Synthesis,conformational studies and anthelmintic activity of a constrained PF1022A analogue

A mono-proline analogue of the potent anthelmintic cyclooctadepsipeptide PF1022A has been synthesized. NMR studies in combination with molecular dynamics simulations demonstrate that the confirmation of this analogue is both rigidified and distorted compared with the asymmetric conformation of PF1022A. The backbone conformation is significant with respect to anthelmintic activity. © 1999 Society of Chemical Industry     

中国柽柳幼苗叶片生理特性对碱胁迫的响应

以中国柽柳为试材,通过盆栽试验,研究混合碱(NaHCO3和Na2CO3摩尔比为9:1)在不同浓度胁迫下(100、200、300和400 mmol/L)对中国柽柳幼苗叶片生理特性和株高的影响。结果表明：与对照相比,中国柽柳叶片的相对含水量在碱浓度为100、200、300和400 mmol/L时均显著降低,分别下降8.82%、34.49%、43.27%和45.43%;而叶片丙二醛、可溶性糖和脯氨酸含量则随着碱浓度的升高呈递增的趋势,其中100、200、300和400 mmol/L碱处理的脯氨酸含量分别较对照显著高出36.37%、56.41%、77.35%和84.25%。此外,不同碱浓度处理的株高大小次序为：对照>100 mmol/L>200 mmol/L>300 mmol/L≈400 mmol/L,其中100、200、300和400 mmol/L处理的株高分别比对照显著降低45.95%、62.16%、70.27%和74.05%,表明不同程度的碱胁迫均显著抑制了中国柽柳的生长。综合分析认为,以NaHCO3和Na2CO3为主要盐分的碱胁迫对中国柽柳的生长发育具有一定的抑制作用,随着碱胁迫程度的加剧,抑制作用越来越大。     

11个苹果野生砧木品种低温处理抗性指标的综合评价

对苹果野生砧木品种进行抗寒性综合评价,为耐寒性砧木的开发利用提供科学依据。以11个野生砧木品种为试验材料,在-10~-45℃设置7个低温梯度处理,对枝条萌芽率,电导率、脯氨酸、丙二醛含量进行研究。结果表明,低温处理后,围矮4号和Sdw1萌芽率迅速下降,11个野生砧木品种的相对电导率随处理温度下降呈“S”形增加,计算得半致死温度（LT₅₀）介于-22.32~-38.58℃。丙二醛含量呈双峰变化趋势,Sdw1、串铃海棠、围矮4号丙二醛含量较高,围矮2号、Spy227、特大果山定子丙二醛含量低且稳定。围矮4号、Sdw1、串铃海棠Pro累积较早,围矮2号和特大果山定子脯氨酸含量最大。利用隶属函数法进行抗寒性综合评价,11个野生砧木抗寒性强弱顺序为围矮2号＞特大果山定子＞Spy227＞八棱海棠＞围矮3号＞克勒沟林场大果山定子＞围矮1号＞五峰山4号＞串铃海棠＞围矮4号＞Sdw1,与根据LT₅₀所得抗寒性排序相近。     

OsSCE1 Encoding SUMO E2-Conjugating Enzyme Involves in Drought Stress Response of Oryza sativa

Small ubiquitin-like modifier (SUMO)-conjugating enzymes are involved in post-translational regulatory processes in eukaryotes, including the conjugation of SUMO peptides to protein substrate (SUMOylation). SUMOylation plays an important role in improving plant tolerance to abiotic stress such as salt, drought, heat and cold. Herein, we reported the isolation of OsSCE1 (LOC_Os10g39120) gene encoding a SUMO-conjugating enzyme from rice (Oryza sativa cv. Nipponbare) and its functional validation in response to drought stress. The E2 enzyme, OsSCE1, is one of three key enzymes involved in the conjugation of SUMO to its target proteins. Activated SUMO is transferred to the cysteine of an E2 enzyme and then to the target lysine residue of the substrate, with or without the help of an E3 SUMO ligase. Expression of OsSCE1 was strongly induced by polyethylene glycol 6000 (PEG6000) treatment, which suggested OsSCE1 may be involved in the drought stress response. Overexpression of OsSCE1 (OsSCE1-OX) in Nipponbare reduced the tolerance to drought stress. Conversely, the drought tolerance was slightly improved by the knockdown of OsSCE1 (OsSCE1-KD). These results were further supported by measurement of proline content in OsSCE1-OX and OsSCE1-KD transgenic lines under induced drought stress, which showed OsSCE1-KD transgenic lines accumulated higher proline content than the wild type, whereas OsSCE1-OX line had lower proline content than the wild type. These findings suggested OsSCE1 may play a role as a negative regulator in response to drought stress in rice.     

Effect of Nephthyl Acetic Acid Foliar Spray on Amelioration of Drought Stress Tolerance in Maize (Zea mays L.)

The present study aimed to determine the effect of nephthyl acetic acid (NAA) on the physiological mechanism of drought tolerance in selected maize (Zea mays L.) varieties under induced drought stress at the vegetative stage. Maize seeds were sown in plastic pots (14 cm lower inside diameter, 18.5 cm upper inner diameter, 15.6 cm height, and 0.5 cm thickness) filled with 3 kg of air-dried soil and sand (3:1) in triplicate in the greenhouse of the Botany Department, Bacha Khan University, Charsadda in 2014. Results showed that the activities of antioxidant enzymes and proline accumulation were associated with the dry mass production and consequently with the drought tolerance of the maize varieties. It has been concluded that the inhibitory effects of water stress were ameliorated by exogenous application of NAA and were found to be significant for antioxidant enzymes at the vegetative stage in both varieties.     

Soybean (Glycine max) Extracts Impact on Plant and Soil Biology

The aim of the present investigation was to determine the phytotoxic effect of aqueous extract from fresh and oven-dried leaves and roots of soybean plants on maize growth and on rhizosphere soil. The extract prepared from fresh leaves of drought-stressed soybean plants significantly increased the accumulation of proline, soluble sugar, and endogenous abscisic acid (ABA) content of maize-treated plants. Increase in antioxidant activity like superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), catalase (CAT), and endogenous ABA was recorded in treated plants. The soybean leaf extracts prepared from drought-stressed plants significantly decreased the soil pH and electrical conductivity (EC) of maize cultivated soil. The soybean drought-stressed leaf extracts prepared plants were found more effective in modulating the physiology of maize, indicating the higher allelopathic potential of soybean.     

Proline and Glutamine Improve in vitro Callus Induction and Subsequent Shooting in Rice

This study was conducted to evaluate the effects of proline and glutamine on in vitro callus induction and subsequent regeneration and to develop a reproducible and highly efficient plant regeneration protocol in four rice genotypes, viz. Pawana, Jaya, Indrayani and Ambemohar. Considerable variation in response to plant growth regulators and amino acid supplements used was observed in all the four genotypes. Medium supplemented with proline and glutamine was shown to be superior to medium without proline and glutamine. The best callusing from mature embryo was observed on Murashige and Skoog(MS) medium supplemented with 2.0 mg/L 2,4-dichlorophenoxyacetic acid(2,4-D), 500 mg/L proline and 500 mg/L glutamine. Shoot induction was higher in the callus obtained from medium supplemented with 500 mg/L proline and 500 mg/L glutamine. The highest shoot regeneration frequency(83.2%) was observed on MS medium with 2.0 mg/L benzylaminopurine, 0.5 mg/L 1-naphthaleneacetic acid, 500 mg/L proline, and 500 mg/L glutamine in the callus obtained from MS medium supplemented with 2.0 mg/L 2,4-D, 500 mg/L proline and 500 mg/L glutamine. Among the four genotypes, Pawana has the highest regeneration efficiency(83.2%), whereas the regeneration efficiency of the rest three rice genotypes was in the range of 32.0% to 72.3%. This optimized regeneration protocol can be efficiently used for Agrobacterium mediated genetic transformation in rice.     

4种优良观赏竹耐高温与抗旱性研究及其综合评价

以3年生圣音竹、龟甲竹、黄秆乌哺鸡竹、黄秆京竹4种观赏竹为试验材料,进行持续高温干旱胁迫试验,通过对叶片形态观察和测定叶片含水量、丙二醛(MDA)含量、SOD活性和游离脯氨酸量,探究高温干旱胁迫对4种观赏竹的影响。结果表明,1）在持续高温干旱胁迫下,4种观赏竹的叶片相对含水量和叶绿素含量呈下降趋势,黄秆京竹的叶片相对含水量下降了17.5%,叶绿素含量下降了31.71%,下降均较少,表明其生长状况较好。MDA含量和游离脯氨酸含量呈增加趋势,黄秆京竹的MDA含量相对其他3种观赏竹仅增加了5.13倍,相对较小,表明其所受伤害少;游离脯氨酸相对于其他3种增加了1.93倍,增幅最大,表明其抗旱性较好。SOD活性呈先增加后下降的变化趋势,黄秆京竹的SOD活性增加了3.7倍,明显高于其他3种竹,提高其抗旱性。2）5个生理生化指标之间有显著相关性。3）4种观赏竹因子分析得分中,黄秆京竹得分最高为1 016,其抗旱性较好,与试验观察和指标测定结果相符。4）在持续高温干旱胁迫下,应及时进行遮荫浇水进行合理抚育措施,可维持植物正常生长。     

聚乙二醇胁迫下不同苜蓿品种愈伤组织生理指标的变化

以聚乙二醇(PEG)作为渗透胁迫剂,对5个苜蓿Medicago sativa品种愈伤组织进行干旱胁迫.用生理生化方法对各品种愈伤组织的过氧化物酶(POD)活性、脯氨酸积累量、质膜相对透性3项抗旱性鉴定指标进行测定,各项结果趋于一致,其抗旱性强弱的顺序为:龙牧803、草原2号、中牧1号、龙牧80l、准格尔.同时,证明了POD活性、游离脯氨酸含量和质膜透性均可作为苜蓿抗旱性鉴定的生理指标.     

PEG处理葡萄试管苗生理反应及叶片组织形态研究

应用不同浓度的聚乙二醇(PEG10000)处理红地球葡萄生根试管苗,在造成一定程度水分亏缺的情况下,观察葡萄试管苗的生理反应和植株生长、叶片形态解剖结构的变化。结果表明:在PEG处理下,葡萄生长发育迟滞,植株节间变短,株高变矮,但发根数量增加,根变长;新生叶片与对照比,叶片小而皱缩,气孔指数降低,上皮细胞排列更紧凑;同时葡萄试管苗脯氨酸的积累和内源ABA迅速增加。说明在一定强度的水分胁迫下,葡萄试管苗叶片的发育向增强其耐旱能力的方向进行,其渗透调节物质的积累是葡萄试管苗对长期水分胁迫的生理反应。