Characterization of lodging variation of weedy rice.

Weedy rice (Oryza spp.), one of the most notorious weeds of cultivated rice, evades eradication through stem lodging and seed shattering. Many studies have focused on seed shattering, whereas variations in lodging have received less attention and the underlying mechanisms that cause the differences in lodging between weedy and cultivated rice have not been studied in detail. Here, we compared lodging variation among diverse Chinese weedy rice strains and between weedy rice and co-occurring cultivated rice. The chemical composition of basal stems was determined, and transcriptome and methylome sequencing were used to assess the variation in expression of lodging-related genes. The results showed that the degree of lodging varied between indica-derived weed strains with high lodging levels, which occurred predominantly in southern China, and japonica-derived strains with lower lodging levels, which were found primarily in the north. The more lodging-prone indica weedy rice had a smaller bending stress and lower lignin content than non-lodging accessions. In comparison to co-occurring cultivated rice, there was a lower ratio of cellulose to lignin content in the lodging-prone weedy rice. Variation in DNA methylation of lignin synthesis-related OsSWN1, OsMYBX9, OsPAL1, and Os4CL3 mediated the differences in their expression levels and affected the ratio of cellulose to lignin content. Taken together, our results show that DNA methylation in lignin-related genes regulates variations in stem strength and lodging in weedy rice, and between weed strains and co-occurring cultivated rice.

Acyl-CoA synthetases from Physcomitrella, rice and Arabidopsis: different substrate preferences but common regulation by MS188 in sporopollenin synthesis.

MAIN CONCLUSION: ACOS5, OsACOS12 and PpACOS6 are all capable of fatty acyl-CoA synthetase activity but exhibit different substrate preferences. The transcriptional regulation of ACOS for sporopollenin synthesis appears to have been conserved in Physcomitrella, rice and Arabidopsis during evolution. Sporopollenin is the major constituent of spore and pollen exines. In Arabidopsis, acyl-CoA synthetase 5 (ACOS5) is an essential enzyme for sporopollenin synthesis, and its orthologues are PpACOS6 from the moss Physcomitrella and OsACOS12 from monocot rice. However, knowledge regarding the evolutionary conservation and divergence of the ACOS gene in sporopollenin synthesis remains limited. In this study, we analysed the function and regulation of PpACOS6 and OsACOS12. A complementation test showed that OsACOS12 driven by the ACOS5 promoter could partially restore the male fertility of the acos5 mutant in Arabidopsis, while PpACOS6 did not rescue the acos5 phenotype. ACOS5, PpACOS6 and OsACOS12 all complemented the acyl-CoA synthetase-deficient yeast strain (YB525) phenotype, although they exhibited different substrate preferences. To understand the conservation of sporopollenin synthesis regulation, we constructed two constructs with ACOS5 driven by the OsACOS12 or PpACOS6 promoter. Both constructs could restore the fertility of acos5 plants. The MYB transcription factor MS188 from Arabidopsis directly regulates ACOS5. We found that MS188 could also bind the promoters of OsACOS12 and PpACOS6 and activate the genes driven by the promoters, suggesting that the transcriptional regulation of these genes was similar to that of ACOS5. These results show that the ACOS gene promoter region from Physcomitrella, rice and Arabidopsis has been functionally conserved during evolution, while the chain lengths of fatty acid-derived monomers of sporopollenin vary in different plant species.

The transcription factors MS188 and AMS form a complex to activate the expression of CYP703A2 for sporopollenin biosynthesis in Arabidopsis thaliana.

The sexine layer of pollen grain is mainly composed of sporopollenins. The sporophytic secretory tapetum is required for the biosynthesis of sporopollenin. Although several enzymes involved in sporopollenin biosynthesis have been reported, the regulatory mechanism of these enzymes in tapetal layer remains elusive. ABORTED MICROSPORES (AMS) and MALE STERILE 188/MYB103/MYB80 (MS188/MYB103/MYB80) are two tapetal cell-specific transcription factors required for pollen wall formation. AMS functions upstream of MS188. Here we report that AMS and MS188 target the CYP703A2 gene, which is involved in sporopollenin biosynthesis. We found that AMS and MS188 were localized in tapetum while CYP703A2 was localized in both tapetum and locule. Chromatin immunoprecipitation (ChIP) showed that MS188 directly bound to the promoter of CYP703A2 and luciferase-inducible assay showed that MS188 activated the expression of CYP703A2. Yeast two-hybrid and electrophoretic mobility shift assays (EMSAs) further demonstrated that MS188 complexed with AMS. The expression of CYP703A2 could be partially restored by the elevated levels of MS188 in the ams mutant. Therefore, our data reveal that MS188 coordinates with AMS to activate CYP703A2 in sporopollenin biosynthesis of plant tapetum.

Highly ordered asymmetric cellulose-based honeycomb membrane for moisture-electricity generation and humidity sensing.

Moisture-trigged electricity generator (MEG) that can convert ubiquitous moisture into electricity are highly desirable for developing renewable energy supply and ameliorating the crisis in energy. Constructing an asymmetric ordered, namely gradient ordered porous membrane has great potential in MEG. Herein, a series of cellulose acetate (CA)-based membranes with ordered asymmetric honeycomb membranes were fabricated by Breath Figure method, along with silver nanowires (AgNWs) coating. The asymmetric gradient honeycomb pores were achieved by graft modification of lauroyl chloride and adjustment of relative humidity, which not only endowed the MEG with sensitive sensing signals transport under tension and humidity fluctuations but also enhanced voltages generation speed under flowing moisture. The current study provides a facile and scalable strategy for constructing asymmetric gradient ordered porous materials and creates more possibilities for MEG self-powered flexible wearable electronic devices.

Cellulose nanofibril/mineral composites induced by H-bond/ionic coordination in co-refining system.

Mineral fillers hinder cellulosic fiber bonding and thus limit the increase of filler content in paper. Herein, precipitated calcium carbonate (PCC)/cellulose nanofibrils (CNF) composites were fabricated by a facile and efficient strategy, i.e., co-refining process (CRP). During this process, CNF and PCC were activated by mechanochemical effect and formed encapsulation structure by calcium ion coordination and hydrogen bonding. The encapsulation structure and H-bond/ionic coordination interactions not only endowed the composite with excellent size stability but also enhanced interfacial interaction between composite fillers and cellulosic fibers. Compare with the paper filled with only PCC, PCC + CNF mixture, the tensile index of the cellulosic paper containing PCC/CNF composite was increased by 44.48% and 12.14%, respectively. These results not only provide a facile and scalable approach to increase interaction between cellulosic fiber and mineral filler but also create more possibilities for special paper-based materials with requiring high content of inorganic materials.

Transcription-mediated tissue-specific lignification of vascular bundle causes trade-offs between growth and defence capacity during invasion of Solidago canadensis.

Allocation of more resources to growth but less to defense causing growth vigor of invasive alien plant populations contributes to successful invasion. However, few studies has addressed to relationship between vascular development variation and this mechanism. In this study, a common garden experimentwas established to compare the growth and vascular bundle development between native and introduced populations of Solidago canadensis, which is a wide-distributed invasive species in China. Our results suggested that the rapid growth of introduced populations could be explained by the well-developed and highly lignified xylem; while native populations present more developed and highly lignified phloem, which contributed more resistance to the infection of Sclerotiun rofsii compared with introduced populations. This difference was resulted from tissue-specific tradeoff distribution of lignification related gene expression between xylem and phloem, which is regulated by upstream MYB transcription factors. Our study gives a novel insight of mechanism that explain invasion success: lignin-related gene transcription-mediated tissue-specific lignification of vascular bundle contributes tradeoffs in resource allocation between growth and defence capacity during successful invasion of S. canadensis.

Plant diversity in herbal tea and its traditional knowledge in Qingtian County, Zhejiang Province, China.

Herbal teas composed of locally occurring plant species have long been used as the primary form of health care in Qingtian County, Zhejiang Province, China. However, large-scale emigration overseas and an aging population threaten the conservation of traditional knowledge of these herbal teas. Traditional knowledge about the plants used for these herbal teas is not well documented in Qingtian, despite their widespread use. The aim of this study was to assess the plant-cultural diversity of plants used as herbal teas, and to point out the prospective value of herbal teas used by Qingtian people. This study was conducted using semi-structured interviews, as well as field and market surveys. Forty-three local informants were interviewed. We recorded plant resources, plant parts used, local names, and medicinal uses. Quantitative ethnobotanical indices, including cognitive salience (CS), frequency of citation (FC), index of informant consensus (Fic) and use value (UV), were calculated to analyze the level of representativeness and relative importance of plants used in herbal teas. One hundred and twenty-nine species belonging to 75 families and 113 genera were reported to be used in herbal tea, with Compositae being the richest family. Whole plants are most commonly used to make herbal teas (66.7%). In this study, informants reported that 92.2% of plant species used in herbal teas are wild. The most utilized herbal preparation form is dry/fresh. Informants reported that herbal teas are used to treat 31 ailments. Our results show that the highest representativeness, based on CS and FC, was recorded for species Actinidia eriantha. Based on UV, the top five most used species are Goodyera schlechtendaliana, Plantago asiatica, Prunella vulgaris, Lophatherum gracile and Leonurus japonicus. The highest Fic was cited for dental medicine. This study helps document the status of current herbal teas in Qingtian. The use value and traditional knowledge of herbal teas have provided basic data for further research focused on bioactivity studies and sustainable utilization of the most important species.

Enhancing the targeting ability of nanoparticles via protected copolymers.

It is important to maintain the balance between therapeutic efficiency and cytotoxicity when using nanomaterials for biomedical applications. Here, we propose a new method (i.e., non-covalent coating of protected copolymers onto the nanoparticle surface) to enhance the active targeting of nanoparticles to the cancer cells by combining the dissipative particle dynamics simulation and in vitro experiments. When coating the protected copolymer onto the nanoparticle surface, the uptake efficiency could be greatly altered due to the competition between the copolymer-ligand interaction and the receptor-ligand interaction-the non-covalent coating is more efficient than the covalent coating. Furthermore, the effect of the physicochemical properties of the protected copolymer on the targeting ability of nanoparticles was also investigated. This study offers useful insight into the optimal design of nanocarriers in biomedicine.

Liposome-based co-delivery of siRNA and docetaxel for the synergistic treatment of lung cancer.

Combination of more than one therapeutic strategy is the standard treatment in clinics. Co-delivery of chemotherapeutic drug and small interfering RNA (siRNA) within a nanoparticulate system will suppress the tumor growth. In the present study, docetaxel (DTX) and BCL-2 siRNA was incorporated in a PEGylated liposome to systemically deliver in a lung cancer model (A549). The resulting nanoparticle (lipo-DTX/siRNA) was stable and exhibited a sustained release profile. The co-delivery of therapeutic moieties inhibited the cell proliferation (A549 and H226) in a time-dependent manner. Moreover, the co-delivery system of DTX and siRNA exhibited a remarkable apoptosis of cancer cells with elevated levels of caspase 3/7 activity (apoptosis markers). Cell cycle analysis further showed remarkable increase in sub-G0/G1 phase, indicating increasing hypodiploids or apoptotic cells. Pharmacokinetic study showed a long circulating profile for DTX from lipo-DTX/siRNA system facilitating the passive tumor targeting. In vivo antitumor study on A549 cell bearing xenograft tumor model exhibited a remarkable tumor regression profile for lipo-DTX/siRNA with 100% survival rate. The favorable tumor inhibition response was attributed to the synergistic effect of DTX potency and MDR reversing ability of BCL-2 siRNA in the tumor mass. Overall, experimental results suggest that co-delivery of DTX and siRNA could be promising approach in the treatment of lung cancers.