.AP3.a specified petal and stamen development, whereas B.AP3.b only specified stamen development. In B. rapa, the mutations of both genes generated the SC mutant HGMS. In B. napus that contained two B.AP3.a and two B.AP3.b, loss of the two B.AP3.a functions was the key reason for the apetalous mutation, however, the loss-of-function in all four AP3 was related to the SC mutant AMS. We inferred that the 8 residues or the PI-derived motif in AP3 gene probably relates to petal formation.

Production of viable male unreduced gametes in Brassica interspecific hybrids is genotype specific and stimulated by cold temperatures

BACKGROUND

Unreduced gametes (gametes with the somatic chromosome number) may provide a pathway for evolutionary speciation via allopolyploid formation. We evaluated the effect of genotype and temperature on male unreduced gamete formation in Brassica allotetraploids and their interspecific hybrids. The frequency of unreduced gametes post-meiosis was estimated in sporads from the frequency of dyads or giant tetrads, and in pollen from the frequency of viable giant pollen compared with viable normal pollen. Giant tetrads were twice the volume of normal tetrads, and presumably resulted from pre-meiotic doubling of chromosome number. Giant pollen was defined as pollen with more than 1.5 × normal diameter, under the assumption that the doubling of DNA content in unreduced gametes would approximately double the pollen cell volume. The effect of genotype was assessed in five B. napus, two B. carinata and one B. juncea parents and in 13 interspecific hybrid combinations. The effect of temperature was assessed in a subset of genotypes in hot (day/night 30°C/20°C), warm (25°C/15°C), cool (18°C/13°C) and cold (10°C/5°C) treatments.

RESULTS

Based on estimates at the sporad stage, some interspecific hybrid genotypes produced unreduced gametes (range 0.06 to 3.29%) at more than an order of magnitude higher frequency than in the parents (range 0.00% to 0.11%). In nine hybrids that produced viable mature pollen, the frequency of viable giant pollen (range 0.2% to 33.5%) was much greater than in the parents (range 0.0% to 0.4%). Giant pollen, most likely formed from unreduced gametes, was more viable than normal pollen in hybrids. Two B. napus × B. carinata hybrids produced 9% and 23% unreduced gametes based on post-meiotic sporad observations in the cold temperature treatment, which was more than two orders of magnitude higher than in the parents.

CONCLUSIONS

These results demonstrate that sources of unreduced gametes, required for the triploid bridge hypothesis of allopolyploid evolution, are readily available in some Brassica interspecific hybrid genotypes, especially at cold temperatures.

Fate and distribution of nitrogen in soil and plants irrigated with landfill leachate

Landfill leachate contains a high concentration of ammoniacal substances which can be a potential supply of N for plants. A bioassay was conducted using seeds of Brassica chinensis and Lolium perenne to evaluate the phytotoxicity of the leachate sample. A soil column experiment was then carried out in a greenhouse to study the effect of leachate on plant growth. Two grasses (Paspalum notatum and Vetiver zizanioides) and two trees (Hibiscus tiliaceus and Litsea glutinosa) were irrigated with leachate at the EC50 levels for 12 weeks. Their growth performance and the distribution of N were examined and compared with columns applied with chemical fertilizer. With the exception of P. notatum, plants receiving leachate and fertilizer grew better than those receiving water alone. The growth of L. glutinosa and V. zizanioides with leachate irrigation did not differ significantly from plants treated with fertilizer. Leachate irrigation significantly increased the levels of NH(x)-N in soil. Although NO(x)-N was below 1 mg NL(-1) in the leachate sample, the soil NO(x)-N content increased by 9-fold after leachate irrigation, possibly as a result of nitrification. Leachate irrigation at EC50 provided an N input of 1920 kg N ha(-1) over the experimental period, during which up to 1050 kg N ha(-1) was retained in the soil and biomass, depending on the type of vegetation. The amount of nutrient added seems to exceed beyond the assimilative capability. Practitioners should be aware of the possible consequence of N saturation when deciding the application rate if leachate irrigation is aimed for water reuse.

[Effects of spent mushroom compost on greenhouse cabbage growth under soil salt stress]

A pot experiment was conducted to study the effect of spent mushroom compost (SMC) in alleviating greenhouse soil secondary salinization and cabbage salt stress. With the amendment of SMC, the salinized soil after 60 day cabbage cultivation had a pH value close to 7.0, its organic matter and available phosphorous contents increased significantly, and the increment of total water-soluble salt content reduced, compared with the control. When the amendment amount of SMC was 10 g x kg(-1), the increment of soil water soluble salt content was the least, suggesting that appropriate amendment with SMC could reduce the salt accumulation in greenhouse soil. Amendment with SMC increased the cabbage seed germination rate, plant height, plant fresh mass, chlorophyll SPAD value, and vitamin C content, and decreased the proline content significantly. All the results indicated that SMC could improve the growth environment of greenhouse cabbage, and effectively alleviate the detrimental effect of salt stress.

Growth promotion of Chinese cabbage and Arabidopsis by Piriformospora indica is not stimulated by mycelium-synthesized auxin

Piriformospora indica, an endophytic fungus of the order Sebacinales, interacts with the roots of a large variety of plant species. We compared the interaction of this fungus with Chinese cabbage (Brassica campestris subsp. chinensis) and Arabidopsis seedlings. The development of shoots and roots of Chinese cabbage seedlings was strongly promoted by P. indica and the fresh weight of the seedlings increased approximately twofold. The strong stimulation of root hair development resulted in a bushy root phenotype. The auxin level in the infected Chinese cabbage roots was twofold higher compared with the uncolonized controls. Three classes of auxin-related genes, which were upregulated by P. indica in Chinese cabbage roots, were isolated from a double-subtractive expressed sequence tag library: genes for proteins related to cell wall acidification, intercellular auxin transport carrier proteins such as AUX1, and auxin signal proteins. Overexpression of B. campestris BcAUX1 in Arabidopsis strongly promoted growth and biomass production of Arabidopsis seedlings and plants; the roots were highly branched but not bushy when compared with colonized Chinese cabbage roots. This suggests that BcAUX1 is a target of P. indica in Chinese cabbage. P. indica also promoted growth of Arabidopsis seedlings but the auxin levels were not higher and auxin genes were not upregulated, implying that auxin signaling is a more important target of P. indica in Chinese cabbage than in Arabidopsis. The fungus also stimulated growth of Arabidopsis aux1 and aux1/axr4 and rhd6 seedlings. Furthermore, a component in an exudate fraction from P. indica but not auxin stimulated growth of Chinese cabbage and Arabidopsis seedlings. We propose that activation of auxin biosynthesis and signaling in the roots might be the cause for the P. indica-mediated growth phenotype in Chinese cabbage.

Production of well-matured compost from night-soil sludge by an extremely short period of thermophilic composting

The effect of various operational conditions on the decomposition of organic material during the composting of night-soil treatment sludge was quantitatively examined. The optimum composting conditions were found to be a temperature of ca. 60°C and an initial pH value of 8. Rapid decomposition of organic matter ceased by the sixth day of composting under these optimum conditions, and the final value of the cumulative emission of carbon (E(C)), which represents the degree of organic matter decomposition, was less than 40%, indicating that the sludge contained only a small amount of easily degradable organic material. A plant growth assay using Komatsuna (Brassica campestris L. var. rapiferafroug) in a 1/5000a standard cultivation pot was then conducted for the compost at various degrees of organic matter decomposition: the raw composting material, the final compost obtained on day 6, and the 2 intermediate compost products (i.e., E(C)=10% and 20%). It was found that the larger the E(C), the greater the yield of Komatsuna growth. It was also found that 6 days of composting is sufficient to promote Komatsuna growth at the standard loading level, which is equivalent to a 1.5 g N/pot, since the promotion effect was as high as that obtained using chemical fertilizer. It can therefore be concluded that well-matured compost could be obtained in a short period of time (i.e., as early as 6 days), when night-soil sludge is composted under optimum conditions.

Generation of Se-fortified broccoli as functional food: impact of Se fertilization on S metabolism

Selenium (Se)-fortified broccoli (Brassica oleracea var. italica) has been proposed as a functional food for cancer prevention, based on its high glucosinolate (GSL) content and capacity for Se accumulation. However, as selenate and sulphate share the initial assimilation route, Se fertilization could interfere with sulphur metabolism and plant growth. Consequently, GSL accumulation could be compromised. To evaluate these potentially adverse effects of Se fertilization, we performed a comprehensive study on sand-grown young broccoli plants (weekly selenate applications of 0.8 µmol plant(-1) via the root) and field-grown adult broccoli plants during head formation (single foliar selenate application: 25.3 or 253 µmol plant(-1) ). The results show that under these conditions, Se application does not affect plant growth, contents of cysteine, glutathione, total GSL, glucoraphanin (major aliphatic GSL) or the expression of BoMYB28 (encoding a functionally confirmed master regulator for aliphatic GSL biosynthesis). Conversely, due to the changed expression of sulphate transporters (BoSULTR1;1, 1;2, 2;1, and 2;2), sulphate and total S contents increased in the shoot of young plants while decreasing in the root. We conclude that broccoli can be fertilized with Se without reduction in GSL content, even with Se accumulation exceeding the level recommended for human consumption.

Oviposition of diamondback moth in the presence and absence of a novel host plant

The diamondback moth (DBM, Plutella xylostella L. (Lepidoptera: Plutellidae)) consumes a wide variety of brassicaceous host plants and is a common pest of crucifer crops worldwide. A highly unusual infestation of a sugar pea crop was recorded in Kenya in 1999, which persisted for two consecutive years. A strain (DBM-P) from this population was established in the laboratory and is the only one of several strains tested that can complete larval development on sugar peas. The oviposition acceptance and preference of the DBM-P strain was assessed in the presence of cabbage plants, sugar pea plants or both, in comparison to another strain (DBM-Cj) that was collected from cabbage and is unable to grow on pea plants. As expected, DBM-Cj females preferred to oviposit on cabbage plants. Surprisingly, DBM-P females also laid most eggs on cabbage and very few on peas. However, they laid significantly more eggs on the cabbage plant when pea plants were present. Our findings suggest that DBM-P manifested the initial stages of an evolutionary host range expansion, which is incomplete due to lack of oviposition fidelity on pea plants.

[Effects of exogenous dimethylarsinic acid on Brassica campestris growth and soil arsenic bioavailability]

A pot experiment was conducted to study the effects of exogenous dimethylarsinic acid (DMA) on the growth of Brassica campestris and the bioavailability of soil arsenic (As). With the increasing concentration of applied DMA, the emergence rate and biomass of B. campestris increased at low concentration DMA, but decreased at high concentration DMA. When the DMA concentration reached 90 mg x kg(-1), the emergence rate and biomass of B. campestris in the second cropping decreased by 9.5% and 57.0%, respectively, compared with those in the control, indicating that exogenous DMA had longer-term effects on the growth of B. campestris. The soil available As and the As uptake by B. campestris all increased with increasing concentration of exogenous DMA, and there existed significant correlations among them. After applied into soil, the exogenous DMA demethylated, with As(V) as the main product and lesser amount of As (III), and the concentrations of soil As(V) and As(III) increased with increasing application rate of exogenous DMA.

[Effects of organic fertilization on arsenic absorption of pakchoi (Brassica chinensis) on arsenic-contaminated red soil]

A pot experiment with arsenic-contaminated red soil was conducted to study the effects of applying pig dung and chicken manure on the growth and arsenic absorption of pakchoi (Brassica chinensis), and on soil available arsenic. Applying pig dung and chicken manure to the arsenic-contaminated red soil increased the biomass of pakchoi to some extent. Comparing with the control, applying pig dung increased the pakchoi biomass significantly (P < 0.05). The soil available arsenic content after applying pig dung increased by 394.9%-1033.6% (P < 0.05), and that after applying chicken manure increased by 30.4%-94.1%. Organic fertilization promoted the arsenic absorption of pakchoi, with the arsenic uptake after applying pig dung increased by 20.7%-53.9%. The application of pig dung and chicken manure to arsenic-contaminated red soil could somewhat increase the soil available arsenic content and the arsenic uptake by crops, and thus, increase the risks of agricultural product quality and environment.

Response of glucosinolate and flavonoid contents and composition of Brassica rapa ssp. chinensis (L.) Hanelt to silica formulations used as insecticides

Silica-based substances have increased in popularity in recent years as alternative insecticides in horticultural crop protection. However, no research has been conducted into the influence of silica on plant biochemistry. Formulations (Fossil Shield 90.0s, AE R974, AL-06-109, Surround) were applied electrostatically on pak choi. Plants were harvested on two dates to measure immediate (first) and decelerated (second) influence, as well as recovery following the removal of silica formulations. The predominant individual glucosinolate (GS) in pak choi Black Behi was 1-methoxy-3-indolylmethyl GS. A significant increase in total glucosinolate contents in all treatments was measured from the first to second harvest. During the first harvest, no changes in glucosinolate levels in plants were found in any of the treatments. After a 48 h recovery period, two substances showed decreased amounts for indole GS compared to the control. Flavonoids (kaempferol and isorhamnetin) decreased from the first to second harvest. Kaempferol in particular decreased in treated plants from the first to second harvest date. The shading of leaves by silica mainly caused the decrease in secondary metabolites in treated plants. Treatments with silica formulations as an alternative insecticide cause shifts in the composition and contents of bioactive secondary metabolites in Brassica rapa spp. chinensis plants and should, therefore, be used with care to control insects.

[Effects of applying controlled-release fertilizer blended with conventional nitrogen fertilizer on Chinese cabbage yield and quality as well as nitrogen losses]

An open field experiment was conducted to study the effects of applying controlled-release fertilizer blended with rapidly available chemical N fertilizer on Chinese cabbage yield and quality as well as nitrogen losses, including ammonia volatilization and NO3- -N accumulation and leaching in Beijing suburb. The results showed that a combined application of 2:1 controlled-release fertilizer and urea fertilizer (total N rate 150 kg x hm(-2)) did not induce the reduction of Chinese cabbage yield, and decreased the leaf nitrate and organic acid contents significantly, compared with conventional urea N application (300 kg x hm(-2)), and had no significant difference in the cabbage yield and leaf nitrate content, compared with applying 150 kg x hm(-2) of urea N. The combined application of 2:1 controlled-release fertilizer and urea fertilizer improved the N use efficiency of Chinese cabbage, and reduced the ammonia volatilization and NO3- -N leaching. At harvest, the NO3- -N concentrations in 20-40, 60-80 and 80-100 cm soil layers were significantly lower in the combined application treatment than in urea N treatment.

Effect of insect density, plant age, and residue duration on acetamiprid efficacy against swede midge

The Swede midge, Contarinia nasturtii Kieffer (Diptera: Cecidomyiidae), a common insect pest in Europe, is a newly invasive pest in North America that constitutes a major threat to crucifer vegetable and field crops. Chemical control of Swede midge with synthetic insecticides under laboratory conditions indicated that insecticides generally could provide very effective control; however, insecticide treatments in the field were rarely able to maintain damage levels within marketable limits. In the current study, factors affecting insecticide efficacy were investigated using a neonicotinoid insecticide, acetamipird, as a foliar spray on cauliflower plants. Our results indicated that Swede midge density did not affect the efficacy of acetamirpid, although it significantly increased the subsequent Swede midge population on the unsprayed cauliflower plants. Additionally, cauliflower plant age did not significantly affect spray coverage and acetamipird efficacy on Swede midge. However, acetamiprid only provided 6-d control of Swede midge and its efficacy was reduced by up to 50% 9 d after spraying. Implications of our results on the development of an overall integrated pest management (IPM) program for Swede midge also are discussed.

[Effects of winter cover crop on methane and nitrous oxide emission from paddy field]

Static chamber-GC technique was employed to study the effects of different treatment winter cover crops, including no-tillage and directly sowing ryegrass (T1), no-tillage and directly sowing Chinese milk vetch (T2), tillage and transplanting rape (T3), no-tillage and directly sowing rape (T4), and fallowing (CK), on the CH4 and N2O emission from double cropping rice paddy field. During the growth period of test winter cover crops, the CH4 and N2O emission in treatments T1-T4 was significantly higher than that in CK (P < 0.01). Treatments T1 and T3 not only had the largest CH4 emission (0.60 and 0.88 g x m(-2)), but also had the largest N2O emission (0.20 and 0.23 g x m(-2), respectively). After the winter cover crops returned to field, the CH4 emission from early and late rice fields in treatments T1, T2, T3, and T4 was larger than that in CK. In early rice field, treatments T1 and T2 had the largest CH4 emission (21.70 and 20.75 g x m(-2)); while in late rice field, treatments T3 and T4 had the largest one (58.90 and 54.51 g x m(-2) respectively). Treatments T1-T4 also had larger N2O emission from early and late rice fields than the CK did. The N2O emission from early rice field in treatments T1, T2, T3, and T4 was increased by 53.7%, 12.2%, 46.3%, and 29.3%, and that from late rice field in corresponding treatments was increased by 28.6%, 3.8%, 34.3%, and 27.6%, respectively, compared with CK.

Characterization, quantification, and yearly variation of the naturally occurring polyphenols in a common red variety of curly kale ( Brassica oleracea L. convar. acephala var. sabellica cv. 'Redbor')

This study focuses on the characterization and quantification of polyphenols in the edible leaves of red curly kale ( Brassica oleracea L. convar. acephala (DC.) Alef. var. sabellica L.), variety 'Redbor F1 hybrid'. The kale was grown at an experimental field (59° 40' N) in the years 2007-2009. The analysis of kale extract by HPLC-DAD-ESI-MS has allowed the determination of 47 different acylated and nonacylated flavonoid glycosides and complex hydroxycinnamic acids. Those compounds included mono- to tetraglycosides of quercetin, kaempferol, and cyanidin and derivatives of p-coumaric, ferulic, sinapic, and caffeic acid. Among the compounds characterized, four flavonols, three anthocyanins, and three phenolic acids were identified in the Brassica family for the first time. Aglycones and conjugated polyphenols were quantified by HPLC-DAD using commercially available standards. The main flavonol, anthocyanin, and phenolic acid were kaempferol-3-sinapoyl-diglucoside-7-diglucoside, cyanidin-3-sinapoyl-feruloyl-diglucoside-5-glucoside, and disinapoyl-diglucoside, respectively, each representing 9.8, 10.3, and 4.9% of the total amount of 872 mg polyphenol equivalents per 100 g of fresh kale. Variations between individual plants and growing seasons were of the same order of magnitude for total phenolics and total monomeric anthocyanins.

Elucidating the process of co-composting of biosolids and spent activated clay

This study elucidates the co-composting of biosolids and spent activated clay (SAC) using physio-chemical, bioassay, and spectroscopic methods. A pilot-scale pile of blended limed biosolids, SAC, and rice husk was composted for 15weeks. The changes in temperature, pH, Fourier-transform infrared (FT-IR) spectra, C/N, and germination index (GI) of Chinese cabbage (Brassica chinensis) seeds with time support the goal of producing a mature compost with a decline in the SAC acidity of associated with biosolids. Cadmium, Cr, Cu, Ni, and Pb in the initial biosolids were converted from labile fractions into relatively immobile phases upon maturation. Temperature, moisture, pH, C/N, and GI were used to separate the composting process into three phases - initial, thermophilic, and cooling, based on a score plot of principal component analysis (PCA). The values of the parameters of interest reveal that the compost fulfills the requirements of compost maturity in the literature.

Seed coat phenolics and the developing silique transcriptome of Brassica carinata

Structures for nine compounds were elucidated in seed coats of two genetically related Brassica carinata lines. The yellow-seeded line accumulated monomeric kaempferols, phenylpropanoids, and lignans, while extractable and unextractable proanthocyanidins and a high-performance liquid chromatography peak containing polymeric-like quercetin/lignan structures were strongly reduced. The brown-seeded line accumulated large amounts of both types of proanthocyanidins (extractable and unextractable), as well as phenylpropanoids and lignans equivalent to the amounts in the yellow-seeded seed coats, but the brown-seeded seed coats lacked kaempferols. A Brassica napus 15K oligoarray experiment indicated that yellow-seeded siliques had more extreme gene expression changes and a 2.4-fold higher number of upregulated genes than brown-seeded siliques, including a host of transcription factors and genes with unknown function. Transcripts for six flavonoid genes (CHS, F3H, FOMT, DFR, GST, and TTG1) were lower and two (F3'H and FLS) were higher in yellow-seeded siliques, but expression of CHI, PAP1, and phenylpropanoid genes was unchanged.

Inoculation of food waste with the thermo-tolerant lipolytic actinomycete Thermoactinomyces vulgaris A31 and maturity evaluation of the compost

The ability of the thermo-tolerant lipolytic actinomycete, Thermoactinomyces vulgaris A31, to efficiently decompose food waste into mature compost was studied. Using a range of chemical parameters (pH, total organic carbon content (TOC), total nitrogen content, C/N ratio), CO(2) evolution, enzymatic activities (dehydrogenase, polyphenol oxidase, urease) and germination assays, the composition, stability and maturity of the compost produced were assessed. Inoculation reduced crude fat and decreased the maturation time of the compost when compared with the control. TOC, C/N ratio, CO(2) evolution, and enzymatic activities (dehydrogenase, polyphenol oxidase, urease) decreased, pH, total nitrogen content, germination rate, and germination index increased. The dehydrogenase, polyphenol oxidase, and urease activities were shown to be useful indicators for the stability of food waste composts. Based on germination assays, the food waste composts were phytotoxicity free and matured after composting for 2 months. Therefore, inoculation of food waste with the thermo-tolerant lipolytic actinomycete, T. vulgaris A31, presents as a feasible strategy to convert food wastes into mature compost efficiently.

Interaction of 8-hydroxyquinoline with soil environment mediates its ecological function

Background

Allelopathic functions of plant-released chemicals are often studied through growth bioassays assuming that these chemicals will directly impact plant growth. This overlooks the role of soil factors in mediating allelopathic activities of chemicals, particularly non-volatiles. Here we examined the allelopathic potential of 8-hydroxyquinoline (HQ), a chemical reported to be exuded from the roots of Centaurea diffusa.

Methodology/Principal Findings

Growth bioassays and HQ recovery experiments were performed in HQ-treated soils (non-sterile, sterile, organic matter-enriched and glucose-amended) and untreated control soil. Root growth of either Brassica campestris or Phalaris minor was not affected in HQ-treated non-sterile soil. Soil modifications (organic matter and glucose amendments) could not enhance the recovery of HQ in soil, which further supports the observation that HQ is not likely to be an allelopathic compound. Hydroxyquinoline-treated soil had lower values for the CO₂ release compared to untreated non-sterile soil. Soil sterilization significantly influenced the organic matter content, PO₄-P and total organic nitrogen levels.

Conclusion/Significance

Here, we concluded that evaluation of the effect of a chemical on plant growth is not enough in evaluating the ecological role of a chemical in plant-plant interactions. Interaction of the chemical with soil factors largely determines the impact of HQ on plant growth.

Characterization of nucleases involved in seedling development of cauliflower

The ability of cells to control the degradation of their own DNA is a common feature of most living organisms. In plants, extensive hydrolysis of nuclear DNA occurs during different forms of programmed cell death (PCD). In addition to the removal of unwanted cells, the PCD process allows for the remobilization of cellular constituents, including the products of DNA hydrolysis. Although programmed cell death occurs widely during normal development and plant defense responses to pathogens, only one class of deoxyribonucleases, the S1 type, involved in these processes, has been well characterized. Using DNA-SDS-PAGE, we identified the activities of 14 deoxyribonucleases expressed in different organs of cauliflower seeds, seedlings and the flower head. These enzymes represent several classes based on their substrate specificity and ion dependency. In addition to four Zn(2+)-dependent enzymes, we identified five Ca(2+)-dependent, two Mg(2+)-dependent, three Ca(2+)/Mg(2+)-dependent and one nuclease whose activities seem to be independent of any divalent cations. We also identified a set of DNases whose expression seems to be common for different organs and different stages of development, as well as a few highly tissue-specific nucleases. Expression of three nucleases was inducible by drought stress and hydrogen peroxide.

[Effects of simulated acid rain on oilseed rape (Brassica napus) physiological characteristics at flowering stage and yield]

A pot experiment was conducted to study the effects of different acidity simulated acid rain on the physiological characteristics at flowering stage and yield of oilseed rape (B. napus cv. Qinyou 9). Comparing with the control (pH 6.0), weak acidity (pH = 4.0-5.0) simulated acid rain stimulated the rape growth to some extent, but had less effects on the plant biomass, leaf chlorophyll content, photosynthetic characteristics, and yield. With the further increase of acid rain acidity, the plant biomass, leaf chlorophyll content, photosynthetic rate, antioxidative enzyme activities, and non-enzyme antioxidant contents all decreased gradually, while the leaf malonyldialdehyde (MDA) content and relative conductivity increased significantly. As the results, the pod number per plant, seed number per pod, seed weight, and actual yield decreased. However, different yield components showed different sensitivity to simulated acid rain. With the increasing acidity of simulated acid rain, the pod number per plant and the seed number per pod decreased significantly, while the seed weight was less affected.