Effect of NaCl and Proline on Bean Seedlings Cultured in vitro

Effects of NaCl (150 mM), proline (10 mM) and their combination on growth and contents of chlorophyll, proline and protein of bean (Phaseolus vulgaris cv. Kizilhaç) seedlings in vitro were investigated. NaCl decreased seedling growth. Proline added to control seedlings did not change seedling growth but decreased chlorophyll and increased protein contents. When proline added to NaCl-treated seedlings growth was increased in comparison with NaCl-treated only. Thus, proline alleviated salinity stress in bean seedlings.     

Bean lectins

Summary The relationship between the polypeptide composition and the agglutination behaviour of the lectin-containing G2/albumin protein groups has allowed the identification of the active lectin polypeptides in different cultivars of Phaseolus vulgaris (Brown et al. accompanying paper). These results were used to ascertain the particular G2/albumin group contained in the various lectin sources used previously for the purification of lectin proteins. Many studies were found to have included lectin sources which contained the same G2/albumin pattern (T_G2) and this common denominator has permitted the direct comparison of the properties reported for these purified lectins. Thus, much of the extensive literature on bean lectins is concurred.     

Effects of Brassmosteroids on Growth, Nodulation, Phytohormone Content and Nitrogenase Activity in French Bean Under Water Stress

Effect of pre-treatments of 1 and 5 M epibrassinolide or homobrassinolide prior to water stress induction on changes in root nodulation and contents of endogenous abscisic acid (ABA) and cytokinin trans-zeatin riboside (ZR), and nitrogenase activity was investigated in the nodulated roots of Phaseolus vulgaris L. cv. Arka Suvidha. Brassinosteroids in the unstressed plants increased root nodulation, ZR content and nitrogenase activity, and also ameliorated their stress-induced decline in the nodulated roots. The ABA contents in the nodules of control or stressed plants were not altered by brassinosteroids treatment. There was an increase in pod yield by brassinosteroids treatment (5 M) in the irrigated control as well as stressed plants without influencing pod number or pod length. Among the brassinosteroids, epibrassinolide was relatively more effective.     

Proline metabolism in response to nitrogen deficiency in French Bean plants (Phaseolus vulgaris L. cv Strike)

The objective of the present work was to determine the impact ofnitrogen deficiency on proline metabolism in French Bean plants(Phaseolus vulgaris L. cv. Strike). The nitrogen wasapplied to the nutrient solution in the form of NH₄NO₃ at1.45 mM (N1), 2.90mM (N2) and 5.80mM (N3, optimal level). Our results indicateNdeficiency is characterised by a decline in proline accumulation both in theroot and leaves, fundamentally because proline degradation is encouraged by thestimulation of the enzyme proline dehydrogenase. By contrast, under conditionsof adequate N (N3), proline levels rise due to the action of ornithine,suggesting predominance of the ornithine pathway over the glutamine pathway, inaddition to the inhibition of proline dehydrogenase activity.     

甘蓝型油菜苗期生长阶段对NaCl胁迫的生理响应

以甘蓝型油菜自交系2205(强耐盐型)、487(中耐盐型)和1423(敏盐型)为材料,采用土培+水培方法于五叶期研究了0(无盐胁迫,CK)、60 mmol·L-1(低盐)、120 mmol·L-1(中低盐)、180 mmol·L-1(中盐)、240mmol·L-1(高盐)NaCl胁迫后的叶片MDA、可溶性糖、甜菜碱和叶绿素含量的变化特征,为油菜耐盐性评价提供理论依据。结果显示:(1)叶片MDA含量在低盐和中低盐胁迫下降低且显著低于CK,在中盐和高盐胁迫下显著升高,并以品系2205含量最低且升幅最小,品系1423最高且升幅最大。(2)叶片可溶性糖含量在低盐和中低盐胁迫下减少(但2205在中低盐胁迫下显著高于CK),在中盐和高盐胁迫下升高且显著高于CK,并以品系2205含量最高增幅最大且显著高于品系487和1423,品系1423含量最低且增幅最小。(3)叶片甜菜碱含量随NaCl浓度升高增加,品系2205和487在中低以上盐浓度胁迫下显著升高,品系1423仅在高盐胁迫下显著升高,并以品系2205含量最高且增幅最大,1423含量最低且增幅最小。(4)叶片叶绿素含量在低盐和中低盐胁迫下显著增加,且以2205叶片叶绿素含量最高且增幅最大,但在中盐和高盐胁迫下显著减少,并以品系1423含量最低且降幅最高。研究表明,120mmol·L-1以下NaCl胁迫对油菜苗期生长可能有促进作用,180mmol·L-1以上NaCl胁迫则有明显抑制作用,且NaCl浓度越高油菜受伤害越重;油菜苗期生长阶段,NaCl胁迫浓度在120~180mmol·L-1时各生理指标发生显著变化,可能是鉴定耐盐性强弱的适宜浓度;综合分析认为,品系2205具有强的耐盐性,品系1423耐盐性最差,这与之前萌芽期和幼苗期鉴定结果一致。     

NaCl对小麦苗叶片脯氨酸氧化酶活性和游离脯氨酸累积的影响

在含NaCl营养液中培养的小麦幼苗较之无NaCl营养液中的幼苗。其脯氨酸氧化酶活性降低,而游离脯氨酸含量则升高;培养液的渗透势越低,培养时间越长,则脯氨酸氧化酶的活性越低,且游离脯氨酸的含量越高。去除胁迫后酶活性恢复,脯氯酸含量下降。不同渗透剂对氧化酶活性抑制强弱顺序为MgCl_2>NaCl>甘露醇,引起脯氨酸累积效应的强度顺序为MgCl_2>NaCl>甘露醇。超微结构显示,高NaCl浓度下部分线粒体结构受损伤,膜和嵴部分消失。     

Effect of NaCl on Biomass and Contents of Sugars, Proline and Proteins in Seedlings and Leaf Explants of Nicotiana tabacum Grown in vitro

Effects of NaCl on growth in vitro and contents of sugars, free proline and proteins in the seedlings and leaf explants of Nicotiana tabacum cv. Virginia were investigated. The fresh and dry mass of the seedlings decreased under salinity. These growth parameters in leaf explants decreased at 50 mM NaCl and increased up to 150 mM NaCl and then decreased at higher level of salinity. Free proline content in both seedlings and leaf explants increased and polysaccharide content decreased continuously with increasing of NaCl concentration. Reducing sugars, oligosaccharides, soluble sugars and total sugars contents in both seedlings and leaf explants decreased up to 150 mM NaCl and then increased at higher concentrations of NaCl.     

外源ABA对楸树幼苗NaCl胁迫的缓解效应及其生长生理响应特征

以2年生楸树(苏楸1号和008-1)扦插苗为材料,采用盆栽试验法,分析盐胁迫(0.5%NaCl)处理下楸树幼苗生长、生理的变化,并分析不同浓度外源ABA(15、25、35 mg/L)对盐胁迫(30 d)楸树幼苗的缓解效应及其生理生化特性,以探索重度盐胁迫下适合楸树幼苗生长的适宜外源ABA浓度,为增强盐碱地楸树的耐盐性、提高盐碱地的利用提供理论依据。结果显示:(1)0.5%NaCl胁迫下,两品种楸树幼苗叶片表现出不同程度的盐害症状,且‘苏楸1号’叶片盐害症状较‘008-1’严重;随胁迫时间延长,两品种楸树幼苗的相对电导率(REC)均呈先上升后下降的变化趋势,叶绿素(Chl)、相对含水量(RWC)均呈降低趋势,可溶性糖(SS)、可溶性蛋白(SP)、脯氨酸(Pro)以及超氧化物歧化酶(SOD)活性均呈先上升后下降趋势,但‘008-1’的REC显著低于‘苏楸1号’,Chl、RWC、SS、SP、Pro、SOD均显著高于苏楸1号,表明‘008-1’的耐盐性较‘苏楸1号’更强。(2)喷施外源ABA使得盐胁迫下‘008-1’楸树的苗高显著增加、新叶提前萌发,表明外源ABA在一定程度上能够缓解盐胁迫对楸树生长的影响;喷施外源ABA降低了盐胁迫下‘008-1’楸树幼苗叶片的REC,提高了Chl、RWC、SS、SP、Pro、SOD、过氧化物酶(POD)以及过氧化氢酶(CAT)活性,促进了内源激素生长素(IAA)、脱落酸(ABA)、赤霉素(GA3)以及玉米素核苷(ZR)的积累。研究表明,楸树品种‘008-1’的耐盐性更强;外源喷施适宜浓度ABA能够缓解盐胁迫对楸树幼苗生长的影响,降低幼苗叶片细胞膜透性,促进幼苗渗透调节物质的积累,增强渗透调节能力,并提高盐胁迫下幼苗的抗氧化酶活性,促进植物对内源激素含量的调节,从而提高楸树的耐盐性,且以25 mg/L ABA处理的效果最好。     

NaCl胁迫对苦豆子幼苗光合机构及生物量积累的影响

该研究通过测定盐生药用植物苦豆子幼苗气体交换、叶绿素荧光参数及生长指标,研究了中度(200mmol/L NaCl)和重度(400mmol/L NaCl)盐胁迫对其生长特性的影响,探讨盐生植物对盐化环境的生理响应机制。结果显示:(1)中度盐胁迫1d后,苦豆子幼苗光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)及胞间二氧化碳浓度(C_i)显著低于对照,随着胁迫时间延长,P_n下降显著,而气体交换参数降低不明显,C_i值甚至有上升趋势;重度盐胁迫处理1d后,苦豆子气体交换值出现了显著降低,随着胁迫时间延长,降低程度增大;中度盐胁迫导致苦豆子光合速率出现下降的原因是由气孔因素和非气孔因素共同作用的结果,而重度盐胁迫下,Pn的下降主要是非气孔因素引起的。(2)处理1d后,相对于对照组,中度和重度盐胁迫下的苦豆子幼苗最大光化学效率(F_v/F_m)、光化学猝灭系数(qP)、实际光化学效率(Φ_(PSⅡ))出现了不同程度的降低,而重度盐胁迫下降低更加显著;处理5d后,中度盐胁迫荧光参数变化不明显,但重度盐胁迫处理下降低显著。(3)随着胁迫程度的加重,幼苗含水量及生长指标(株高、根长、干重)降低幅度加大,以致严重抑制了植株生长。研究表明,盐生植物苦豆子对盐胁迫的耐受性也有一定限度,其在200mmol/L NaCl胁迫下植株光合作用受到轻微抑制,但能维持正常生长,而在400mmol/L NaCl胁迫下光合生理受到严重抑制,且随着胁迫时间的延长,受到伤害程度加重,甚至死亡。     

Influence of Drought,High Temperature,and Carbamide Cytokinin 4-PU-30 on Photosynthetic Activity of Bean Plants. 1. Changes in Chlorophyll Fluorescence Quenching

Fifteen-day-old bean plants (Phaseolus vulgaris L.) grown in a climatic chamber were exposed to water deficit (WD) and high temperature (HT) stresses applied separately or in combination. Changes in chlorophyll fluorescence quenching were investigated. Bean plants that endured mild (42 °C, 5 h for 2 d) WD separately or in combination with HT did not change their q_P and q_N quenching (measured at 25 °C) compared with those of the control. After 5 min testing at 45 °C, q_P in control and droughted plants strongly decreased, while q_P of plants that experienced combined WD+HT stress was insignificantly influenced, suggesting the acclimation effect of HT treatments. At more severe stresses (after 3 d-treatment), q_P measured at 25 °C was the lowest in WD+HT plants and q_N values were the highest. But when measured at 45 °C, q_P of WD+HT plants had practically the same values as at 25 °C. Under these conditions q_P of WD plants also showed an adaptation to HT. Twenty-four hours after recovery, the unfavourable effects of the stresses were strongly reduced when measured at 25 °C, but they were still present when measured at 45 °C. Positive effect of the carbamide cytokinin 4-PU-30 was well expressed only in droughted plants. This revised version was published online in June 2006 with corrections to the Cover Date.     

Bean lectins

Summary Seeds of forty bean cultivars having different lectin types based on two-dimensional isoelectric focusing-sodium dodecyl sulfate polyacrylamide gel electrophoresis (IEF-SDS/PAGE) were analyzed for quantities of lectin, phaseolin and total protein. Significant differences were found among groups of cultivars with different lectin types for the quantity of lectin and phaseolin. Cultivars with more complex lectin types based on IEF-SDS/PAGE tended to have higher quantities of lectin and lower quantities of phaseolin than cultivars with simple lectin types. An association between lectin type and the quantity of lectin and phaseolin was found also in the seeds of F₂ plants that segregated in a Mendelian fashion for two lectin types. Seeds from plants with the complex lectin type had more lectin and less phaseolin than seeds from plants with the simple lectin type. Therefore, the genes controlling qualitative lectin variation also may influence the quantitative variation of lectin and phaseolin. The results of this study are related to other studies on the quantitative variation for seed proteins and to the possible molecular basis for variation in the quantity of lectins in beans.     

Bean lectins

Summary Single seeds of over 100 bean cultivars were analyzed by two-dimensional electrophoresis. The cultivars could be classified into eight groups by virtue of their G2/albumin electrophoretic patterns: T_G2, S_G2, V_G2, Pr_G2, B_G2, M_G2, P_G2, and Pi_G2, The polypeptide compositions of these types were largely inter-related having particular polypeptides in common. It was possible to correlate the G2/albumin patterns with agglutinating activity of cow and rabbit blood cells as measured by the agglutination ratio (minimum concentration of extract required to agglutinate cow blood cells: minimum concentration of extract required to agglutinate rabbit blood cells). The active lectin polypeptides were identified by extracting lectins from agglutinated erythrocytes and by comparing the qualitative similarities and differences of the G2/albumin patterns and their agglutination activities. A reference catalogue of over 100 bean cultivars giving their phaseolin and G2/albumin electrophoretic patterns, and agglutination ratios is presented.     

Bean arcelin

Summary Crude proteins from seeds of wild bean accessions of Mexican origin were analyzed by one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS/PAGE). Several accessions had electrophoretic patterns showing unique protein bands. When analyzed by two-dimensional isoelectric focusing (IEF)-SDS/PAGE, four protein variants which had electrophoretic mobilities similar to each other but different from the other major seed proteins, phaseolin and lectin, were observed. All four variants, which have not been described in cultivated beans, were tentatively named arcelin proteins and designated as arcelin 1, 2, 3 and 4. Arcelins 3 and 4 had polypeptides that comigrated on two-dimensional gels and these variants occurred in accessions that were collected in the same location. Analysis of single F₂ seeds from crosses among arcelin-containing lines and from crosses between cultivated beans lines without arcelin and arcelin-containing lines revealed that differences in arcelin polypeptide expression were inherited monogenically. The alleles for different arcelin variants were codominant to each other and dominant to the absence of arcelin. The gene(s) controlling arcelin proteins were unlinked to those controlling phaseolin expression and tightly linked to genes controlling the presence of lectin proteins (< 0.30% recombination). The possible origins of arcelin genes and their potential role in bruchid resistance are discussed.     

Bean arcelin

Summary SDS-PAGE of seed proteins from the seeds of a nondomesticated bean of Mexican origin (Phaseolus vulgaris L., PI 325690) revealed the presence of a novel 38 kd protein which appeared to be neither an altered phaseolin nor a lectin fraction. The protein was named arcelin, after Arcelia, the town in the state of Guerrero near which PI 325690 had been collected. The pure line, UW 325, was derived by self fertilization of the plant from a single arcelin-containing seed of PI 325690. Despite a low percentage seed phaseolin (14.6%), seed phenotype, seed germination, plant growth, pollen fertility, and percentage seed protein of UW 325 were normal. Analyses of F₂ and F₃ seeds from a single F₁ plant of the cross SanilacXPI 325690-3 revealed that arcelin expression was inherited as a single gene and that presence was dominant to absence of arcelin. The mean percentage phaseolin in the seeds of homozygous dominant Arc/Arc F₃ families (14.0%) was significantly lower than that of the homozygous recessive arc/arc seeds (44.7%). The distribution of percentage phaseolin values for seeds within segregating families was bimodal and nonoverlapping. Without exception, seeds containing arcelin (Arc+phenotype) contained a lower percentage phaseolin than seeds lacking arcelin (Arc-phenotype). Although arcelin presence was associated with low percentage phaseolin, the Arc/Arc and Arc/arc genotypes were similar for seed weight and percentage total seed protein.     

外源脯氨酸对盐胁迫下甜瓜脯氨酸代谢的影响

为探明外源脯氨酸对盐胁迫下甜瓜脯氨酸代谢的影响,以甜瓜品种‘雪美’为材料采用营养液栽培,对盐胁迫(100mmol·L-1 NaCl)、盐胁迫下添加外源脯氨酸(100mmol·L-1 NaCl+0.2mmol·L-1 Proline)以及对照3种处理后甜瓜幼苗叶片脯氨酸(Pro)含量、吡咯啉-5-羧酸合成酶(P5CS)、鸟氨酸转氨酶(OAT)和脯氨酸脱氢酶(ProDH)活性进行测定,并对OAT和ProDH基因进行克隆及半定量表达分析。结果显示:与对照相比较,盐胁迫条件下甜瓜幼苗叶片内Pro含量显著增加,P5CS活性增幅大于OAT活性,OAT基因表达量大部分时段内没有增加,ProDH活性下降,ProDH基因表达量减少;盐胁迫下添加外源脯氨酸进一步使幼苗叶片内Pro含量增加、OAT、ProDH活性提高、P5CS活性降低,并且使OAT基因表达量迅速增加、ProDH基因表达量先增加后回落。研究表明,盐胁迫条件下,甜瓜幼苗体内脯氨酸积累主要是通过增强脯氨酸的谷氨酸合成途径和抑制脯氨酸降解来实现;适量外源脯氨酸可以增强盐胁迫幼苗脯氨酸的鸟氨酸合成途径,但对谷氨酸合成途径有一定的抑制作用;通过调节合成和降解2种代谢途径进一步提高了脯氨酸含量,从而增强甜瓜幼苗耐盐胁迫能力。     

逆境胁迫对菜豆黄化苗转绿过程中交替呼吸途径与叶绿素荧光特征的影响

以菜豆黄化幼苗作为试验材料,探讨了铅(Pb)或PEG(聚乙二醇)胁迫下交替呼吸途径在植物转绿过程中对叶绿素含量以及叶绿素荧光特性的影响,以阐明逆境胁迫下植物交替呼吸途径的生理学作用。结果显示：(1)与菜豆黄化幼苗正常转绿过程(对照)相比,Pb或PEG胁迫导致菜豆黄化幼苗的叶绿素含量积累延迟,使叶片PSⅡ潜在最大光化学量子效率(F_v/F_m)、光适应下最大光化学效率(F_v′/F_m′)、PSⅡ光适应下实际光化学效率(Y(Ⅱ))和光化学荧光猝灭系数(qP)显著下降,而非光化学猝灭系数(NPQ)则显著增加。(2)在菜豆黄化幼苗转绿过程中,Pb或PEG胁迫导致其交替呼吸途径容量较对照均显著上升。(3)Pb或PEG胁迫下,交替呼吸途径抑制剂［水杨基氧肟酸(SHAM,1 mmol/L)］使菜豆黄化幼苗转绿过程中叶绿素含量、F_v/F_m、F_v′/F_m′、Y(Ⅱ)和qP进一步下降, NPQ却进一步增加,说明抑制交替呼吸途径会加剧Pb或PEG胁迫对PSⅡ反应中心活性的进一步抑制,使还原力积累加剧,造成热耗散进一步增加。研究表明,Pb或PEG胁迫均显著降低了菜豆黄化幼苗PSⅡ对光能的利用率,进而阻碍了菜豆黄化幼苗转绿进程;交替呼吸途径有助于在胁迫条件下缓解PSⅡ的过度还原,可能在一定程度上缓解了Pb或PEG胁迫对其转绿进程的阻碍作用。     

Pre-Treatment of Bean Seedlings with Choline Compounds Increases the Resistance of Photosynthetic Apparatus to UV-B Radiation and Elevated Temperatures

Bean (Phaseolus vulgaris L. cv. Berbukskaya) seedlings were pre-treated with choline compounds, 19 mM 2-ethyltrimethylammonium chloride (Ch) or 1.6 mM 2-chloroethyltrimethylammonium chloride (CCh), during 24 h, then after 6 d the excised primary leaves were exposed to UV-B and high temperature stress. Chlorophyll (Chl) fluorescence, delayed light emission, accumulation of photosynthetic pigments, contents of thiobarbituric acid reactive substances, and activities of the active oxygen detoxifying enzymes (superoxide dismutase, ascorbate peroxidase, and glutathione reductase) were examined. Pre-treatment of plants with Ch or CCh enhanced the resistance of photosystem 2 (PS2) photochemistry to UV-B and heat injuries. The higher stress resistance can be explained by the increased activity of the detoxifying enzymes. The increased content of UV-B-absorbing pigments may also contribute to the enhanced resistance of choline-treated plants to UV-B radiation.     

Changes in Antioxidative Protection in Bean Cotyledons During Natural and Continuous Irradiation-Accelerated Senescence

We employed continuous irradiation (CL) for induction of premature senescence caused by enhanced production of reactive oxygen species. As a model plant we used bean (Phaseolus vulgaris L. cv. Jantar) cotyledons because they have well defined and a quite short life span. Senescence of bean cotyledons induced by CL progressed more rapidly than natural senescence: the life span of CL cotyledons was 13 d compared to 16 d in controls (C). Chl content was significantly lower in 10- and 13-d-old CL plants than in C plants and the change with age was not statistically significant. Activities of all antioxidative enzymes declined either with senescence onset or during whole life span. Activity of antioxidative enzymes, except ascorbate peroxidase, was lower in CL plants compared to C plants. On the contrary, contents of non-enzymatic antioxidants -carotene and ascorbate were higher in CL plants than in C plants. No significant difference, except in the youngest cotyledons, was observed in glutathione content.     

Effects of kelp (Macrocystis integrifolia) on soil chemical properties and crop response

In 1981 a two-year field plot experiment was established to assess the effects of quantities (0, 7.5, 15, 30, 60 and 120 t ha⁻¹) of fresh kelp (Macrocystis integrifolia) on crop growth and nutritional response and chemical properties of a fine-textured soil. Soil was analyzed for NO₃−N, NH₄−N, electrical conductivity, pH, Cl and exchangeable cations (K, Mg, Ca, Mn and Na). The plots were planted to beans (Phaseolus vulgaris) in the first year and peas (Pisum sativum) in the second year. Marketable bean yields increased in the first year with kelp applications up to 60 t ha⁻¹, with yields, emergence and flowering being reduced by the 120 t ha⁻¹ application. Soluble salts (EC) and Cl concentrations in the soil eight days after application increased linearly and sharply with increasing quantities of kelp. Increased K concentration and moisture content, characteristics of plants growing in a salt-stressed soil environment, were measured. A subsequent companion greenhouse experiment confirmed that the reduced bean emergence and growth with 120 t ha⁻¹ applications of kelp were primarily due to soluble salts. The only growth effects upon peas in the second year was a slight reduction in leaf plus stem yields with increasing applications of kelp.     

Amelioration of NaCl Stress by Arginine in Rice Seedlings: Changes in Endogenous Polyamines

Effects of NaCl (0.1 – 0.2 M) alone or in combination with 1 mM arginine on growth and endogenous polyamine (PA) content have been observed in two cultivars of rice differing in NaCl stress tolerance. The germination, seedlings fresh mass and water content decreased with increase in salinity in both the cultivars. This inhibition was partially alleviated by application of arginine. Cv. CSR-27 exhibited relatively better germination than cv. Bas-370 at different salinities. Total PA content increased in both the cultivars under NaCl stress alone and in combination with arginine. Putrescine to spermidine and spermine ratio was higher in NaCl-treated seedlings being more in cv. Bas-370 as compared to cv. CSR-27 and the ratio reversed to almost control level when arginine was applied along with NaCl.