小麦拔节期盐胁迫对小麦近等基因系生理指标的影响

小麦近等基因系H8706,H8706-44,RH8706－48,RH8706－49在拔节期用0.7%NaCl进行盐胁迫,7d后耐盐性强的RH8706－49的SOD活性最高,是耐盐性差的H8706－34的SOD活性的1.875倍;且RH8706－49的MDA含量最低,比H8706－34低44.3%;ＲＨ８７０６－４９的细胞质膜透性也最低,为Ｈ８７０６－３４的５０％。     

Prefoldins 3 and 5 Play an Essential Role in Arabidopsis Tolerance to Salt Stress

During the last years, our understanding of the mechanisms that control plant response to salt stress has been steadily progressing. Pharmacological studies have allowed the suggestion that the cytoskeleton may be involved in regulating such a response. Nevertheless, genetic evidence establishing that the cytoskeleton has a role in plant tolerance to salt stress has not been reported yet. Here, we have characterized Arabidopsis T-DNA mutants for genes encoding proteins orthologous to prefoldin （PFD） subunits 3 and 5 from yeast and mammals. In these organisms, PFD subunits, also known as Genes Involved in Microtubule biogenesis （GIM）, form a heterohexameric PFD complex implicated in tubulin and actin folding. We show that, indeed, PFD3 and PFD5 can substitute for the loss of their yeast orthologs, as they are able to complement yeast gim2Δ and gim5Δ mutants, respectively. Our results indicate that pfd3 and pfd5 mutants have reduced levels of α- and β-tubulin compared to the wild-type plants when growing under both control and salt-stress conditions. In addition, pfd3 and pfd5 mutants display alterations in their developmental patterns and microtubule organization, and, more importantly, are hypersensitive to high concentrations of NaCl but not of LiCl or mannitol. These results demonstrate that the cytoskeleton plays an essential role in plant tolerance to salt stress.     

诱发小麦花药愈伤组织及其再生植株抗盐性变异的研究

不同基因型小麦花药愈伤组织对化学诱变剂的敏感性不同。选用对诱变剂敏感的类型,经EMS(甲基磺酸乙酯)诱变可以产生耐盐变异。实验获得的耐盐变异株, 离开盐胁迫3代后,经盐池鉴定后代中有52.9%的品系达到一级耐盐,表现了一定的遗传稳定性。耐盐品系的结实率也逐渐得到恢复,达到92.4%。利用其高代材料进行耐盐性的遗传分析结果表明,小麦的耐盐性不仅受核基因的控制,也受细胞质因子的影响。经酸性聚丙烯酰胺凝胶电泳分析,发现耐盐突变体特有的Rf值为0.19的醇溶蛋白能稳定遗传。 Abstract:The study discovered that the sensibilities of anther calli in different wheat genetypes to chemical mutagenic agent were different.The mutation-sensitive type might generate salt-tolerant variation after mutagenizing with EMS.The fourth generation of salt-tolerant plants which were planted for three generations in usual soil expressed tolerance stability after planting in the salt pond of a 0.45% salt concentration,52.9% of the lines in the offspring belonged to first grade of salt-tolerance,showing that the salt-tolerant variant had a certain stability.The fertility of salt-tolerant lines was gradually recovered and reached 92.4%.The high generation materials were used for genetic analysis of the salt-tolerance.The results indicated that the wheat salt-tolerant trait is not only controlled by nuclear gene,but also effected by cytoplasmic factor.In addition,A-PAGE(Acid-Polyacrylamide gel electrophoresis)discovered that the salt-resistant mutant had a unique gliadin band with a Rf value of 0.19,and that this unique band was stable inherited.     

Seed Treatment with Auxins Modulates Growth and Ion Partitioning in Salt-stressed Wheat Plants

Experiments were performed to determine whether seed priming with different concentrations （100, 150, and 200 mg/L） of auxins （indoleacetic acid （IAA）, indolebutyric acid （IBA）, or their precursor tryptophane （Trp）） could alter salinity induced perturbances in salicylic acid and ion concentrations and, hence, growth in wheat （Triticum aestivum L.） cultivars, namely M.H.-97 （salt intolerant） and tnqtab-91 （salt tolerant）. Primed and non-primed seeds were sown in Petri dishes in a growth room, as well as in a field treated with 15 dS/m NaCl salinity. All priming agents, except IBA, increased the final germination percentage in both cultivars. The seedlings of either cultivar raised from Trp-treated seeds had greater dry biomass when under salt stress. In field experiments, Trp priming was much more effective in mediating the increase in grain yield, irrespective of the cultivar, under salt stress. The alleviatory effect of Trp was found to be associated with reduced uptake of Na^＋ in the roots and subsequent translocation to the shoots, as well as increased partitioning of Ca^＋ in the roots of salt-stressed wheat plants. Plants of both cultivars raised from Trp-and IAA-treated seeds accumulated free salicylic acid in their leaves when under salt stress. Overall, the Trp priming-induced improvement in germination and the subsequent growth of wheat plants could be related to ion homeostasis when under salt stress. The possible involvement of salicylic acid in the Trp priming-induced better growth under Conditions of salt stress is discussed.     

拟南芥低盐敏感突变体的筛选

通过对ein3-1功能缺失型突变体种子进行EMS诱变,筛选到47株盐敏感突变体。根据对盐敏感程度的不同将其分为3类,分别为低盐超敏感突变体(low concentration of salt hyper-sensitive mutants,lsh),低盐中等敏感突变体(low con-centration of salt moderate-sensitive mutants,lsm)和低盐弱敏感突变体(lowconcentration of salt slight-sensitive mutants,lss)。以其中一株lss-3为例,进行了深入研究。根据遗传分析和生理试验表明,lss-3是以ein3-1为背景的隐性双突变体,而且具有比Col-0和ein3-1更加敏感的盐表型。三重反应表明,lss-3与ein3-1类似,表现出对ACC不敏感的表型。推测lss-3突变的基因可能与乙烯信号途径组分EIN3有关,也可能与之无关,仅是参与抗盐的一个新基因。     

Possible Involvement of Anti-Oxidant Enzymes in the Cross-Tolerance of the Germination/Growth of Wheat Seeds to Salinity and Heat Stress

The germination/growth of wheat （Triticum aestivum L. cv. Zimai 1） seeds and changes in the activities of superoxide dismutase （SOD）, ascorbate peroxidase （APX）, and catalase （CAT）, as well as in the content of thiobarbituric acid-reactive substances （TBARS）, in response to salt and heat stress, as well as cross-stress, were investigated in the present study. With increasing temperature and decreasing water potential caused by NaCI solution, the germination percentage of seeds and the fresh weight of seedlings decreased markedly, SOD activity increased, activities of APX and CAT decreased distinctly, and the TBARS content increased gradually. Seeds pretreated at 33℃ for different times displayed increased tolerance to subsequent salt stress, enhanced SOD, APX, and CAT activities, and decreased TBARS content. Seeds pretreated at -0.8 MPa NaCI for different times displayed increased tolerance to subsequent heat stress and marked increases in SOD, APX, and CAT activities, which were associated with decreased TBARS content. It is considered that the common component in the cross-tolerance of the germination and growth of wheat seeds to salinity and heat stress is the anti-oxidant enzyme system.     

Kinetics of the Anti-oxidant Response to Salinity in the Halophyte Cakile maritima

The effects of NaCl stress on the activity of anti-oxidant enzymes （superoxide dismutase, catalase （CAT）, peroxidase （POD）, ascorbate peroxidase （APX）, monodehydroascorbate reductase, dehydroascorbate reductase （DHAR）, and glutathione reductase （GR））, anti-oxidant molecules （ascorbate and glutathione）, and parameters of oxidative stress （malondialdehyde （MDA）, electrolyte leakage, and H2O2 concentrations） were investigated in Cakile maritima, a halophyte frequent along the Tunisian seashore. Seedlings were grown in the presence of salt （100, 200, and 400 mmol/L NaCl）. Plants were harvested periodically over 20 days. Growth was maximal in the presence of 0-100 mmol/L NaCl. At 400 mmol/L NaCl, growth decreased significantly. The salt tolerance of C. maritima, at moderate salinities, was associated with the lowest values of the parameters indicative of oxidative stress, namely the highest activities of POD, CAT, APX, DHAR, and GR and high tissue content of ascorbate and glutathione. However, prolonged exposure to high salinity resulted in a decrease in anti-oxidant activities and high MDA content, electrolyte leakage, and H2O2 concentrations. These results suggest that anti-oxidant systems participate in the tolerance of C. maritima to moderate salinities.     

Ectopic Expression of a Bacterium NhaD-type Na~+/H~+ Antiporter Leads to Increased Tolerance to Combined Salt/Alkali Stresses

AaNhaD,a gene isolated from the soda lake alkaliphile Alkalimonas amylolytica,encodes a Na+/H+ antiporter crucial for the bacterium’s resistance to salt/alkali stresses.However,it remains unknown whether this type of bacterial gene may be able to increase the tolerance of flowering plants to salt/alkali stresses.To investigate the use of extremophile genetic resources in higher plants,transgenic tobacco BY-2 cells and plants harboring AaNhaD were generated and their stress tolerance was evaluated.Ectopic expression of AaNhaD enhanced the salt tolerance of the transgenic BY-2 cells in a pH-dependent manner.Compared to wild-type controls,the transgenic cells exhibited increased Na+concentrations and pH levels in the vacuoles.Subcellular localization analysis indicated that AaNhaD-GFP fusion proteins were primarily localized in the tonoplasts.Similar to the transgenic BY-2 cells,AaNhaD-overexpressing tobacco plants displayed enhanced stress tolerance when grown in saline-alkali soil.These results indicate that AaNhaD functions as a pH-dependent tonoplast Na+/H+antiporter in plant cells,thus presenting a new avenue for the genetic improvement of salinity/alkalinity tolerance.     

Does Seed Priming Induce Changes in the Levels of Some Endogenous Plant Hormones in Hexaploid Wheat Plants Under Salt Stress？

In order to assess whether salt tolerance could be Improved In spring wheat （Triticum aestivum L.）, the present study was performed by soaking the seeds of two cultlvars, namely MH-97 （salt sensitive） and Inqlab-91 （salt tolerant）, for 12 h In distilled water or 100 mol/m^3 CaCl2, KCI, or NaCI. Primed seeds from each treatment group and non-primed seeds were sown In a field In which NaCI salinity of 15 dS/m was developed. Priming of seeds with CaCl2, followed by priming with KCI and NaCI, was found to be effective In alleviating the adverse effects of salt stress on both wheat cultivars In terms of shoot fresh and dry weights and grain yield. Priming with CaCl2 alleviated the adverse effects of salt stress on hormonal balance In plants of both cultlvars. In MH-97 plants, CaCl2 pretreatment considerably reduced leaf absclslc acid （ABA） concentrations and Increased leaf free salicylic acid （SA） concentrations under both saline and non-saline conditions. In contrast, In the Inqlab-91 plant, CaCl2 Increased free Indoleacetic acid （IAA） and indolebutyrlc acid （IBA） content. However, priming of seeds with CaCl2 did not alter free polyamlne levels in either cultlvar, although spermldlne levels were considerably lower In plants raised from seeds treated with CaCl2 for both cultlvars under saline conditions. Priming with KCI Increased growth In Inqlab-91 plants, but not In MH-97 plants, under saline conditions. The salinity Induced reducUon In auxins （IAA and IBA） was alleviated by NaCI priming In both cultlvars under saline conditions. However, NaCI Increased leaf free ABA content and lowered leaf SA and putresclne levels In Inqlab-91 plants under saline conditions. In conclusion, although all three priming agents （I.e. CaCl2, KCI, and NaCI） were effective In alleviating the adverse effects of salt stress on wheat plants, their effects on altering the levels of different plant hormones were different In the two cuItlvars.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细