Study on remediation of cadmium contaminated paddy field by ramie (Boehmeria nivea L.) floating island and its supporting technology.

Ramie (Boehmeria nivea L.) is an ideal crop for cadmium (Cd) pollution remediation due to its advantages of both remediating and utilizing, however, it is mainly carried out in dry land, whose restoration effect is relatively slow. Previously, we found that the ramie plants cultivated by hydroponics has several tens of times higher Cd absorption capacity than that planted in soil. However, the issue of how to use hydroponic ramie to remediate Cd contaminated paddy fields needs to be addressed. In this study, we innovatively developed the ramie floating island technology and studied its remediation model on simulated Cd contaminated paddy fields. Different ramie varieties were used to compare the remediation effects, and the results showed that there were differences in adaptability among different varieties on floating islands and the remediation ability of the tested ramie varieties was Z2 > Z1 > Z3. Different harvested times were set to analyze the effects of harvested model on remediation, and it was suggested that multiple harvests can be carried out according to the plant growth status of ramie floating island after 30 days of remediation to achieve better remediation effects. Low water level height (5 cm) of paddy field was beneficial for the accumulation of Cd in the roots, but considering the adaptability of various ramie varieties and the effect of long-term restoration, it was recommended that the water level height of 20 cm for the cultivation of ramie floating island was more suitable. Moreover, we found that low concentration of citric acid (≤2 g L-1) or polyaspartic acid (≤3 g L-1) can improve the remediation effects for ramie floating island. Our study opens up a novel approach for ramie to remediate heavy metal pollution and provides a technical reference for water body Cd remediation by plants.

A comparative study of different methods for the determination of cadmium in various tissues of ramie (Boehmeria nivea L.).

Remediation of cadmium (Cd) pollution is one of the priorities of global environmental governance and accurate detection of Cd content is a key link in remediation of Cd pollution. This study aimed to compare three methods (inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), and graphite furnace-atomic absorption spectrometry (GF-AAS)) for the determination of Cd with different tissues of various ramie varieties, and distinguish the advantage and disadvantage of each method. In total, 162 samples of ramie (Boehmeria nivea L.), which is an ideal plant for heavy metal remediation, were detected and the results showed that the three methods were all suitable for the de-termination of Cd content in ramie. ICP-OES and ICP-MS were simpler, faster, and more sensitive than GF-AAS. ICP-MS could be recommended for the determination of samples with various concentrations of Cd. ICP-OES could be used for measurement of samples with > 100 mg/kg Cd content, while GF-AAS was suitable for the detection of samples with very high (> 550 mg/kg) or very low (< 10 mg/kg) Cd content. Overall, considering the accuracy, stability, and the cost of measurement, ICP-MS was the most suitable method for determination of Cd content. This study provides significant reference information for the research in the field of Cd pollution remediation.

Genome-wide analysis of R2R3-MYB transcription factors in Boehmeria nivea (L.) gaudich revealed potential cadmium tolerance and anthocyanin biosynthesis genes.

Gene family, especially MYB as one of the largest transcription factor family in plants, the study of its subfunctional characteristics is a key step in the study of plant gene function. The sequencing of ramie genome provides a good opportunity to study the organization and evolutionary characters of the ramie MYB gene at the whole genome level. In this study, a total of 105 BnGR2R3-MYB genes were identified from ramie genome and subsequently grouped into 35 subfamilies according to phylogeny divergence and sequences similarity. Chromosomal localization, gene structure, synteny analysis, gene duplication, promoter analysis, molecular characteristics and subcellular localization were accomplished using several bioinformatics tools. Collinearity analysis showed that the segmental and tandem duplication events is the dominant form of the gene family expansion, and duplications prominent in distal telomeric regions. Highest syntenic relationship was obtained between BnGR2R3-MYB genes and that of Apocynum venetum (88). Furthermore, transcriptomic data and phylogenetic analysis revealed that BnGMYB60, BnGMYB79/80 and BnGMYB70 might inhibit the biosynthesis of anthocyanins, and UPLC-QTOF-MS data further supported the results. qPCR and phylogenetic analysis revealed that the six genes (BnGMYB9, BnGMYB10, BnGMYB12, BnGMYB28, BnGMYB41, and BnGMYB78) were cadmium stress responsive genes. Especially, the expression of BnGMYB10/12/41 in roots, stems and leaves all increased more than 10-fold after cadmium stress, and in addition they may interact with key genes regulating flavonoid biosynthesis. Thus, a potential link between cadmium stress response and flavonoid synthesis was identified through protein interaction network analysis. The study thus provided significant information into MYB regulatory genes in ramie and may serve as a foundation for genetic enhancement and increased productivity.

Protective effect of methionine on the intestinal oxidative stress and microbiota change induced by nickel.

Nickel is a common heavy metal pollutant in industrial areas and can cause oxidative damage to human and animal organs. As an essential amino acid with antioxidant function, methionine (Met) may protect the body from the oxidative stress induce by nickel, however, there is not enough research to study in this aspect. The study aims at investigating the effect of Met on the nickel-induced intestinal oxidative stress and further detected the gut microbiota changes. Mice were gavaged with quantitative NiCl2 (1.6 mg/ml, 0.25 ml) and fed with different doses of methionine in each group. The contents of intestinal oxidation product and antioxidant enzymes were determined by different biochemical quantitative methods, and the data showed that NiCl2 increased the content of intestinal oxidation product (MDA), and the antioxidant enzymes (GSH-Px, GR, SOD and CAT) were decreased. But this situation was alleviated in the group fed with additional methionine solution (0.5 mg/ml). In addition, we detected changes in the gut microbiota using high-throughput sequencing, the results showed that the structure of intestinal flora was disturbed by NiCl2, but methionine restored the germs with antioxidant capacity. Based on the results, we speculate that methionine can alleviate the impact of NiCl2 on the intestinal by enhancing the activity of antioxidant enzymes and the number of gut bacteria with anti-oxidation, suggesting that methionine as a nutritional additive may have the potential to treat nickel poisoning.

Analysis of WRKY Resistance Gene Family in Boehmeria nivea (L.) Gaudich: Crosstalk Mechanisms of Secondary Cell Wall Thickening and Cadmium Stress.

A total of 60 WRKY family genes of ramie were identified in the ramie. The genes were unevenly distributed across 14 chromosomes in the specie and highly concentrated (72%) in the distal telomeric region. Phylogenetic analysis placed these genes into seven distinct subfamilies groups: I, II (a, b, c, d, e), and III, with group IIc containing only the variant of heptapetide sequence (WRKYGKK). Segmental duplication events (41.7%) was found to be the main driver of BnGWRKY evolution. Thirty eight from among the genes showed collinear relationships with WRKY genes from Arabidopsis thaliana, Cannabis sativa, Oryza sativa, and Zea mays. The number and density of stress and hormone responsives cis-acting elements were comparably higher than other elements, with abundant ARE and rare LTR cis-acting elements indicating the long-standing adaptability of ramie to its natural environment. GO and KEGG enrichment analysis of the WRKY target genes revealed their involvement in response to stimuli, immune system processes, transporter protein activity and antioxidant activity. Expression analysis show that most WRKYs were activated by the cadmium stress, more especially the BnGWRKY2, BnGWRKY15, BnGWRKY20, BnGWRKY50 and BnGWRKY58. Combining transcriptome, orthologous gene relationships and qPCR result, we established the possible involvement of BnGWRKY50 and BnGWRKY58 in crosstalk mechanism between secondary cell wall thickening and Cd2+ stress. This provided information into the role of BnGWRKY proteins in ramie secondary wall development and cadmium stress response to, and could serve as basis for improvement of the ramie.

Genome wide characterization of R2R3 MYB transcription factor from Apocynum venetum revealed potential stress tolerance and flavonoid biosynthesis genes.

MYB transcription factors are crucial in regulating stress tolerance and expression of major genes involved in flavonoid biosynthesis. The functions of MYBs is well explored in a number of plants, yet no study is reported in Apocynum venetum. We identified a total of 163 MYB candidates, that comprised of 101 (61.96%) R2R3, 6 3R, 1 4R and 55 1R. Syntenic analysis of A. venetum R2R3 (AvMYBs) showed highest orthologous pairs with Vitis vinifera MYBs followed by Arabidopsis thaliana among the four species evaluated. Thirty segmental duplications and 6 tandem duplications were obtained among AvMYB gene pairs signifying their role in the MYB gene family expansion. Nucleotide substitution analysis (Ka/Ks) showed the AvMYBs to be under the influence of strong purifying selection. Expression analysis of selected AvMYBs under low temperature and cadmium stresses resulted in the identification of AvMYB48, AvMYB97, AvMYB8, AvMYB4 as potential stress responsive genes and AvMYB10 and AvMYB11 in addition, proanthocyanidin biosynthesis regulatory genes which is consistent with their annotated homologues in Arabidopsis. Tissue specific expression profile analysis of the AvMYBs further supported the qPCR analysis result. MYBs with higher transcript levels in root, stem and leaf like AvMYB4 for example, was downregulated under the stresses and such with low transcript level such as AvMYB48 which had low transcript in the leaf was upregulated under both stresses. Transcriptome and phylogenetic analyses suggested AvMYB42 as a potential regulator of anthocyanin biosynthesis. Thus, this study provided valuable information on AvR2R3-MYB gene family with respect to stress tolerance and flavonoid biosynthesis.

Comparative study of the histomorphological structure of the small intestine of Lonchura striata and Copsychus saularis / Estudio comparativo de la estructura histomorfológica del intestino delgado de Lonchura striata y Copsychus saularis

SUMMARY: Six Lonchura striata and six Copsychus saularis birds were selected in this study, morphological index of the small intestine was measured by quantitative biology and image analysis. The changes of goblet cells and Na+/K+ATPase were detected by AB-PAS staining and ELISA to inform the different mechanisms of the digestion and absorption of nutrients between the Lonchura striata and Copsychus saularis. The villus height, crypt depth and muscle thickness of each segment of small intestine of Lonchura striata were smaller than those of Copsychus saularis, and the difference of ileum muscle thickness was significant. In addition, the ileum villus height/crypt depth (VH/CD) value of Lonchura striata was significantly less than that of Copsychus saularis. The number of goblet cells in duodenum and jejunum of Lonchura striata and Copsychus saularis had no significant difference, but the number of goblet cells in ileum of Copsychus saularis was significantly larger than that of Lonchura striata. The vitality of Na+/K+-ATPase in different intestinal segments of the Lonchura striata and the Copsychus saularis was different. The vitality of Na+/K+-ATPase in the Lonchura striata was significantly higher than that of the Copsychus saularis. It can be concluded that the digestion and absorption capacity of Copsychus saularis and Lonchura striata are significantly different, and the reason may be due to their different diets and intestinal floras.

RESUMEN: En este estudio se seleccionaron seis aves Lonchura striata y seis Copsychus saularis, a las cuales se midió mediante biología cuantitativa y análisis de imágenes el índice morfológico del intestino delgado. Los cambios de las células caliciformes y Na+/K+ATPasa se detectaron mediante tinción AB- PAS y ELISA para informar los diferentes mecanismos de digestión y absorción de nutrientes entre Lonchura striata y Copsychus saularis. La altura de las vellosidades, la profundidad de las criptas y el grosor del músculo de cada segmento del intestino delgado de Lonchura striata fueron menores que los de Copsychus saularis, y se observó una diferencia significativa en el grosor de la músculatura del íleon. Además, el valor de la altura de la vellosidad del íleon/profundidad de la cripta (VH/CD) de Lonchura striata fue significativamente menor que el de Copsychus saularis. En el número de células caliciformes del duodeno y del yeyuno de Lonchura striata y Copsychus saularis no hubo una diferencia significativa, pero el número de células caliciformes en el íleon de Copsychus saularis fue significativamente mayor que el de Lonchura striata. Hubo diferencias en la vitalidad de Na+/K+-ATPasa en diferentes segmentos intestinales de Lonchura striata y Copsychus saularis. La vitalidad de Na+/K+-ATPasa en Lonchura striata fue significativamente mayor que la de Copsychus saularis. Se puede concluir que la capacidad de digestión y absorción de Copsychus saularis y Lonchura striata son significativamente diferentes, posiblemente debido a sus distintas dietas y floras intestinales.