Selection of waterlogging-tolerant and water purification herbaceous plants for the construction of a sponge city in Shenzhen, China

In recent years, seeking solutions to urban waterlogging and water pollution has always been one of the topics of concern. The problem of urban water accumulation occurs frequently in most areas of China in July and August. The contradiction between supply and demand of urban ecological water is prominent. In order to solve the problem of urban water accumulation caused by rainfall concentration, and to achieve the overall goal of building a water-saving green ecological city, the Shenzhen City should be built into a sponge city. Under this background, the physiological response of different forages to waterlogging stress and the removal of pollutants in rainwater were studied. In this study, ten herbaceous plants commonly used in Shenzhen were used as experimental materials. After 0, 7, 14, 21, 28 days of waterlogging stress treatment, six physiological indexes, such as MDA, SP, and Pro contents and SOD, POD, and CAT activities, were comprehensively evaluated. Combined with the morphological changes of the plants after waterlogging, seven plants with strong waterlogging tolerance were determined, which were O. bodinieri, H. coronarium, I. tectorum, D. ensifolia, R. brittoniana, C. indica, and A. zerumbet. Then, according to their comprehensive evaluation of the removal capacity of pollutants in the rainwater, it is suggested to select O. bodinieri, H. coronarium, I. tectorum and D. ensifolia in areas with serious waterlogging. In areas with serious water pollution, R. brittoniana, A. zerumbet, D. ensifolia and H. coronarium are recommended. However, H. coronarium and D. ensifolia not only have a strong adaptability in the waterlogged environment, but also have a strong ability to remove pollutants in the rainwater, so they are suggested to be alternative herbaceous plants for sponge city in Shenzhen, China

Analysis of gene expression in Kalanchoe daigremontiana leaves during plantlet formation under drought stress

Background: Kalanchoe daigremontiana is an attractive model system for the study of the molecular mechanisms of somatic embryogenesis and organogenesis competence due to its formation of plantlets with adventitious roots on the leaf margins that are derived from somatic embryos. The suppression subtractive hybridization technique was used to investigate gene expression during asexual reproduction. Leaves from plants subjected to drought stress provided the source of \u2018Tester\u2019 DNA, and leaves from plants grown under normal conditions provided the \u2018Driver\u2019 DNA for subtractive hybridization. Results: A total of 481 high quality ESTs were generated, which clustered into 390 unigenes. Of these unigenes, 132 grouped into 12 functional categories, suggesting that asexual reproduction is a complicated process involving a large number of genes. The expression characteristics of selected genes from the SSH library were determined by real-time PCR and were classified into five groups, suggesting that gene expression patterns during asexual reproduction are complex. Up-regulation of S-adenosylhomocysteine hydrolase suggested that a decrease in cytokinin levels promotes the initiation of plantlet formation. Many other genes, such as inorganic pyrophosphatase and glutamate decarboxylase, play important roles in gene regulation during asexual reproduction. Conclusion: Our results provide a framework and unified platform on which future research on asexual reproduction in K. daigremontiana can be based. This represents the first genome-wide study of asexual reproduction in K. daigremontiana

Genome-wide analysis reveals four key transcription factors associated with cadmium stress in creeping bentgrass (Agrostis stolonifera L.)

Cadmium (Cd) toxicity seriously affects the growth and development of plants, so studies on uptake, translocation, and accumulation of Cd in plants are crucial for phytoremediation. However, the molecular mechanism of the plant response to Cd stress remains poorly understood. The main objective of this study was to reveal differentially expressed genes (DEGs) under lower (BT2_5) and higher (BT43) Cd concentration treatments in creeping bentgrass. A total of 463,184 unigenes were obtained from creeping bentgrass leaves using RNA sequencing technology. Observation of leaf tissue morphology showed that the higher Cd concentration damages leaf tissues. Four key transcription factor (TF) families, WRKY, bZIP, ERF, and MYB, are associated with Cd stress in creeping bentgrass. Our findings revealed that these four TFs play crucial roles during the creeping bentgrass response to Cd stress. This study is mainly focused on the molecular characteristics of DEGs under Cd stress using transcriptomic analysis in creeping bentgrass. These results provide novel insight into the regulatory mechanisms of respond to Cd stress and enrich information for phytoremediation

Overexpression of MsSAG113 gene promotes leaf senescence in alfalfa via participating in the hormone regulatory network

IntroductionAlfalfa (Medicago sativa) is a kind of high quality leguminous forage species, which was widely cultivated in the world. Leaf senescence is an essential process in plant development and life cycle. Here, we reported the isolation and functional analysis of an alfalfa SENESCENCE-ASSOCIATED GENE113 (MsSAG113), which belongs to the PP2C family and mainly plays a role in promoting plant senescence.MethodsIn the study, Agrobacterium-mediated, gene expression analysis, next generation sequencing, DNA pull-down, yeast single hybridization and transient expression were used to identify the function of MsSAG113 gene.ResultsThe MsSAG113 gene was isolated from alfalfa, and the transgenic plants were obtained by Agrobacterium-mediated method. Compared with the wildtype, transgenic plants showed premature senescence in leaves, especially when cultivated under dark conditions. Meanwhile, application of exogenous hormones ABA, SA, MeJA, obviously acclerated leaf senescence of transgenic plants. Furthermore, the detached leaves from transgenic plants turned yellow earlier with lower chlorophyll content. Transcriptome analysis identified a total of 1,392 differentially expressed genes (DEGs), involving 13 transcription factor families. Of which, 234 genes were related to phytohormone synthesis, metabolism and transduction. Pull-down assay and yeast one-hybrid assay confirmed that alfalfa zinc finger CCCH domain-containing protein 39 (MsC3H-39) could directly bind the upstream of MsSAG113 gene. In conclusion, the MsSAG113 gene plays a crucial role in promoting leaf senescence in alfalfa via participating in the hormone regulatory network.DiscussionThis provides an essential basis for further analysis on the regulatory network involving senescence-associated genes in alfalfa

Differential Regulations of Antioxidant Metabolism and Cold-Responsive Genes in Three Bermudagrass Genotypes under Chilling and Freezing Stress

As a typical warm-season grass, bermudagrass growth and turf quality begin to decrease when the environmental temperature drops below 20 °C. The current study investigated the differential responses of three bermudagrass genotypes to chilling stress (8/4 °C) for 15 days and then freezing stress (2/−2 °C) for 2 days. The three genotypes exhibited significant variation in chilling and freezing tolerance, and Chuannong-3, common bermudagrass 001, and Tifdwarf were ranked as cold-tolerant, -intermediate, and -sensitive genotypes based on evaluations of chlorophyll content, the photochemical efficiency of photosystem II, oxidative damage, and cell membrane stability, respectively. Chuannong-3 achieved better tolerance through enhancing the antioxidant defense system to stabilize cell membrane and reactive oxygen species homeostasis after being subjected to chilling and freezing stresses. Chuannong-3 also downregulated the ethylene signaling pathway by improving CdCTR1 expression and suppressing the transcript levels of CdEIN3-1 and CdEIN3-2; however, it upregulated the hydrogen sulfide signaling pathway via an increase in CdISCS expression under cold stress. In addition, the molecular basis of cold tolerance could be associated with the mediation of key genes in the heat shock pathway (CdHSFA-2b, CdHSBP-1, CdHSP22, and CdHSP40) and the CdOSMOTIN in Chuannong-3 because the accumulation of stress-defensive proteins, including heat shock proteins and osmotin, plays a positive role in osmoprotection, osmotic adjustment, or the repair of denatured proteins as molecular chaperones under cold stress. The current findings give an insight into the physiological and molecular mechanisms of cold tolerance in the new cultivar Chuannong-3, which provides valuable information for turfgrass breeders and practitioners

Heterologous expression of ZjOMT from Zoysia japonica in Escherichia coli confers aluminum resistance through melatonin production.

Melatonin is a molecule that can enhance the resistance of plants to abiotic stress. It can alleviate the damage of heavy metal ions, and other chemical substances, changes in temperature and humidity, oxidative stress in higher plants, and enhance resistance of plants to abiotic stress. The transformation of N-Acetyl-5-hydroxy tryptamin into melatonin requires the involvement of methyltransferase. In this study, a methyltransferase gene ZjOMT has been cloned from Zoysia japonica. The gene was induced by aluminum (Al) stress in the leaves and roots of Zoysia japonica, and was up-regulated by 20.86- and 31.18-folds, respectively. The expression of ZjOMT in Escherichia coli increased the content of melatonin by about 8-fold in the recombinant strain compared with that of the empty vector strain. Al resistance test showed that the resistance of recombinant strain BL21-pET32-ZjOMT to Al was significantly higher than that of the empty vector strain BL21-pET32. The survival rate of the recombinant strain expressing ZjOMT was about 100-fold higher than that of the empty vector strain when treated with 0.35 mM Al. These findings suggest that the heterologous expression of ZjOMT improved the resistance of E. coli to Al by increasing the content of melatonin

Uncovering a Phenomenon of Active Hormone Transcriptional Regulation during Early Somatic Embryogenesis in Medicago sativa

Somatic embryogenesis (SE) is a developmental process in which somatic cells undergo dedifferentiation to become plant stem cells, and redifferentiation to become a whole embryo. SE is a prerequisite for molecular breeding and is an excellent platform to study cell development in the majority of plant species. However, the molecular mechanism involved in M. sativa somatic embryonic induction, embryonic and maturation is unclear. This study was designed to examine the differentially expressed genes (DEGs) and miRNA roles during somatic embryonic induction, embryonic and maturation. The cut cotyledon (ICE), non-embryogenic callus (NEC), embryogenic callus (EC) and cotyledon embryo (CE) were selected for transcriptome and small RNA sequencing. The results showed that 17,251 DEGs, and 177 known and 110 novel miRNAs families were involved in embryonic induction (ICE to NEC), embryonic (NEC to EC), and maturation (EC to CE). Expression patterns and functional classification analysis showed several novel genes and miRNAs involved in SE. Moreover, embryonic induction is an active process of molecular regulation, and hormonal signal transduction related to pathways involved in the whole SE. Finally, a miRNA–target interaction network was proposed during M. sativa SE. This study provides novel perspectives to comprehend the molecular mechanisms in M. sativa SE

Growth of BL21 -pET32a and BL21-pET32-ZjOMT under Al stress.

<p>Growth of BL21 -pET32a and BL21-pET32-ZjOMT under Al stress.</p

Production of melatonin by BL21-pET32-ZjOMT and BL21-pET32a empty vector strains induced by IPTG.

<p>The column chart was presented as mean±SD, white indicated an empty vector strain, the dark grey indicated ZjOMT recombinant strain, “**” indicated the difference of P<0.01 in t test.</p