摘　要： 盐胁迫是全球农业生产上的一个主要逆境因子。解析耐盐分子机制有助于培育耐盐能力提高的作物新品种。我们综述了植物对盐胁迫的感应及信号传导、主要Na^＋运输体、盐胁迫下的解毒途径以及耐盐途径中涉及到的表观遗传研究。此外,我们还讨论了利用遗传改良手段提高作物耐盐性的研究进展。

文章对盐胁迫下大麦幼苗生理指标进行了分析研究.结果表明,随NaCl浓度的升高,大麦茎叶中可溶性糖、脯氨酸含量增高,K+/Na+降低;大麦茎叶中脯氨酸含量随NaCl浓度升高呈倍数升高,在0.6%NaCl胁迫下,‘CM72'脯氨酸含量最高达1.526μmol·g-1.在同一NaCl浓度下,不同大麦品种间可溶性糖、脯氨酸含量及K+/Na+差异明显,‘CM72'渗透物质合成能力最强,耐盐性较好,‘泰兴9425'和‘苏啤3号'次之.

以马齿苋为材料,采用温室盆栽法研究了14dNaCl胁迫处理对其幼苗生长、光合作用和叶绿素荧光特性的影响。结果显示:(1)马齿苋幼苗的鲜重和株高在25mmol.L-1 NaCl胁迫时与对照无显著差异,但其随着NaCl浓度的继续增加均显著降低,且其生物量受到的抑制早于株高。(2)NaCl胁迫下,马齿苋幼苗叶片净光合速率(Pn)降低,胞间二氧化碳浓度(Ci)增大,且两者的变化幅度随着NaCl浓度增加而增大。(3)NaCl胁迫下,马齿苋幼苗叶片的初始荧光(F0)、最大荧光(Fm)、可变荧光(Fv)、恒态荧光(Fs)、恒态荧光与初始荧光差值(△F0)、PSⅡ潜在光化学效率(Fv/F0)和PSⅡ最大光化学效率(Fv/Fm)均降低,叶片光化学荧光猝灭系数(qP)也在NaCl胁迫下降低,而非光化学荧光猝灭系数(NPQ)则上升;在0～50mmol.L-1 NaCl胁迫下,幼苗叶片各荧光参数下降幅度小于其他高浓度NaCl胁迫。研究表明,在NaCl胁迫条件下,马齿苋幼苗叶片的光合作用受光抑制伤害,但在低浓度NaCl下能够较多地将光能用于光化学反应,光抑制程度较低,保持了较高的净光合速率,明显减轻盐胁迫对植株生长的影响,表现出一定的耐盐性。

In order to explore the drought tolerance of Rhododendron latoucheae in seed germination and seedling growth stage,we studied the effects of drought stress on seed germination,growth,cell membrane permeability,malondialdehyde(MDA) content,the organic osmoregulation substances and antioxidant enzyme activities by choosing dry seeds and seedlings with 90 d age and using different concentrations of polyethylene glycol(PEG-6000) simulated drought stress.The regression analyses were done between seed germination,early seedling growth and PEG stress.The results showed that:(1)the initial germination time of R.latoucheae seeds was delayed with the increasing of drought stress degree in 5%-25% PEG range,and the germination duration was prolonged.The seed germination rate,germination potential,germination index,vigor index and early seedling growth were all significantly reduced.The seed could not germinate absolutely at severe drought stress(25% PEG).(2)The changes of seed germination rate,germination potential,germination index,vigor index and early seedling growth were showed very significant negative correlation with the degree of drought stress.The regression equation between seed germination,early seedling growth and PEG stress showed that the half lethal PEG drought stress concentration was 15.68%,while the semi dwarfing PEG drought stress concentration was 15.37%.(3)With the increase of PEG concentration,SOD activity of R.latoucheae seedling leaves increased firstly and then decreased,but were significantly higher in all the stress treatments than that of CK(0% PEG).Cell membrane permeability,MDA content,proline content,soluble sugar content,POD and CAT activities increased significantly in moderate(15%-20% PEG) and severe drought stress,and the changes of these indexes were showed very significantly positive correlation with the degree of drought stress.The research found that seed germination and seedling growth of R.latoucheae were significantly inhibited by drought stress,and cell membrane was also damaged in different degrees.Thus it could be seen that R.latoucheae increased contents of the osmoregulation substances and antioxidant enzyme activities in vivo to adapt to drought stress environment at the same time,making the inhibition and damage degree to the minimum.

为探明鹿角杜鹃种子萌发和幼苗生长期的耐旱性,以鹿角杜鹃干种子和90 d苗龄幼苗为材料,采用聚乙二醇(PEG-6000)模拟不同程度的干旱胁迫,研究干旱胁迫对其种子萌发、早期幼苗生长及幼苗的细胞膜透性、MDA含量、有机渗透调节物质和抗氧化酶活性的影响,并对种子萌发率、早期幼苗生长量与PEG胁迫浓度间进行了回归分析。结果表明:(1)5%～25% PEG胁迫范围内,随着干旱胁迫程度的增加,鹿角杜鹃种子的发芽启动时间推迟,发芽持续时间延长,发芽率、发芽势、发芽指数、活力指数和幼苗生长量显著降低;重度干旱胁迫(25% PEG)下,鹿角杜鹃种子完全未萌发。(2)发芽率、发芽势、发芽指数、活力指数以及幼苗生长量的变化均与干旱胁迫程度呈极显著负相关关系,回归分析求得鹿角杜鹃种子萌发的半致死PEG干旱胁迫浓度为15.68%、半致矮PEG干旱胁迫浓度为15.37%。(3)随着PEG胁迫浓度的增加,鹿角杜鹃幼苗叶片SOD活性呈先升后降的趋势,但各胁迫处理仍显著高于CK(0% PEG);细胞膜透性、MDA、脯氨酸、可溶性糖含量、POD和CAT活性则在中度(15%～20% PEG)和重度胁迫下显著升高,与干旱胁迫程度呈极显著正相关关系。研究表明,干旱胁迫显著抑制了鹿角杜鹃种子萌发和早期幼苗生长,使其细胞膜受到损伤,同时鹿角杜鹃可通过体内渗透调节物质和抗氧化酶活性的增加来适应干旱环境,使得自身受抑制、损伤程度降到最低。

In our experiment,28 hulless barley cultivars were choose to study their water consumption rate and dehydration rate when the first leaf spread out.A drought tolerant and a water sensitive hulless barley cultivar were selected.To understand the regulating effect of polyethylene glycol (PEG) under drought stress ,we examined the effects of 5%~30% PEG pretreatment on the seed germination,seedling growth and physiological characteristics of different barley varieties.The results were as following:(1)Relative water content of 28 hulless barley varieties increased gradually,while dehydration rate showed the opposite trend.The relative water content ranked the highest (60.16%) and dehydration rate ranked the lowest (8.80%) in Handizi,while relative water content ranked the lowest (38.98%) and dehydration rate ranked the highest (20.20%) in Dama,it indicated Dama was greatest sensitive to water and Handizi was least sensitive to water.(2)Germination and rooting rate in hulless barley seed,root length,shoot height and fresh weight in hulless barley seedlings showed ‘rises first,falls later’ with the increase of PEG concentration.The best treatment concentration on Handizi hulless barley and Dama were 15% and 10% respectively and the difference was significant with the control ( P <0.05).The best treatment concentration on root length,shoot height and fresh weight in two hulless barley seedlings was 10% and no significant difference was found between the treatments and the control in Dama.(3)Soluble protein and chlorophyll content of Handizi hulless barley leaves was correlation with PEG concentration and malondialdehyde (MDA) presented negatively correlation.They were obvious at 0.01 degree in 30% PEG.Soluble protein and chlorophyll content of Dama hulless barley leaves showed ‘rises first,falls later’,and the MDA showed the opposite change.20%PEG was the best treatment.To sum up,low concentration of PEG pretreatment promoted seed germination,seedling growth and improvement of physiological function of hulless barley;high concentration of PEG inhibited seed germination,seedling growth and improvement of physiological function of hulless barley.The variety with stronger drought tolerance had a strong resistance to PEG and self regulation ability from the beginning of seed germination period,and the variety with weak drought tolerance had a weak resistance and self regulation ability when subjected to higher degree of stress.So the treatment of appropriate PEG concentration not only could significantly promote the seed germination and seedling growth of hulless barley,but also could improve the physiological function,including protein,chlorophyll,MDA content and relative conductivity,which could enhance the resistance ability.The results of this study suggested that it can make dormant seed rapidiy activing using a proper concentration of PEG solution to soak,and improve the efficiency of seed breeding,which lays a foundation for the PEG widely application in agriculture.

选择国内外28份青稞品种材料幼苗第一片展开叶，分别测定其相对含水量和失水率，并选择其中对水分胁迫敏感与不敏感的材料各1份，研究不同浓度（5%～30%）聚乙二醇（PEG）预处理对青稞种子萌发、幼苗生长和生理特性的影响，探讨短期水分胁迫对青稞生长发育的调节作用。结果显示：（1）28个青稞材料中‘旱地紫青稞’幼苗叶片的相对含水量最高（60.16%）、‘大麻青稞’最低（38.98%），而离体失水率‘旱地紫青稞’最低（8.80%）、‘大麻青稞’最高（20.20%）。说明‘大麻青稞’对水分胁迫最敏感，而‘旱地紫青稞’最不敏感。（2）随着胁迫程度的增加，青稞种子的萌发率和生根率，幼苗的根长、苗高和鲜重均呈先增加后降低的趋势，‘旱地紫青稞’和‘大麻青稞’种子分别在15%和10% PEG处理下发芽和生根最佳且均与对照差异显著( P P <0.01)；‘大麻青稞’叶片可溶性蛋白和叶绿素含量随PEG处理浓度增加呈先增加后降低的趋势，丙二醛含量和相对电导率呈先降低后增加的趋势，并在20% PEG处理下最佳。研究表明，短时间低浓度PEG处理对青稞种子萌发、幼苗生长及可溶性蛋白、叶绿素、丙二醛含量和相对电导率等生理指标的改善均有一定的促进作用；高浓度PEG处理却具有抑制作用，且高浓度PEG胁迫条件下，耐旱性强比耐旱性弱品种的自我调控能力更强。

In order to study the water tolerance of Quercus variabilis in seed germination stage,the effects of different concentrations (0%,5%,10%,20%,30%) of PEG stress on seed germination,growth,protective enzyme activities and the organic osmoregulation substances were measured with choosing fresh cork oak seeds and using Petri dish and filter paper germination method.The correlation analyses were done between seed germination,radicle growth rate and PEG stress.The results showed that:(1)With the increasing of drought stress,seed germination rate,vigor index,germination index and radicle length of cork oak were all increased then decreased,showing that low concentration PEG stress (5%,10%) can promote the cork oak seed germination and growth,whereas high concentrations (20%,30%) had inhibition effects.(2)The regression equation between seed germination,radicle growth rate and PEG stress showed that the critical and the maximum value of the seed germination of Q.variabilis were 32.01% and 36.99%,while the corresponding radicle growth rates were 30.1% and 33.35% under the PEG stress.(3)With the increase of PEG concentration,three protective enzyme (SOD,POD and CAT) activities and contents of three kinds of organic osmoregulation substances were presented different responses,but had a same rising trend.Thus it can be seen that cork oak seeds increased protective enzyme activities and contents of osmotic regulation substances in vivo to adapt to the water stress,making the inhibition degree of germination and growth to the minimum.

为了阐明栓皮栎种子萌发期对水分胁迫的耐受性,以当年采集的栓皮栎种子为材料,采用培养皿滤纸萌发的方法研究了不同浓度（0%、5%、10%、20%、30%）PEG-6000溶液对其种子萌发、生长、保护酶活性和有机渗透调节物质的影响,并对种子萌发率、胚根生长速率等与PEG浓度进行了回归分析。结果表明:（1）随着干旱胁迫程度的加剧,栓皮栎种子的发芽率、发芽指数、胚根长度、胚根生长速率和活力指数均呈先升高后下降趋势,说明低浓度（5%、10%）PEG胁迫可以促进栓皮栎种子萌发及生长,而高浓度（20%、30%）则具有抑制作用。（2）建立水分胁迫条件下种子萌发率、胚根生长速率等与PEG浓度的回归方程发现,栓皮栎种子在PEG胁迫下的萌发临界值和极限值分别为32.01%和36.99%,胚根生长速率的临界值和极限值分别为30.1%和33.35%。（3）随着PEG浓度的升高,栓皮栎种子中3种保护酶（SOD、POD、CAT）活性和3种有机渗透调节物质（可溶性蛋白、脯氨酸、可溶性糖）含量呈现不同的变化,但均有不同程度升高趋势。由此可见,栓皮栎种子可通过增加保护酶活性和体内渗透调节物质来适应水分胁迫环境,使自身萌发和生长受抑制程度降到最低。

以赣晚籼1号为材料,探讨了PEG预处理对水稻种子萌发期盐胁迫的缓解效应。结果表明,质量分数为0.1%～1.0%的NaCl溶液胁迫对水稻种子萌发有抑制作用,且随NaCl浓度的增加,水稻种子发芽率、发芽势、发芽指数、胚根长、胚芽长和胚鲜重均逐渐降低;在盐胁迫前采用10%PEG溶液浸种的各处理种子各发芽指标和胚生长指标均较蒸馏水浸种有所提高。说明PEG预处理可缓解盐胁迫对水稻种子萌发的抑制,即水稻在干旱胁迫与盐胁迫间存在交叉适应能力。

In order to provide the academic basis of application and popularization, morphological and physiological characteristics of Phalaris arundinacea cv. Picta under drought stress simulated by PEG6000 with different concentrations and different periods were studied in this experiment.  The results showed that the percentage of withered leaves, leaf relative electrolytic leakage, contents of MDA and free proline increased gradually; while content of water soluble protein declined firstly and then increased. SOD and POD activities welevated at begainning then declined. Above 7 parameters showed a significant positive correlation with PEG stress. However, the leaf relative water content decreased continuously and showed an obvious negative correlation with PEG stress. According to the morphological and physiological parameters under drought stress, P.arundinacea cv. Picta could be determined as a drought tolerance species and grew normally under moderate drought stress, but it would be damaged under severe drought stress.

采用PEG6000模拟干旱胁迫的方法，研究了不同质量浓度PEG6000胁迫不同时间后玉带草（Phalaris arundinacea cv.Picta）叶片的形态和生理特性的变化，分析玉带草的耐旱性，以期为玉带草的应用和推广提供理论基础。结果表明，在胁迫下玉带草的叶枯率、细胞膜透性、丙二醛含量、游离脯氨酸含量呈升高趋势，可溶性蛋白含量先降低后升高，超氧化物歧化酶活性、过氧化物酶活性先升高后降低，且此7项指标均与胁迫质量浓度呈显著正相关；叶片含水量呈降低趋势，与胁迫质量浓度呈显著负相关。比较不同胁迫质量浓度下的形态和生理指标的变化，可以确定玉带草具有一定的耐旱性，但重度干旱胁迫会严重损伤玉带草。

In order to evaluate drought resistance of non-heading Chinese cabbage NILs (near isogenic line) of 11H lines characterized by leaf-lobed phenotype and 11B lines characterized by smooth margin phenotype, the leaf wilting index and physiological changes were examined in a hypertonic gradients created by PEG-6000. The results indicated that with the increase of PEG concentration, their leaf wilting index, water loss rate, relatively permeability of plasma membrane and content of malondialdehyde (MDA) increased gradually. All the indexes were significantly greater than the control (CK), while there was a greater increase in 11H compared with 11B.The leaf relative water content of 11B and 11H decreased gradually with the increase of PEG concentration. As for 11B, with the drought stress intensity increasing, the activity of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) showed the trend of increasing initially and then decreasing. Compared with 11B, the POD activity of 11 H increased primarily and then decreased, lastly maintain at a high level. The SOD and CAT activity of 11H increased gradually. At high concentration of PEG, the SOD and CAT activity of 11H were higher than that of 11B. After comparing the physiological characteristics between 11H and 11B at the different concentrations of PEG stress, we draw the conclusion that the drought-resistant ability of 11H was greater than 11B.

研究PEG模拟干旱胁迫下小白菜近等基因系叶缘深裂（11H）和叶缘全缘（11B）幼苗萎蔫指数和生理特性的变化。结果表明，随着PEG胁迫质量浓度增大，2种材料幼苗叶片的萎蔫指数、失水率、相对电导率及丙二醛（MDA）含量均呈上升趋势，显著大于对照（CK），且11B较11H上升幅度大；二者叶片相对含水量随干旱胁迫加重而逐渐下降，11B的下降幅度大于11H。11B的超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性随着胁迫增强均呈先较大程度上升后大幅度下降趋势；11H的POD活性先上升再下降，最终持续维持在较高水平，11H的SOD和CAT活性表现为持续上升的趋势。在高质量浓度PEG胁迫下，11H的SOD和CAT活性较11B高。综合比较不同质量浓度PEG胁迫下11H和11B的生理特性变化，确定11H抗旱能力强于11B。