Search

Glandular trichomes (GTs) are one of the epidermal tissues of medicinal plants which function in the synthesis, storage, and secretion of secondary metabolites. The active ingredients of Chinese medicinal materials are mostly secondary metabolites of plants. Accordingly, it is of great research value to explore the quality of medicinal materials using the GTs of medicinal plants as the starting point. However, most of the current studies on GTs of medicinal plants are still at the simple morphological identification stage, and there are few studies on the compounds secreted by GTs and secondary metabolic processes. Here, we reviewed the literature, summarized the morphological types of medicinal plant GTs, separation and purification technology, analysis technology, and biological activities of secondary metabolites, and established a research approach to medicinal plant GTs. We hope to provide a reference for future research on GT inclusions and secondary metabolism. [ABSTRACT FROM AUTHOR]

Glandular trichomes (GTs) are one of the epidermal tissues of medicinal plants which function in the synthesis, storage, and secretion of secondary metabolites. The active ingredients of Chinese medicinal materials are mostly secondary metabolites of plants. Accordingly, it is of great research value to explore the quality of medicinal materials using the GTs of medicinal plants as the starting point. However, most of the current studies on GTs of medicinal plants are still at the simple morphological identification stage, and there are few studies on the compounds secreted by GTs and secondary metabolic processes. Here, we reviewed the literature, summarized the morphological types of medicinal plant GTs, separation and purification technology, analysis technology, and biological activities of secondary metabolites, and established a research approach to medicinal plant GTs. We hope to provide a reference for future research on GT inclusions and secondary metabolism. [ABSTRACT FROM AUTHOR]

Secondary soil salinization causes plant stress, which can be relieved by different ratios of red to far-red light (R:FR). Our study aimed to elucidate the role of low R:FR ratios treatments on photosynthesis and growth of tomato seedlings in salinized soils. Tomato seedlings were treated under three R:FR ratios and calcium nitrate was applied simultaneously. The results showed that the treatments under low R:FR ratios stimulated growth parameters of tomato seedlings under calcium nitrate stress, the best impact being achieved at the R:FR ratio of 0.7 in this experiment. Low R:FR ratios treatments increased proline content as well as PSII maximum efficiency, actual electron transport operating efficiency, and photochemical quenching of tomato seedlings under calcium nitrate stress but decreased the value of nonphotochemical quenching. Moreover, low R:FR ratios treatments promoted net photosynthetic rate and increased the expression of a Rubisco gene. In conclusion, low R:FR ratios treatments could improve the salt resistance of greenhouse tomato plants. [ABSTRACT FROM AUTHOR]

Superoxide dismutase (SOD) is a crucial reactive oxygen species (ROS) scavenger, which converts superoxide radical to H2O2, so it is thought to enhance abiotic stress tolerance by reducing ROS and thus avoiding oxidative damage. In this study, we isolated a salt- and oxidative stress-responsive copper-zinc (Cu/Zn) SOD encoding gene TaSOD5 from wheat. The ectopic overexpression of TaSOD5 in Arabidopsis thaliana increased total SOD and Cu/Zn SOD activities and enhanced tolerance to salt stress. Arabidopsis ectopically expressing TaSOD5 possessed a superior resistance to oxidative stress stimulated by exogenous H2O2. Ectopic overexpression of TaSOD5 elevated the activities of both ROS scavengers and an O2 ·-producer - NADPH oxidase. These findings show that Cu/Zn SOD enhanced salt tolerance via regulating the machinery of redox homeostasis rather than improving SOD activity alone. [ABSTRACT FROM AUTHOR]

The present study investigated the effects of ultrasonic seed treatment and Cu application on grain yield, photosynthesis, grain quality, and Cu contents of aromatic rice. The ultrasonic treated and nontreated seeds of two aromatic rice cultivars, i.e., Nongxiang 18 and Meixiangzhan 2, were sown in Cu-contaminated soil with 1.5 and 3.0 g(Cu) m-2 whereas the soil without Cu application was taken as control (CK). Ultrasonic seed treatment and Cu application increased grain yield by 2.7-33.5% in Nongxiang 18 and by 12.9-20.2% in Meixiangzhan 2 owing to substantial improvements in morphophysiological and yield-related traits. Both ultrasonic seed treatment and Cu application also improved the 2-acetyl- 1-pyrroline contents as a result of increased proline contents and proline dehydrogenase activity. The Cu contents in plant parts were higher in Cu-containing soil than that of CK. Overall, ultrasonic seed treatment and optimum Cu application improved aromatic rice grain yield, dry biomass, aroma, and grain quality of aromatic rice. [ABSTRACT FROM AUTHOR]

Inferior tillers contribute negligibly to rice grain yields as their late occurrence or prematurity curtails growth. However, 6-benzylaminopurine (6-BA, a synthetic cytokinin) can delay tiller senescence. Our results indicate that foliar application of 6-BA enhanced the distribution and allocation of light energy for the photochemical reactions of PSII, under appropriate N supply. The percentage of thermal energy dissipation also decreased following the application of 6-BA as a consequence of the reduced risk of chloroplast oxidative damage through excess excitations. Moreover, leaf peroxidase, catalase, and ascorbate peroxidase activities were augmented by adding 6-BA, which significantly inhibited the accumulation of malondialdehyde and H2O2. The application of 6-BA increased the grain numbers of the inferior tillers and further enhanced tiller yields under 82.5 and 165 kg(N) ha-1 supply. The effect of 6-BA was negligible for the untreated or excessive N-treated plants. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H2S) is regarded as gaseous signaling molecule in plant response to various biotic and abiotic stresses. In this study, we investigated potential role of H2S in modulating photosynthesis in low light (LL) stress-induced tall fescue (Festuca arundinacea Schreb.) seedlings. Results demonstrated that LL significantly reduced the plant height, leaf width, tiller number, dry mass, turf quality, chlorophyll content, net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, transpiration rate, maximal quantum yield of PSII photochemistry, photochemical efficiency of PSII, photochemical quenching, electron transport rate, and enzymatic activity of ribulose-1,5-bisphosphate carboxylase. Then, these parameters were found to be considerably alleviated by H2S donor application. Moreover, exogenous application of NaHS decreased the concentration of malondialdehyde, increased activities of peroxidase, superoxide dismutase, ascorbate peroxidase, total soluble sugar, soluble protein, and endogenous concentration of H2S. In addition, these responses could be reversed by treatment with hypotaurine (H2S scavenger) and aminooxy acetic acid (H2S biosynthesis inhibitor). These results suggested that H2S was possibly involved in the regulation of photosynthesis to strengthen LL tolerance by maintaining a high level of photochemical efficiency and improving antioxidant enzyme activities in tall fescue. [ABSTRACT FROM AUTHOR]

The NAC (NAM, ATAF1/2, and CUC2) transcription factor family participates in responses to various kinds of environmental stimuli in plants. However, the roles of NAC protein in cold resistance, especially in the cold resistance of tomatoes, are not completely understood. This study examined the roles of a tomato (Solanum lycopersicum) NAC transcription factor (SlNAC35) in resisting chilling using transgenic tomatoes. GUS staining and expression analysis revealed that SlNAC35 expression was induced at 4 °C, thereby suggesting its involvement in plant responses to chilling stress. Moreover, transgenic lines over-expressing SlNAC35 exhibited high chlorophyll content, fresh mass, and low accumulation of reactive oxygen species and membrane damage under chilling stress. These results indicated that SlNAC35 overexpression enhanced the chilling tolerance of transgenic tomatoes. High expressions of cold tolerance markers SlCOR518 and SlCOR413IM1 were observed under chilling stress in transgenic lines. This observation suggested that SlNAC35 overexpression enhanced the chilling tolerance of transgenic lines by involving the c-repeat binding factor-cold stress response (CBF-COR) signaling pathway and by regulating SlCOR expression. [ABSTRACT FROM AUTHOR]

About 70 % of the total land area in the world are affected by soil freeze and thaw (FT) cycles. Root is the first organ of plant to sense soil environment and it is unclear how it copes with the soil FT. Based on the different functions of firstorder pioneer and fibrous roots in woody plants, we hypothesize that pioneer and fibrous roots respond differently. The experiment was conducted in a growth chamber using Picea asperata seedlings. We designed the FT based on field observation data. The physiological responses in fibrous and pioneer roots were examined. Fibrous roots had higher root vitality and N content, whereas pioneer roots exhibited higher total nonstructural saccharide content. The accumulation of O under FT treatment was similar in the two types of roots. Pioneer roots showed higher osmolyte (especially proline) content, whereas fibrous roots had higher peroxidase activity. The present study confirmed that fibrous roots have stronger metabolism ability, whereas pioneer roots are the key storage organs. FT in the temperature range from -5 to 5 °C are mild and do not cause serious injury to roots. Pioneer roots have higher tolerance to soil FT in spring than fibrous roots. The roots have different strategies to FT: fibrous roots increase the antioxidant system, whereas pioneer roots accumulate more osmolytes. Such knowledge can help us to understand how roots of woody plants cope with soil FT. [ABSTRACT FROM AUTHOR]

Homogeneous low phosphorus availability was reported to regulate root architecture in Arabidopsis via auxin, but the roles of auxin in root architecture plasticity to heterogeneous P availability remain unclear. In this study, we employed auxin biosynthesis-, transport- and signalling-related mutants. Firstly, we found that in contrast to low P (LP) content in the whole medium, primary root (PR) growth of Arabidopsis was partially rescued in the medium divided into two parts: upper with LP and lower with high P (HP) content or in the reverse arrangement. The down part LP was more effective to arrest PR growth as well as to decrease density of lateral roots (DLR) than the upper LP, and effects were dependent on polar auxin transport. Secondly, we verified that auxin receptor TIR1 was involved in the responses of PR growth and lateral root (LR) development to P supply and loss of function of TIR1 inhibited LR development. Thirdly, effects of heterogeneous P on LRD in the upper part of PR was dependent on PIN2 and PIN4, and in the down part on PIN3 and PIN4, whereas density of total LRs was dependent on auxin transporters PIN2 and PIN7. Finally, heterogeneous P availability altered the accumulation of auxin in PR tip and the expression of auxin biosynthesisrelated genes TAA1, YUC1, YUC2, and YUC4. Taken together, we provided evidences for the involvement of auxin in root architecture plasticity in response to heterogeneous phosphorus availability in Arabidopsis. [ABSTRACT FROM AUTHOR]