Regulation of Glandular Size and Phytoalexin Biosynthesis by a Negative Feedback Loop in Cotton.

Plants have evolved diverse defense mechanisms encompassing physical and chemical barriers. Cotton pigment glands are known for containing various defense metabolites, but the precise regulation of gland size to modulate defense compound levels remains enigmatic. Here, it is discovered that the VQ domain-containing protein JAVL negatively regulates pigment gland size and the biosynthesis of defense compounds, while the MYC2-like transcription factor GoPGF has the opposite effect. Notably, GoPGF directly activates the expression of JAVL, whereas JAVL suppresses GoPGF transcription, establishing a negative feedback loop that maintains the expression homeostasis between GoPGF and JAVL. Furthermore, it is observed that JAVL negatively regulates jasmonate levels by inhibiting the expression of jasmonate biosynthetic genes and interacting with GoPGF to attenuate its activation effects, thereby maintaining homeostatic regulation of jasmonate levels. The increased expression ratio of GoPGF to JAVL leads to enlarged pigment glands and elevated jasmonates and defense compounds, enhancing insect and pathogen resistance in cotton. These findings unveil a new mechanism for regulating gland size and secondary metabolites biosynthesis, providing innovative strategies for strengthening plant defense.

Development of a predictive nomogram for intermediate-risk differentiated thyroid cancer patients after fixed 3.7GBq (100mCi) radioiodine remnant ablation.

Objectives: The objective of this study was to develop a predictive nomogram for intermediate-risk differentiated thyroid cancer (DTC) patients after fixed 3.7GBq (100mCi) radioiodine remnant ablation (RRA). Methods: Data from 265 patients who underwent total thyroidectomy with central lymph node dissection (CND) and received RRA treatment at a single institution between January 2018 and March 2023 were analyzed. Patients with certain exclusion criteria were excluded. Univariate and multivariate logistic regression analyses were performed to identify risk factors for a non-excellent response (non-ER) to RRA. A nomogram was developed based on the risk factors, and its performance was validated using the Bootstrap method with 1,000 resamplings. A web-based dynamic calculator was developed for convenient application of the nomogram. Results: The study included 265 patients with intermediate-risk DTC. Significant differences were found between the ER group and the non-ER group in terms of CLNM>5, Hashimoto's thyroiditis, sTg level, TgAb level (P < 0.05). CLNM>5 and sTg level were identified as independent risk factors for non-ER in multivariate analysis. The nomogram showed high accuracy, with an area under the curve (AUC) of 0.833 (95% CI = 0.770-0.895). The nomogram's predicted probabilities aligned closely with actual clinical outcomes. Conclusions: This study developed a predictive nomogram for intermediate-risk DTC patients after fixed 3.7GBq (100mCi) RRA. The nomogram incorporates CLNM>5 and sTg levels as risk factors for a non-ER response to RRA. The nomogram and web-based calculator can assist in treatment decision-making and improve the precision of prognosis information. Further research and validation are needed.

A dirigent protein complex directs lignin polymerization and assembly of the root diffusion barrier.

Functionally similar to the tight junctions present in animal guts, plant roots have evolved a lignified Casparian strip as an extracellular diffusion barrier in the endodermis to seal the root apoplast and maintain nutrient homeostasis. How this diffusion barrier is structured has been partially defined, but its lignin polymerization and assembly steps remain elusive. Here, we characterize a family of dirigent proteins (DPs) essential for both the localized polymerization of lignin required for Casparian strip biogenesis in the cell wall and for attachment of the strip to the plasma membrane to seal the apoplast. We reveal a Casparian strip lignification mechanism that requires cooperation between DPs and the Schengen pathway. Furthermore, we demonstrate that DPs directly mediate lignin polymerization as part of this mechanism.

Single-cell RNA sequencing reveals a hierarchical transcriptional regulatory network of terpenoid biosynthesis in cotton secretory glandular cells.

Plants can synthesize a wide range of terpenoids in response to various environmental cues. However, the specific regulatory mechanisms governing terpenoid biosynthesis at the cellular level remain largely elusive. In this study, we employed single-cell RNA sequencing to comprehensively characterize the transcriptome profile of cotton leaves and established a hierarchical transcriptional network regulating cell-specific terpenoid production. We observed substantial expression levels of genes associated with the biosynthesis of both volatile terpenes (such as ß-caryophyllene and ß-myrcene) and non-volatile gossypol-type terpenoids in secretory glandular cells. Moreover, two novel transcription factors, namely GoHSFA4a and GoNAC42, are identified to function downstream of the Gossypium PIGMENT GLAND FORMATION genes. Both transcription factors could directly regulate the expression of terpenoid biosynthetic genes in secretory glandular cells in response to developmental and environmental stimuli. For convenient retrieval of the single-cell RNA sequencing data generated in this study, we developed a user-friendly web server . Our findings not only offer valuable insights into the precise regulation of terpenoid biosynthesis genes in cotton leaves but also provide potential targets for cotton breeding endeavors.

[Response of Organic Carbon Loss to Soil Erosion and Its Drivers: A Meta-analysis].

Soil erosion is the main driving force of soil organic carbon (SOC) loss and plays an important role in the global carbon cycle. It is helpful to understand the mechanism of SOC loss under soil erosion by evaluating the main driving factors of SOC loss under soil erosion and their influence degree. Therefore, based on 24 cases published in domestic and foreign journals from 2007 to 2021, this study investigated the effects of soil erosion on SOC loss in China under different climatic factors (climate types, rainfall, and rainfall intensity) and soil factors (soil types, bulk density, and aggregate size) by using Meta-analysis. The results showed that:① compared with that under no erosion disturbance, the SOC content under erosion decreased significantly (overall decreased 16.0%), showing obvious negative response characteristics. ② Under the erosion background, the negative response degree of SOC to different factors was as follows:rainfall intensity (65.0%)>mean annual rainfall (24.3%)>soil types (21.4%)>bulk density (20.2%)>aggregate size (16.5%)>climate types (9.1%). ③ Principal component analysis showed that climate was the dominant factor affecting SOC loss, and rainfall intensity was again shown to be the key factor. In this study, the characteristics and influencing factors of SOC loss under soil erosion in China were analyzed, which provided theoretical reference for the systematic understanding of the role of soil erosion in the carbon cycle.

Effects of a long-term operation wetland for wastewater treatment on the spatial pattern and function of microbial communities in groundwater.

Constructed wetlands have been used globally for wastewater treatment owing to low energy inputs and operating costs. However, the impact of their long-term operation on groundwater microbial communities is still unclear. This study aims to investigate the effects and further reveal the linkage between a large-scale surface flow constructed wetland (in operation for 14 years) and groundwater. Changes in the characteristics of groundwater microbial communities and their potential influencing factors were studied based on hydrochemical analysis, Illumina MiSeq sequencing, and multivariate statistical analysis methods. Results show that the long-term operation wetland significantly elevated groundwater nutrient levels and increased the risk of ammonia nitrogen pollution compared to background values. An apparent heterogeneity of microbial communities exhibited in the vertical direction and a similarity in the horizontal direction. Wetland operations substantially altered the structure of microbial communities at 3, 5, and 12 m depths, particularly a reduced abundance of denitrifying and chemoheterotrophic functional genera. The formation and evolution of groundwater microbial community structure mainly subjected to the contributions of dissolved oxygen (33.70%), total nitrogen (21.40%), dissolved organic carbon (11.09%), and pH (10.60%) variations resulted from the wetland operation and largely differed in depths. A combined effect of these factors on the groundwater should be concerned for such a long-term running wetland system. This study provides a new insight into the responses of groundwater microbial community structure driving by wetland operation and a better understanding of corresponding variation of microbial-based geochemical processes.

Dirigent gene editing of gossypol enantiomers for toxicity-depleted cotton seeds.

Axial chirality of biaryls can generate varied bioactivities. Gossypol is a binaphthyl compound made by cotton plants. Of its two axially chiral isomers, (-)-gossypol is the bioactive form in mammals and has antispermatogenic activity, and its accumulation in cotton seeds poses health concerns. Here we identified two extracellular dirigent proteins (DIRs) from Gossypium hirsutum, GhDIR5 and GhDIR6, which impart the hemigossypol oxidative coupling into (-)- and (+)-gossypol, respectively. To reduce cotton seed toxicity, we disrupted GhDIR5 by genome editing, which eliminated (-)-gossypol but had no effects on other phytoalexins, including (+)-gossypol, that provide pest resistance. Reciprocal mutagenesis identified three residues responsible for enantioselectivity. The (-)-gossypol-forming DIRs emerged later than their enantiocomplementary counterparts, from tandem gene duplications that occurred shortly after the cotton genus diverged. Our study offers insight into how plants control enantiomeric ratios and how to selectively modify the chemical spectra of cotton plants and thereby improve crop quality.

Construction of Hierarchical Micro/Nanostructured ZnO/Cu-ZnMOFs@SA Superhydrophobic Composite Coatings with Excellent Multifunctionality of Anticorrosion, Blood-Repelling, and Antimicrobial Properties.

Naked medical devices are often damaged by blood, bacteria, and other extreme environmental conditions (heat, humidity, acid, alkali, salts, and others), causing device failure and increasing difficulty for the operator. They can also cause inflammation and coagulation resulting in severe complications and even death. In this work, the superhydrophobic ZnO/copper-zinc metal-organic frameworks@stearic acid (ZnO/Cu-ZnMOFs@SA) composite coatings with hierarchical micro/nanostructures were fabricated on Zn substrates via a one-step hydrothermal method. The effects of hierarchical micro/nanostructures on surface wettability, physicochemical stability, and biological properties have been studied in this manuscript. The structure not only provided the coatings with robust waterproofing, abrasive resistance, durability, and thermal and light irradiation stability but also successfully recovered their superhydrophobicity by remodifying the surface with SA, showing excellent repeatability. In addition, the coating demonstrates excellent corrosion resistance and self-cleaning ability and rejects various solid and liquid contaminants. The superhydrophobic ZnO/Cu-ZnMOFs@SA composite coatings also exhibited excellent antibacterial and thrombosis resistance. The findings indicated that the superhydrophobic composite coatings have a strong potential for application in medical instruments for exhibiting multifunctional properties in various extreme environments.

Comparative Genomics and Functional Studies of Putative m6A Methyltransferase (METTL) Genes in Cotton.

N6-methyladenosine (m6A) RNA modification plays important regulatory roles in plant development and adapting to the environment, which requires methyltransferases to achieve the methylation process. However, there has been no research regarding m6A RNA methyltransferases in cotton. Here, a systematic analysis of the m6A methyltransferase (METTL) gene family was performed on twelve cotton species, resulting in six METTLs identified in five allotetraploid cottons, respectively, and three to four METTLs in the seven diploid species. Phylogenetic analysis of protein-coding sequences revealed that METTL genes from cottons, Arabidopsis thaliana, and Homo sapiens could be classified into three clades (METTL3, METTL14, and METTL-like clades). Cis-element analysis predicated the possible functions of METTL genes in G. hirsutum. RNA-seq data revealed that GhMETTL14 (GH_A07G0817/GH_D07G0819) and GhMETTL3 (GH_A12G2586/GH_D12G2605) had high expressions in root, stem, leaf, torus, petal, stamen, pistil, and calycle tissues. GhMETTL14 also had the highest expression in 20 and 25 dpa fiber cells, implying a potential role at the cell wall thickening stage. Suppressing GhMETTL3 and GhMETTL14 by VIGS caused growth arrest and even death in G. hirsutum, along with decreased m6A abundance from the leaf tissues of VIGS plants. Overexpression of GhMETTL3 and GhMETTL14 produced distinct differentially expressed genes (DEGs) in A. thaliana, indicating their possible divergent functions after gene duplication. Overall, GhMETTLs play indispensable but divergent roles during the growth of cotton plants, which provides the basis for the systematic investigation of m6A in subsequent studies to improve the agronomic traits in cotton.

Acupoint Autohemotherapy Attenuates Atopic Dermatitis Lesions by Regulating Th1/Th2 Balance in DNCB-Induced BALB/c Mice.

OBJECTIVE: To evaluate the therapeutic effects of acupoint autohemotherapy (A-AHT) on 1-chloro-2,4-dinitrobenzene (DNCB)-induced atopic dermatitis (AD) in mice focusing on regulating T helper 1/T helper 2 (Th1/Th2) immune responses. METHODS: Thirty BALB/c mice were divided into 5 groups by a random number table, including normal control (NC), AD model (AD), A-AHT, sham A-AHT (sA-AHT), and acupoint injection of normal saline (A-NS) groups, 6 mice per group. Mice were challenged by DNCB for the establishment of experimental AD model. On the 8th day, except for the NC and AD groups, the mice in the other groups received management once every other day for a total of 28 days. For the A-AHT and sA-AHT groups, 0.05 mL of autologous whole blood (AWB) was injected into bilateral Zusanli (ST 36) and Quchi (LI 11) and sham-acupoints (5 mm lateral to ST 36 and LI 11), respectively. The A-NS group was administrated with 0.05 mL of normal saline by acupoint injection into ST 36 and LI 11. Dermatitis severity for dorsal skin of mice was determined using the Severity Scoring of Atopic Dermatitis (SCORAD) every week. The total immunoglobulin E (IgE), interleukin-4 (IL-4), and interferon-gamma (IFN-γ) cytokine levels in serum were examined by enzyme-linked immunosorbent assay (ELISA). Spleen Th1/Th2 expression were analyzed via flow cytometry and immunohistochemical assay was used to detect T-box expressed in T cell (T-bet) and GATA-binding protein 3 (GATA3) expressions in skin lesions of mice. RESULTS: Compared with the AD group, both A-AHT and sA-AHT reduced the SCORAD index and serum IgE level (P<0.05 or P<0.01); A-AHT, sA-AHT and A-NS down-regulated serum IL-4 level and upregulated IFN-γ/IL-4 ratio (P<0.05 or P<0.01); A-AHT regulated the Th1/Th2 shift specifically and increased the related transcription factors such as T-bet expression and T-bet/GATA3 ratio (P<0.05). CONCLUSION: A-AHT showed significant effectiveness on the AD model mice, through regulating Th1/Th2 immune responses.

Comprehensive identification and expression analysis of CRY gene family in Gossypium.

BACKGROUND: The cryptochromes (CRY) are specific blue light receptors of plants and animals, which play crucial roles in physiological processes of plant growth, development, and stress tolerance. RESULTS: In the present work, a systematic analysis of the CRY gene family was performed on twelve cotton species, resulting in 18, 17, 17, 17, and 17 CRYs identified in five alloteraploid cottons (Gossypium hirsutum, G. barbadense, G. tomentosum, G. mustelinum and G. darwinii), respectively, and five to nine CRY genes in the seven diploid species. Phylogenetic analysis of protein-coding sequences revealed that CRY genes from cottons and Arabidopsis thaliana could be classified into seven clades. Synteny analysis suggested that the homoeolog of G. hirsutum Gh_A02G0384 has undergone an evolutionary loss event in the other four allotetraploid cotton species. Cis-element analysis predicated the possible functions of CRY genes in G. hirsutum. RNA-seq data revealed that Gh_D09G2225, Gh_A09G2012 and Gh_A11G1040 had high expressions in fiber cells of different developmental states. In addition, the expression levels of one (Gh_A03G0120), 15 and nine GhCRY genes were down-regulated following the PEG, NaCl and high-temperature treatments, respectively. For the low-temperature treatment, five GhCRY genes were induced, and five were repressed. These results indicated that most GhCRY genes negatively regulate the abiotic stress treatments. CONCLUSION: We report the structures, domains, divergence, synteny, and cis-elements analyses systematically of G. hirsutum CRY genes. Possible biological functions of GhCRY genes in differential tissues as well as in response to abiotic stress during the cotton plant life cycle were predicted.

1,10/1,11-Cyclization catalyzed by diverged plant sesquiterpene synthases is dependent on a single residue.

The exquisite chemodiversity of terpenoids is the product of the large diverse terpene synthase (TPS) superfamily. Here, by using structural and phylogenetic analyses and site-directed mutagenesis, we identified a residue (Cys440 in Nicotiana tabacum 5-epi-aristolochene synthase) proximal to an ion-binding motif common to all TPSs and named the preNSE/DTE residue, which determines the product specificity of sesquiterpene synthases from different plant species. In sesquiterpene synthases catalyzing 1,10-cyclization (1,10-cyclases) of farnesyl diphosphate, mutation of the residue in both specific and promiscuous 1,10-cyclases from different lineages leads to the accumulation of monocyclic germacrene A-11-ol, which is "short-circuited" from complex cyclization cascades, suggesting a key role of this residue in generating the first common intermediate of 1,10-cyclization. Altering this residue in a specific 1,11-cyclase results in alternative 1,10-cyclization products. Moreover, the preNSE/DTE residue can be harnessed to engineer highly specific sesquiterpene synthases for an improved proportion of high-value terpenoids, such as patchoulol, a main constituent of several traditional Chinese medicines that could treat SARS-CoV-2.

Side Products of Recombinant Amorpha-4,11-diene Synthase and Their Effect on Microbial Artemisinin Production.

Amorpha-4,11-diene synthase (ADS) is the first committed enzyme in the biosynthesis of artemisinin. Artemisinin production by biobased fermentation is considered a reliable alternative pathway. Heterologously expressed ADS has been established to generate several minor products, including structural analogues of amorpha-4,11-diene, but their fate in fermentation is still unknown. Here, using chiral analysis, we found that ADS produces one of the analogues, amorpha-4-en-11-ol, as a pair of epimers. Labeling experiments revealed that ADS mutants yielded amorphene-type sesquiterpenes, indicating the co-occurrence of initial 1,6 and 1,10 cyclization of farnesyl diphosphate in a single enzyme. Interestingly, the immediate downstream oxidase CYP71AV1 had very low affinity to the side products of the recombinant ADS, including amorpha-4-en-7-ol, which is structurally similar to amorpha-4,11-diene. Our data uncover the complex catalytic mechanism of recombinant ADS and reveal a potential negative effect of the side products of recombinant ADS on the production of the artemisinin precursor in microbes.

Recent Advances and Future Perspectives in Cotton Research.

Cotton is not only the world's most important natural fiber crop, but it is also an ideal system in which to study genome evolution, polyploidization, and cell elongation. With the assembly of five different cotton genomes, a cotton-specific whole-genome duplication with an allopolyploidization process that combined the A- and D-genomes became evident. All existing A-genomes seemed to originate from the A0-genome as a common ancestor, and several transposable element bursts contributed to A-genome size expansion and speciation. The ethylene production pathway is shown to regulate fiber elongation. A tip-biased diffuse growth mode and several regulatory mechanisms, including plant hormones, transcription factors, and epigenetic modifications, are involved in fiber development. Finally, we describe the involvement of the gossypol biosynthetic pathway in the manipulation of herbivorous insects, the role of GoPGF in gland formation, and host-induced gene silencing for pest and disease control. These new genes, modules, and pathways will accelerate the genetic improvement of cotton.

Genome-wide characterization of the GRF family and their roles in response to salt stress in Gossypium.

BACKGROUND: Cotton (Gossypium spp.) is the most important world-wide fiber crop but salt stress limits cotton production in coastal and other areas. Growth regulation factors (GRFs) play regulatory roles in response to salt stress, but their roles have not been studied in cotton under salt stress. RESULTS: We identified 19 GRF genes in G. raimondii, 18 in G. arboreum, 34 in G. hirsutum and 45 in G. barbadense, respectively. These GRF genes were phylogenetically analyzed leading to the recognition of seven GRF clades. GRF genes from diploid cottons (G. raimondii and G. arboreum) were largely retained in allopolyploid cotton, with subsequent gene expansion in G. barbadense relative to G. hirsutum. Most G. hirsutum GRF (GhGRF) genes are preferentially expressed in young and growing tissues. To explore their possible role in salt stress, we used qRT-PCR to study expression responses to NaCl treatment, showing that five GhGRF genes were down-regulated in leaves. RNA-seq experiments showed that seven GhGRF genes exhibited decreased expression in leaves under NaCl treatment, three of which (GhGRF3, GhGRF4, and GhGRF16) were identified by both RNA-seq and qRT-PCR. We also identified six and three GRF genes that exhibit decreased expression under salt stress in G. arboreum and G. barbadense, respectively. Consistent with its lack of leaf withering or yellowing under the salt treatment conditions, G. arboreum had better salt tolerance than G. hirsutum and G. barbadense. Our results suggest that GRF genes are involved in salt stress responses in Gossypium. CONCLUSION: In summary, we identified candidate GRF genes that were involved in salt stress responses in cotton.

RES transformation for biosynthesis and detoxification.

The reactive electrophilic species (RES), typically the molecules bearing α,ß-unsaturated carbonyl group, are widespread in living organisms and notoriously known for their damaging effects. Many of the mycotoxins released from phytopathogenic fungi are RES and their contamination to cereals threatens food safety worldwide. However, due to their high reactivity, RES are also used by host organisms to synthesize specific metabolites. The evolutionary conserved glyoxalase (GLX) system scavenges the cytotoxic α-oxoaldehydes that bear RES groups, which cause host disorders and diseases. In cotton, a specialized enzyme derived from glyoxalase I (GLXI) through gene duplications and named as specialized GLXI (SPG), acts as a distinct type of aromatase in the gossypol pathway to transform the RES intermediates into the phenolic products. In this review, we briefly introduce the research progress in understanding the RES, especially the RES-type mycotoxins, the GLX system and SPG, and discuss their application potential in detoxification and synthetic biology.

Regionalization of Soil and Water Conservation Aimed at Ecosystem Services Improvement.

To effectively control soil erosion, three hierarchies of the National Soil and Water Conservation Regionalization Scheme have been established in China. However, the scheme has its limits, which can be summarized by two points: first, the tertiary hierarchy functional region exhibits obvious heterogeneity; second, the ecosystem function does not influence the regionalization scheme results during the process of regionalization. To enhance the guidance of the regionalization, a new indicator system included soil erosion risk, soil erosion intensity and ecosystem service value was developed to explore the subdivision of the tertiary hierarchy functional region. Moreover a scheme for the subdivision of the tertiary hierarchy functional region was formed. In this scheme, the central Hunan hilly soil conservation and living environmental protection section was divided into three subregions: Luoxiao-Xuefeng Mountain high ecological value section, Xiangjiang middle and downstream medium ecological value section, and Hengyang Basin low ecological value section. Specifically, with regard to soil and water conservation regionalization, the concept of subregions within the tertiary hierarchy-based functional region was proposed and the new indicator system that highlighted ecosystem functions was applied for the first time on a regional scales; this method provides a new way of thinking about other regionalization schemes.

Aromatization of natural products by a specialized detoxification enzyme.

In plants, lineage-specific metabolites can be created by activities derived from the catalytic promiscuity of ancestral proteins, although examples of recruiting detoxification systems to biosynthetic pathways are scarce. The ubiquitous glyoxalase (GLX) system scavenges the cytotoxic methylglyoxal, in which GLXI isomerizes the α-hydroxy carbonyl in the methylglyoxal-glutathione adduct for subsequent hydrolysis. We show that GLXIs across kingdoms are more promiscuous than recognized previously and can act as aromatases without cofactors. In cotton, a specialized GLXI variant, SPG, has lost its GSH-binding sites and organelle-targeting signal, and evolved to aromatize cyclic sesquiterpenes bearing α-hydroxyketones to synthesize defense compounds in the cytosol. Notably, SPG is able to transform acetylated deoxynivalenol, the prevalent mycotoxin contaminating cereals and foods. We propose that detoxification enzymes are a valuable source of new catalytic functions and SPG, a standalone enzyme catalyzing complex reactions, has potential for toxin degradation, crop engineering and design of novel aromatics.

A gossypol biosynthetic intermediate disturbs plant defence response.

Plant secondary metabolites and their biosynthesis have attracted great interest, but investigations of the activities of hidden intermediates remain rare. Gossypol and related sesquiterpenes are the major phytoalexins in cotton. Among the six biosynthetic intermediates recently identified, 8-hydroxy-7-keto-δ-cadinene (C234) crippled the plant disease resistance when accumulated upon gene silencing. C234 harbours an α,ß-unsaturated carbonyl thus is a reactive electrophile species. Here, we show that C234 application also dampened the Arabidopsis resistance against the bacterial pathogen Pseudomonas syringae pv. maculicola ( Psm). We treated Arabidopsis with C234, Psm and ( Psm+C234), and analysed the leaf transcriptomes. While C234 alone exerted a mild effect, it greatly stimulated an over-response to the pathogen. Of the 7335 genes affected in the ( Psm+C234)-treated leaves, 3476 were unresponsive without the chemical, in which such functional categories as 'nucleotides transport', 'vesicle transport', 'MAP kinases', 'G-proteins', 'protein assembly and cofactor ligation' and 'light reaction' were enriched, suggesting that C234 disturbed certain physiological processes and the protein complex assembly, leading to distorted defence response and decreased disease resistance. As C234 is efficiently metabolized by CYP71BE79, plants of cotton lineage have evolved a highly active enzyme to prevent the phytotoxic intermediate accumulation during gossypol pathway evolution. This article is part of the theme issue 'Biotic signalling sheds light on smart pest management'.

Effect of moisture condition on the immobilization of Cd in red paddy soil using passivators.

In this study, the immobilization of cadmium (Cd) was evaluated in red paddy soil amended with four different passivators (biochar, lime (CaO), calcium dihydrogen phosphate (Ca(H2PO4)2) and zeolite (modified with NaOH)) for three moisture regimes (70% water-holding capacity (WHC), continuous flooding (CF) and wetting-drying cycle (WDC)). The results showed that: the pH of the soil was obviously influenced by the moisture regimes and decreased in the general order of CF > WDC > 70% WHC, and the addition of lime and Ca(H2PO4)2 could obviously enhance and reduce the values to some extent, respectively. Flooding condition could enhance soil pH and increase the content of free Fe-oxides, amorphous Fe-oxides and water-soluble organic/inorganic carbon in paddy soil. The efficiency in decreasing the exchangeable Cd of different moisture regimes followed the order: CF > 70%WHC > WDC. CF combined with lime was the most effective treatment for reducing exchangeable Cd. The transformation of Cd fractions mainly occurred between the acid-extractable and reducible fractions in the immobilization experiments. The most effective passivator is Ca(H2PO4)2, and CF is the most favorable regime in promoting the transformation of Cd in red paddy soil from acid-extractable to reducible fraction.