Adaptive strategy of Nitraria sibirica to transient salt,alkali and osmotic stresses via the alteration of Na+/K+fluxes around root tips

Nitraria sibirica Pall.is an important shrub with a strong salt-alkali tolerance,but the mechanism underlying this tolerance remains obscure.In this study,N.sibirica,with salt-sensitive Vigna radiata(Linn.)Wilczek as the control,was subjected to transient salt stress(100 mM NaCl),alkali stress(50 mM Na_(2)CO_(3)),and osmotic stress(175 mM mannitol).The ionic fluxes of Na^(+)and K^(+)in the root apical region were measured.Results show that,under salt and alkali stress,N.sibirica roots exhibited higher capacities to limit Na+influx and reduce K+efflux,thereby resulting in lower Na^(+)/K^(+)ratios compared with V.radiata roots.Alkali stress induced stronger Na^(+)influx and K+efflux in the root salt stress treatment;Na^(+)influx was mainly observed in the root cap,while K^(+)efflux was mainly observed in the elongation zone.While under osmotic stress,N.sibirica roots showed stronger Na+efflux and weaker K+efflux than V.radiata roots.Na+efflux was mainly observed in the root elongation zone,while K+efflux was in the root cap.These results reveal the ionic strategy of N.sibirica in response to transient salt,alkali,and osmotic stresses through the regulation of Na+/K+flux homeostasis.

Overexpression of vacuolar proton pump ATPase(V-H^+-ATPase) subunits B, C and H confers tolerance to salt and saline-alkali stresses in transgenic alfalfa(Medicago sativa L.)

The vacuolar proton pump ATPase（V-H^＋-ATPase）, which is a multi-subunit membrane protein complex, plays a major role in the activation of ion and nutrient transport and has been suggested to be involved in several physiological processes, such as cell expansion and salt tolerance. In this study, three genes encoding V-H^＋-ATPase subunits B（Sc VHA-B, Gen Bank： JF826506）, C（Sc VHA-C, Gen Bank： JF826507） and H（Sc VHA-H, Gen Bank： JF826508） were isolated from the halophyte Suaeda corniculata. The transcript levels of Sc VHA-B, Sc VHA-C and Sc VHA-H were increased by salt, drought and saline-alkali treatments. V-H^＋-ATPase activity was also examined under salt, drought and saline-alkali stresses. The results showed that V-H^＋-ATPase activity was correlated with salt, drought and saline-alkali stress. Furthermore, V-H^＋-ATPase subunits B, C and H（Sc VHA-B, Sc VHA-C and Sc VHA-H） from S. corniculata were introduced separately into the alfalfa genome. The transgenic alfalfa was verified by Southern and Northern blot analysis. During salt and saline-alkali stresses, transgenic lines carrying the B, C and H subunits had higher germination rates than the wild type（WT）. More free proline, higher superoxide dismutase（SOD） activity and lower malondialdehyde（MDA） levels were detected in the transgenic plants under salt and saline-alkali treatments. Moreover, the Sc VHA-B transgenic lines showed greater tolerance to salt and saline-alkali stresses than the WT. These results suggest that overexpression of Sc VHA-B, Sc VHA-C and Sc VHA-H improves tolerance to salt and saline-alkali stresses in transgenic alfalfa.

Analysis on Maize EST Database under the Co-stress of Drought,Salt and Alkali

[Objective] The research aimed to construct maize cDNA library under the co-stress of drought,salt and alkali,and initially analyze the expression of gene which related to the cellular function.[Method] The total RNA of mixed tissue（leaf,stem and blossom bud） of maize YQ7-96 in the male and female differentiation period（12-leaf age） was extracted.By using SMART technology,cDNA library of pDNR-LIB vector was constructed.BlastX contrast and MIPS classification analysis of EST sequence were carried out by randomly picking the clone.[Result] 3 027 cDNA clones were picked out to sequence.The length of 94.45% EST was bigger than 400 bp,and 1 861 single gene clusters were obtained.The gene which maintained the normal physiological activity occupied 65.36%.The genes which involved in the intracellular transportation,signal transduction,cell defense and cycle,DNA metabolic process were respectively 9.26%,6.58%,2.63% and 3.16%.[Conclusion] Based on the successful construction of maize cDNA library under the co-stress of drought,salt and alkali,EST was sequenced,analyzed and classified.EST which related to the cellular function was screened.It laid the foundation for the following research.

Synergistic effects of carbon cycle metabolism and photosynthesis in Chinese cabbage under salt stress

Chinese cabbage(Brassica rapa ssp. pekinensis) has a long cultivation history and is one of the vegetable crops with the largest cultivation area in China. However, salt stress severely damages photosynthesis and hormone metabolism, nutritional balances, and results in ion toxicity in plants. To better understand the mechanisms of salt-induced growth inhibition in Chinese cabbage, RNA-seq and physiological index determination were conducted to explore the impacts of salt stress on carbon cycle metabolism and photosynthesis in Chinese cabbage. Here, we found that the number of thylakoids and grana lamellae and the content of starch granules and chlorophyll in the leaves of Chinese cabbage under salt stress showed a time-dependent response, first increasing and then decreasing. Chinese cabbage increased the transcript levels of genes related to the photosynthetic apparatus and carbon metabolism under salt stress, probably in an attempt to alleviate damage to the photosynthetic system and enhance CO_(2) fixation and energy metabolism. The transcription of genes related to starch and sucrose synthesis and degradation were also enhanced;this might have been an attempt to maintain intracellular osmotic pressure by increasing soluble sugar concentrations. Soluble sugars could also be used as potential reactive oxygen species(ROS) scavengers, in concert with peroxidase(POD)enzymes, to eliminate ROS that accumulate during metabolic processes. Our study characterizes the synergistic response network of carbon metabolism and photosynthesis under salt stress.

Genome-Wide Exploration of the Grape GLR Gene Family and Differential Responses of VvGLR3.1 and VvGLR3.2 to Low Temperature and Salt Stress

Grapes,one of the oldest tree species globally,are rich in vitamins.However,environmental conditions such as low temperature and soil salinization significantly affect grape yield and quality.The glutamate receptor(GLR)family,comprising highly conserved ligand-gated ion channels,regulates plant growth and development in response to stress.In this study,11 members of the VvGLR gene family in grapes were identified using whole-genome sequence analysis.Bioinformatic methods were employed to analyze the basic physical and chemical properties,phylogenetic trees,conserved domains,motifs,expression patterns,and evolutionary relationships.Phylogenetic and collinear analyses revealed that the VvGLRs were divided into three subgroups,showing the high conservation of the grape GLR family.These members exhibited 2 glutamate receptor binding regions(GABAb and GluR)and 3-4 transmembrane regions(M1,M2,M3,and M4).Real-time quantitative PCR analysis demonstrated the sensitivity of all VvGLRs to low temperature and salt stress.Subsequent localization studies in Nicotiana tabacum verified that VvGLR3.1 and VvGLR3.2 proteins were located on the cell membrane and cell nucleus.Additionally,yeast transformation experiments confirmed the functionality of VvGLR3.1 and VvGLR3.2 in response to low temperature and salt stress.Thesefindings highlight the significant role of the GLR family,a highly conserved group of ion channels,in enhancing grape stress resistance.This study offers new insights into the grape GLR gene family,providing fundamental knowledge for further functional analysis and breeding of stress-resistant grapevines.

Analysis of Organic Acids Accumulated in Kochia Scoparia Shoots and Roots by Reverse-phase High Performance Liquid Chromatography Under Salt and Alkali Stress

Several organic acids accumulated in Kochia Scoparia shoots and roots were studied by means of reverse-phase high performance liquid chromatography with a C18 column. Five types of binary organic acids were separated. The organic acid concentrations were determined in K. Scoparia seedlings stressed by saline （NaCI） and alkaline （NaHCO3） at the same Na^＋ concentration. Concentrations of organic acids are stimulated by alkaline because the cells will adjust their pH values through the accumulation of organic acids, when the environment is basic. The concentrations of oxalic acid and succinic acid are higher than those of other organic acids, including tartaric acid and malic acid, and the concentration of citric acid is the lowest. The concentrations of the organic acids in the roots are higher than those in the shoots under salt（NaCI） stress, but the results are opposite while the roots are under alkali （ NaHCO3 ） stress. This indicates that there are different adaptive strategies for K. Scopar/a seedlings in organic acid metabolism under salt and alkali stress.

Effects of salt and alkali stress on Reaumuria soongorica germination

Seed germination and early seedling growth are crucial stages for plant establishment. Two neutral(Na Cl and Na2SO4) and two alkali(Na HCO3 and Na2CO3) salts were selected to investigate their effects on germination and recovery responses in Reaumuria soongorica. Results show that both salt types significantly reduced germination and radicle elongation. The rate of germination and emergence of R. soongorica seeds continuously decreased as salinity increased, and the time to achieve maximum germination rate was delayed. The speed of seed germination dropped rapidly as salt concentration increased.Alkaline salts restricted the germination rate of R. soongorica seeds, and stresses resulting from alkaline salts and high concentrations of neutral salts resulted in many deformed seedlings. The length of the radicle and germ decreased with increasing salt concentration, but certain concentrations of salt and increased p H promoted germ growth. The results of regression analysis show that salt concentration was the dominant factor inhibiting R. soongorica seed germination rate. Salinity, buffering capacity, and p H all affected embryo growth, but salinity had the most pronounced effect. Seed viability under highly saline conditions appears to be a better indicator of adaptation to saline environments than seed germination under saline conditions.

Nitrogen application regulates antioxidant capacity and flavonoid metabolism,especially quercetin,in grape seedlings under salt stress

Salt stress is a typical abiotic stress in plants that causes slow growth,stunting,and reduced yield and fruit quality.Fertilization is necessary to ensure proper crop growth.However,the effect of fertilization on salt tolerance in grapevine is unclear.In this study,we investigated the effect of nitrogen fertilizer(0.01 and 0.1 mol L^(-1)NH_(4)NO_(3))application on the salt(200 mmol L^(-1)NaCl)tolerance of grapevine based on physiological indices,and transcriptomic and metabolomic analyses.The results revealed that 0.01 mol L^(-1)NH_(4)NO_(3) supplementation significantly reduced the accumulation of superoxide anion(O_(2)^(-)·),enhanced the activities of superoxide dismutase(SOD)and peroxidase(POD),and improved the levels of ascorbic acid(AsA)and glutathione(GSH)in grape leaves compared to salt treatment alone.Specifically,joint transcriptome and metabolome analyses showed that the differentially expressed genes(DEGs)and differentially accumulated metabolites(DAMs)were significantly enriched in the flavonoid biosynthesis pathway(ko00941)and the flavone and flavonol biosynthesis pathway(ko00944).In particular,the relative content of quercetin(C00389)was markedly regulated by salt and nitrogen.Further analysis revealed that exogenous foliar application of quercetin improved the SOD and POD activities,increased the AsA and GSH contents,and reduced the H_(2)O_(2) and O_(2)^(-)·contents.Meanwhile,10 hub DEGs,which had high Pearson correlations(R^(2)>0.9)with quercetin,were repressed by nitrogen.In conclusion,all the results indicated that moderate nitrogen and quercetin application under salt stress enhanced the antioxidant system defense response,thus providing a new perspective for improving salt tolerance in grapes.

Comparative Transcriptome Profiling of Glycine soja Roots Under Salinity and Alkalinity Stresses Using RNA-seq

Saline-alkaline stress can dramatically inhibit plant growth and limit crop production. Wild soybean （Glycine soja） is a crop that adapts well to such environmental stresses. In this study, RNA-sequencing technology was used to analyze the transcriptome profles of G. soja roots subjected to 50 mmol·L^-1 NaHCO3 and 150 mmol·L^-1 NaCl treatments. Totally, 2 125 differentially-expressed genes （DEGs） after NaCl treatment and 1 839 DEGs after NaHCO3 treatment were identifed. The top 14 DEGs revealed by RNA-seq were analyzed using qRT-PCR （quantitative real-time polymerase chain reaction）. Gene ontology （GO） annotation showed that most of DEGs under salt and alkali stresses were enriched in ＂metabolic process＂, ＂catalytic activity＂ and ＂binding＂ terms. To search for transcription factors （TFs） among DEGs, the data were screened against TF database PlantTFDB, and it was found that fve TF families, Apetala2/ethylene-responsive element binding proteins （AP2-EREBP）, V-myb avian myeloblastosis viral oncogene homolog （MYB）, WRKYGQK and Zinc fnger motif （WRKY）, NAM, ATAF1/2, CUC1/2 （NAC） and Cys2/His2 （C2H2） were involved in salt stress response. Other fve TF families, NAC, WRKY, MYB, AP2-EREBP and bZIP were involved in response to alkali stress. These two stress treatments shared NAC, WRKY, AP2-EREBP and MYB, and the only two different TFs were bZIP and C2H2. Forty-eight MYB TFs were differentially expressed under salt and alkali stresses, and most of them were up-regulated. This study provided useful information for further investigation of DEGs and TFs in response to saline and alkaline stresses and helped in understanding the molecular basis of the response of G. soja to saline and alkaline stresses.

Melatonin Alleviates Abscisic Acid Deficiency Inhibition on Photosynthesis and Antioxidant Systems in Rice under Salt Stress

Melatonin and abscisic acid,as major plant hormones,play important roles in the physiological and biochemical activities of crops,but the interaction between the two under salt stress is not yet clear.This study investigated the endogenous levels of melatonin and abscisic acid in rice by using exogenous melatonin,abscisic acid,and their synthetic inhibitors,and examined their interactions under salt stress.The research results indicate that melatonin and abscisic acid can improve rice salt tolerance.Melatonin alleviated the salt sensitivity caused by abscisic acid deficiency,increased antioxidant enzyme activity and antioxidant content in rice treated with abscisic acid synth-esis inhibitors,and reduced total reactive oxygen species content and thiobarbituric acid reactive substance accu-mulation.Melatonin also increased the activity of key photosynthetic enzymes and the content of photosynthetic pigments,maintaining the parameters of photosynthetic gas exchange and chlorophyllfluorescence.In summary,melatonin alleviated the effects of abscisic acid deficiency on photosynthesis and antioxidant systems in rice and improved salt tolerance.This study is beneficial for expanding the understanding of melatonin regulation of crop salt tolerance.

Overexpression of GmProT1 and GmProT2 increases tolerance to drought and salt stresses in transgenic Arabidopsis

financially supported by the Genetically Modified Organisms Breeding Major Projects of China （2014ZX08004）;the National Natural Science Foundation of China （31301340）;the Modern Agro-industry Technology Research System of China （CARS-004-PS10）;the Program for Changjiang Scholars and Innovative Research Team in University, China （PCSIRT13073）;the Jiangsu Collaborative Innovation Center for Modern Crop Production;an Openend Fund by State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, China （ZW2013009）

EuSHT Acts as a Hub Gene Involved in the Biosynthesis of 6-Hydroxyluteolin and Quercetin Induced by Salt Stress in Eucommia ulmoides

Salt stress inhibits plant growth and affects the biosynthesis of its secondary metabolites.Flavonoids are natural compounds that possess many important biological activities,playing a significant role in the medicinal activity of Eucommia ulmoides(E.ulmoides).To investigate the mechanism by which salt stress affects the biosynthesis of flavonoids in E.ulmoides,a comprehensive analysis of metabolomics and transcriptomics was conducted.The results indicated that salt stress led to the wilting and darkening of E.ulmoides leaves,accompanied by a decrease in chlorophyll levels,and significantly induced malondialdehyde(MDA)and relative electrical conductivity.During salt stress,most metabolites in the flavonoid biosynthesis pathway of E.ulmoides were upregulated,indicating that flavonoid biosynthesis is likely the main induced pathway under salt stress.Among them,secondary metabolites such as 6-Hydroxyluteolin and Quercetin are likely key metabolites induced by salt stress.The correlation analysis of transcriptomics and metabolomics revealed that EuSHT is a hub gene induced by salt stress,promoting the production of flavonoids such as 6-Hydroxyluteolin.The co-expression network showed a strong positive correlation between EuSHT and the biosynthesis of 6-Hydroxyluteolin and Quercetin,while it exhibited a negative correlation with Catechin biosynthesis.The branches leading to Luteolin and Dihydroquercetin are likely the main pathways for flavonoid compound biosynthesis in the plant stress response during salt stress.The results of this study provided a preliminary mechanism of secondary metabolites such as flavonoids in the medicinal plant E.ulmoides induced by salt stress and provided new theoretical support for discussing the mechanism of plant stress response.It also provided useful information for subsequent exploration of resistance genes in E.ulmoides.

Photosynthetic Characteristics of Clerodendrum trichotomum Thumb. Responses to Drought, Salt and Water-logging Stresses

In order to reveal the photosynthetic characteristics of C. trichotomum responses to drought, salt and water-logging stresses, one-year-old potted seedlings were taken as materials, and the several stresses including natural drought, submergence stress, water-logging and different salt treatments （0.2%, 0.4%, 0.6% and 0.8% NaCl） were carried out on August 15, 2012. The morphological and photosynthetic characteristics were observed and determined. The results showed that adverse enviromental stress had a significant effect on the morphological changes and photosynthetic characteristics of C. trichotomum. On the 14th day after natural drought, the leaves wilted and could not recovery at night, and 60% of the seedlings could recover after re-watering. From the 7th day to the 10th day after submergence stress treatment, the 2nd and the 3rd leaves at the base of 60% seedling turned yellow and the lenticels were observed. At the early stage of water-logging stress, white lenticels appeared at the base of seedlings, and the leaves wilted, chlorina and fallen off on the 8th day. A large number of leaves fallen off under 0.6% NaCl or more salt stress, and even the whole plant died. The chlorophyll content, net photosynthetic rate （Pn） and transpiration rate （Tr） decreased gradually with the stress process, such as 8 days after natural drought, less than 0.4% salt stress and water-logging stress, but the changes were not significant compared with those of the control. With the increase of the stress intensity and the prolonged time, the changes of photosynthetic index were significant. All the results indicated that C. trichotomum had a certain degree of tolerance to drought, water and salt, but it was not suitable for living, in water-logging condition for a long time.

Transcriptome profile of Dunaliella salina in Yuncheng Salt Lake reveals salt-stress-related genes under diff erent salinity stresses

Salt stress is an abiotic stress to plants in especially saline lakes.Dunaliella,a halophilic microalga distributed throughout salt lakes and seas,can respond to different salinity stresses by regulating the expression of some genes.However,these genes and their function and biological processes involved remain unclear.Profi ling these salt-stress-related genes in a high-salt-tolerant Dunaliella species will help clarify the salt tolerance machinery of Dunaliella.Three D.salina_YC salt-stress groups were tested under low(0.51 mol/L),moderate(1.03 mol/L),and high(3.42 mol/L)NaCl concentrations and one control group under very low(0.05 mol/L)NaCl concentration and 3 transcriptome results that were deep sequenced and de novo assembled were obtained per group.Twelve high-quality RNA-seq libraries with 46585 upregulated and 47805 downregulated unigenes were found.Relative to the control,188 common differentially expressed genes(DEGs)were screened and divided into four clusters in expression pattern.Fifteen of them annotated in the significant enriched Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)were validated via qPCR.Their qPCR-based relative expression patterns were similar to their RNA-seq-based patterns.Two significant DEGs,the geranylgeranyl diphosphate synthase coding gene(1876-bp cDNA)and diacylglycerol O-acyltransferase coding gene(2968-bp cDNA),were cloned and analyzed in silico.The total lipid content,superoxide dismutase specific activity,and betacarotene content of D.salina_YC increased gradually with increasing salinity.In addition,the expression of 11 validated genes involved in fatty acid biosynthesis/degradation,active oxygen or carotenoid metabolisms showed significant changes.In addition,algal photochemical efficiency was diminished with increasing salinity,as well as the expression of 4 photosynthesis-related genes.These results could help clarify the molecular mechanisms underlying D.salina responses to the Yuncheng Salt Lake environment and lay a foundation for further utilization of this algal resource.

Different Approaches to Reduce Salinity in Salt-Affected Soils and Enhancing Salt Stress Tolerance in Plants

Salt stress is one of the most harmful environmental stresses in recent times and represents a significant threat to food security. Soil salinization is caused by spontaneous natural processes of mineral dissolution and human activities such as inappropriate irrigation practices. Natural geological progressions like weathering of rocks, arid climate, and higher evaporation, as well as anthropogenic activities, including the use of brackish water for irrigation, and poor tillage operations, are the foremost causes of soil salinization. Typical characteristics of saline soils are salt stress, high pH, and lack of organic carbon, as well as low availability of nutrients. Disruption of precipitation patterns as well as high average annual temperatures due to climate change additionally negatively affects the process of soil salinization. Productivity and ability to support crop growth are reduced on saline soil. Salinity-induced stress reduces plant growth by modulating the antioxidative system and nutrient orchestration. The aim of this work is to show that the mentioned problems can be alleviated in several ways such as the addition of biochar, exogenous application of several elicitors, seed priming, etc. Research has shown that the addition of biochar can significantly improve the recovery of saline soil. The addition of biochar has no significant effect on soil pH, while the cation exchange capacity of the soil increased by 17%, and the electrical conductivity of the saturated paste extract decreased by 13.2% (depends on the initial salinity and the type of biochar raw material). Moreover, biochar enriched with silicon increases the resistance of bananas to salt stress. In addition, exogenous application of several elicitors helps plants to alleviate stress by inducing stress-related physicochemical and molecular changes (selenium, sulfur, silicon, salicylic acid). Finally, seed priming showed positive effects on metabolomics, proteomics and growth of plants subjected to abiotic stress. Priming usually involves immersing the seed in a solution for a period of time to induce physiological and metabolic progression prior to germination.

Effects of salt-alkali stress on active oxygen metabolism in roots of Spiraea × bumalda 'Gold Mound' and Spiraea × bumalda 'Gold Flame'

Under artificially-simulated complex salt-alkali stress, the levels of active oxygen metabolism in roots were studied using three-year-old cutting seedlings of Spiraea × bumalda ‘Gold Mound＇ and Spiraea × bumalda ‘Gold Flame＇. The present study aimed at exploring the antioxidant capacity in roots of spiraeas and revealing their adaptability to salt-alkali stress. Results indicate that the oxygen free radicals contents, electrolyte leakage rates and MDA contents in roots of Spiraea × bumalda ＇Gold Mound＇ and Spiraea × bumalda ＇Gold Flame＇ show an increasing tendency with the increases of the salinity and pH value, whereas the activities of superoxide dismutase （SOD）, peroxidase （POD） and catalase （CAT） all increased firstly and then decreased. With the increase in intensity of salt-alkali stress, the CAT activity in roots of Spiraea × bumalda ‘Gold Flame＇ is higher and the increasing extents in the oxygen free radicals contents, electrolyte leakage rates as well as MDA contents are lower compared with Spiraea × bumalda ‘Gold Mound＇, indicating that Spiraea × bumalda ‘Gold Flame＇ has a stronger antioxidant capacity.

Characters and structures of the nucleobase-ascorbate transporters(NAT)family genes in Gossypium hirsutum and their roles in responding to salt and drought stresses

Background: Nucleobase-ascorbate transporters(NAT), synonymously called nucleobase-cation symporter 2(NCS2) proteins, were earlier reported to be involved in plant growth, development and resistance to stress. Previous studies concluded that s a polymorphic SNP associated with NAT12 was significant di erent between salt-tolerant and salt-sensitive materials of upland cotton. In current study, a comprehensive analysis of NAT family genes was conducted for the first time in cotton.Results: In this study, we discovered 32, 32, 18, and 16 NAT genes in Gossypium hirsutum, G. barbadense, G. raimondii and G. arboreum, respectively, which were classified into four groups(groups I–IV) based on the multiple sequence analysis. These GhNAT genes were unevenly distributed on At and Dt sub-genome in G. hirsutum. Most GhNAT members in the same group had similar gene structure characteristics and motif composition. The collinearity analysis revealed segmental duplication as well as tandem duplication contributing to the expansion of the GhNATs. The analysis of cis-acting regulatory elements of GhNATs showed that the function of GhNAT genes in cotton might be related to plant hormone and stress response. Under di erent conditions, the expression levels further suggested the GhNAT family genes were associated with plant response to various abiotic stresses. GhNAT12 was detected in the plasma membrane. And it was validated that the GhNAT12 gene played an important role in regulating cotton resistance to salt and drought stress through the virus-induced gene silencing(VIGS) analysis.Conclusions: A comprehensive analysis of NAT gene family was performed in cotton, including phylogenetic analysis, chromosomal location, collinearity analysis, motifs, gene structure and so on. Our results will further broaden the insight into the evolution and potential functions of NAT genes in cotton. Current findings could make significant contribution towards screening more candidate genes related to biotic and abiotic resistance for the improvement in cotton.

Genome-Wide Identification of Genes Responsive to ABA and Cold/Salt Stresses in Gossypium hirsutum by Data-Mining and Expression Pattern Analysis

For making better use of nucleic acid resources of Gossypium hirsutum, a data-mining method was used to identify putative genes responsive to various abiotic stresses in G. hirsutum. Based on the compiled database including genes involved in abiotic stress response in Arabidopsis thaliana and the comprehensive analysis tool of GENEVESTIGATOR v3, 826 genes up-regulated or down-regulated significantly in roots or leaves during salt or cold treatment in Arabidopsis were identified. As compared to these 826 Arabidopsis genes annotated, 38 homologous expressed sequence tags （ESTs） from G. hirsutum were selected randomly and their expression patterns were studied using a quantitative real-time reverse transcription-polymerase chain reaction method. Among these 38 ESTs, about 55% of the genes （21 of 38） were different in response to ABA between cotton and Arabidopsis, whereas 70% of genes had similar responses to cold and salt treatments, and some of them which had not been characterized in Arabidopsis are now being investigated in gene function studies. According to these results, this approach of analyzing ESTs appears effective in large-scale identification of cotton genes involved in abiotic stress and might be adopted to determine gene functions in various biologic processes in cotton.

Study on Salinity Tolerance of Tomatoes during Seed Germination under Different Salt Stress Conditions

[Objective] The aim of this study was to provide the theoretical basis for screening and utilizing salt-tolerant tomato varieties as well as for cultivating salt-resistance.[Method] Salinity tolerance of tomato during seed germination under simple salt sodium chloride and double salt calcium nitrate or sodium chloride stress were studied by Petri dish culturing.[Result] As the two kinds salt concentration increased,the germination regularity,the germination rate,the germination index and the growing vigor index of tomato seedlings decreased,but the germination losing rate increased.When salt concentration was from 0.2% to 0.4%,there was little difference among all indexes under two kinds of salt stress.However,when salt concentration was from 0.6% to 1.0%,the difference among all indexes under two kinds of salt stress was significant.[Conclusion] Salinity tolerance of tomato seeds under double salt calcium nitrate or sodium chloride stress was higher than that under simple salt sodium chloride stress.

Effects of Salt Stress on Fatty Acid Composition of Thylakoid Membrane of Two Rice Cultivars Differing in Salt Tolerance

[Objective] The aim of the study is to understand the changes of fatty acid composition of rice thylakoid membrane under salt stress.[Method] Under salt stress of different concentrations of NaCl,rice seedlings of Pokkali and Peta with six leaves and one central leaf were used as experimental materials to extract the fatty acid from their thylakoid membranes,and gas chromatograph(1890)was used to analyze fatty acid composition.[Result] Fatty acid component 14∶0,18∶0,16∶1(3t),18∶1 in both the two experimental materials showed little variations in the first four days of salt stress,whereafter they increased slightly;while the fatty acid component 16∶0 and level of saturation of fatty acid(LSFA)showed the similar variation trend in the first four days of treatment compared to those of the fatty acid components mentioned above,whereafter they rose in Pokkali and presented an opposite variation trend in Peta;fatty acid component 18∶3 and level of unsaturation of fatty acid(LUFA)reduced all the time under stress condition,and the reducing amplitude in 100 mmol/L NaCl treatment group was smaller than that of 100 mmol/L NaCl treatment group,and in Pokkali was smaller than that in Peta under specific conditions.Meanwhile,level of saturation of fatty acid in both experimental materials increased,and the rising amplitude in Peta was smaller than that of Pokkali.[Conclusion] With regard to LUFA,Pokkali is endowed with more salt tolerance than Peta.