老化玉米种子在外源NO供体硝普钠作用下的萌发和生理反应

以玉米品种先玉335和良玉99经高温高湿老化的种子为试材,通过外源一氧化氮(NO)供体硝普钠(SNP)的不同浓度溶液浸种处理并进行发芽试验,研究老化玉米种子的发芽、活力特性及萌发后幼苗的生理反应。结果表明,老化玉米种子在一定的SNP浓度时,两个品种均表现为生活力、发芽势、发芽指数、活力指数显著高于对照(P0.05),其中当SNP浓度为1.50和1.25 mmol/L时以上各指标达最高;当SNP浓度为1.25 mmol/L时,老化玉米种子萌发后幼苗的SOD、POD和CAT等活性酶含量最高(P0.05),其次是1.00 mmol/L处理。经SNP处理的老化种子提高了幼苗内的游离脯氨酸含量和可溶性糖含量,但对MDA含量没有显著影响(P0.05)。综合而言,SNP浓度为1.25 mmol/L时,老化玉米种子的萌发能力、活力及幼苗生理特性改善和提高效果最显著。     

NO参与Spd诱导白三叶抗氧化酶活性及其基因表达

以‘拉丁诺’白三叶为试材,采用药理学实验,探讨一氧化氮(NO)信号在外源亚精胺(Spd)诱导抗氧化酶活性及其基因表达中的作用。研究结果显示,20 μmol/L的外源Spd可显著提高白三叶叶片硝酸还原酶(NR)和一氧化氮合酶(NOS)活性,诱导白三叶离体叶片NO积累,并且具有时间效应,在处理第2 h达到最大值;50 μmol/L NO清除剂牛血红蛋白(Hb)、5 mmol/L 硝酸还原酶(NR)抑制剂偏钒酸钠(NaVO₃)以及200 μmol/L一氧化氮合酶(NOS)抑制剂NG-硝基-L-精氨酸甲酯盐酸盐(L-NAME)处理均可不同程度地逆转Spd诱导的NO含量的升高。外源Spd亦可提高白三叶叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)的活性及其基因的相对表达量,而Hb、NaVO₃和L-NAME不同程度地抑制了Spd诱导的SOD、POD、CAT、APX酶活性及其基因表达。以上结果表明:Spd可能通过激活硝酸还原酶和一氧化氮合酶途径诱导产生NO,且NO信号参与了Spd调控白三叶叶片抗氧化酶活性及其基因表达。     

Response of soil N_2O emissions to precipitation pulses under different nitrogen availabilities in a semiarid temperate steppe of Inner Mongolia,China

Short-term nitrous oxide（N2O） pulse emissions caused by precipitation account for a considerable portion of the annual N2O emissions and are greatly influenced by soil nitrogen（N） dynamics. However, in Chinese semiarid temperate steppes, the response of N2O emissions to the coupling changes of precipitation and soil N availability is not yet fully understood. In this study, we conducted two 7-day field experiments in a semiarid temperate typical steppe of Inner Mongolia, China, to investigate the N2O emission pulses resulting from artificial precipitation events（approximately equivalent to 10.0 mm rainfall） under four N addition levels（0, 5, 10 and 20 g N/（m2·a）） using the static opaque chamber technique. The results show that the simulated rainfall during the dry period in 2010 caused greater short-term emission bursts than that during the relatively rainy observation period in 2011（P〈0.05）. No significant increase was observed for either the N2O peak effluxes or the weekly cumulative emissions（P〉0.05） with single water addition. The peak values of N2O efflux increased with the increasing N input. Only the treatments with water and medium（WN10） or high N addition（WN20） significantly increased the cumulative N2O emissions（P〈0.01） in both experimental periods. Under drought condition, the variations in soil N2O effluxes were positively correlated with the soil NH4-N concentrations in the three N input treatments（WN5, WN10, and WN20）. Besides, the soil moisture and temperature also greatly influenced the N2O pulse emissions, particularly the N2O pulse under the relatively rainy soil condition or in the treatments without N addition（ZN and ZWN）. The responses of the plant metabolism to the varying precipitation distribution and the length of drought period prior to rainfall could greatly affect the soil N dynamics and N2O emission pulses in semiarid grasslands.     

外源一氧化氮对遮阴胁迫下高羊茅抗氧化系统的调控机理

在不同遮阴胁迫下（20%遮阴、60%遮阴和90%遮阴）,采用叶面喷施外源一氧化氮（NO）方法,研究了外源NO对遮阴胁迫下高羊茅瑞德3号（Festuca arundinacea ‘Arid 3’）的形态指标、叶绿素含量、膜透性、丙二醛（MDA）含量、抗氧化酶活性及脯氨酸含量的影响。结果表明：20%遮阴对高羊茅植株几乎没有伤害,而60%和90%遮阴的伤害作用较严重,并且随着遮阴时间的增加高羊茅受伤害程度加强。外源NO可以显著提高遮阴胁迫下高羊茅叶片的叶绿素含量,降低质膜相对透性的增加,减少膜质过氧化产物MDA含量的升高,促进脯氨酸的积累,提高超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）的活性。外源NO的保护作用随着遮阴时间与遮阴强度的增加而变化,外源NO对20%遮阴和60%遮阴的高羊茅效果较好,而对90%遮阴高羊茅效果较差;此外,随着遮阴时间增加,外源NO对不同遮阴强度高羊茅作用效果不同,处理14 d效果较好。综上表明,外源NO对遮阴胁迫下的高羊茅具有一定的保护作用,但是这种保护作用随着遮阴时间与遮阴强度的增加而下降。     

减量施氮对雨养区春玉米产量和环境效应的影响

通过3年田间试验,研究了减量施氮（N）对雨养区春玉米产量、温室气体排放、土壤硝态氮（NO-3-N）残留的影响。试验于2013年4月至2015年9月在中国科学院长武黄土高原农业生态试验站进行,供试作物为春玉米,半覆膜种植,设常规施氮（N200）和减量施氮（N150）2个处理,定期测定土壤矿质N和氧化亚氮（N2O）气体含量。结果表明：虽然N150处理较N200处理施N量减少了25%,但玉米产量无显著变化（P>0.05）,三年平均为13.4（N200）、13.3（N150）t·hm-2;N150处理N2O累积排放量较N200处理降低24.3%;N200处理0~200 cm土壤剖面NO-3-N残留量平均为210.2 kg·hm-2,N150处理则低至115.1 kg·hm-2;N200和N150处理的生育期耗水量差异不显著（P>0.05）。在渭北雨养农业区,春玉米在常规施N的基础上减量25%,不仅能维持作物产量,还能有效降低N2O排放和NO-3-N的残留。     

一氧化氮在植物响应重金属胁迫中的作用

一氧化氮(Nitric oxide,NO)是一种具有扩散性的气体分子,在哺乳动物中被鉴定为血管内皮细胞舒张因子,是一种有效的内源性血管舒张药。植物也具有合成和释放NO的能力,NO在植物中参与多种生理过程和胁迫响应。因此,NO被认为是植物及动物体内重要的气体信号分子。近年来,由于各种人类活动的影响导致重金属对农业生态环境造成了越来越严重的污染,威胁农作物生产与食品安全。尽管重金属影响植物生长发育的机制并不完全清楚,但越来越多的证据显示NO是植物体内响应重金属胁迫的重要成分之一。就目前重金属胁迫对植物内源NO的代谢以及外源NO对植物重金属毒害的影响的研究进展进行了综述。     

Effect of the number of tillages in fallow season and fertilizer type on greenhouse gas emission from a rice (Oryza sativa L.) paddy field in Ehime,southwestern Japan

Agricultural fields, including rice (Oryza sativa L.) paddy fields, constitute one of the major sources of atmospheric methane (CH₄) and nitrous oxide (N₂O). Organic matter application, such as straw and organic fertilizer, enhances CH₄ emission from paddy fields. In addition, rice straw management after harvest regulates CH₄ emissions in the growing season. The interaction of tillage times and organic fertilizer application on CH₄ and N₂O emissions is largely unknown. Therefore, we studied the effects of fallow-season tillage times and fertilizer types on CH₄ and N₂O emissions in paddy fields in Ehime, southwestern Japan. From November 2011 to October 2013, four treatments, two (autumn and spring) or one (spring) in the first year, or two (autumn and spring) or three (autumn, winter, and spring) in the second year times of tillage with chemical or organic fertilizer application, were established. Gas fluxes were measured by the closed-chamber method. Increasing the number of tillage times from one to two decreased succeeding CH₄ emission and the emission factor for CH₄ (EF_CH4) in the rice-growing season, suggesting that the substrate for CH₄ production was reduced by autumn and spring tillage in the fallow season. Higher EF_CH4 [1.8–2.0 kg carbon (C) ha^?1 d^?1] was observed when more straw was applied (6.9–7.2 Mg ha^?1) in the second year. Organic fertilizer application induced higher CH₄ emission just after the application as basal and supplemental fertilizers, especially at a lower straw application rate. This indicated that EF_CH4 in the organically managed fields should be determined individually. Organic fertilizer application with two tillage times induced N₂O efflux during the rice-growing season in the second year, but N₂O emissions were not affected by winter tillage. Although paddy fields can act as an N₂O sink because of reduced soil conditions when straw application was high, application of organic C and nitrogen as fertilizer can enhance N₂O production by the denitrification process during the growing season, especially in the ripening stage when soil anaerobic conditions became moderate. These results suggest that negative emission factors for N₂O (EF_N2O) can be applied, and EF_N2O of organic fertilizer should be considered during the estimation of N₂O emission in the paddy field.     

水稻WRKY转录因子基因家族响应外源一氧化氮的表达谱分析

一氧化氮(nitric oxide,NO)信号分子与WRKY转录因子均参与植物抗逆、发育与代谢等许多生理过程。采用Agilent水稻全基因组cDNA芯片分析了NO处理后1、6和12h水稻幼苗WRKY转录因子基因的表达谱,鉴定出在1个时间点有两倍或两倍以上表达变化的WRKY基因32个,主要分布在WRKY的Ⅰ和Ⅱ组,其中75%的Ⅱa和45.6%的Ⅱd亚组成员为差异表达基因;鉴定出至少在2个时间点有两倍或两倍以上表达变化的WRKY基因15个,均为早期(1h)应答,且多数(64.2%)持续上调;基因功能预测分析表明,这些基因主要参与生物学过程中的细胞过程、代谢过程和刺激响应,以及分子功能中的转录调节活性和结合;代谢通路分析表明,WRKY24涉及植物与病原菌相互作用代谢通路。实时荧光定量PCR验证结果与芯片杂交结果基本一致,印证了芯片杂交结果的有效性。上述发现提示,NO信号可能参与了WRKY转录因子介导的生物学调控功能,并为这些基因的进一步功能分析奠定基础。     

Gelam honey inhibits lipopolysaccharide-induced endotoxemia in rats through the induction of heme oxygenase-1 and the inhibition of cytokines, nitric oxide, and high-mobility group protein B1

Malaysian Gelam honey has anti-inflammatory and antibacterial properties, a high antioxidant capacity, and free radical-scavenging activity. Lipopolysaccharide (LPS) stimulates immune cells to sequentially release early pro- and anti-inflammatory cytokines and induces the synthesis of several related enzymes. The aim of this study was to investigate the effect of the intravenous injection of honey in rats with LPS-induced endotoxemia. The results showed that after 4h of treatment, honey reduced cytokine (tumor necrosis factor-α, interleukins 1β, and 10) and NO levels and increased heme oxygenase-1 levels. After 24h, a decrease in cytokines and NO and an increase in HO-1 were seen in all groups, whereas a reduction in HMGB1 occurred only in the honey-treated groups. These results support the further examination of honey as a natural compound for the treatment of a wide range of inflammatory diseases.     

Sesquiterpenes inhibiting NO production from Celastrus orbiculatus

Two new (1 and 2) and one known (3) β-dihydroagarofuran sesquiterpenes were isolated from the fruits of Celastrus orbicultus Thunb. Their structures were elucidated as 1β,13-diacetoxy-8β,9β-dibenzoyloxy-β-dihydroagarofuran (1), 1β,13-diacetoxy-8α-hydroxy-9β-benzoyloxy-β-dihydroagarofuran (2), and 1β,6α,13-triacetoxy-9α-benzoyloxy-β-dihydroagarofuran (3), on the basis of spectroscopic data analyses. All the compounds exhibited inhibitory effects on LPS-induced nitric oxide production in murine microglial BV-2 cells.