星星草脂氧合酶基因家族鉴定及生物信息学分析

星星草（Puccinellia tenuiflora）具有较强的耐盐碱特性，是改良土壤盐碱化的优良牧草。脂氧合酶（Lipoxygenase，LOX）广泛存在于动植物中，催化多不饱和脂肪酸的双加氧反应，最终生成各种氧脂素，从而在植物生长发育、响应逆境胁迫中发挥重要的生物学功能。目前，星星草中的LOX家族基因仍未见报道。本研究利用生物信息学方法对PutLOX基因家族成员进行鉴定，并对其理化性质、亚细胞定位和系统进化进行了分析。结果表明，星星草基因组中共有8个LOX基因，它们均具有Lipoxygenase homology 2（beta barrel）（简称LH2）和Lipoxygenas结构域，均不包含跨膜结构域，预测定位于细胞质或叶绿体。系统发生分析表明PutLOXs蛋白分为9-LOX和13-LOX两个亚家族，并且与水稻和玉米这类单子叶植物的LOXs系统发生关系更近。本研究将为后期深入解析星星草耐盐碱分子机制提供理论依据。     

拒盐型盐生植物小花碱茅肌动蛋白基因片段的克隆及序列分析

本研究根据其它植物Actin基因的保守序列设计一对简并性引物，以拒盐型盐生植物小花碱茅根部总RNA为模板，采用RT-PCR的方法扩增出Actin基因片段并克隆到PUCm-T载体，阳性克隆经PCR检测后进行测序，在GenBank中注册；序列分析结果表明：该片段长约600bp，编码198个氨基酸；所得序列与GenBank中注册的其它植物Actin基因序列同源性均在84％以上，与其它肌动蛋白的氨基酸序列同源性达94％以上。     

The Key Physiological Response to Alkali Stress by the Alkali‐Resistant Halophyte Puccinellia tenuiflora is the Accumulation of Large Quantities of Organic Acids and into the Rhyzosphere

Eight‐week‐old seedlings of Puccinellia tenuiflora were stressed by exposure to 1 : 1 molar ratio mixtures either of the two neutral salts NaCl and Na₂SO₄ or of the two alkali salts, NaHCO₃ and Na₂CO₃. To identify the physiological mechanisms involved in this plant’s resistance to alkali stress, the relative growth rates, the quantities and compositions of organic acids accumulated and secreted through the roots into the rhyzosphere, the concentrations of inorganic ions, proline and other solutes accumulating in the shoots were measured. The results show that the organic acid constituents in the shoots and roots were much the same. These were predominantly malic acid, oxalic acid, citric acid and succinic acid. The total concentration of organic acids in the shoots increased strongly with increasing alkali stress. However, these either did not increase or they decreased slightly with increasing salt stress. Of the four organic acids, the concentration difference between salt‐ and alkali‐stressed plants was most striking for citric acid. This became the dominant organic acid component under alkali stress. Results show that proline is the main organic osmolyte, whereas the contribution of betaine to osmotic adjustment is insignificant under either salt or alkali stress. The main organic acid accumulated was not only an important organic osmotic regulator, but also an important negative charge contributor, playing important roles in ionic balance and pH adjustment. The concentrations of Na⁺, K⁺, Cl^? and of organic acid were 80.7% of all solutes under salt stress. The concentrations of Na⁺, K⁺, Cl^? and of organic acid were 85.4% of all solutes under alkali stresses. The ionic balance was disrupted by the strong increase in Na⁺ content under alkali stress. This perhaps explains why large amounts of the organic acids were accumulated. The organic acid concentration in the roots was lower than in the shoots. The roots secreted citric acid into the rhyzosphere only under alkali stress, secretion of the other organic acids was not detected. Therefore, citric acid secreted from the roots probably plays an important role in pH adjustment in the rhyzosphere of P. tenuiflora.     

抗盐碱植物星星草的研究进展

本文从生理、解剖、分子生物学等方面对抗盐碱植物星星草的研究进展进行了综述，并对其今后发展进行了展望。     

碱茅生长发育节律的研究

通过小区及大田的调查研究，论述了碱茅各生育株高及生物量的发育规律和动态。研究结果，前期碱茅的株高及地上生物量生长缓慢，后期增长迅速，地上风干物质增长峰值出现在孕穗一抽穗期，达５．３３ｇ／（ｄ．ｍ＾２），最高产量出现在成熟期为３１６．２ｇ。ｍ＾－２，地下生物量，前期增长迅速，后期增长缓慢，与地上生物恰成相反趋势，在拔节一孕穗期产量达峰值，日增重达１．９３ｇ。ｍ＾－２。研究结果表明，碱茅是一种抗旱、耐     

盐胁迫对碱茅生长及碳水化合物含量的影响

为揭示碱茅不同发育阶段受盐胁迫后生长受抑的一致性，对盆栽碱茅植株各部位碳水化合物含量进行了动态分析，结果表明：成株叶片和根中总碳水化合物含量的下降主要是由可溶性糖减少引起的。盐逆境中碱茅物质代谢的变化是其生长发育受抑制的重要原因，其中糖类物质的变化起着基础性作用。     

东北松嫩草原碱茅群落的土壤呼吸同枯枝落叶分解释放CO2贡献量研究

应用静态气室法测定了碱茅群落的土壤呼吸和枯枝落叶分解释放CO2贡献量的季节动态,结果表明:①土壤呼吸的季节动态呈现单峰曲线,7月中旬达最大值11.4 gC/(m2@d);②土壤呼吸的季节变化与地上绿色体生物量季节动态同步;③土壤呼吸的季节动态同枯枝落叶分解速率的季节动态同步;④土壤呼吸量与0～10 cm的土壤层中的含水量显著正相关;⑤地表枯枝落叶层分解直接排放CO2量的季节动态呈现单峰曲线,7月中旬达最大值2.93 gC/(m2@d),有减缓土壤向大气排放CO2的作用;⑥枯枝落叶分解释放CO2量同现存地表枯枝落叶量显著正相关.     

小花碱茅HKT1;4基因片段的克隆与序列分析

摘要：为研究小花碱茅(Puccinellia tenuiflora)拒Na+的分子机制,根据GenBank中已登录的植物HKT1;4基因保守序列设计一对简并引物,从小花碱茅幼根中提取总RNA,采用RT PCR方法扩增出HKT1;4基因片段并连接到pMD19 T Simple载体上,经亚克隆,PCR阳性检测后测序,得到一段长629 bp的序列。序列分析表明,该片段编码209个氨基酸,与GenBank中注册的高等植物HKT1;4基因核苷酸序列同源性在74%以上,与HKT1;4蛋白氨基酸序列同源性在60%以上,最后将其命名为PutHKT1;4。     

碱茅根际土壤盐分动态变化研究

A glasshouse experiment using a rhizobox technique was conducted to examine salt dynamics in the rhizosphere of a salt-tolerant grass, Puccinellia ciliata Bor. ‘Irwin Hunter', grown in a loamy soil, and to study the effect of rainfall flush on salt accumulation in the rhizosphere. The rhizobox (10 × 5.5 × 50 cm) had a nylon mesh (1 μm) positioned vertically in the middle to create two compartments filled with soil amended with 1 g NaCl kg^-1. The plants were grown in one compartment only. Flushed treatments received 275 mL of deionized water two days before harvest. In the plant-growing compartment, soils were sectioned vertically at 5 cm intervals. Significant differences in soil electrical conductivity (EC) (P < 0.05) and pH (P < 0.05) were observed for depths, but not between flushed and non-flushed treatments. In the no-plant compartment (rhizosphere), soil cores were taken horizontally at depths of 5, 20 and 40 cm and sliced at 1, 2, 3, 4, 5, 7, 10, 15 and 20 mm away from the roots. Soil EC and Cl^- concentration at the 5 and 20 cm depths, and Na⁺ concentration at the 5 cm depth significantly decreased (P < 0.05) with the distance away from the root, but no significant differences were observed in soil pH and concentrations of the K⁺ and Ca²⁺. The flush treatment only had significant influence on soil EC, pH, and Cl^- concentration at the 20 cm depth. Thus, salt accumulation could occur in the rhizosphere of salt-tolerant species on saline soils, and the periodic low rainfall might not have a strong influence on salt distribution in the rhizosphere and/or root zone.     

松嫩平原星星草无性系生殖分蘖株数量性状的定量研究

通过对籽实成熟期星星草独立分蘖丛的取样调查,定量地分析了松嫩平原星星草无性系生殖株生物量的数量特征.结果表明:在籽实成熟期,割草地每丛中星星草丛生殖株数量、丛生殖株生物量、丛茎生物量、丛花序生物量分别为放牧地的1.30倍、1.39倍、1.33倍和1.22倍;叶生物量平均值表现为放牧地大于割草地,为割草地的1.51倍;两样地星星草无性系丛生殖株组分生物量与丛生殖株生物量、丛生殖数量、丛叶生物量之间均为幂函数变化,各自的相关性均达到了极显著水平(P<0.01).