一氧化氮对低温贮藏桃果实线粒体氧化损伤的影响

【目的】分析一氧化氮(NO)对冷藏过程中桃果实线粒体氧化损伤的影响。【方法】分别用15 μmol/L NO、5 μmol/L c-PTIO (NO清除剂)、对照(去离子水)浸泡30 min处理桃果实。测定0℃下桃果实的线粒体完整性、活性氧含量、抗氧化酶的活性及相关品质指标。【结果】在桃果实低温冷藏过程中,NO处理可以维持桃果实硬度、色差L值及可溶性固形物含量,降低线粒体耗氧量和减少活性氧的积累,调节线粒体呼吸控制率(RCR)、线粒体膜电势,线粒体细胞色素C含量以及线粒体抗氧化酶活性。【结论】NO通过减少线粒体氧化损伤,维持线粒体的完整性,延长桃果实的贮藏期。     

Dieback and decline of wild almond (Amygdalus scoparia Spach) in the Harat protected forest of Yazd Province,Iran

Wild almond (Amygdalus scoparia) is a dominant shrub species in mountain forests of the Irano‐Turanian region. Dieback and decline symptoms of wild almond shrubs were first observed in Harat protected forest (Yazd, Iran) in the autumn of 2014. Since then, the incidence and severity of the disease have increased. To study the aetiology and estimate losses from the disease, field studies were conducted in 2016 and 2017. For this purpose, eight stands were selected, in which 24%–99% of the trees were wild almond in their species composition. In total, 50 cankers and 50 infected twigs of wild almond shrubs were collected. Fungal isolates were identified based on morphological and cultural characteristics, as well as sequence data of ITS1 + 5.8S + ITS2 rDNA. Pathogenicity of fungi was checked on detached shoots and evaluated after 40 days by measuring the discoloured lesion length at the inoculation site. Among 681 wild almond shrubs checked, 84.44% showed decline symptoms with different severities; only 15.56% did not show observable disease symptoms. The most frequent colonizers of infected tissues taken from cankers were Wilsonomyces carpophilus (56%), Thyrostroma cornicola (40%) and Collophorina paarla (30%). Infected twigs were extensively colonized by W. carpophilus (36%), Th. cornicola (24%) and Ulocladium consortiale (24%). Other species, such as Endoconidioma populi, Microsphaeropsis olivacea, Trichoderma asperellum, Paecilomyces formosus, Saccothecium rubi, Preussia sp. and Chaetomium globosum, had lower isolation frequencies. W. carpophilus, Th. cornicola, C. paarla and U. consortiale were found as pathogens on detached wild almond shoots. Based on the frequency of the isolates and the pathogenicity tests, four fungi, such as W. carpophilus, Th. cornicola, C. paarla and U. consortiale, are considered serious contributing agents playing a significant role in the dieback and decline of wild almond. All isolated species are reported for the first time on the wild almond shrubs of the world.     

山桃幼苗响应镉胁迫的生理机制研究

为探究山桃(Amygdalus davidiana)幼苗响应镉(Cd)胁迫的生理机制,通过盆栽试验研究了山桃幼苗在10 mg·kg^-1Cd处理后1、15、30、90 d的生理响应和富集特征。结果表明,山桃幼苗叶片O2-·和丙二醛(MDA)相对含量随Cd处理时间的延长而上升,叶绿素a含量、叶绿素b含量、净光合速率(Pn)则逐渐降低。叶绿素a/b值在Cd处理后1~15 d上升,而在30~90 d下降,表明Cd处理前期对叶绿素b的影响较大,而后期主要影响叶绿素a的合成。Mg、Mn元素相对含量随Cd处理时间延长而显著降低,而Cu、Fe含量上升,表明Cd胁迫诱导的山桃幼苗叶绿素合成受限和Pn的降低与Mg、Mn的降低紧密相关,这是由于Mg、Mn分别参与叶绿素合成和光系统Ⅱ(PSII)反应过程。超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性在Cd处理1~15 d显著上升,30~90 d则逐渐降低;过氧化物酶(POD)活性则在处理1~15 d无显著性差异,在30~90 d显著上升;谷胱甘肽还原酶(GR)活性、还原型谷胱甘肽(GSH)和抗坏血酸(AsA)含量均随着Cd处理时间的延长显著上升;ATP硫酸化酶活性和半胱氨酸含量均随着Cd处理时间的延长而显著上升,硫醇代谢物非蛋白硫醇(NPT)和植物螯合素(PCs)在Cd处理前期(1~15 d)差异不显著,而在30 d后显著上升。综上,山桃幼苗在Cd处理前期主要发挥抗氧化酶(SOD、CAT)的功能,并促进抗氧化物质(GSH、AsA)的合成,而Cd处理后期,则以POD、GSH、AsA的功能为主,并增强NPT和PCs的合成,从而促进Cd向液泡中转移,这与Cd处理后期液泡中Cd含量增加的变化趋势一致。本研究结果为山桃可作为重金属植物修复材料提供了理论依据。     

野生光核桃和栽培桃对高浓度CO_2抗性的比较

为了研究大气CO_2浓度升高对西藏特有植物的影响,以野生光核桃为研究材料,以栽培桃为对照,以高浓度CO_2为胁迫条件,分析野生光核桃和栽培桃的叶绿素含量、酶活性、叶片呼吸与光合指标的变化特征。结果表明:在高浓度CO_2条件下,栽培桃植株的部分叶片有黄化趋势,野生光核桃变化不明显。在高浓度CO_2条件下,野生光核桃抗氧化酶、光合和呼吸等指标均做出了积极的响应,保持了较高的酶活性,同时保持了正常的电子传递效率,且光合效率的下降主要是由非气孔因素引起。因此,与栽培桃相比,野生光核桃对高浓度CO_2逆境的抗性更强。     

光周期处理对油桃芽休眠诱导效应及呼吸速率的影响

 【目的】分析光周期处理对油桃芽休眠诱导及发展进程的影响,并探讨休眠诱导期内桃芽呼吸速率的变化规律。【方法】以曙光油桃（Prunus persica var. nectariana cv. Shuguang）为材料,设置3个光周期处理：短日照（8 h）、长日照（16 h）和自然日照,结合测定枝梢的生长和桃芽萌芽能力界定桃芽休眠状态,利用氧电极测定桃芽呼吸速率的变化。【结果】短日照能够诱导曙光油桃新梢提前停长,使桃芽提前7 d进入休眠诱导期,且促进休眠迅速向深度发展,较对照提前21 d进入自然休眠期;长日照明显延迟油桃新梢停长,并且延缓桃芽休眠诱导及发展的进程。呼吸速率随着休眠诱导而降低,桃芽进入休眠诱导期7 d后出现呼吸速率低谷,休眠诱导期内呼吸速率出现回升后降低并在休眠诱导期结束时维持在较低水平。另外,短日照明显减弱芽体的呼吸速率,并维持其在较低水平,长光照略使呼吸速率上升。【结论】短日照对休眠的产生具有明显诱导效应,长日照可推迟休眠诱导的发生,呼吸速率变化与休眠的诱导与发展进程相关,也与光周期有关。     

单叶蔷薇的花芽形态分化

 单叶蔷薇花芽分化从3月下旬开始至4月下旬完成, 历时30 d, 其过程可分为形态分化前、苞叶原基分化期、萼片原基分化期、花瓣原基分化期、雄蕊原基分化期、雌蕊原基分化期。其中花瓣原基的分化只进行1次, 这是形成单轮花瓣的原因。各花器官原基起源于花分生组织的边缘区细胞。生殖生长锥直径和细胞数的增加在生长锥膨大期和心皮分化期较高。     

毛桃对北方根结线虫的抗性研究

以实生钵苗为试材,采用人工接种、根系次氯酸钠-酸性品红染色等方法研究了毛桃对北方根结线虫的抗性。结果表明:毛桃的根结指数为24.67,接种侵入率2.6%,根中雌成虫数量占接种量的0.16%,依据有无根结和雌成虫数量占接种线虫数量的百分比标准判定其高抗北方根结线虫;毛桃实生群体对北方根结线虫的抗性具有显著的株间分离现象,免疫、高抗和中抗3种基因型个体分别占13.3%、80%和6.7%。毛桃对北方根结线虫具有极强的抗侵入与抗发育能力,是极优异的抗北方根结线虫桃树砧木树种和种质资源。     

毛桃砧木对土壤盐胁迫的生理响应

对毛桃在盐胁迫条件下,其8项生理指标的响应进行了初步研究。结果表明,毛桃的Pn、MDA、NR等指标对盐胁迫的反应较对照表现出极显著差异;Pro、POD、E、RWC、Ψw在轻度处理时与对照差异不显著,但当处理浓度升高时,其反应与对照表现出极显著差异。随着盐浓度的增加,毛桃受到的伤害大幅度增加,这与其自身清除活性氧的能力降低有关。     

桃果实蛋白质双向电泳影响因素的研究

以‘大久保’桃（^{Prunus persica} L.'Okubao'）果实为试材,通过比较不同上样量、不同上样缓冲液、不同平衡缓冲液、不同染色方式等条件下的双向电泳图谱,探讨以上各因素对桃果实双向电泳图谱效果的影响。结果表明考马斯亮蓝染色后的电泳图谱虽然蛋白质点的数量少于银染色后的图谱,但背景较为清晰,适用于蛋白质组分析。采用固相pH梯度17 cm胶条,100 μg蛋白质上样量,样品干粉溶于375 μL含有硫脲、磺基三甲基胺乙内脂3~10的上样缓冲液中,等电聚焦后用含有磷酸三丁酯的平衡缓冲液还原,进行SDS-PAGE,银染色得出的双向电泳图有蛋白点1 209个,纹理较少,适用于桃果实蛋白质组学分析且兼容于下游技术的蛋白质质谱鉴定。     

Yield and protein content of barley as affected by release rate of coated urea and rate of nitrogen application

Coated urea consists of a urea core and a polymer coating. It meters out urea over a period of time. In the market place, price is favorable for high protein content feed barley. The objectives of this study were to determine release rate of urea from coated urea products and relative effectiveness of urea, coated urea or a mixture of coated urea products with different release rates in increasing yield and protein content of barley. Release rate of coated urea Mini I (quick release) and Mini II (slow release) in water was determined at 23°C by recovering ten pre‐weighed granules from 500 mL water at 6 h, 2, 4, 6, 8, 10, and 12 days. The recovered granules were dried and then weighed. Barley (Hordium vulgare L. cv. Duke) was grown in potted soil (2 L) at 15°C for 90 days in a growth chamber with treatments of Nil, non‐coated urea, Mini I, Mini II, Mixture I (1/3 urea+1/3 Mini I+1/3 Mini II) and Mixture II (1/5 urea+2/ 5 Mini I+2/5 Mini II). The nitrogen (N) application rates were 100, 200 and 300 kg N ha^‐1. Above‐ground plant samples were taken at 22, 44, 66, and 90 (maturity) days after seeding, and dry matter mass per pot and N content of the plant samples were determined. The release of urea from Mini I and Mini II followed a lognomial pattern. Increasing N application rate increased dry matter yield of barley. Dry matter yield from urea tended to be higher than other treatments at each rate of N application, but that did not couple with high grain protein content. At 100 kg N ha^‐1, there was no post anthesis N assimilation (PANA) for urea and Mini I, but there were 4, 14, and 13% PANA for Mini II, Mixture I, and Mixture II, respectively. However, when N application rate was increased to 200 and 300 kg N ha^‐1, there was PANA even for urea treatment. Protein content of barley grain was higher with coated urea or mixture treatments than with urea at each rate of N application. The potential N loss (i.e., difference between percentN released from fertilizers and percent fertilizer N recovered by barley) was Mini II<Mini I<Mixture II<Mixture I for the same N application rate, and was 100<200<300 kg N ha^‐1 for the same fertilizer treatment. In conclusion, at a limited N application rate, coated urea with a slow release rate or a combination of two coated urea products (quick and slow release) with urea increased grain protein content of barley. The potential N loss was less with coated urea applied alone than with a mixture of coated urea and urea.