Synergistic effects of rhizosphere effect and combined organic and chemical fertilizers application on soil bacterial diversity and community structure in oilseed rape cultivation.

The combined application of chemical and organic fertilizers has been recognized to enhance soil fertility and foster the soil microbial ecosystem. However, the optimal ratio of chemical and organic fertilizers in oilseed rape cultivation is still uncertain, and the role of rhizosphere effect is still unclear. Thus, this study aimed to elucidate the impacts of varying ratios of chemical and organic fertilizers on the structure and potential functionalities of rhizosphere and non-rhizosphere soil microbial communities. The interplay of microbial communities with soil properties and oilseed rape root exudates was investigated in controlled pot cultivations receiving varying ratios of chemical and organic fertilizers. Results indicated clear segregation in the soil bacterial community, influenced by both fertilization treatments and rhizosphere effects. The bacterial community structure significantly correlated with nitrate nitrogen, organic acids, and dissolved organic carbon (DOC) content. Rhizosphere effects led to increased bacteria abundance, reduced diversity, and decreased network stability. Notably, F3 treatment receiving 25% chemical and 75% organic fertilizers showed a significantly higher abundance at 1.43 × 1011 copies g-1 dry soil, accompanied by increased species and genetic diversity, and ecological network complexity. This treatment also yielded the highest aboveground biomass of oilseed rape. However, the application of organic fertilizers also increased the risk of plant pathogenicity. This study reveals the impact of fertilizers and rhizosphere effects on soil microbial community structure and function, shedding light on the establishment of more effective fertilization schemes for oilseed rape agriculture.

Current progress on fluoride occurrence in the soil environment: Sources, transformation, regulations and remediation.

Fluorine is a halogen element widely distributed in nature, but due to excessive emissions from industrial manufacturing and agricultural production, etc., the soil is over-enriched with fluoride and the normal growth of plants is under stress, and it also poses a great threat to human health. In this review, we summarized the sources of fluoride in soil, and then analyzed the potential mechanisms of fluoride uptake in soil-plant systems. In addition, the main influences of soil ecosystems on plant fluoride uptake were discussed, soil management options to mitigate fluoride accumulation in plants were also summarized. The bioremediation techniques were found to be a developmental direction to improve fluoride pollution. Finally, we proposed other research directions, including fluoride uptake mechanisms in soil-plant systems at the molecular expression levels, development of visualization techniques for fluoride transport in plants, interactions mechanisms between soil microhabitats and plant metabolism affecting fluoride uptake, as well as combining abiotic additives, nanotechnology and biotechnology to remediate fluoride contamination problems.

[Clinical Features and Outcomes of the Patients with B-Cell Chronic Lymphoproliferative Disease in the New Drug Era].

OBJECTIVE: To analyze the clinical characteristics of the patients with B-cell chronic lymphoproliferative disease（B-CLPD） in the new drug era and the effect of new drug treatment on efficacy and survival. METHODS: The clinical and laboratory data of 200 cases B-CLPD patients diagnosed between April 2015 and August 2021 were analyzed retrospectively. The clinical efficacy and survival of the patients under different treatments including Bruton tyrosine kinase（BTK） inhibitors， rituximab， and chemotherapy alone were analyzed. The prognostic factors affecting the survival of patients were analyzed by univarite analysis and multivariate analysis. RESULTS: There were 119 male（59.5％） and 81 female（40.5%） in 200 cases B-CLPD patients， the sex ratio(male/female) was 1.5∶1 with median age of 61（30- 91） years old. The distribution of subtypes were as fallows: 51 cases (25.5%) of chronic lymphocytic leukemia/small lymphocytic lymphoma（CLL/SLL）， 64（32.0%） cases of follicular lymphoma（FL）， 40（20.0%） cases mantle cell lymphoma（MCL）， 30（15.0%） cases of marginal zone lymphoma（MZL）， 10（5%） cases of lymphoplasmacytic lymphoma/waldenstrom macroglobulinemia（LPL/WM）， 5（2.5%） cases of B cell chronic lymphoproliferative disorders unclassified（B-CLPD-U） . The main clinical manifestation of 102 patients was lymph node enlargement, 32 cases were complicated with B symptoms. Among CLL/SLL patients， there were 12（23.5%） cases in Binet A and 39（76.5%） cases in Binet B/C. There were 29 patients（20.9%） in Ann Arbor or Lugano stage I-II and 110 cases（79.1%） in stage III-IV of other subtypes. The complete remission（CR） rate was 43.1%（25/58）， 40.2%（39/97）， 7.1%（1/14）， and overaIl response rate（ORR） was 87.9%（51/58）， 62.9%（61/97）， 28.6%（4/14） in the groups of BTK inhibitors， rituximab-based therapy， and chemotherapy alone. The 3-year OS rate and PFS rate in all patients was 79.2% and 72.4% respectively. The 3-year OS rate of patient with MZL, CLL/SLL, FL,WM was 94.7%, 87.7%, 86.8% and 83.3% respectively, while the 3-year OS rate of MCL was only 40.6%, which was significantly lower than other subtypes. The median OS of patients treated with BTK inhibitors and rituximab-based therapy was 20.5 and 18.5 months respectively， and the 3-year OS rate was 97.4% and 90.7%. However， the median PFS of patients receiving chemotherapy alone was 4 months， and the 1-year OS rate was 52.7%， which was statistically significant compared with the other two groups（P<0.05）. Univarite analysis showed that anemia， elevated lactate dehydrogenase， elevated ß2-microglobulin， and splenomegaly were the poor prognostic factors for OS（P<0.05）， elevated lactate dehydrogenase was also poor prognostic factors for PFS（P<0.05）. Multifactor analysis showed that anemia and elevated lactate dehydrogenase were the independent poor prognostic factors for survival（P<0.05）. CONCLUSION: The clinical features of B-CLPD was various， anemia and elevated lactate dehydrogenase are the prognostic factors for poor survival. BTK inhibitors and new immunotherapy can improve the survival and prognosis of patients in the new drug era.

Compost with spent mushroom substrate and chicken manure enhances rice seedling quality and reduces soil-borne pathogens.

Using cultivated soils for rice seedlings can reduce the sustainability of arable land and thus giving negative impacts to food production. As a substitute, spent mushroom compost (SMC), which has high water-holding capacity and nutrient content, shows great potentials. To determine the impacts of the proportion of SMC and paddy soil on seedling quality, rhizosphere microbial characteristics, and fungal pathogens in rice seedling substrates, we conducted a 21-day pot experiment for rice seedling under five treatments: CK, 100% paddy soil; R1, 20% SMC and 80% paddy soil; R2, 50% SMC and 50% paddy soil; R3, 80% SMC and 20% paddy soil; and R4, 100% SMC. The results showed that incorporating SMC into the substrate, especially at 50% volume (R2), increased seedling growth and vitality at the seedling growth stage without external fertilization. Moreover, the SMC amendment increased microbial activity and promoted rice seedling recruitment of plant growth-promoting rhizobacteria (PGPR) and fungi (PGPF). In addition, using SMC significantly reduced the abundance of pathogenic fungi, especially Magnaporthe grisea. Overall, the multi-faceted benefits exhibit the strong possibilities of using SMC in sustainable rice productions.

Ratoon rice with direct seeding improves soil carbon sequestration in rice fields and increases grain quality.

Increasing both carbon (C) sequestration and food production is essential for a sustainable future. However, increasing soil C sequestration or graining yield/quality in rice (Oryza sativa L.) systems has been a tradeoff in that pursuing one goal may compromise the other goal. Field experiments were designed to evaluate methane emission and grain yield in two rice systems in southern China, including the traditional double rice with a seedling transplanting system and innovative ratoon rice with a direct seeding system. Grain yield, grain quality, methane (CH4) emission, and total organic carbon (TOC) loss rate were investigated, and yield-scaled CH4 gas emission was assessed. It is found that double rice has a higher grain yield than ratoon rice. However, the grain quality (processing, appearance of chalkiness degree and chalky grain percentage, and nutritional quality) of ratoon rice is superior to double rice, especially the ratoon crop. The yield-scaled CH4 emission of ratoon rice (0.06 kg kg-1) decreased by 49.29% than double rice (0.12 kg kg-1) throughout the growth period. Compared with the TOC loss rate of double rice (2.95 g kg-1), the rate of ratoon rice was lower (1.97 g kg-1). As a result, ratoon rice with direct seeding can not only improve grain quality but also mitigate yield-scaled CH4 gas emission and TOC loss rate of rice fields. Therefore, we suggest to use ratoon rice with a direct seeding technique to promote agricultural C sequestration.

Ecological rice-cropping systems mitigate global warming - A meta-analysis.

Ecological rice-cropping systems (ERSs) are prosperous rice ecosystems that have a profound influence on global greenhouse (GHG) effects. However, the high variation in research results requires an accurate evaluation of the ERS effects. In this study, three typical ERS modes, rice-crayfish, rice-duck, and rice-fish were selected, and a meta-analysis was conducted using the data of 34 studies to comprehensively evaluate the effects of ERSs on GHG emissions, the global warming potential (GWP), and GHG intensity (GHGI). The results showed that the ERSs reduced CH4 emissions significantly (-12.5%), but increased N2O emissions by 11.3% as compared with traditional rice-cropping systems (TRSs). Further, ERSs have slightly lower GWP, rice yield, and GHGI values (6.5%, 5.5%, and 5.6%, respectively) than TRSs. The rice-crayfish and rice-duck modes significantly alleviated the GWP by 18.0% and 11.1%, respectively, whereas the rice-fish mode enhanced the GWP by 20.8%. Moreover, the rice-duck mode significantly reduced the GHGI by 17.2%, while the ricecrayfish and rice-fish modes increased the GHGI by 9.7% and 8.8%, respectively. Further, the ERSs significantly changed the dissolved oxygen concentration in the flood water as well as the Eh, dissolved organic carbon, and ammonium nitrogen in the soil, wherein the effect sizes of the ERSs on the GHG emissions were significantly correlated with their respective increase. Considering the net ecosystem economic budget and CO2 emissions equivalent/output, ERSs were found to be effective "green technologies". Further, we found that the rice-duck ERS was a good ecological ricecropping system for global warming mitigation. Our study provided new ideas for sustainable agriculture.

Survival strategies based on the hydraulic vulnerability segmentation hypothesis, for the tea plant [Camellia sinensis(L.) O. Kuntze] in long-term drought stress condition.

Tea plants are important economic perennial crops that can be negatively impacted by drought stress (DS). However, their survival strategies in long-term DS conditions and the accumulation and influence of metabolites and mineral elements (MEs) in their organs, when facing hydraulic vulnerability segmentation, require further investigation. The MEs and metabolites in the leaf, stem, and root after long-term DS (20 d) were examined here, using inductively coupled plasma optical emission spectrometry (ICP-OES) and liquid chromatograph-mass spectrometry (LC-MS). The accumulation patterns of 116 differentially accumulated metabolites (DAMs) and nine MEs were considerably affected in all organs. The concentration of all MEs varied significantly in at least one organ, while the K and Ca levels were markedly altered in all three. Most DAM levels increased in the stem but decreased in the root and leaf, implying that vulnerability segmentation may occur with long-term DS. The typical nitrogen- and carbon-compound levels similarly increased in the stem and decreased in the leaf and root, as the plant might respond to long-term DS by stabilizing respiration, promoting nitrogen recycling, and free radical scavenging. Correlation analysis showed several possible DAM-ME interactions and an association between Mn and flavonoids. Thus, survival strategies under long-term DS included sacrificing distal/vulnerable organs and accumulating function-specialized metabolites and MEs to mitigate drought-induced oxidative damage. This is the first study that reports substance fluctuations after long-term DS in different organs of plants, and highlights the need to use whole plants to fully comprehend stress response strategies.

Cover crops and chicken grazing in a winter fallow field improve soil carbon and nitrogen contents and decrease methane emissions.

Using symbiotic farming methods [cover crops and chicken grazing (+ C)] in a winter fallow field, we found that the soil organic matter and total nitrogen of the + C treatment were 5.2% and 26.6% higher, respectively, than those of a treatment with cover crops and no chicken grazing (- C). The annual rice grain yield of the + C treatment was 3.8% higher than that of the - C treatment and 12.3% higher than that of the bare fallow field (CK), while the annual CH4 emissions of the + C treatment were 26.9% lower than those of the - C treatment and 10.6% lower than those of the CK treatment. The 100-year global warming potential of the + C treatment was 6.2% lower than that of the - C treatment. Therefore, the use of winter cover crops and chicken grazing in a winter fallow field was effective at reducing CH4 emissions and significantly improving soil nutrients and rice yield.

Integrating cover crops with chicken grazing to improve soil nitrogen in rice fields and increase economic output.

Winter fallow is important for renewing and improving soil fertility under double-cropping rice systems, such as those in southern China. Using a regenerative farming technology of integrating grass-chicken farming in a winter fallow field, we investigated soil nitrogen conversion and assessed the agricultural economic benefits of the whole farmland ecosystem. To test the effects of chicken grazing on the fallow system, we established field treatments involving adding chickens to a field planted with the cover crops, including cover milk vetch (Astragalus sinicus) with chicken grazing treatment (MC) and cover ryegrass (Lolium spp.) with chicken grazing (RC); cover crops only, including cover milk vetch (Astragalus sinicus) treatment (M) and cover ryegrass (Lolium spp.) (R); and a bare fallow field treatment (CK). We found that both cover crops (M and R) and cover crops with chicken grazing (MC and RC) increased nitrate, ammonium, dissolved organic nitrogen, and total nitrogen contents, and the increase was higher in MC and RC treatments. We also observed increased straw biomass and grain yield in the all four treatments, with more increases with chicken treatments as compared with CK. On the economic profits, MC increased by 101.72% and RC increased by 104.12% as compared with CK, while R increased by 5.19% and M reduced by 1.86% as compared with CK. The nitrogen transfer rate (the output/input ratio) of MC, RC, M, and R increased by 66.71%, 71.50%, 65.97%, and 59.97%, respectively, while the nitrogen accumulation rate (input-output) of MC, RC, M, and R increased by 480.56%, 612.98%, 356.74%, and 267.65%, respectively. Our study demonstrates that retaining nitrogen and gaining economic profit by integrating cover crops with chicken grazing is potentially more sustainable than adding cover crops alone. We further suggest that using the integrated grass-livestock farming technology can reduce environmental damage caused by commercial fertilizers.

[Differences and Relationship Between Rhizosphere Characteristics and Methane Emissions of Double-cropping Rice Variety].

Six field varieties of early rice and late rice were selected as test materials for field experiments to explore the difference in CH4 emissions among different rice varieties, and Static Obscura-Gas Chromatography was used to determine the CH4 gas. The results demonstrated a significant difference in the CH4 emissions flux between early and late rice varieties. The average yield of total fertility CH4 emissions was highest in Xiangzaoxian 24 and lowest in Zhuliangyou 819, with a difference of 34.6%. Of the late rice varieties, Tyou 15 was the highest and the Ziyou 299 was the lowest, with a difference of 33.9%. Differences in CH4 emissions and the greenhouse effect of unit yields between different double cropping rice varieties differed significantly. The cumulative CH4 emissions from early rice varieties ranged from 198.3-303.44 kg·hm-2, and the lowest emissions were from Zhuliangyou 819. The greenhouse effect per yield ranged from 0.67 to 1.40 kg·kg-1, and Luliangyou 996 had the lowest emission value. The late-season rice varieties exhibited significantly higher cumulative CH4 emissions compared to early rice, ranging from 291.93 to 388.28 kg·hm-2, and Ziyou 299 had the lowest emission value. The greenhouse effect of per yields rice varieties, while the late rice varieties were contrary to early rice. Reducing carbon and nitrogen concentrations in the rhizosphere and increasing Eh values could reduce CH4 emissions.

Genome-wide functional analyses of plant coiled-coil NLR-type pathogen receptors reveal essential roles of their N-terminal domain in oligomerization, networking, and immunity.

The ability to induce a defense response after pathogen attack is a critical feature of the immune system of any organism. Nucleotide-binding leucine-rich repeat receptors (NLRs) are key players in this process and perceive the occurrence of nonself-activities or foreign molecules. In plants, coevolution with a variety of pests and pathogens has resulted in repertoires of several hundred diverse NLRs in single individuals and many more in populations as a whole. However, the mechanism by which defense signaling is triggered by these NLRs in plants is poorly understood. Here, we show that upon pathogen perception, NLRs use their N-terminal domains to transactivate other receptors. Their N-terminal domains homo- and heterodimerize, suggesting that plant NLRs oligomerize upon activation, similar to the vertebrate NLRs; however, consistent with their large number in plants, the complexes are highly heterometric. Also, in contrast to metazoan NLRs, the N-terminus, rather than their centrally located nucleotide-binding (NB) domain, can mediate initial partner selection. The highly redundant network of NLR interactions in plants is proposed to provide resilience to perturbation by pathogens.

Genome assembly with in vitro proximity ligation data and whole-genome triplication in lettuce.

Lettuce (Lactuca sativa) is a major crop and a member of the large, highly successful Compositae family of flowering plants. Here we present a reference assembly for the species and family. This was generated using whole-genome shotgun Illumina reads plus in vitro proximity ligation data to create large superscaffolds; it was validated genetically and superscaffolds were oriented in genetic bins ordered along nine chromosomal pseudomolecules. We identify several genomic features that may have contributed to the success of the family, including genes encoding Cycloidea-like transcription factors, kinases, enzymes involved in rubber biosynthesis and disease resistance proteins that are expanded in the genome. We characterize 21 novel microRNAs, one of which may trigger phasiRNAs from numerous kinase transcripts. We provide evidence for a whole-genome triplication event specific but basal to the Compositae. We detect 26% of the genome in triplicated regions containing 30% of all genes that are enriched for regulatory sequences and depleted for genes involved in defence.

Acetylation of an NB-LRR Plant Immune-Effector Complex Suppresses Immunity.

Modifications of plant immune complexes by secreted pathogen effectors can trigger strong immune responses mediated by the action of nucleotide binding-leucine-rich repeat immune receptors. Although some strains of the pathogen Pseudomonas syringae harbor effectors that individually can trigger immunity, the plant's response may be suppressed by other virulence factors. This work reveals a robust strategy for immune suppression mediated by HopZ3, an effector in the YopJ family of acetyltransferases. The suppressing HopZ3 effector binds to and can acetylate multiple members of the RPM1 immune complex, as well as two P. syringae effectors that together activate the RPM1 complex. These acetylations modify serine, threonine, lysine, and/or histidine residues in the targets. Through HopZ3-mediated acetylation, it is possible that the whole effector-immune complex is inactivated, leading to increased growth of the pathogen.

Effects of simulated acid rain on microbial characteristics in a lateritic red soil.

A laboratory experiment was performed to examine the impact of simulated acid rain (SAR) on nutrient leaching, microbial biomass, and microbial activities in a lateritic red soil in South China. The soil column leaching experiment was conducted over a 60-day period with the following six SAR pH treatments (levels): 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0 and one control treatment (pH = 7). Compared with the control treatment, the concentrations of soil organic matter, total nitrogen, total phosphorus, total potassium, soil microbial biomass carbon (MBC), soil microbial biomass nitrogen (MBN), and average well color density (AWCD) in the Ecoplates were all significantly decreased by leaching with SAR at different pH levels. The decrease in MBC and MBN indicated that acid rain reduced the soil microbial population, while the decrease in AWCD revealed that acid rain had a negative effect on soil bacterial metabolic function. Soil basal respiration increased gradually from pH 4.0 to 7.0 but decreased dramatically from pH 2.5 to 3.0. The decrease in soil nutrient was the major reason for the change of soil microbial functions. A principal component analysis showed that the major carbon sources used by the bacteria were carbohydrates and carboxylic acids.

Distinctive profiles of small RNA couple inverted repeat-induced post-transcriptional gene silencing with endogenous RNA silencing pathways in Arabidopsis.

The experimental induction of RNA silencing in plants often involves expression of transgenes encoding inverted repeat (IR) sequences to produce abundant dsRNAs that are processed into small RNAs (sRNAs). These sRNAs are key mediators of post-transcriptional gene silencing (PTGS) and determine its specificity. Despite its application in agriculture and broad utility in plant research, the mechanism of IR-PTGS is incompletely understood. We generated four sets of 60 Arabidopsis plants, each containing IR transgenes expressing different configurations of uidA and CHALCONE Synthase (At-CHS) gene fragments. Levels of PTGS were found to depend on the orientation and position of the fragment in the IR construct. Deep sequencing and mapping of sRNAs to corresponding transgene-derived and endogenous transcripts identified distinctive patterns of differential sRNA accumulation that revealed similarities among sRNAs associated with IR-PTGS and endogenous sRNAs linked to uncapped mRNA decay. Detailed analyses of poly-A cleavage products from At-CHS mRNA confirmed this hypothesis. We also found unexpected associations between sRNA accumulation and the presence of predicted open reading frames in the trigger sequence. In addition, strong IR-PTGS affected the prevalence of endogenous sRNAs, which has implications for the use of PTGS for experimental or applied purposes.

The negative effects of cadmium on Bermuda grass growth might be offset by submergence.

Revegetation in the water-level-fluctuation zone (WLFZ) could stabilize riverbanks, maintain local biodiversity, and improve reservoir water quality in the Three Gorges Reservoir Region (TGRR). However, submergence and cadmium (Cd) may seriously affect the survival of transplantations. Bermuda grass (Cynodon dactylon) is a stoloniferous and rhizomatous prostrate weed displaying high growth rate. A previous study has demonstrated that Bermuda grass can tolerate deep submergence and Cd stress, respectively. In the present study, we further analyzed physiological responses of Bermuda grass induced by Cd-and-submergence stress. The ultimate goal was to explore the possibility of using Bermuda grass for revegetation in the WLFZ of China's TGRR and other riparian areas. The Cd-and-submergence-treated plants had higher malondialdehyde contents and peroxidase than control, and both increased with the Cd concentration increase. All treated plants catalase activity increased with the experimental duration increases, and their superoxide dismutase also gradually increased with the Cd concentration from 1 day to 15 days. Total biomass of the same Cd-and-submergence plants increased along the experimental duration as well. Plants exposed to Cd-and-submergence stress showed shoot elongation. The heights of all treated plants were taller than those of the control. Leaf chlorophyll contents, maximum leaf length, and soluble sugars contents of all the Cd-and-submergence-treated plants were more than those of the untreated control. Although Cd inhibits plants growth, decreases chlorophyll and biomass content, and with the submergence induced the leaf and shoot elongation, more part of the Cd-and-submergence stress plants appeared in the air, exhibited fast growth with maintenance of leaf color, which guaranteed the plants' photosynthesis, and ensured the total biomass and carbohydrate sustainability, further promoting Cd-and-submergence tolerance. The results imply that the negative effects of cadmium on Bermuda grass growth might be offset by submergence.

An Ultra-High-Density, Transcript-Based, Genetic Map of Lettuce.

We have generated an ultra-high-density genetic map for lettuce, an economically important member of the Compositae, consisting of 12,842 unigenes (13,943 markers) mapped in 3696 genetic bins distributed over nine chromosomal linkage groups. Genomic DNA was hybridized to a custom Affymetrix oligonucleotide array containing 6.4 million features representing 35,628 unigenes of Lactuca spp. Segregation of single-position polymorphisms was analyzed using 213 F7:8 recombinant inbred lines that had been generated by crossing cultivated Lactuca sativa cv. Salinas and L. serriola acc. US96UC23, the wild progenitor species of L. sativa The high level of replication of each allele in the recombinant inbred lines was exploited to identify single-position polymorphisms that were assigned to parental haplotypes. Marker information has been made available using GBrowse to facilitate access to the map. This map has been anchored to the previously published integrated map of lettuce providing candidate genes for multiple phenotypes. The high density of markers achieved in this ultradense map allowed syntenic studies between lettuce and Vitis vinifera as well as other plant species.

Responses of earthworm to aluminum toxicity in latosol.

Excess aluminum (Al) in soils due to acid rain leaching is toxic to water resources and harmful to soil organisms and plants. This study investigated adverse impacts of Al levels upon earthworms (Eisenia fetida) from the latosol (acidic red soil). Laboratory experiments were performed to examine the survival and avoidance of earthworms from high Al concentrations and investigate the response of earthworms upon Al toxicity at seven different Al concentrations that ranged from 0 to 300 mg kg(-1) over a 28-day period. Our study showed that the rate of the earthworm survival was 100 % within the first 7 days and decreased as time elapsed, especially for the Al concentrations at 200 and 300 mg kg(-1). A very good linear correlation existed between the earthworm avoidance and the soil Al concentration. There was no Al toxicity to earthworms with the Al concentration ≤ 50 mg kg(-1), and the toxicity started with the Al concentration ≥ 100 mg kg(-1). Low Al concentration (i.e., <50 mg kg(-1)) enhanced the growth of the earthworms, while high Al concentration (>100 mg kg(-1)) retarded the growth of the earthworms. The weight of earthworms and the uptake of Al by earthworms increased with the Al concentrations from 0 to 50 mg kg(-1) and decreased with the Al concentrations from 50 to 300 mg kg(-1). The protein content in the earthworms decreased with the Al concentrations from 0 to 100 mg kg(-1) and increased from 100 to 300 mg kg(-1). In contrast, the catalase (CAT) and superoxide dismutase (SOD) activities in the earthworms increased with the Al concentrations from 0 to 100 mg kg(-1) and decreased from 100 to 300 mg kg(-1). The highest CAT and SOD activities and lowest protein content were found at the Al concentration of 100 mg kg(-1). Results suggest that a high level of Al content in latosol was harmful to earthworms.

[Impact of Mikania micrantha invasion on soil meso- and micro-invertebrate community structure].

Mikania micrantha, a notorious exotic weed of Asteraceae family, has invaded successfully in southern China, and caused serious damages to native ecosystems. In this paper, a field survey was conducted in the Huolushan Forest Park of Guangzhou, China, aimed to understand the impact of M. micrantha invasion on the soil meso- and micro-invertebrate community. Three sampling sites were installed, including M. micrantha-invaded site, ecotone, and native vegetation site. Through four samplings in 2009, a total of 5206 soil meso- and micro-invertebrate individuals were collected, belonging to 4 phyla, 10 classes, and 19 orders, among which, Nematoda was the dominant group, and Acarina, Collembolan, and Rotifera were the common groups. M. micrantha invasion altered the characteristics of soil meso- and micro-invertebrate community structure. Compared with those at the other two sampling sites, the numbers of total individuals, Nematoda, and Acarina at M. micrantha-invaded site increased significantly, but the groups of soil meso- and micro-invertebrates had less change. At M. micrantha-invaded site, the density-group index (DG) of soil meso- and micro-invertebrates was significantly higher, Margalef richness index (D) and Simpson dominance index (C) tended to ascend, but Pielou evenness index (E) and Shannon index (H') tended to descend. The similarity coefficient of soil meso- and micro-invertebrate community between M. micrantha-invaded site and ecotone was higher than that between M. micrantha-invaded site and native vegetation site. The changes of local climate conditions, plant litters, root secretions, and soil physical-chemical properties caused by M. micrantha invasion could be the major contributing factors that altered the community structure of soil meso- and micro-invertebrates at M. micrantha-invaded site.

Comparative large-scale analysis of interactions between several crop species and the effector repertoires from multiple pathovars of Pseudomonas and Ralstonia.

Bacterial plant pathogens manipulate their hosts by injection of numerous effector proteins into host cells via type III secretion systems. Recognition of these effectors by the host plant leads to the induction of a defense reaction that often culminates in a hypersensitive response manifested as cell death. Genes encoding effector proteins can be exchanged between different strains of bacteria via horizontal transfer, and often individual strains are capable of infecting multiple hosts. Host plant species express diverse repertoires of resistance proteins that mediate direct or indirect recognition of bacterial effectors. As a result, plants and their bacterial pathogens should be considered as two extensive coevolving groups rather than as individual host species coevolving with single pathovars. To dissect the complexity of this coevolution, we cloned 171 effector-encoding genes from several pathovars of Pseudomonas and Ralstonia. We used Agrobacterium tumefaciens-mediated transient assays to test the ability of each effector to induce a necrotic phenotype on 59 plant genotypes belonging to four plant families, including numerous diverse accessions of lettuce (Lactuca sativa) and tomato (Solanum lycopersicum). Known defense-inducing effectors (avirulence factors) and their homologs commonly induced extensive necrosis in many different plant species. Nonhost species reacted to multiple effector proteins from an individual pathovar more frequently and more intensely than host species. Both homologous and sequence-unrelated effectors could elicit necrosis in a similar spectrum of plants, suggesting common effector targets or targeting of the same pathways in the plant cell.