Growth,Mineral Composition,and Biochemical Changes of Broad Bean as Affected by Sodium Chloride and Zinc Levels and Sources

Plants grown in salt‐affected soils may suffer from limited available water, ion toxicity, and essential plant nutrient deficiency, leading to reduced growth. The present experiment was initiated to evaluate how salinity and soil zinc (Zn) fertilization would affects growth and chemical and biochemical composition of broad bean grown in a calcareous soil low in available Zn. The broad bean was subjected to five sodium chloride (NaCl) levels (0, 10, 20, 30, and 40 m mol kg^?1 soil) and three Zn rates [0, 5, and 10 mg kg^?1 as Zn sulfate (ZnSO₄) or Zn ethylenediaminetetraaceticacid (EDTA)] under greenhouse conditions. The experiment was arranged in a factorial manner in a completely randomized design with three replications. Sodium chloride significantly decreased shoot dry weight, leaf area, and chlorophyll concentration, whereas Zn treatment strongly increased these plant growth parameters. The suppressing effect of soil salinity on the shoot dry weight and leaf area were alleviated by soil Zn fertilization, but the stimulating effect became less pronounced at higher NaCl levels. Moreover, rice seedlings treated with ZnSO₄ produced more shoot dry weight and had greater leaf area and chlorophyll concentration than those treated with Zn EDTA. In the present study, plant chloride and sodium accumulations were significantly increased and those of potassium (K), calcium (Ca), and magnesium (Mg) strongly decreased as NaCl concentrations in the soil were increased. Moreover, changes in rice shoot Cl^?, Na⁺, and K⁺ concentrations were primarily affected by the changes in NaCl rate and to a lesser degree were related to Zn levels. The concentrations of Cl^? and Na⁺ associated with 50% shoot growth suppression were greater with Zn‐treated plants than untreated ones, suggesting that Zn fertilization might increase the plant tolerance to high Cl^? and Na⁺ accumulations in rice shoot. Zinc application markedly increased Zn concentration of broad bean shoots, whereas plants grown on NaCl‐treated soil contained significantly less Zn than those grown on NaCl‐untreated soil. Our study showed a consistent increase in praline content and a significant decrease in reducing sugar concentration with increasing salinity and Zn rates. However, Zn‐treated broad bean contained less proline and reducing sugars than Zn‐untreated plants, and the depressing impact of applied Zn as Zn EDTA on reducing sugar concentration was greater than that of ZnSO₄. In conclusion, it appears that when broad bean is to be grown in salt‐affected soils, it is highly advisable to supply plants with adequate available Zn.     

大豆根部水压胁迫耐逆指数遗传体系解析

大豆是重要的植物蛋白质和植物油脂来源,干旱是影响大豆产量的重要环境因子之一。为解析大豆耐旱性的遗传基础,本研究在PEG水压胁迫条件下,对由409个家系组成的巢式关联作图群体(具有1个共同亲本的2个重组自交系群体组成)进行叶片脯氨酸含量测定,通过限制性二阶段多位点全基因组关联分析(restrictivetwo-stagemultilocus genome-wide association study,RTM-GWAS),解析了大豆根部水压胁迫耐逆指数(root hydraulic stress tolerance index,RHSTI)的遗传体系。结果表明,在春季和夏季环境下,3个亲本蒙8260(共同亲本)、通山薄皮黄豆甲和正阳白毛平顶在RHSTI上均存在显著差异,其衍生群体RHSTI表型变异丰富,变幅分别为0.11~2.94和0.03~1.93,遗传力分别为97.7%和97.9%;2个环境联合分析发现,家系遗传力和家系与环境互作遗传力分别为37.9%和60.1%,说明群体RHSTI的变异受遗传和环境共同控制。通过RTM-GWAS方法,共检测到45个与RHSTI相关的QTL,分布在大豆18条染色体上,可以解释37.58%的表型变异,其中7个QTL的表型贡献率超过1%,为大贡献位点;这些QTL中,有34个位点与环境存在显著互作,可以解释12.50%的表型变异。结合PEG胁迫下大豆转录组数据,在定位区间500kb范围内共筛选到38个差异表达基因,可归为ABA响应因子、逆境响应因子、转录因子、发育因子、蛋白代谢因子、未知功能和其他等7类,其中逆境响应因子、转录因子和发育因子是最大的3类;其中位于主效位点的6个基因,与ABA响应因子、逆境响应因子、转录因子相关,应为主要候选基因。上述结果表明,大豆耐旱性是一个由多位点、多基因控制的复杂数量性状,且与环境存在互作,遗传基础复杂。研究结果为大豆耐旱性分子育种提供了依据。     

分蘖期水分对香稻香气及生理特性的影响

以常规香稻品种桂香占和美香占为材料,采用盆栽试验,研究了分蘖期水分对香稻香气及生理特性的影响。结果表明,分蘖期土壤水势维持在0～(-25±5)kPa时,显著增加了二香稻品种糙米的香气成分和籽粒的游离脯氨酸以及成熟期叶片、茎鞘和籽粒的脯氨酸氧化酶活性。分蘖期土壤水势维持在0～(-50±5)kPa时,降低了二品种籽粒脯氨酸氧化酶活性、糙米的香气成分和有效分蘖。因此,适当的分蘖期节水灌溉模式能有效提高香稻香气成分,且不影响水稻后期生理特性。     

多年生黑麦草P5CS基因的定点突变及其在拟南芥中的转化

 在前期克隆获得Lp5CS基因的全长ｃＤＮＡ 序列基础上,采用ＰＣＲ 扩增技术对多年生黑麦草脯氨酸合成酶基因p5CS的定点突变体系进行了探讨,并运用农杆菌转化技术对突变后的基因进行了功能验证。根据突变位点序列设计一对引物,使用Ｐｆｕ高保真ＤＮＡ 聚合酶和超级感受态细胞ＤＭＴ,通过ＰＣＲ 扩增,获得含有所要突变位点的犔狆犘５犆犛Ｆ１２８Ａ,定向克隆入真核表达载体ｐＣＡＭＢＩＡ１３００中,转化拟南芥验证基因功能。结果表明,预期位点上发生了突变,Lp5CS编码的第１２８位密码子已由苯丙氨酸残基（Ｐｈｅｎｙｌａｌａｎｉｎｅ,简称Ｐｈｅ或Ｆ）变为丙氨酸残基（Ａｌａｎｉｎｅ,Ａｌａ）,证明用ＰＣＲ 技术已成功地使Lp5CS基因发生定点突变。转基因拟南芥Ｔ１ 代植株进行ＰＣＲ和ＲＴ－ＰＣＲ检测,获得４个转基因阳性株系。拟南芥Ｔ２代植株经１００ ｍｍｏｌ／Ｌ ＮａＣｌ处理７ｄ后,转基因株系脯氨酸含量分别为４２６２和５６２３μｇ／ｇＦＷ,显著高于野生型株系的２５８１μｇ／ｇＦＷ。说明转基因株系能积累更多地脯氨酸。     

干旱对玉米植株K~+分布及叶片游离脯氨酸积累的影响

在干旱条件下,玉米茎或下位叶内的K~+向上位叶转移,叶片中的游离脯氨酸浓度显著增加,尤以抗旱型杂交种最为显著。在正常供水或干旱条件下,抗旱型杂交种根系含K~+量显著高于敏感型杂交种。作者认为,游离脯氨酸的积累量和根系的含K~+量可能是筛选抗旱型玉米品种的生理指标。     

盐胁迫对石榴和樱桃脯氨酸含量和硝酸还原酶活性及电导率的影响

本文以石榴和樱桃为试验材料,测定两树种在不同盐浓度胁迫下的3个生理指标的反应。樱桃受低盐胁迫时，能大量迅速合成脯氨酸。低盐胁迫并没有刺激石榴叶片内脯氨酸酸的合成，高盐胁迫刺激了石榴叶片内脯氨酸的合成。石榴和樱桃受盐胁迫时，硝酸还原酶的活性均有显著提高。盐协迫伤害了细胞膜，使膜透性增大，这种盐害反应比较缓慢。     

高温对黄瓜幼苗生长、脯氨酸含量及SOD酶活性的影响

研究了高温胁迫对耐热性不同的黄瓜品种幼苗生长及子叶电导率、脯氨酸含量和超氧物歧化酶活性的影响。结果表明 ,在高温胁迫下不耐热品种幼苗生长明显受阻 ,子叶相对电导率大幅度提高 ,而耐热品种幼苗生长未受到明显影响 ,子叶细胞膜稳定性较高。耐热品种在常温或高温下 ,子叶游离脯氨酸含量和超氧物歧化酶活性均高于不耐热品种     

盐胁迫对阿月浑子可溶性糖、淀粉、脯氨酸含量的影响

本研究用NaCl和Na2SO4处理两个阿月浑子品种,处理浓度均为50,150,250,500mmol·L-1,盐胁迫5,10,20d后取叶样,并测定可溶性糖、淀粉、脯氨酸含量变化。NaCl,Na2SO4胁迫下,长果和Kerman叶片内可溶性糖含量明显增高,借此来维持细胞内的渗透平衡,其中Kerman植株中可溶性糖含量增加幅度大,而长果增加幅度较小;叶片内淀粉含量略有增高,使其能够维持一定的渗透平衡,其中Kerman植株中淀粉含量增加幅度大,长果的增加幅度相对较小;叶片内脯氨酸(Pro)含量迅速上升,来维持渗透平衡,当阿月浑子植株受到盐胁迫时,叶片中的Pro含量成倍增长。     

水分胁迫对刚毛柽柳可溶性蛋白、可溶性糖和脯氨酸含量变化的影响

本研究在土壤相对含水量分别为90％，70％，50％，30％，10％时，探讨了刚毛柽柳（Tamarix hispida）同化枝中可溶性蛋白、可溶性糖和脯氨酸含量的变化规律，并分析了三者之间的关系。结果表明，在土壤相对含水量逐渐减少时，刚毛柽柳同化枝中可溶性糖、脯氨酸含量持续升高，但前者的增幅明显小于后者。可溶性蛋白的变化规律则有所不同，土壤相对含水量从90％减小到70％时，可溶性蛋白含量开始小幅增加；随着水分胁迫加深，可溶性蛋白急剧增加，在土壤相对含水量为30％时达到最大；而当土壤相对含水量下降到10％时，可溶性蛋白开始分解，含量迅速下降。蛋白质的双向电泳图谱表明，当土壤相对含水量从70％减小到50％时，刚毛柽柳中出现了至少4个新的蛋白点。水分胁迫下可溶性糖和脯氨酸的积累为刚毛柽柳体内与抗旱有关的新蛋白的表达提供了物质基础，增强了刚毛柽柳的抗旱性。     

Silicon application positively alters pollen grain area,osmoregulation and antioxidant enzyme activities in wheat plants under water deficit conditions

Role of exogenously-applied silicon (Si) on antioxidant enzyme activities was investigated in wheat under drought stress using a completely randomized factorial design with four replications. Drought stress significantly enhanced activities of ascorbate peroxidase, peroxidase, superoxide dismutase and catalase, and elevated accumulation of osmotically active molecules, soluble sugars and proline. Si application further enhanced activities of enzymes involved in oxidative defense system and accumulation of osmotically active molecules in drought-stressed plants. Under drought stress conditions, water shortage decreased protein content in all cultivars; however, application of Si increased it. Pollen area ratio was lower than 1 for cvs. Shiraz and Marvdasht under drought, but greater than 1 for cvs. Chamran and Sirvan. Water-limited regimes resulted in decreased leaf Ψ_w in all cultivars, but Si supply was effective in improving Ψ_w under water-limited regimes. Water shortage increased leaf K, Mg, and Ca concentrations. Under drought stress, Si-treated plants had higher K concentration than the none-treated plants.