ABA对水稻幼苗抗冷性的影响

水稻幼苗叶随着低温(8～10℃)时间越长,ABA含量就越多,抗冷性较强的品种(组合)叶片所积累ABA含量比不抗冷的要多。外施ABA大大提高了水稻幼苗的抗冷性,减少叶的电解质渗漏率、减慢叶褪色速率和阻止叶鲜重下降。低温期间,水稻幼苗的可溶性糖含量增加。外施ABA提高可溶性糖的含量,在低温第4天更为明显,因此,ABA与秧苗抗冷性有密切的关系。     

抗感水稻品种受灰飞虱为害后的生理反应差异

灰飞虱Laodelphax striatellus Fallén(SPBH)是我国水稻生产上的一种重要害虫。为探明水稻抗灰飞虱的生理基础,在不同灰飞虱虫口密度(0、5、10、20头/株)及不同为害时间(3 d、6 d)下,检测了抗感水稻品种相关生理指标的变化差异。结果表明,灰飞虱为害后,抗感水稻植株中叶绿素、可溶性糖及可溶性蛋白含量均呈下降趋势,感虫品种中的下降幅度显著大于抗虫品种,且感虫品种的叶绿素、可溶性糖及可溶性蛋白含量在不同虫口密度及不同为害时间下,均存在显著差异。当灰飞虱以20头/株为害6 d后,武育粳3号、Kinmaze、DV85和Mudgo中叶绿素下降幅度分别为46.0%、46.0%、2.3%和2.1%,可溶性糖含量下降幅度分别为55.5%、46.3%、9.2%和11.7%,可溶性蛋白含量下降幅度分别为22.3%、29.5%、8.5%和6.7%。抗感水稻中过氧化物酶活性随虫量增大和为害时间延长而显著升高,过氧化氢酶活性则随虫量增加和为害时间延长而降低,但抗虫植株中保护性酶活性对虫害胁迫的响应明显早于感虫材料。游离脯氨酸和丙二醛含量均随着灰飞虱虫量增大及为害时间延长而上升,其中,游离脯氨酸在抗虫材料中的上升幅度高于感虫品种,丙二醛含量则在感虫品种的上升幅度显著高于抗虫材料。     

不同波长蓝光LED对两个品种水稻秧苗生长的影响

传统的大田育秧方式容易受到自然条件的影响,如在连续的阴雨天容易导致烂秧,而采用人工可控的工厂化育秧则有助于解决此类问题。LED光源具有光质纯、光效高以及低能耗等优势,是一种有望在工厂化育秧中应用的人工光源。该研究以生长特性差异明显的水稻天优998(籼稻)和圣稻14(粳稻)为材料,在光强为(60±5)μmol·m~-2·s~-1、光周期为12 h·d~-1的条件下,以450、470和490 nm 3个波长的蓝光LED照射天优998和圣稻14秧苗,考察了不同波长蓝光对两个品种的三叶期和五叶期水稻秧苗生长的影响。结果表明:蓝光处理下两个品种、不同秧龄幼苗的壮苗指数、根系活力和根数增加,体内碳、氮代谢活性增强,抗氧化物酶活性也会增加。3个波长的蓝光对两个品种、不同秧龄水稻秧苗生长的影响存在差异,450 nm照射下水稻秧苗的各项生长指标较优,生产上育秧可根据秧龄选择450 nm或490 nm作为独立和组合光源。     

利福平对盐胁迫下水稻活性氧代谢的影响

用特效诱抗剂(HI)、药物利福平(RFP)及其组合处理盐胁迫条件下的水稻品种‘R6’,研究利福平对水稻‘R6’叶片活性氧代谢的影响。结果表明:(1)在盐胁迫下水稻‘R6’的各种保护酶活性显著增加,氧自由基产生速率也显著提高;(2)利福平单独处理可一定程度提高水稻‘R6’的耐盐性,但在HI预处理后可极显著地提高水稻‘R6’耐盐性;(3)HI-RFP-S、RFP-S处理通过提高保护酶SOD、POD、CAT的活性抑制水稻‘R6’植株内的氧自由基水平,以减少氧自由基对细胞膜的损伤而提高水稻的抗盐性。     

树莓粗多糖对UVB诱导HaCaT细胞光损伤的防护作用

多糖是树莓功能性成分之一,具有抗炎、抗氧化、抗疲劳、降血糖、免疫调节等多种药理作用。但树莓多糖对紫外线造成的皮肤细胞光损伤是否具有防护作用尚未见报道。本研究旨在探究树莓粗多糖(raspberry crude polysaccharide,RCP)对中波紫外线(ultraviolet B,UVB)诱导的人永生化角质形成细胞(human immortalized keratinocytes,HaCaT)光损伤的防护作用。通过建立HaCaT细胞的UVB光损伤模型,利用CCK-8法测定细胞活力,酶联免疫吸附法(enzyme linked-immuno-sorbent assay,ELISA)和微板法测定HaCaT细胞中炎症因子、基质金属蛋白酶和抗氧化因子的含量,评估RCP的抗UVB活性。采用体外自由基清除实验检测RCP对DPPH自由基(DPPH·)和ABTS自由基(ABTS·⁺)的清除能力。结果表明,RCP能明显提高被UVB损伤的HaCaT细胞活力,且随浓度升高作用增强(P < 0.01或P < 0.05)。与未加入RCP处理的HaCaT细胞比较,人基质金属蛋白酶-3(matrix metalloproteinase-3,MMP-3)、人白介素-1β(interleukin-1β,IL-1β)、人白介素-6(interleukin-6,IL-6)、人肿瘤坏死因子-α(tumor necrosis factor α,TNF-α)的含量明显降低(P < 0.01或P < 0.05),超氧化物歧化酶(superoxide dismutase,SOD)、还原型谷胱甘肽(glutathione,GSH)以及人硫氧还蛋白(thioredoxin,TRX)的含量显著升高(P < 0.05)。此外,RCP对DPPH·和ABTS·⁺的最大清除率分别为91%和94%。以上结果表明,RCP能够通过降低炎症水平和缓解氧化应激来预防UVB对HaCaT细胞造成的光损伤,为天然抗UVB物质的研发提供新思路,也为树莓资源的高值化利用和精深开发提供参考。     

空心莲子草具有较强抗盐能力的原因初探

为了探讨空心莲子草(Alternantheraphiloxeroides(Mart.)Griseb)的抗盐机理,测定了盐胁迫条件下的空心莲子草和水稻中保护酶活性和渗透调节物质的变化。结果表明,在盐胁迫下,空心莲子草中的脯氨酸、甜菜碱以及SOD、POD等含量增加速度比水稻快,膜脂过氧化产物丙二醛的含量在两种植物中虽亦增加,但在空心莲子草叶中的增加幅度小于水稻。证明盐胁迫下保护酶活性和渗透调节物质含量的迅速增加是空心莲子草具有较强抗盐能力的重要生理学基础。     

棉花抗蚜性与苯丙氨酸解氨酶活性的关系

为探讨苯丙氨酸解氨酶活性与棉花抗蚜性的关系,在室内人工接蚜危害和田间自然蚜群2种条件下,测定不同抗蚜性棉花品种受棉蚜Aphis gossypii Glover危害后叶片的PAL活性。结果表明:未受棉蚜危害时,抗、感品种PAL活性无明显差异;棉蚜危害胁迫棉花PAL活性升高,抗蚜品种受到棉蚜危害诱导所产生的PAL活性远比感蚜品种高。田间有蚜株率与棉花叶片苯丙氨酸解氨酶活性的呈显著的负相关关系。研究说明PAL酶活性对棉花的抗蚜性有一定的影响。     

缺磷条件下不同磷效率水稻品种光合特性和细胞保护酶活性

以6个不同磷吸收效率粳稻品种为材料,研究了缺磷条件下各种磷效率类型水稻品种的光合特性和细胞保护酶活性.结果表明:缺磷条件下,随着植株生长进程,不同磷效率水稻品种的光合速率(Pn)和可溶性蛋白质含量(pro)均不断下降;与丰磷处理相比,缺磷处理各测定时期的Pn和pro均有所降低.不同磷效率水稻品种中,磷高效品种的Pn(10.06～10.83μmolCO2.m-2.s-1)、叶绿素含量(3.32～3.56mg.g-1FM)和pro(33.08～33.95mg.g-1FM)最高,磷中效品种次之,磷低效品种最低;不同品种的气孔导度(Gs)差异不明显.随着磷胁迫时间的延长,各品种的超氧化物歧化酶(SOD)活性降低,表现为磷高效品种>中效品种>低效品种;各品种丙二醛含量的变化趋势与SOD活性相反;而过氧化物酶(POD)活性的变化规律不明显.因此,缺磷条件下,较高的SOD活性和较低的细胞膜脂过氧化程度在改善磷高效品种的光合生理功能中具有重要作用.     

脱硫废弃物对盐碱地水稻活性氧代谢的影响

以'96-D10'水稻品种为材料,测定了不同脱硫废弃物施用量下盐碱地水稻不同生育期的抗氧化酶活性及膜脂过氧化指标的变化,以探讨脱硫废弃物对水稻生长影响的生理机制及脱硫废弃物对盐碱地改良的效果.结果表明,随着脱硫废弃物施用量的增加,水稻各生育期叶片和根系丙二醛(MDA)含量、细胞质膜相对透性、超氧阴离子自由基(t/hm2脱硫废弃物施用量处理在水稻整个生育期内抗氧化保护酶的活性最高,而活性氧的含量和膜脂过氧化作用最低.研究发现,施用22.5 t/hm2脱硫废弃物能够显著提高盐碱地水稻植株不同生育期保护酶活性,减少体内活性氧过量累积,从而增强其耐盐性.     

甜高粱茎秆不同节间糖分累积与相关酶活性的变化

为了进一步了解甜高粱茎秆糖分代谢的规律,利用高效液相色谱等方法测定了考利、拉马达和MN-2747等3个甜高粱品种成熟期6个节间果糖、葡萄糖和蔗糖含量以及中性转化酶(NI)、可溶性酸性转化酶(SAI)、蔗糖磷酸合成酶(SPS)和蔗糖合成酶(SS)的酶活性,并对其变化规律和相关性进行了分析。结果表明:不同品种间,果糖、葡萄糖和蔗糖含量变化范围较大,分别为2.32～4.34mg/g、2.30～4.14mg/g和35.92～95.92mg/g。随着节间的变化,3个品种果糖和葡萄糖均呈现"U"型变化趋势,而蔗糖无明显的变化规律,只是略有增高的趋势。3个品种成熟期茎秆中NI、SAI、SPS和SS酶活性普遍较低,随着节间的提高均呈现降低的趋势。节间蔗糖含量与SAI酶活性呈显著负相关(R=-0.71,P0.01),与NI、SPS和SS酶活性无明显相关性。SAI可能为甜高粱茎秆糖分代谢的关键调控酶。     

低剂量微波辐射对增强UV-B辐射损伤菘蓝幼苗抗氧化酶活性的影响

为了探讨低剂量微波对增强UV-B辐射损伤菘蓝(Isatis indigotica Fort.)的修复作用,将经过10.08 kJ·m-2·d-1辐射损伤(PAR=220 μmol·m-2·s-1)的菘蓝幼苗分别经0、3、6、9和12 s等不同时间的微波辐照(126 mW·cm-2,2 450 MHz),然后测定其幼苗MDA含量、紫外吸收物质含量、抗坏血酸含量以及3种抗氧化酶SOD、CAT和POD活性.结果表明,增强UV-B辐射损伤菘蓝在微波的作用下其菘蓝幼苗中SOD、CAT和POD活性及紫外吸收物质含量、抗坏血酸含量提高,MDA含量得到显著的降低,说明微波对增强UV-B辐射伤害菘蓝幼苗具有修复作用.但是,随着微波剂量的增加,这种修复效应减弱,甚至消失.上述参数的变化说明适量时间的微波处理可以提高菘蓝对增强UV-B辐射的抵抗能力,并在此基础上初步探讨了微波的修复机理.     

Pre-Treatment of Bean Seedlings with Choline Compounds Increases the Resistance of Photosynthetic Apparatus to UV-B Radiation and Elevated Temperatures

Bean (Phaseolus vulgaris L. cv. Berbukskaya) seedlings were pre-treated with choline compounds, 19 mM 2-ethyltrimethylammonium chloride (Ch) or 1.6 mM 2-chloroethyltrimethylammonium chloride (CCh), during 24 h, then after 6 d the excised primary leaves were exposed to UV-B and high temperature stress. Chlorophyll (Chl) fluorescence, delayed light emission, accumulation of photosynthetic pigments, contents of thiobarbituric acid reactive substances, and activities of the active oxygen detoxifying enzymes (superoxide dismutase, ascorbate peroxidase, and glutathione reductase) were examined. Pre-treatment of plants with Ch or CCh enhanced the resistance of photosystem 2 (PS2) photochemistry to UV-B and heat injuries. The higher stress resistance can be explained by the increased activity of the detoxifying enzymes. The increased content of UV-B-absorbing pigments may also contribute to the enhanced resistance of choline-treated plants to UV-B radiation.     

Protective role of selenium in wheat seedlings subjected to enhanced UV-B radiation

Selenium (Se) is beneficial for some plants and is able to increase resistance and antioxidant capacity of plants subjected to stressful environment. In this work, the effects of enhanced ultraviolet-B (UV-B) radiation, Se supply, and their combination on growth and physiological traits of wheat (Triticum aestivum L., cv. Han NO.7086) seedlings were studied. The objective was to elucidate whether Se could alleviate the expected adverse effects of UV-B stress on seedlings. UV-B treatment caused a marked decline in growth parameters and total chlorophyll content and changed biomass allocation between aboveground and underground parts, which led to an increase in the root/shoot ratio. UV-B treatment also increased MDA content and the rate of superoxide radical (O₂^·−) production, although it increased some antioxidant (proline, phenolic compounds, and flavonoids) content and activity of antioxidant enzymes (peroxidase, superoxide dimutase, catalase (CAT)). Se treatment only increased total chlorophyll content and CAT activity. Compared with UV-B treatment alone, the combined treatment with UV-B and Se induced a significant increase in the biomass, total chlorophyll content, antioxidant content, and activity of antioxidant enzymes, and an evident decrease in MDA content and the rate of O₂^·− production. The results of this study demonstrated that Se alleviated the damage caused by UV-B to wheat seedlings to some extent by increasing antioxidant enzyme activity and antioxidant content.     

茉莉酸对小麦幼苗UV-B抗性的生理学效应研究

以小麦品种‘西农88’(Triticum aestivum L.,cv.Xinong 88)为材料,研究了外源施加不同浓度茉莉酸(1、2.5、5、10 mmol/L)对UV-B辐射(1.5 kJ·m-2·d-1)下小麦幼苗光合色素、抗氧化酶、丙二醛、游离脯氨酸、紫外吸收物、花青素、根系活力等生理指标以及对其生长的影响,探讨了茉莉酸在UV-B辐射胁迫中的可能作用及其作用机制.研究结果表明,外源茉莉酸对小麦幼苗生理指标产生显著影响,并且表现出浓度效应,其中较低浓度的茉莉酸(1 mmol/L和2.5 mmol/L)能明显提高小麦幼苗的UV-B抗性.表现为低浓度茉莉酸显著提高UV-B辐射下小麦幼苗叶片中的总叶绿素含量、过氧化氢酶(CAT)、过氧化物酶(POD)和超氧化物歧化酶(SOD)活性.并且外源施加的茉莉酸还能够增加小麦幼苗的游离脯氨酸含量,降低脂质过氧化水平,提高花青素含量,增强根系活力.可见,茉莉酸通过提高小麦幼苗的抗氧化酶活性,增加渗透调节物含量以及保护性色素含量,从而缓解膜脂过氧化程度和提高防御物质含量,进而增强植物抵抗UV-B辐射胁迫的能力,保证小麦幼苗正常生长.     

Effects of Enhanced UV- B Radiation on Protein Metabolism of Bean Leaves

Bean ( Phaseolus vulgaris L. ) seedlings were grown in a greenhouse condition under UV-B (280 ~ 320 nm) radiation and an UV-B-free control condition. At early stage of bean growth, UV-B radiation(UV- BBE: 16 kJ·m-2·d-1 ) increased the synthetic rate of protein in bean leaves. UV-B radiation decreased the synthetic rate of protein and the content of soluble protein, increased the activities of caseolytic enzymes and the content of total amino acids in bean leaves at later growth stage. The results of SDS-PAGE indicated that UV-B radiation increased the contents of polypeptide in a range of 99 kD, 88 kD, 76 kD, 42 kD, 35 kD and 33 kD at the early stage, and increased that of 10 ~ 14 kD, 29 kD, 33 kD and 35 kD at later growth stage. It is suggested that the increase of these polypeptides is an adaptation response of plants to the enhanced UV-B radiation.     

Over-expression of a small heat shock protein,sHSP17.7, confers both heat tolerance and UV-B resistance to rice plants

Exposure of rice (Oryza sativa L.) seedlings to a high temperature (42°C) for 24 h resulted in a significant increase in resistance to UV-B damage. UV-B resistance was enhanced in parallel with the period of heat treatment. sHSP17.7 was isolated from heated rice seedlings, and the influence of rice sHSP17.7 expression on the viability of E. coli under heat-shock conditions was assessed. After heating, the survival rate of sHSP17.7 cells was 2-fold higher than that of the control cells. The molecular chaperone activity of sHSP17.7 was investigated using catalase as a substrate. Recombinant sHSP17.7 had heat-stable chaperone properties that were capable of protecting stressed catalase from precipitation. sHSP17.7 was overexpressed in the rice cultivar Hoshinoyume, by Agrobacterium-mediated transformation, under the control of a CaMV 35S promoter. Transgenic rice plants with increased levels of sHSP17.7 protein exhibited significantly increased thermotolerance compared to untransformed control plants. The level of increased thermotolerance was correlated with the level of increased sHSP17.7 protein in the transgenic plants. The transgenic rice plant with the highest constitutive expression of sHSP17.7 had significantly greater resistance to UV-B stress than untransformed control plants. Increase in the degree of resistance of transgenic plants to UV-B was accompanied by an increase in production of sHSP17.7 protein.     

UV-B辐射胁迫对杨桐幼苗生长及光合生理的影响

通过对UV-B辐射胁迫下亚热带典型木本杨桐幼苗的生长及光合生理的研究,探讨植物对于UV-B辐射胁迫的生理响应及适应性机理,进而揭示UV-B辐射变化对亚热带森林树种的影响.实验设置UV-B辐射滤光组、自然光对照组以及辐射增强组,选择亚热带典型树种杨桐(Cleyera japonica Thunb.)幼苗为实验材料.研究结果表明:(1)增强UV-B辐射会降低杨桐幼苗的叶绿素含量,而降低辐射则会显著促进叶绿素的增加,且这种胁迫在时间上具有积累性.(2)增强或降低辐射强度都会抑制杨桐地径的生长,增强辐射会产生更显著的抑制;降低辐射强度会对杨桐幼苗的株高生长产生促进作用,反之,则会抑制其生长.3个测定期数据综合分析显示随着处理时间的加长,这种胁迫作用有减小的趋势.(3)对光响应曲线的分析表明相对于自然光条件下的UV-B辐射,降低其强度对杨桐幼苗光合作用有显著的促进作用,反之则会抑制,不过抑制作用并不显著;对于光合特征参数的分析表明增强或降低UV-B辐射会显著降低杨桐幼苗的光饱和点(LSP)和光补偿点(LcP),而对最大净光合速率(Amax)、表观光合量子效率(AQY)、暗呼吸速率(Rd)影响均不显著,表明辐射胁迫对杨桐幼苗利用光能的效率影响不大,从而也并未对杨桐的光合作用产生显著性的伤害,但是由于森林树种的多年生特性,这种影响将是积累性的或延迟的,UV-B所造成的光合作用或光能利用率的微小变化都可能会积累成长期影响.因此,对森林树种进行长期研究是必要的.     

Effects of UV-B radiation on antioxidant parameters of iron-deficient barley plants

Iron deficiency is a stress frequently experienced by plants, owing to the low solubility of Fe(III) salts in neutral or alcaline soils. Iron is an essential plant nutrient as it is involved in fundamental metabolic processes. Furthermore, it is a constituent of important antioxidant enzymes, which are involved in maintaining the balance of cell redox state. UV-B radiation is an environmental problem which can alter the redox state of plants through the increased production of reactive oxygen species. In order to investigate if iron deficiency influences the antioxidant response of plants to UV-B radiation, barley seedlings, Hordeum vulgare L. cv. Express, were exposed to UV-B radiation while growing in nutrient solutions with or without iron. After eight days of growth, plants were harvested and analysed. Results show that, during the 8 days of the experimental period, in neither of the two nutritional conditions considered does UV-B exposure reduce shoot weight or induce evident alterations of thylakoid membranes in respect to controls. However, different responses to UV-B radiation between iron-deficient and iron-sufficient plants were observed at the level of parameters related to oxidative stress. In fact, in iron-sufficient plants the contents of photosynthetic pigments and ascorbate, and the enzyme activities of ascorbate peroxidase (EC 1.11.1.11) and catalase (EC 1.11.1.6) were not affected by UV-B radiation. Conversely, in iron-deficient plants the contents of ascorbate and zeaxanthin and the activity of ascorbate peroxidase increased under UV-B exposure, whereas catalase activity decreased. Furthermore, UV-B radiation induced an increase of hydrogen peroxide content which was higher in iron-deprived plants than in iron-sufficient ones. This may indicate that plants growing in an environment enriched in UV-B radiation may develop a high level of oxidative stress when iron supply is limited.     

Responses of the flavonoid pathway to UV-B radiation stress and the correlation with the lipid antioxidant characteristics in the desert plant Caryopteris mongolica

Caryopteris mongolica is a dwarf shrub mainly found in grassland and desert areas of north-west China, and which can survive severe environmental stress. This study aimed to assess the responses of the flavonoid pathway to UV-B radiation treatments and its correlation to the lipid peroxide and antioxidant systems in C. mongolica. In UV-B radiation experiments, plants were exposed to UV-B radiation treatments with a intensity of 30 J/s for 1, 4 and 24 h, respectively. A control group without UV-B radiation treatment was also used. The chlorophyll fluorescence parameters, contents of chlorophyll and carotenoid, levels of lipid peroxidation, activities of antioxidant system enzymes, accumulations of total flavonoids and anthocyanins, and activities of phenylalanine ammonialyase (PAL) and chalcone isomerase (CHI) under different UV-B radiation treatments were investigated. The correlations between products and key enzymes in the flavonoid pathway and the lipid peroxide and antioxidant systems were also analyzed. The results showed that chlorophyll fluorescence parameters decreased within 24 h of treatment. The chlorophyll contents decreased within 4 h and remained stable after 24 h. Carotenoid content significantly increased. The level of MDA, the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX) and peroxidase (POD) and the contents of total flavonoids and anthocyanidins increased, while catalase (CAT) activity decreased under UV-B stress. The activities of PAL and CHI also increased with the increased content of total flavonoids. The flavonoid products anthocyanidins had a significant positive correlation with MDA level, as well as the activities of antioxidant enzyme SOD. In conclusion, UV-B radiation induced the degradation of photosynthetic pigments and decreased photochemical efficiency of Photosystem II; increased the contents of MDA, total flavonoids and anthocyanidins; and also enhanced activities of antioxidant enzymes (SOD, APX and POD) and key enzymes (PAL and CHI) in the flavonoid pathway in C. mongolica. Thus, we speculate that the flavonoid pathway were involved in the regulation of stress resistance in C. mongolica.     

Protective Effect of Cerium Ion Against Ultraviolet B Radiation-Induced Water Stress in Soybean Seedlings

Effects of cerium ion (Ce(III)) on water relations of soybean seedlings (Glycine max L.) under ultraviolet B radiation (UV-B, 280–320 nm) stress were investigated under laboratory conditions. UV-B radiation not only affected the contents of two osmolytes (proline, soluble sugar) in soybean seedlings, but also inhibited the transpiration in soybean seedlings by decreasing the stomatal density and conductance. The two effects caused the inhibition in the osmotic and metabolic absorption of water, which decreased the water content and the free water/bound water ratio. Obviously, UV-B radiation led to water stress, causing the decrease in the photosynthesis in soybean seedlings. The pretreatment with 20 mg L⁻¹ Ce(III) could alleviate UV-B-induced water stress by regulating the osmotic and metabolic absorption of water in soybean seedlings. The alleviated effect caused the increase in the photosynthesis and the growth of soybean seedlings. It is one of the protective effect mechanisms of Ce(III) against the UV-B radiation-induced damage to plants.