Influences of Na_2CO_3 Stress on Physiological Metabolisms of Different Alkali Tolerant Varieties of Stevia rebaudiana

[Objective] The research aimed to reveal physiological mechanisms of alkali tolerances of different Stevia rebaudiana varieties under alkali stress.[Method] By using matrix culture method,the influences of Na2CO3 on chlorophyll content,malondialdehyde（MDA）,superoxide dismutase（SOD）,peroxidase（POD） and Proline（Pro） content of leaves from different alkali tolerance varieties of S.rebaudiana [No.2 Shoutian（relative alkali tolerance variety） and No.4 Zhongshan（alkali sensitivity variety）] were studied.[Result] 1.2 g/L of Na2CO3 stress made that the chlorophyll contents of leaves from No.2 Shoutian and No.4 Zhongshan seedlings both decreased in different degrees.Moreover,MDA content of No.4 Zhongshan was higher than control during the whole stress period,and the largest increase amplitude was 43.2%.MDA content of No.2 Shoutian was lower than control in early and latter periods of stress,and increased the maximum on the 14th day of alkali stress,which was 24.4% higher than control.SOD activities of No.2 Shoutian and No.4 Zhongshan both showed a trend of first increasing and declining then in the alkali stress period,but the increasing extent of SOD activity in No.2 Shoutian was higher than that in No.4 Zhongshan.In latter period of Na2CO3 stress,SOD activity of No.2 Shoutian declined,but POD activity was higher than that of No.4 Zhongshan.It illustrated that POD had stronger scavenging capability of active oxygen.Pro contents of No.2 Shoutian and No.4 Zhongshan were higher than control in the stress period.It showed that the osmoregulation of Pro might not be key regulatory factor of alkali tolerance difference of the two S.rebaudiana varieties.[Conclusion] The research not only provided theoretical basis for further breeding new salt tolerance variety of S.rebaudiana,but also had important significance for improving utilized ratio of kaline soil and growing environment for mudflat in China.

Effect of Different Kinds of Growth-promoting Rhizobacteria on Physiological and Biochemical Characteristics of Medicago sative Linn. Seedlings under the Stress of Na_2CO_3

[Objective] The study aimed to explore the influences of Plant growth-promoting rhizobacteria（PGPR）on salt tolerance and physiological effect of seedlings of Medicago sative L.[Method] Three different kinds of growth-promoting rhizobacteria solutions were used to spray on M.sative seedlings and the influences of different kinds of growth-promoting rhizobacteria on physiological and biochemical characteristics of M.sative seedlings under 75 mmol/L of Na2CO3 were studied.[Results] Compared with the control group,the chlorophyll,free proline,soluble sugar and soluble protein content of M.sative seedlings treated with different kinds of growth-promoting rhizobacteria were increased,while the effect of CS3 treatment was the best.[Conclusion] The growth-promoting rhizobacteria could promote growth and development of M.sative as well as increased its resistance.

NaCl和Na_2CO_3对玉米生长和生理胁迫效应的比较研究

分别用不同浓度的NaCl和Na2 CO3溶液处理玉米 ,然后测定干重、渗透调节能力的变化 ,离子、丙二醛 (MDA)、氨基酸 (AA)、有机酸 (OA)、脯氨酸 (Pro)、可溶性糖 (SS)的含量 ,液泡膜H+ ATPase(V H+ ATPase) ,液泡膜H+ PPase(V H+ PPase)、超氧化物歧化酶 (SOD)的活性。结果表明 ,玉米在Na2 CO3作用下 ,其生长和生理变化和NaCl胁迫是不一样的。玉米在Na2 CO3胁迫下 ,离子均衡遭到极大破坏 ,酸性物质对pH值的缓冲作用较小 ,Na+ 区域化能力的提高受到限制 ,活性氧清除能力显著减小 ,膜系统受到严重损害。所有这些变化导致了Na2 CO3对玉米的伤害作用远大于NaCl。

Na_2CO_3对星星草种子保护酶活性的影响

星星草种子萌发时过氧化物酶和超氧化物歧化酶活性逐渐增加 ,过氧化氢酶活性在吸涨后迅速增加 ,到第4d达到高峰 ,随后稳中略降 ,至第 8d后又开始上升。在 Na2 CO3 胁迫下 ,过氧化物酶活性降低 ,并与 Na2 CO3 浓度呈显著负相关 ;在较低浓度时 ,过氧化物酶和超氧化物歧化酶活性随着星星草种子萌发逐渐增加 ,浓度大于 3.0 %时 ,超氧化物歧化酶活性变化很小 ,在萌发第 7d,超氧化物歧化酶活性与 Na2 CO3 浓度呈极显著负相关关系。

Na_2CO_3胁迫下星星草胁变反应部位的差异

对砂培星星草用 0～ 175mmol/L的碱性盐Na2 CO3进行了胁迫处理 ,测定了植株不同部位的主要胁变指标 ,比较了各个部位之间对碱性盐胁迫的生理响应差异。结果表明 :在Na2 CO3胁迫下 ,衰老组织中的含水量及氮素水平都明显下降 ,而幼嫩部位则变化很小。植株不同部位的渗透调节作用明显不同 ,趋于衰老的部位以降低含水量和积累无机离子为主特征 ,而代谢旺盛的幼嫩部位则以大量合成并积累有机渗透调节剂为主特征。以柠檬酸为主的有机酸积累与Na+积累相平行 ,而且都主要分布在液泡化程度高的衰老部位 ,其作用可能是中和Na+离子、降低离子毒害及调节细胞内的

Na_2CO_3胁迫对星星草种子萌发过程中水分吸收及膜透性的影响

星星草种子萌发吸水过程可以分为３个阶段。吸水量随着Ｎａ２ＣＯ３浓度增高而逐渐降低。但不同阶段吸水量随着盐浓度的上升而下降的幅度不同，第１阶段降低幅度较小，第３阶段则较大。盐浓度大于２．７５％时，星星草种子不萌发，吸水停滞于第２阶段。星星草种子吸涨初始时，膜透性较大，随着吸涨的进行，膜逐渐得以修复。Ｎａ２ＣＯ３胁迫下，膜系统修复受阻，Ｎａ２ＣＯ３浓度与膜透性正相关极其显著。发芽率和膜透性之间极其显著的负相关关系表明，膜修复受阻是Ｎａ２ＣＯ３胁迫抑制星星草种子萌发的重要原因之一。

Early Transcriptomic Adaptation to Na_2CO_3 Stress Altered the Expression of a Quarter of the Total Genes in the Maize Genome and Exhibited Shared and Distinctive Profles with NaCl and High pH Stresses

Sodium carbonate （Na2CO3） presents a huge challenge to plants by the combined damaging effects of Na＋, high pH, and CO32. Little is known about the cellular responses to Na2CO3 stress. In this study, the transcriptome of maize （Zea mays L. cv. B73） roots exposed to Na2CO3 stress for 5 h was compared with those of NaCI and NaOH stresses. The expression of 8,319 genes, representing over a quarter of the total number of genes in the maize genome, was altered by Na2CO3 stress, and the downregulated genes （5,232） outnumbered the upregulated genes （3,087）. The effects of Na2CO3 differed from those of NaCI and NaOH, primarily by downregulating different categories of genes. Pathways commonly altered by Na2CO3, NaCI, and NaOH were enriched in phenylpropanoid biosynthesis, oxidation of unsaturated fatty acids, ATP- binding cassette （ABC） transporters, as well as the metabolism of secondary metabolites. Genes for brassinosteroid biosynthesis were specifically upregulated by Na2CO3, while genes involved in ascorbate and aldarate metabolism, protein processing in the endoplasmic reticulum and by N-glycosylation, fatty acid biosynthesis, and the circadian rhythm were downregulated. This work provides the first holistic picture of early transcriptomic adaptation to Na2CO3 stress, and highlights potential molecular pathways that could be manipulated to improve tolerance in maize.

盐胁迫对星星草幼苗保护酶系统的影响

在盐胁迫下 ,星星草幼苗过氧化氢酶活性随着胁迫时间的延长而增强 ,并与盐浓度呈显著正相关。超氧化物歧化酶活性随着胁迫浓度的增强而增强 ,当超过一定浓度 (3.0 % Na2 CO3)时则趋减弱 ,尔后随着胁迫时间的延长而增强。过氧化物酶活性的变化规律与超氧化物歧化酶活性相似 ,但变化幅度较小。丙二醛含量随着胁迫时间的延长和胁迫强度的增强而增加。

钾素营养对星星草幼苗抗碱性的影响

通过不同水平钾素营养培养星星草幼苗，研究钾素营养对星星草幼苗抗碱性的影响。结果表明：在２．０％Ｎａ２ＣＯ３胁迫下，星星草幼苗钾素营养的最适浓度为１．３５ｍｍｏｌＬ－１ＫＣｌ，此条件不仅对株高、干重和鲜重的增长有促进作用，而且受害程度最小，对Ｎａ２ＣＯ３胁迫的缓解作用最强，在一定程度上可提高星星草幼苗对Ｎａ２ＣＯ３胁迫的抗性。