查看更多>>摘要：In this study, we focused on the plant-growth-promoting properties of two strains isolated from Codonopsis pilosula, and the effect of inoculation with different strain treatments on physiological and metabolite accumulation of C. pilosula. The strains RHBA19 and RHBA17 were isolated and identified as Geobacillu sp. and Pseudomonas fluorescens, respectively. The two strains produced indole acetic acid (IAA), siderophore, biofilm, and various exoenzymes. Based on the pot experiments, inoculation of RHBA19 (G group) and the two mixed bacteria (M group) significantly improved the growth, root development, and photosynthesis of C. pilosula. Compared with the no-inoculation group (CK), the total polysaccharide content of root in the G and M groups was dramatically enhanced by 59.27% and 96.07%, and the lobetyolin (root) improved by 58.4% and 66.0%, respectively. After inoculation with bacteria agents, the activities of antioxidant enzymes (CAT, POD, SOD) of C. pilosula increased differentially. Inoculation with two types of bacterial agents significantly increased the activities of sucrose synthase (SS) and sucrose phosphate synthase (SPS) in root, and phenylalanine ammonia lyase (PAL) in leaf of C. pilosula. In addition, the content of signaling molecules (NO and H2O2) in three types of tissue increased significantly. The magnitude of these results was higher with mixtures than with individual strains. These results imply that the two types of bacterial agents induce physiological metabolism changes to accumulate polysaccharides and lobetyolin by regulating stress resistance enzymes and signal molecules, especially NO and H2O2.
查看更多>>摘要：Phalaris arundinacea, with its characteristics of rapid growth and high biological yield, is regarded as an excellent forage grass in the Qinghai-Tibetan Plateau region of China. To explore the physiological and molecular response mechanism of Phalaris arundinacea under salt stress, we monitored the biomass and physiological indexes of two locally grown strains under conditions of exposure to 150 and 300 mM NaCl solution. Z0611 exhibited better salt stress tolerance than YS. Transcriptome sequencing analysis showed that YS and Z0611 had 1713 and 4290 differentially expressed genes (DEGs), respectively, including on metabolic processes, single-organism process, catalytic activity, and plant hormone signal transduction in the GO and KEGG databases. We also identified a large number of genes involved in hormone signaling, antioxidant systems, ion homeostasis, and photosynthetic systems. Our study provides physiological and molecular insight for establishing a salt resistance database and mining salt tolerance genes in Phalaris arundinacea, and also provides theoretical guidance for the restoration of saline-alkali land on the Qinghai-Tibet Plateau.
查看更多>>摘要：Psoralea corylifolia L. is a popular herb and has long been used in traditional Ayurvedic and Chinese medicine owing to its extensive pharmacological activities, especially in the treatment of various shin diseases. To date, the systematic evaluation and selection of the optimum reference genes for gene expression analysis of P. corylifolia were not reported. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) is a method for gene expression quantification. Selecting appropriate reference genes is the prerequisite for accurate normalization of RT-qPCR results. This study assessed the expression stability of 10 candidate reference genes under different abiotic stresses. First, amplification primers for RT-qPCR were designed and received testing and optimization. Then, expression data from each candidate gene were evaluated based on three statistical algorithms, and their results were further integrated into a comprehensive ranking based on the geometric mean. Additionally, one target gene, i.e., 1-aminocyclopropane-1-carboxylate oxidase (ACO), was used to validate the effectiveness of the selected reference. Our analysis suggested that thioredoxin-like protein YLS8 (YLS8), TIP41-like family protein (TIP41), and cyclophilin 2 (CYP2) genes provided superior expression normalization under different abiotic stresses. Overall, this work constitutes the first effort to select optimal endogenous controls for RT-qPCR studies of gene expression in P. corylifolia. It also provides a reasonable normalization standard and basis for further analysis of the gene expression of bioactive components in P. corylifolia.
查看更多>>摘要：Pectin, cellulose, and hemicelluloses are major components of primary cell walls in plants. In addition to cell adhesion and expansion, pectin plays a central role in seed mucilage. Seed mucilage contains abundant pectic rhamnogalacturonan-I (RG-I) and lower amounts of homogalacturonan (HG), cellulose, and hemicelluloses. Previously, accumulated evidence has addressed the role of pectin RG-I in mucilage production and adherence. However, less is known about the function of pectin HG in seed coat mucilage formation. In this study, we analyzed a novel mutant, designated things fall apart2 (tfa2), which contains a mutation in HG methyltransferase QUASIMODO2 (QUA2). Etiolated tfa2 seedlings display short hypocotyls and adhesion defects similar to qua2 and tumorous shoot development2 (tsd2) alleles, and show seed mucilage defects. The diminished uronic acid content and methylesterification degree of HG in mutant seed mucilage indicate the role of HG in the formation of seed mucilage. Cellulosic rays in mutant mucilage are collapsed. The epidermal cells of seed coat in tfa2 and tsd2 display deformed columellae and reduced radial wall thickness. Under polyethylene glycol treatment, seeds from these three mutant alleles exhibit reduced germination rates. Together, these data emphasize the requirement of pectic HG biosynthesis for the synthesis of seed mucilage, and the functions of different pectin domains together with cellulose in regulating its formation, expansion, and release.
查看更多>>摘要：Methyl jasmonate (MeJA) is an airborne hormonal elicitor that induces a fast rise of emissions of characteristic stress marker compounds methanol and green leaf volatiles (GLV), and a longer-term release of volatile terpe-noids, but there is limited information of how terpene emissions respond to MeJA in terpene-storing species. East -Indian lemongrass (Cymbopogon flexuosus), an aromatic herb with a large terpenoid storage pool in idio-blasts, was used to investigate the short-(0-1 h) and long-term (1-16 h) responses of leaf net assimilation rate (A), stomatal conductance (Gs) and volatile emissions to MeJA concentrations ranging from moderate to lethal. Both A and Gs were increasingly inhibited with increasing MeJA concentration in both short and long term. MeJA exposure resulted in a rapid elicitation, within 1 h after exposure, of methanol and GLV emissions. Subsequently, a secondary rise of GLV emissions was observed, peaking at 2 h after MeJA exposure for the highest and at 8 h for the lowest application concentration. The total amount and maximum emission rate of methanol and the first and second GLV emission bursts were positively correlated with MeJA concentration. Unexpectedly, no de novo elicitation of terpene emissions was observed through the experiment. Although high MeJA application con-centrations led to visible lesions and desiccation in extensive leaf regions, this did not result in breakage of terpene-storing idioblasts. The study highlights an overall insensitivity of lemongrass to MeJA and indicates that differently from mechanical wounding, MeJA-driven cellular death does not break terpene-storing cells. Further studies are needed to characterize the sensitivity of induced defense responses in species with strongly developed constitutive defenses.
NSTL
Elsevier