Differential Responses of NHX1 and SOS1 Gene Expressions to Salinity in two Miscanthus sinensis Anderss.Accessions with Different Salt Tolerance

The lignocellulosic crop Miscanthus spp.has been identified as a good candidate for biomass production.The responses of Miscanthus sinensis Anderss.to salinity were studied to satisfy the needs for high yields in marginal areas and to avoid competition with food production.The results indicated that the relative advantages of the tolerant accession over the sensitive one under saline conditions were associated with restricted Na^(+)accumulation in shoots.Seedlings of two accessions(salt-tolerant‘JM0119’and salt-sensitive‘JM0099’)were subjected to 0(control),100,200,and 300 mM NaCl stress to better understand the salt-induced biochemical responses of genes involved in Na^(+)accumulation in M.sinensis.The adaptation responses of genes encoding for Na^(+)/H^(+)antiporters,NHX1 and SOS1 to NaCl stress were examined in JM0119 and JM0099.The cDNA sequences of genes examined were highly conserved among the relatives of M.sinensis based on the sequencing on approximate 600 bp-long cDNA fragments obtained from degenerate PCR.These salt-induced variations of gene expression investigated by quantitative real-time PCR provided evidences for insights of the molecular mechanisms of salt tolerance in M.sinensis.The expression of NHX1 was up-regulated by salt stress in JM0119 shoot and root tissues.However,it was hardly affected in JM0099 shoot tissue except for a significant increase at the 100 mM salt treatment,and it was salt-suppressed in the JM0099 root tissue.In the root tissue,the expression of SOS1 was induced by the high salt treatment in JM0119 but repressed by all salt treatments in JM0099.Thus,the remarkably higher expression of NHX1 and SOS1 were associated with the resistance to Na^(+)toxicity by regulation of the Na^(+)influx,efflux,and sequestration under different salt conditions.

Root-associated(rhizosphere and endosphere) microbiomes of the Miscanthus sinensis and their response to the heavy metal contamination

The plant root-associated microbiomes, including both the rhizosphere and the root endosphere microbial community, are considered as a critical extension of the plant genome. Comparing to the well-studied rhizosphere microbiome, the understanding of the root endophytic microbiome is still in its infancy. Miscanthus sinensis is a pioneering plant that could thrive on metal contaminated lands and holds the potential for phytoremediation applications. Characterizing its root-associated microbiome, especially the root endophytic microbiome, could provide pivotal knowledge for phytoremediation of mine tailings. In the current study, M. sinensis residing in two Pb/Zn tailings and one uncontaminated site were collected. The results demonstrated that the metal contaminant fractions exposed strong impacts on the microbial community structures. Their influences on the microbial community, however, gradually decreases from the bulk soil through the rhizosphere soil and finally to the endosphere, which resulting in distinct root endophytic microbial community structures compared to both the bulk and rhizosphere soil. Diverse members affiliated with the order Rhizobiales was identified as the core microbiome residing in the root of M. sinensis. In addition, enrichment of plant-growth promoting functions within the root endosphere were predicted, suggesting the root endophytes may provide critical services to the host plant. The current study provides new insights into taxonomy and potential functions of the root-associated microbiomes of the pioneer plant, M. sinensis, which may facilitate future phytoremediation practices.

Effect of Miscanthus sinensis var.purpurascens Flower Extract on Proliferation and Molecular Regulation in Human Dermal Papilla Cells and Stressed C57BL/6 Mice

Objective： To investigate the hair growth-promoting effect of Miscanthus sinensis var.purpurascens（MSP） flower extracton on in vitro and in vivo models.Methods： MSP flower extract was extracted in 99.9% methanol and applied to examine the proliferation of human dermal papilla cells（h DPCs） in vitro at the dose of 3.92-62.50 μg/m L and hair growth of C57 BL/6 mice in vivo at the dose of 1000 μg/m L.The expression of transforming growth factor β1（TGF-β1）,hepatocyte growth factor（HGF）,β-catenin,substance P was measured by relative quantitative realtime polymerase chain reaction.Histopathological and immunohistochemical analysis were performed.Results： MSP（7.81 μg/m L） down-regulated TGF-β1 and up-regulated HGF and β-catenin in h DPCs（P〈0.01）.MSP（1000 μg/m L）-treated mice showed the earlier transition of hair follicles from the telogen to the anagen phase.The number of mast cells was lower in the MSP-treated mice than in other groups（P〈0.05 vs.NCS group）.Substance P and TGF-β1 were expressed in hair follicles and skin of the MSP group lower than that in negative control.Stem cell factor in hair follicles was up-regulated in the MSP-treated mice（P〈0.01）.Conclusion： The MSP flower extract may have hair growth-promotion activities.

转MINAC2基因芒的获得及其在NaCl胁迫下的表达

芒(Miscanthus sinensis)隶属于多年生高大禾草--芒属(Miscanthus),其生态效应和经济效益备受国内外研究者的关注,是中国广阔边际土地种植与利用的能源植物。为获得芒的转基因株系,同时对MINAC2基因在盐胁迫下的表达特征进行研究,本研究利用农杆菌介导法将MINAC2基因导入芒的基因组,并采用RT-qPCR技术测定了0.6%Na Cl溶液胁迫下转基因株系0、1 h、3 h、9 h、12 h、24 h、48 h的MINAC2相对表达量。获得的主要研究结果如下:(1)经PCR鉴定确定了转MINAC2基因阳性株系;(2)未经NaCl胁迫时转MINAC2基因株系的表达量显著低于对照组,然而在0.6%NaCl处理达到一定时长后转MINAC2基因株系的表达量是显著高于对照组(p<0.05),为对照组的5.93倍。通过本研究,建立了芒的农杆菌转化体系,并对MINAC2基因在芒的耐盐能力提高中所起的作用进行了初步探讨。