查看更多>>摘要：Dioscorea zingiberensis is a valuable medicinal herb rich in steroidal saponins。 To reveal the role of jasmonic acid (JA) on physiology and steroidal saponins accumulation， D。 zingiberensis were treated with different concen-trations of JA。 The antioxidant capacity， photosynthetic parameters， fatty acids and metabolites related to ste-roidal saponins biosynthesis (phytosterols， diosgenin and steroidal saponins) were examined under JA treatment。 The results demonstrated that JA treatment caused a great reduction in MDA， stomatal width， photosynthetic rate and photosynthetic pigment， induced a considerable increase in proline， soluble sugar， soluble protein and antioxidant enzymes (CAT， POD and SOD)， and leaded to a significant up-regulation in the expression of genes related to antioxidant system and chlorophyll degradation。 Specialized metabolites displayed various changes under different concentrations of JA。 The majority of fatty acids exhibited negative responses to JA treatment in leaf and rhizome。 In leaf， JA treatment enhanced the accumulation of phytosterols and diosgenin， but decreased the accumulation of steroidal saponins。 However， steroidal saponins were mainly accumulated in rhizome and were highly increased by JA treatment。 Redundancy analysis illustrated that fatty acids were strongly associated with metabolites related to steroidal saponins。 Among all fatty acids， C16:0， C18:1， C18:3， C22:0 and C24:0 contributed most to the variation in metabolites related to steroidal saponin biosynthesis。 Overall， JA treatment leaded to an increase in steroidal saponins， but an inhibition of plant growth。 Thus， the negative effects of JA application on plant physiology should be carefully assessed before being utilized to increase the production of steroidal saponins in D。 zingiberensis。
查看更多>>摘要：Apple (Malus domestica Borkh。) is not only an important fruit crop distributed worldwide， but also a common model plant。 However， the lack of efficient genetic transformation procedures for apples limits the in-depth studies of their gene functions。 Although leaf-regenerated adventitious shoots (LRAS) are a prerequisite for successful genetic transformation of apple， little is known about the underlying molecular mechanism of LRAS。 Here， we identified the WUSCHEL-related homeobox (WOX) transcription factor in apple， MdWOX4-2， which was a transcriptional activator。 Gene expression as well as morphological and histological observations revealed that MdWOX4-2 is involved in the development of LRAS。 Overexpression of MdWOX4-2 conferred higher regenerative capacity in transgenic tobacco (Nicotiana tabacum) as compared to the wild type (WT)。 The com-bined results of the yeast one-hybrid (Y1H)， electrophoretic mobility shift assay (EMSA)， dual luciferase assays， and transient transactivation assay， revealed that MdWOX4-2 directly bound to and activated the MdLBD41 promoter。 Moreover， transgenic experiments further demonstrated that MdLBD41 could significantly enhance the formation of adventitious shoot in transgenic tobacco。 Collectively， our findings demonstrate that MdWOX4-2 is important for regulating the LRAS development by activating MdLBD41。
查看更多>>摘要：We conducted pot experiments during the 2018-2020 growing seasons to study the effects of night warming at different growth stages of wheat on the photosynthetic performance; accumulation， transportation， and distribution of dry matter; and grain yield of winter wheat。 Night warming at all the different growth stages resulted in an elevation of wheat yield by increasing the 1000-grain weight and the number of grains per ear。 Night warming during the period from jointing to booting stage resulted in the greatest increase in wheat yield。 It also increased the amount of overall dry matter and transferrable amount of dry matter in plants and increased the distribution of dry matter to grains to increase grain weight。 Night warming treatments at three different growth stages enhanced pre-anthesis photosynthetic capacity by increasing flag leaf net photosynthetic rate， chlorophyll content， and photochemical efficiency of winter wheat at the early stage of grain filling， especially in the night warming treatment from jointing to booting stage。 Night warming not only increased the stomatal density and stomatal index of wheat leaves but also increased stomatal conductance and transpiration rate in the early stage of grain filling， thus being conducive to the smooth progress of photosynthesis。 In conclusion， night warming treatment at different growth stages increased the photosynthesis of flag leaves at the early stage of grain filling， and promoted the accumulation of dry matter in plants after anthesis， which was conducive to the grain yield of winter wheat。
查看更多>>摘要：Exploring novel growth regulators for premature senescence regulation is important for tobacco production。 In the present study， chlorine dioxide (ClO2) was explored as a novel plant growth regulator for tobacco growth， particularly its effect on leaf senescence and root development。 The results showed that 0。15 mu M ClO2 maintained the lushness of detached leaves and whole plants。 Also， the leaves of ClO2-treated plants exhibited a chlorophyll content of 58% higher than in CK (control) plants (P < 0。05)。 Besides， ClO2 treatment increased the biomass of roots and aboveground parts by 54 and 16%， respectively。 The ClO2-treated plants also showed enhanced activities of antioxidant enzymes and significantly reduced malondialdehyde contents (P < 0。05)。 Moreover， ClO2 treatment remarkably alleviated drought-caused premature senescence in the tobacco plants and partly rescued the exogenous ethylene-caused plant dwarfism。 The indole-3-acetic acid content in ClO2-treated plants was higher than in non-treated plants (P < 0。05)， but ethylene content was significantly lower (P < 0。05)。 Gene expression analysis showed that ClO2 treatment remarkably suppressed ethylene synthase genes。 However， the auxin biosynthesis and transport genes were up-regulated， with NtIAA17 increasing by five folds (P < 0。05)。 Further， ClO2 remarkably up-regulated the expression of chlorophyll biosynthesis genes， with a >20-fold increase in NtHEMA1 and NtCHLH expressions。 These results designate ClO2 as a potential regulator for improving tobacco productivity by retaining higher chlorophyll content and promoting root growth。
Che, YanhuiYao, TongtongWang, ZihanZhang, Hongbo...
12页
查看更多>>摘要：Although improvement of plant salt tolerance by potassium ions (K+) has been widely studied， whether the tolerance is mediated via hormone signaling or antioxidant systems remains to be explored。 This study combined plant physiology with transcriptomic techniques to study how K+ interacts with hormones and antioxidant enzymes to improve plant salt tolerance。 Tobacco was used as the test material to study the effects of exogenous potassium application on photosynthetic function， hormone signal transduction， and reactive oxygen species (ROS) production under NaCl stress。 The study also evaluated the function of the Ca2+ signaling pathway in salt stress tolerance。 Transcriptome data showed that 4413 up-regulated genes and 3743 down-regulated genes were found in tobacco leaves treated with NaCl compared with the control。 Compared with NaCl， the down-regulated genes in tobacco leaves were significantly reduced under NaCl + KCL treatment。 The results showed that NaCl stress caused oxidative damage to tobacco leaves due to increased superoxide anion (O-2(-)) content， superoxide dismutase (SOD) dismutates superoxide anion to produce hydrogen peroxide and the accumulation of H2O2 caused by reduced ascorbate peroxidase (APX) and peroxidase (POD) activities。 NaCl stress also increased abscisic acid (ABA) content in tobacco leaves， resulting in stomatal closure and reduced photosynthetic capacity。 Transcriptome data showed that 5 SOD， 1 POD， 1 CAT， 5 APX， and 3 GPX genes were significantly down -regulated by the NaCl treatment。 Contrarily， NaCl + KCl treatment reduced the accumulation of O-2(-) and SOD activity but increased POD activity， thereby reducing the accumulation of H2O2 and alleviating oxidative damage。 The expression of 2 SOD and 3 APX and 2 GPX genes was significantly higher in NaCl + KCl treatment than that in NaCl treatment。 Sufficient K+ also increased indole acetic acid (IAA) levels in tobacco leaves under NaCl stress but reduced ABA content， promoting stomatal opening and improving the photosynthetic capacity。 In conclusion， K+ can improve plant salt tolerance by alleviating oxidative damage and regulating hormone signal transduction。
Ahmad, SalmanSathish, MandaOkla, Mohammad K.Al-Amri, Saud S....
12页
查看更多>>摘要：Soil secondary salinization is a serious menace that has significant influence on the sustainability of agriculture and threatens food security around the world。 Zinc (Zn) as an essential plant nutrient associated with many physio-biochemical processes in plants and improve resistance against various abiotic stresses。 The role of Zn in acclimation of Solanum lycopersicum L。 challenged with salt stress is miserly understood。 A hydroponic study was performed with two tomato varieties (Riogrande and Sungold) exposed to the salinity stress (0 mM and 160 mM NaCl) under two Zn concentrations (15 mu M and 30 mu M ZnSO4)。 The results revealed that salt stress exerted strongly negative impacts on root and shoot length， fresh and dry biomass， plant water relations， membrane stability， chlorophyll contents， Na+/K+ ratio along with inferior gas exchange attributes and activities of anti-oxidant enzymes。 Moreover， Riogrande was found to be more resistant to salinity stress than Sungold。 However， Zn supply significantly alleviated the hazardous effects of salinity by altering compatible solutes accumulation， photosynthetic activity， water relation， soluble sugar contents and providing antioxidant defense against salt stress。 The salinity + Zn2 treatment more obviously enhanced RWC (19。0%)， MSI (30。8%)， SPAD value (17。8%)， and activities of SOD (31。7%)， POD (28。5%)， APX (64。5%) and CAT (23。3%) in Riogrande than Sungold， compared with the corresponding salinity treatment alone。 In addition， salinity + Zn2 treatment significantly (P > 0。05) ameliorated salinity stress due to the depreciation in Na+/K+ ratio by 63。3% and 40。8%， Na+ ion relocation from root to shoot by 10。4% and 6。4%， and thereby significantly reduced Na+ ion accumulation by 47。4% and 16。3% in the leaves of Riogrande and Sungold respectively， compared to the salinity treatment alone。 Therefore， it was obvious that 30 mu M Zn concentration was more effective to induce resistance against salinity stress than 15 mu M Zn concentration。 Conclusively， it can be reported that exogenous Zn application helps tomato plant to combat adverse saline conditions by modulating photosynthetic and antioxidant capacity along with reduced Na+ uptake at the root surface of tomato plant。
Oberschelp, Gustavo Pedro JavierMorales, Luisina LourdesMontecchiarini, Marina LuciaHarrand, Leonel...
12页
查看更多>>摘要：Eucalypts are the most planted hardwood trees worldwide because of their very rapid growth， exceptional wood quality and adaptability。 However， most commercial species and derived hybrids are sensitive to frost， which remains as the largest obstacle to their introduction in warm/temperate climates。 As evergreen species， Eucalypts have developed the ability to tolerate frost events based on physiological and molecular responses triggered by previous exposure to cold temperatures， globally named cold acclimation。 To characterize the acclimation process in two species with different tolerance to frost， E。 grandis (Eg) and E。 benthamii (Eb)， seedlings were exposed for different times to low temperatures。 Frost tolerance was estimated in leaves by an electrolyte leakage assay， and metabolome and morpho-physiological changes studied and correlated to the observed acclimation responses。 Eb showed higher basal frost tolerance and an earlier and stronger acclimation response to cold temperatures than in the frost sensitive Eg。 Eb was able to modify several morpho-physiological parameters， with a restriction in plant height， leaf area and leaf fresh weight during acclimation。 Metabolome characterization allowed us to differentiate species and strengthen our understanding of their acclimation response dynamics。 Interestingly， Eb displayed an early phase of sugar accumulation followed by a rise of different metabolites with possible roles as osmolytes and antioxidants， that correlated to frost tolerance and may explain Eb higher capacity to acclimate。 This novel approach has helped us to point to the main metabolic processes underlying the cold tolerance acquisition process in two relevant Eucalyptus species。
查看更多>>摘要：Drought stress commonly happens more than once during the life cycle of perennial trees。 Stress memory endows better capacity to cope with repeated stresses for plants， while the underlying mechanisms are not fully eluci-dated。 In this study， 2-month-old saplings of two mulberry cultivars (Husang32 and 7307 of Morus multicaulis) with or without an early soil water deficit were subjected to subsequent drought for 9 days。 The shoot height growth， biomass production， stable carbon isotope discrimination， phytohormones， reactive oxygen species (ROS)， osmotic substances and antioxidant enzymes were analyzed after the first and the second drought， respectively。 Drought priming saplings sustained comparable or slightly higher biomass accumulation under the second drought than those non-priming。 They also exhibited decreased levels of soluble sugars， free proline and soluble proteins， lower accumulation of malonaldehyde (MDA) and superoxide anion (O-2(center dot-))， reduced activities of superoxide dismutase (SOD) and peroxidase (POD) compared to non-priming plants。 Moreover， cultivar Husang32 exhibited elevated abscisic acid (ABA) and jasmonic acid (JA) where 7307 displayed opposite changes。 PCA suggests that MDA， H2O2， free proline， SOD and POD in roots， and ROS， soluble sugars and glutamate reductase in leaves are dominant factors influenced by stress memory。 ABA and JA in leaves also play important roles in exerting drought imprints。 Collectively， stress memory can confer mulberry resistance to recurrent drought via combined regulations of antioxidative protection， osmotic adjustment and phytohormonal responses。
查看更多>>摘要：Lignin is a complex phenolic compound that can enhance the stiffness， hydrophobicity， and antioxidant capacity of the cell wall; it thus provides a critical barrier against pathogen and insect invaders。 Caffeoyl shikimate esterase (CSE) is a key novel enzyme involved in lignin biosynthesis that is associated with genetic improvements in lignocellulosic biomass; however， no research thus far have revealed the role of CSE in resistance to patho-genic stress。 CsCSE1 (Cucsa。134370) has previously been shown to highly associated with the response of cu-cumber to attack by Podosphaera xanthii through RNA sequencing。 Here， we detected the exactly role of CsCSE1 in the defence of cucumber to P。 xanthii infection。 Homologous sequence alignment revealed that CsCSE1 con-tains two highly conserved lyase domains (GXSXG)， suggesting that CsCSE1 possesses CSE activity。 Subcellular localization analysis manifested that CsCSE1 was localized to the plasma membrane and endoplasmic reticulum (ER)。 Functional analysis demonstrated that the transient silencing of CsCSE1 in cucumber dramatically atten-uated resistance to P。 xanthii， whereas overexpression of CsCSE1 in cucumber markedly increased resistance to P。 xanthii。 Further investigation of the abundance of lignin in transient transgenic plants revealed that CsCSE1 might actively mediate the disease resistance of cucumber by promoting lignin biosynthesis。 CsCSE1 also affects the expression of its downstream lignin biosynthesis-related genes， like CsLAC， CsCOMT， CsCCR， and CsCAD。 The results of this study provide targets for the genetic breeding of tolerant cucumber cultivars as well as new insights that could aid the control of plant diseases。
查看更多>>摘要：Given the increasing interest that is being paid to polysaccharides derived from algae as plant natural defense stimulators， the degree of sulfation of exopolysaccharides produced by P。 sordidum for inducing defense re-sponses in date palm vitroplants was investigated。 Firstly， the culture parameters of P。 sordidum were optimized to maximize the amount of sulfate in EPS using a Box-Behnken experimental design and the elicitor effects of two EPS which differ in the sulfation degrees were compared。 Results demonstrated that the concentrations of NaCl， NaNO3 and MgSO4 set at 28， 0。54 and 16。31 g/L， respectively yielded the best sulfate contents。 To elucidate defense-inducing activities in date palm vitroplants， EPS with the highest sulfate content (EPS1) were prepared for comparison with those obtained under standard conditions (EPS0)。 A fucoidan extracted from Cystoseira compressa was used as positive control and MgSO4 as negative control。 Both EPS and the fucoidan displayed H2O2 accumulation and expression of PR1， SOD， PAL and WRKY genes。 Interestingly， EPS1 was significantly more bioactive than EPS0 and the fucoidan suggesting that the elicitor activity is positively correlated with the sulfate groups content of this polysaccharide。
NSTL
Elsevier