Search

Soil contamination by heavy metals is a serious environmental problem worldwide, and reduction of heavy metal accumulation in vegetables grown on contaminated land is a matter of urgency. A pot experiment was conducted to study the effects of intercropping with the Cd hyperaccumulators Solanum nigrum and Solanum photeinocarpum from two ecoclimatic regions, Ya'an and Chengdu, Sichuan Province, China, on the growth and cadmium (Cd) uptake of eggplant (Solanum melongena L.). The biomass, photosynthetic pigment contents, and activities of antioxidant enzymes of eggplant were enhanced by intercropping. The biomass of eggplant was the highest after intercropping with S. photeinocarpum from Ya'an, but did not differ significantly from that after intercropping with S. nigrum from Chengdu. The shoot Cd content of eggplant was significantly reduced by intercropping with the hyperaccumulators, which ranked as follows: S. nigrum from Chengdu > S. nigrum from Ya'an > S. photeinocarpum from Chengdu > S. photeinocarpum from Ya'an, with the decreases being 19.60%, 14.36%, 9.66%, and 6.42%, respectively, as compared with the control. The lowest shoot Cd content and translocation factor of eggplant were attained after intercropping with S. nigrum from Chengdu. Therefore, it was feasible to intercrop eggplant with S. nigrum and S. photeinocarpum on Cd-contaminated soil.

Abscisic acid (ABA) is an important plant hormone that enhances plants’ tolerance to heavy metal stress. In this study, we applied ABA to two ecotypes (mining and farmland) of the cadmium (Cd) hyperaccumulator Bidens pilosa which grown under Cd-contaminated conditions. The effects of ABA on Cd accumulation in the two ecotypes of B. pilosa were evaluated. Exogenous ABA decreased the biomass and plant height of the two ecotypes of B. pilosa compared with their respective controls. The plants treated with 10 μmol L−1 ABA showed the minimum biomass and plant height. Exogenous ABA also decreased the chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid contents of two ecotypes of B. pilosa compared with their controls, but increased the chlorophyll a/b ratio. For both two ecotypes of B. pilosa, application of ABA increased the Cd contents in the roots, stems, leaves, and shoots, compared with the controls, but only 40 μmol L−1 ABA increased the amount of Cd extracted by the two ecotypes (an increase of 30.26% in shoots of the farmland ecotype and 16.36% in shoots of the mining ecotype) of B. pilosa. These results show that ABA inhibits the growth of two ecotypes of B. pilosa, and the high concentration (40 μmol L−1) of ABA can enhance Cd extraction from Cd-contaminated soil. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1643–1649, 2017

Carrizo citrange [Citrus sinensis (L.) Osbeck × Poncirus trifoliata (L.) Raf., CC] is one of the most widely used rootstocks in citriculture worldwide, but its cytogenetic study has been hampered by its inherent small size, morphological similarity to mitotic chromosomes, and lack of accessible cytological landmarks. In our previous study, a spontaneously occurring tetraploid CC seedling was discovered. The main goals of this study were to elucidate the chromosome constitution and construct the karyotypes of diploid CC rootstock and its corresponding spontaneously occurring tetraploid. To accomplish these, the chromosomal characteristics were investigated by sequential multicolor fluorescence in situ hybridization (FISH) with eight properly labeled repetitive DNA sequences, including a centromere-like repeat, four satellite repeats, two rDNAs, and an oligonucleotide of telomeric (TTTAGGG)n repeat. The results nicely demonstrated that these repetitive DNAs are reliable cytogenetic markers that collectively facilitate simultaneous and unequivocal identification of homologous chromosome pairs. Based on chromosome size and morphology together with FISH patterns of repetitive DNAs, an integrated karyotype of CC rootstock was constructed, consisting of 2n = 2x = 12m (1sat) + 6sm with karyotype asymmetry degree being divided into 2B category. Cytogenetically speaking, the variable and asymmetric distribution patterns of these repetitive DNAs were fully confirmed the hybrid nature of CC rootstock. In addition, comparative distribution patterns and chromosomal localizations of these repetitive DNAs convincingly showed that this tetraploid CC material arose from somatic chromosome doubling of diploid CC rootstock. This study revealed, for the first time, the integrated karyotype and chromosomal characteristics of this important citrus rootstock as well as its spontaneously occurring tetraploid plant. Furthermore, this study is a good prospective model for study species with morphologically indistinguishable small chromosomes.

A pot experiment was conducted to study the effects of different rootstocks on the cadmium (Cd) accumulation characteristics of the post-grafting generations of Cd-hyperaccumulator

A study was performed to determine whether self-rooted grafting decreases cadmium (Cd) accumulation in post-grafting soybean (Glycine max (Linn.) Merrill) generations. Pot experiments were performed using ungrafted (UG) seedlings, self-rooted grafting from the same soybean seedling (SG), self-rooted grafting from two soybean seedlings at the same growth stage (TG), and self-rooted grafting from two soybean seedlings at different developmental stages (DG). Growth and Cd accumulation in three post-grafting soybean generations were assessed. In the SG treatment, only the second post-grafting generation had increased shoot biomass and only the first post-grafting generation shoots had decreased Cd contents. The seed Cd content, soluble protein content, and antioxidant enzyme activity were not significantly affected in three post-grafting generations. In the TG and DG treatments, shoot biomass, soluble protein content, and antioxidant enzyme activities were increased, and the shoot and seed Cd contents were decreased in three post-grafting generations. The seed Cd contents in the first, second, and third post-grafting generations were 15.00%, 9.46%, and 12.44%, respectively, lower in the TG than UG treatments. The seed Cd contents in the first, second, and third post-grafting generations were 32.73%, 27.03%, and 32.22%, respectively, lower in the DG than UG treatments. Different grafting methods promoted growth and decreased Cd accumulation to different degrees in three post-grafting generations. Grafting seedlings at different developmental stages had the strongest effects.

To study the effects of intercropping with accumulator plants on heavy metal accumulation of fruit trees, plants of three Bidens species (Bidens pilosa, Bidens biternata, and Bidens parviflora) were intercropped with Ziziphus acidojujuba seedlings under cadmium (Cd)-contaminated conditions (5 mg kg−1). Intercropping with Bidens species increased the biomass and chlorophyll b content of Z. acidojujuba seedlings compared with monoculture, but decreased their carotenoid content. Intercropping with Bidens species also improved the activity of superoxide dismutase, peroxidase, and catalase in Z. acidojujuba seedlings compared with monoculture. Intercropping with Bidens species decreased the Cd content in the roots of Z. acidojujuba seedlings compared with monoculture. Conversely, when intercropped with B. pilosa, B. biternata, and B. parviflora, the Cd content in the shoots of Z. acidojujuba seedlings increased by 62.18%, 60.10%, and 62.18%, respectively, compared with that of those monocultured. When intercropped with Z. acidojujuba seedlings, the Cd accumulation amount of three Bidens species plants were ranked B. parviflora > B. biternata > B. pilosa. Therefore, intercropping with plants of three Bidens species is not suitable for Cd-contaminated jujube orchards.

Two pot experiments were conducted to study the effects of intercropping cadmium (Cd) accumulator plants (Stellaria media (L.) Villars, Cardamine hirsuta, Cerastium glomeratum Thuill, and Galium aparine L.) and applying their straw on the growth and Cd accumulation of Brassica chinensis L. Intercropping with four accumulator plants reduced the biomass, water content, and photosynthetic pigment content of B. chinensis compared with monoculture. Intercropping with accumulator plants increased the Cd content in the roots and shoot of B. chinensis, and the translocation factor (TF), root bioconcentration factor (root BCF), and shoot bioconcentration factor (Shoot BCF) increased. The soil pH decreased and the soil available Cd content increased by intercropping. Thus, intercropping with four accumulator plants can promote the Cd uptake of B. chinensis. The straw of four accumulator plants reduced the biomass, water content, and photosynthetic pigment content of B. chinensis compared with the control. The straw of S. media and C. hirsute increased the Cd content in the roots and shoots of B. chinensis, TF, root BCF, and shoot BCF. The straw of C. glomeratum and G. aparine decreased the Cd content in the roots and shoots of B. chinensis, TF, root BCF, and shoot BCF. The soil pH increased and the soil available Cd content decreased by application of straw. Thus, the straw of C. glomeratum and G. aparine can reduce the Cd uptake of B. chinensis.

The effects of mutual grafting on the cadmium (Cd) accumulation characteristics of two ecotypes (farmland and mining) of the potential Cd-hyperaccumulator Solanum photeinocarpum were studied through a pot experiment for one month. Four treatments were used in the experiment: ungrafted farmland ecotype (F-CK), ungrafted mining ecotype (M-CK), the farmland ecotype as the scion grafted onto rootstocks of the mining ecotype (F-Scion), and the mining ecotype as the scion grafted onto rootstocks of the farmland ecotype (M-Scion). Mutual grafting increased the rootstock biomass of both S. photeinocarpum ecotypes. However, mutual grafting decreased the scion biomass of F-Scion compared with F-CK and M-CK, and the scion biomass of M-Scion was higher than that of M-CK and lower than that of F-CK. The Cd content in the rootstock of M-Scion increased compared with F-CK, and the Cd content in the rootstock of F-Scion increased compared with M-CK, but mutual grafting decreased the Cd content in scions of both S. photeinocarpum ecotypes. Mutual grafting increased Cd extraction by rootstocks of both S. photeinocarpum ecotypes, but decreased extraction by scions. Therefore, mutual grafting can increase Cd accumulation in S. photeinocarpum rootstocks but not increase Cd accumulation in S. photeinocarpum scions in a short period.

An experiment was conducted to study the effect of peach seedlings (Prunus davidiana) grown in nutrient solution with different selenium concentration. The results showed that selenium concentration were 0.05 and 0.10 mg/L which caused a marked increase of roots and shoorts biomass, and the root/shoot ratio were relatively low (0.180 and 0.170) compared with control, and other selenium treatments decreased significantly the biomass. Consequently, 0.05 and 0.10 mg/L selenium treatments were conducive to peach seedlings growth, while the peach seedlings was inhibited significantly by the increasing concentration of selenium (≥ 0.10 mg/L). Selenium content of peach seedlings increased remarkably with the increase of selenium concentration that indicated the accumulation of selenium in peach seedlings had a linear relation with the dose of selenium. Above all, when selenium concentration in the range of 0-0.10 mg/ L, which not only promotes peach seedlings growth, but also increases peach seedlings selenium content.

Additional file 1: Figure S1. Number of DEGs up and down-regulated in most enriched pathways among three stages of dormancy. Table S1. Primers used in this study.

Dehydrins (DHNs) play a vital role in enhancing plant tolerance to abiotic stresses. In kiwifruit, there has not been a comprehensive and systematic study undertaken on the DHN gene family to date. In this study, seven AcDHNs were identified and cloned in kiwifruit, which were divided into two subgroups, YnSKn- and SKn-types. AcDHN2/AcDHN7 and AcDHN4/AcDHN5 originated evolutionarily from segmental duplication. AcDHN2 and AcDHN7 were highly expressed in leaves, stems, roots, and fruits. During leaf growth, the expression levels of AcDHN1, AcDHN4 and AcDHN5 were downregulated; during fruit growth, AcDHN1 and AcDHN6 were upregulated, while AcDHN4 and AcDHN5 were downregulated. These findings suggest that these genes may be involved in the regulation of leaf or fruit development. Under various abiotic stresses (drought, high and low temperatures, and salt stress) and abscisic acid treatment, the transcription levels of AcDHN1, AcDHN2, AcDHN6, and AcDHN7 were significantly increased. AcDHN3 was only induced by low temperature stress, and AcDHN4 and AcDHN5 only slightly responded to high temperature and salt stress. These results lay a foundation for further study of their function under various stress conditions.

Mulching with the straws of Trifolium repens, Conyza canadensis and Stellaria media increased the root, stem, leaf, shoot and whole-plant biomasses of Cyphomandra betacea seedlings under cadmium (Cd) stress compared with the control, increased the chlorophyll a, chlorophyll b, total chlorophyll and carotinoid contents, and improved superoxide dismutase, peroxidase, and catalase activities. However, the straw of Eclipta prostrata decreased the biomass, photosynthetic pigment content and antioxidant enzyme activity of Cyphomandra betacea seedlings under Cd stress compared with the control. Mulching with the straws of Trifolium repens, Eclipta prostrate, and Stellaria media increased the Cd contents in roots, stems, leaves, and shoots of Cyphomandra betacea seedlings compared with control, while the straw of Conyza canadensis decreased the Cd content. Therefore, mulching with Conyza canadensis can promote the growth of Cyphomandra betacea seedlings, and decrease their Cd accumulation, which benefits the safe production of Cyphomandra betacea. © 2016 American Institute of Chemical Engineers Environ Prog, 2016

The effects of uniconazole (S-3307) application on the growth and cadmium (Cd) accumulation of accumulator plant Malachium aquaticum (L.) Fries. were studied through a pot experiment. The application of S-3307 increased the biomass and photosynthetic pigment content of M. aquaticum in Cd-contaminated soil, and also improved the superoxide dismutase (SOD) and peroxidase (POD) activities in M. aquaticum. Application of S-3307 increased Cd content in shoots and decreased Cd content in roots of M. aquaticum, but the translocation factor (TF) of M. aquaticum increased with the increase of S-3307 concentration. For phytoextraction, the application of S-3307 increased Cd extractions by roots, shoots and whole plants of M. aquaticum, and the maxima were obtained at 75 mg L-1 S-3307, which increased by 22.07%, 37.79% and 29.07%, respectively, compared with their respective controls. Therefore, S-3307 can be used for enhancing the Cd extraction ability of M. aquaticum, and 75 mg L-1 S-3307 was the optimal dose.

Pot and field experiments were conducted to study the effects of interspecies rootstocks on cadmium (Cd) accumulation characteristics of the potential Cd-hyperaccumulator Solanum photeinocarpum postgrafting generation plants. Four treatments (ungrafted and S. photeinocarpum seedlings grafted on the rootstocks of eggplant, potato, and tomato) were utilized in the present study. In the 2 pot experiments, eggplant and potato reduced biomass of S. photeinocarpum postgrafting generation plants, whereas tomato increased shoot biomass compared with the control (ungrafted seedlings). Compared with ungrafted seedlings, tomato increased and eggplant decreased Cd contents in shoots of S. photeinocarpum postgrafting generation. Only tomato increased Cd extraction by shoots of S. photeinocarpum postgrafting generation compared with ungrafted seedlings. In the field experiment, only tomato increased shoot Cd content of S. photeinocarpum postgrafting generation by 8.31% and shoot Cd extraction by 9.30% compared with ungrafted seedlings. Therefore, use of tomato as rootstock could enhance the ability of S. photeinocarpum postgrafting generation plants to remediate Cd-contaminated soil. Environ Toxicol Chem 2016;35:2845-2850. © 2016 SETAC.

Summary The safety and efficacy of anti-diabetic drugs are critical for maximizing the benefical impacts of well-controlled blood glucose on the prognosis of individuals with COVID-19 and pre-existing type 2 diabetes (T2D). Metformin is the most commonly prescribed first-line medication for T2D, but its impact on the outcomes of individuals with COVID-19 and T2D remains to be clarified. Our current retrospective study in a cohort of 1,213 hospitalized individuals with COVID-19 and pre-existing T2D indicated that metformin use was significantly associated with a higher incidence of acidosis, particularly in cases with severe COVID-19, but not with 28-day COVID-19-related mortality. Furthermore, metformin use was significantly associated with reduced heart failure and inflammation. Our findings provide clinical evidence in support of continuing metformin treatment in individuals with COVID-19 and pre-existing T2D, but acidosis and kidney function should be carefully monitored in individuals with severe COVID-19., Graphical Abstract, Highlight ● A retrospective study of 1,213 patients on metformin with COVID-19 was performed ● Metformin was associated with increased incidence of acidosis in such patients ● Metformin was not associated with increased 28-day all-cause mortality in the patients ● Metformin was significantly associated with reduced heart failure and inflammation, In a cohort of 1,213 hospitalized patients with COVID-19 and pre-existing type 2 diabetes, Cheng et al. show that metformin use is significantly associated with higher incidence of acidosis, particularly in cases with severe COVID-19, but not with 28-day all-cause mortality. They also found that metformin use is significantly associated with reduced heart failure and inflammation.

Carotenoid level in fruit changes dynamically in response to storage condition, however, the underlying mechanism remains unclear. Here, we investigated the carotenoid profiles and associated gene expression to reveal its responses to different storage temperature (20 °C and 4 °C) in two kiwifruit cultivars, bright-yellow-fleshed Jinshi 1 and pale-yellow-fleshed Jinyan. At harvest, four main carotenoids were detected in cv. Jinshi 1, while only three in cv. Jinyan, excluding β-cryptoxanthin, which accounted for the majority of carotenoids in ‘Jinshi 1’. Storage at 20 °C increased content of the total carotenoid and β-carotene in both cultivars, and up-regulated the expression of biosynthesis gene PSY, but down-regulated the expression of carotenoid degradation genes CCD1 and NCED1. It also induced β-cryptoxanthin and α-carotene production in Jinyan at later stage. On the contrary, storage at 4 °C decreased total carotenoid content, but induced the expression of carotenoid biosynthetic gene PDS, LCYB, LCYE. These results suggested expression of PSY, CCD1 and NCED1 plays an important role in improvement of carotenoids level at 20 °C. Furthermore, high proportion of β-cryptoxanthin might contribute to yellower flesh in Jinshi 1.

In order to further explore the mechanism of &lsquo, sunshine muscat&rsquo, grape russet formation, transcriptomic and metabolomic analyses were performed on &lsquo, grape peels with and without russet. A total of 1491 differentially expressed genes (DEGs) were discovered based on these analyses. The phenylpropane synthesis pathway was the key metabolic pathway identified, and 28 DEGs related to phenylpropane synthesis pathway were screened, of which 16 were related to lignin synthesis. In addition, 60 differential metabolites were screened. There were 29 phenolic substances among the differential metabolites, which were all up-regulated and 10 were quercetin-related glycosides. Our results indicate that phenols likely play a dominant role in the formation of &lsquo, grape russet, and the synthesis of lignin and quercetin may be the key factors underlying russet formation.

An experiment was conducted to study the effect of biochar on absorption of iron (Fe), sodium (Na) and manganese (Mn) in peach. The results showed that compared with the control (CK), the Fe content of roots in wheat straw biochar addition (WB), corn straw biochar addition (MB) and the Fe content of leaves in paddy straw biochar addition (PB) remarkably increased by 244.8%, 265.2% and 28.3% respectively, and other treatments had no pronounced differences or apparently decreased. Biochar treatments significantly reduced the Na content of roots and significantly increased the Na content of stems and leaves with the exception of rape straw biochar addition (RB). RB and PB caused a significant decrease of the Mn content of roots and stems, expect for the Mn content of stems in RB, RB and PB significantly increased the content of Mn in leaves. The Mn content of peach seedlings in WB and MB had opposite change with RB and PB. Stated thus, MB promoted the absorption of Fe by peach seedlings, and most Fe stored in roots. Biochar treatments promoted Na accumulation in stems and leaves. RB and PB promoted the accumulation of Mn in leaves, WB and MB promoted the accumulation of Mn in roots.

The effects of biochar (rape straw, paddy straw, wheat straw and corn straw) on soil water-soluble sodium (Na), calcium (Ca), magnesium (Mn) and soil enzyme activity of peach seedlings was studied by pot experiment. The experimental result indicated that the effect of paddy straw biochar on soil water-soluble Na content was not significant compared with control, but caused a significant increase in the content of soil water-soluble Ca and Mn. Corn straw biochar significantly increased the content of soil water-soluble Na, and the content of soil water-soluble Ca and Mg were little different from that of control. The soil water-soluble Ca content under wheat straw biochar treatments was significant lower than that of other treatments. Soil enzyme activity is a comprehensive index of soil fertility, and all the biochar treatments led to a significant increase in soil urease activity, which significantly decreased the soil invertase and acid phosphatase activities, and the soil catalase activity between biochar treatments and control had no obviously difference. In conclusion, paddy straw biochar and corn straw biochar have a better effect on soil water-soluble mineral elements such as Ca and Mg, and biochar can promote or inhibit soil enzyme activity under planting peach seedlings.

Light is a key environmental factors affecting anthocyanin accumulation in plants. Ubiquitin E3 ligase COP1 has been proved to be a negative regulator involved in light-regulated plant development process, whereas the function and expression specificity of COP1 in anthocyanin biosynthesis in sweet cherry remains unclear. In the present study, we identified a COP1 in sweet cherry, named PacCOP1, it exhibited apparent different expression patterns in red-colored 'Hongdeng' and bi-colored 'Satonishiki', with increasing trend largely in 'Satonishiki', but decreasing trend in 'Hongdeng' after veraison, which was contrary to their variation tendency of anthocyanin content. While the expression abundance of anthocyanin biosynthesis related genes were largely increased after veraison, in accordance with anthocyanin content. Correlation analysis proved that the expression of PacCOP1 was negative correlated with the major genes on anthocyanin accumulation in 'Hongdeng' and 'Satonishiki' fruit, in especial PacDFR, PacANS, PacMYBA and PacbHLH33. Furthermore, over-expression of PacCOP1 in Arabidopsis displayed increased COP1 transcript level with negligible pigmentation and corresponding lower expression level of AtPAP1, AtDFR, AtLDOX, and AtUFGT. These results revealed the negative regular role of PacCOP1 in anthocyanin biosynthesis by repressing the PacMYBA transcription level, followed by down-regulating the structural genes expression abundance, eventually leading to attenuated anthocyanin accumulation in fruits.

To determine whether self-rooted grafting increases the cadmium (Cd) accumulation in post generations of hyperaccumulator or accumulator plants, a pot experiment was conducted to study the effects of self-rooted grafting on growth and Cd accumulation in the post generation of the accumulator plant Cosmos sulphureus. Four treatments were applied in the experiment with soil Cd concentration of 5 mg kg−1: ungrafted (UG), self-rooted grafting of the same C. sulphureus seedling (SG), self-rooted grafting of two C. sulphureus seedlings at the same growth stage (TG), and self-rooted grafting of two C. sulphureus seedlings at different developmental stages (DG). Compared with those of UG plants, the SG, TG, and DG treatments increased the root, stem, leaf, and shoot biomasses of plants in the post-grafting generation, consistent with the rank order DG > TG > SG > UG. The SG, TG, and DG treatments decreased the Cd contents in different organs of the post-grafting generation compared with those of UG plants. Only DG increased Cd extraction by the shoots in the post-grafting generation, which was increased by 6.28% compared with that of the UG treatment. In addition, SG, TG, and DG increased the photosynthetic pigment contents and enhanced antioxidant enzyme activities in the post-grafting generation compared with those of the UG treatment. Thus, self-rooted grafting promoted growth of C. sulphureus plants in the post generation. The DG treatment increased Cd extraction by C. sulphureus plants in the post-grafting generation, which may be exploited for phytoremediation of urban Cd-contaminated soil.

The growth and cadmium (Cd) accumulation of emergent plant Nasturtium officinale R. Br. cuttings taken from plants grafted onto rootstocks of four terrestrial Cruciferae species were studied in a pot experiment. Scions from N. officinale seedlings were grafted onto rootstocks of Brassica chinensis L., Raphanus sativus L., Brassica napus L., and Rorippa dubia (Pers.) H. Hara. Cuttings were taken after 1 month and grown in Cd-contaminated soil (10 mg Cd kg−1) for 60 days. Compared with non-grafted N. officinale, grafting onto R. sativus and B. napus rootstocks increased the root, shoot, and whole plant biomasses of N. officinale cuttings. Brassica napus rootstock was more effective than R. sativus rootstock for increasing the biomass of N. officinale cuttings. The four rootstocks decreased or had no significant effect on photosynthetic pigment contents in N. officinale cuttings compared with non-grafted N. officinale. Only grafting onto B. napus rootstock enhanced antioxidant enzyme activities. Compared with non-grafted N. officinale, R. sativus and B. napus rootstocks decreased the Cd contents in roots and shoots of N. officinale cuttings, whereas the other rootstocks had no significant effect on the shoot Cd content. The four rootstocks had no increase effects on Cd extraction by N. officinale cuttings. Therefore, cutting after grafting did not enhance the phytoremediation ability of N. officinale for growth in Cd-contaminated soil. However, R. sativus and B. napus rootstocks decreased the Cd content in N. officinale cuttings, which offers a potential approach for N. officinale safety production as a wild vegetable in Cd-contaminated soils.

To identify new cadmium (Cd) hyperaccumulators, the artificially high soil Cd concentration method was used to screen six common farmland weeds. Among them, only Pterocypsela laciniata (Houtt.) C. Shih showed characteristics of a Cd hyperaccumulator and was selected for further studies. In pot experiments, soil Cd concentrations of 5, 10, and 25 mg kg−1 increased the biomass and photosynthetic pigment concentrations in P. laciniata when compared with the control, whereas 75 and 100 mg kg−1 decreased them (the maxima were at 10 mg kg−1 soil Cd). The antioxidant enzyme activities and the soluble protein concentrations of P. laciniata showed similar trends as biomass. The Cd concentrations in roots and shoots of P. laciniata increased as soil Cd concentration increased. When the soil Cd concentration was 50 mg kg−1, the Cd concentration in the shoots of P. laciniata was 116 mg kg−1 (the critical value for Cd hyperaccumulators is 100 mg kg−1). Both the root and shoot bioconcentration factors of P. laciniata were larger than 1.0, and the translocation factor exceeded 1.0 in almost all treatments. The Cd extractions by the shoots and whole plants of P. laciniata reached maxima at 208 and 375 μg plant−1, respectively. The Cd extractions by P. laciniata were different between two ecotypes. Therefore, P. laciniata is a Cd hyperaccumulator that could remediate Cd-contaminated soils, but the ecotypes should be considered when using P. laciniata for phytoremediation.

In this study, three cadmium (Cd) accumulator species (Conyza canadensis, Cardamine hirsuta, and Cerastium glomeratum) were co-cultured in Cd-contaminated soil in pots to study the effects of intercropping on co-remediation. Only C. canadensis intercropped with C. glomeratum, C. hirsuta intercropped with C. glomeratum, and three-species intercropping increased plant biomass compared with their respective monocultures. The treatments of C. canadensis intercropped with C. glomeratum and three-species intercropping increased the Cd contents in roots and shoots of C. canadensis, whereas the other intercropping treatments decreased or had no significant impact on Cd contents. As for Cd accumulation, the treatments of C. canadensis intercropped with C. glomeratum, C. hirsuta intercropped with C. glomeratum, and three-species intercropping increased Cd accumulation in a single plant compared with that of their respective monocultures, whereas other intercropping treatments decreased Cd accumulation in individual plants. Only the treatments of C. canadensis intercropped with C. glomeratum and C. hirsuta intercropped with C. glomeratum increased Cd accumulation in shoots of a single pot compared with that of their respective monocultures. Therefore, C. canadensis intercropped with C. glomeratum and C. hirsuta intercropped with C. glomeratum may improve the phytoremediation efficiency for Cd-contaminated soil.

Background During fresh fruit consumption, sensory texture is one factor that affects the organoleptic qualities. Chemical components of plant cell walls, including pectin, cellulose, hemicellulose and lignin, play central roles in determining the textural qualities. To explore the genes and regulatory pathways involved in fresh citrus’ perceived sensory texture, we performed mRNA-seq analyses of the segment membranes of two citrus cultivars, Shiranui and Kiyomi, with different organoleptic textures. Results Segment membranes were sampled at two developmental stages of citrus fruit, the beginning and end of the expansion period. More than 3000 differentially expressed genes were identified. The gene ontology analysis revealed that more categories were significantly enriched in ‘Shiranui’ than in ‘Kiyomi’ at both developmental stages. In total, 108 significantly enriched pathways were obtained, with most belonging to metabolism. A detailed transcriptomic analysis revealed potential critical genes involved in the metabolism of cell wall structures, for example, GAUT4 in pectin synthesis, CESA1, 3 and 6, and SUS4 in cellulose synthesis, CSLC5, XXT1 and XXT2 in hemicellulose synthesis, and CSE in lignin synthesis. Low levels, or no expression, of genes involved in cellulose and hemicellulose, such as CESA4, CESA7, CESA8, IRX9 and IRX14, confirmed that secondary cell walls were negligible or absent in citrus segment membranes. A chemical component analysis of the segment membranes from mature fruit revealed that the pectin, cellulose and lignin contents, and the segment membrane’s weight (% of segment) were greater in ‘Kiyomi’. Conclusion Organoleptic quality of citrus is easily overlooked. It is mainly determined by sensory texture perceived in citrus segment membrane properties. We performed mRNA-seq analyses of citrus segment membranes to explore the genes and regulatory pathways involved in fresh citrus’ perceived sensory texture. Transcriptomic data showed high repeatability between two independent biological replicates. The expression levels of genes involved in cell wall structure metabolism, including pectin, cellulose, hemicellulose and lignin, were investigated. Meanwhile, chemical component contents of the segment membranes from mature fruit were analyzed. This study provided detailed transcriptional regulatory profiles of different organoleptic citrus qualities and integrated insights into the mechanisms affecting citrus’ sensory texture. Electronic supplementary material The online version of this article (10.1186/s12864-018-4669-y) contains supplementary material, which is available to authorized users.

The effects of application of straw derived from cadmium (Cd) accumulator plants (Siegesbeckia orientalis, Conyza canadensis, Eclipta prostrata, and Solanum photeinocarpum) on growth and Cd accumulation of lettuce plants grown under Cd exposure were studied. Treatment with straw of the four Cd-accumulator species promoted growth, photosynthesis, and soluble protein contents and enhanced the activities of peroxidase in leaves of lettuce seedlings. The biomass of shoot of lettuce from high to low in turn is the treatment of C. canadensis straw > S. photeinocarpum straw > S. orientalis > E. prostrata > Control. The Cd content in edible parts (shoots) of the lettuce plants was significantly decreased in the presence of straw from the Cd-accumulator species, except the presence of the straw of E. prostrata. And, the greatest reduction in Cd content in shoots was 27.09% in the S. photeinocarpum straw treatment compared with that of the control. Therefore, application of straw of S. orientalis, C. canadensis, and S. photeinocarpum can promote the growth of lettuce seedlings, and decrease their Cd accumulation, when grown in Cd-contaminated soil, which is beneficial for production of lettuce safe for human consumption.

Evidence exists to suggest that melatonin (MT) is important to abiotic stress tolerance in plants. Here, we investigated whether exogenous MT reduces heat damage on biological parameters and gene expression in kiwifruit (Actinidia deliciosa) seedlings. Pretreatment with MT alleviates heat-induced oxidative harm through reducing H2O2 content and increasing proline content. Moreover, MT application raised ascorbic acid (AsA) levels and the activity of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). We also observed elevation in the activity of enzymes related to the AsA-GSH cycle, such as ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR). Furthermore, MT application increased the expression of 28/31 glutathione S-transferase (GST) genes, reducing oxidative stress. These results clearly indicate that in kiwifruit, MT exerts a protective effect against heat-related damage through regulating antioxidant pathways.