遮荫对濒危植物甜菜树光合生理和叶绿素荧光特性的影响

以西南特有濒危植物甜菜树为材料,研究了不同遮荫处理(全光照、50％遮荫、65％遮荫和80％遮荫)对甜菜树叶片光合特性、叶绿素荧光和气孔特征的影响,为甜菜树种质资源保育和开发利用提供科学依据。结果表明：50％遮荫处理显著提高了甜菜树叶片净光合速率,80％遮荫处理则起抑制作用;50％遮荫和65％遮荫处理提高甜菜树叶蒸腾速率,有利于光合作用的进行;80％遮荫处理下胞间 CO 2浓度提高,抑制了甜菜树叶蒸腾作用和光合作用;50％遮荫和65％遮荫处理下净光合速率提高,说明甜菜树对遮荫有一定的适应性;叶绿素荧光方面,80％遮荫处理导致叶片 PSⅡ最大光化学效率(F v/F m )和实际光化学效率(ФPSⅡ)下降。甜菜树叶片光合特性与气孔结构关系密切,遮荫降低甜菜树叶片气孔密度。     

氮素形态对杉木幼苗侧根生长和叶片光合特性的影响

以3月龄的杉木实生苗为试验材料,分析了不同氮素形态——硝态氮(NO₃^- N)、铵态氮(NH4⁺ N)和硝酸铵(NH₄NO₃)(氮素浓度均为3 mmol·L^-1)对杉木幼苗侧根生长、叶片光合气体交换参数和叶绿素荧光参数的影响,以揭示杉木幼苗对不同形态氮的偏好性,以及不同形态氮肥下杉木幼苗侧根生长和光合生理的响应特征,为杉木苗期氮肥管理提供理论依据。结果显示：(1)不同氮素形态对杉木幼苗地上部和侧根生物量具有显著影响,其中NH₄⁺ N处理下幼苗地上部和侧根生物量最大,NO₃^- N处理次之,而NH₄NO₃处理最小。(2)NH₄⁺ N和NO₃^- N处理下杉木幼苗总根长、根系总表面积和根系总体积均显著高于NH₄NO₃处理(P＜0.05),且NH₄⁺ N处理又显著高于NO₃^- N处理,但不同氮形态处理间侧根数量差异不显著。(3)NH₄⁺ N处理下杉木幼苗叶片净光合速率、气孔导度和蒸腾速率明显高于NO₃^- N和NH₄NO₃处理,但NO₃^- N和NH₄NO₃处理之间无明显差异。(4)NH₄⁺ N处理下杉木叶片初始荧光强度低于NO₃^- N处理,而最大荧光强度、可变荧光强度和PSⅡ潜在活性却高于全硝氮和硝铵氮处理。上述结果表明,NH₄⁺ N处理不仅有利于杉木幼苗侧根生长发育,且其叶片具有较强的光合能力,较高的PSⅡ中心稳定性、光化学活性以及电子传递效率,从而更有利于植株生长。因此,从根系生长和光合特性来看,杉木幼苗对铵态氮具有偏好性。     

赤星病胁迫对不同抗性烟草品种光合作用和叶绿素荧光特性的影响

以不同烟草赤星病抗性品种JYH(抗病品种)和CBH(感病品种)为材料,在盆栽试验条件下,调查不同烟草赤星病胁迫程度(轻度胁迫、中度胁迫和重度胁迫)对光合色素含量、光合作用参数和叶绿素荧光动力学特征的影响。结果显示:1)烟草赤星病胁迫导致2个品种的叶绿素a、叶绿素b、总叶绿素和类胡萝卜素含量均呈下降趋势,且JYH的降幅小于CBH。2)除JYH的净光合速率在轻度胁迫下有所增加外,JYH、CBH的净光合速率、气孔导度因烟草赤星病胁迫而降低。2个品种的胞间CO2浓度、气孔限制值变化具有明显差异,烟草赤星病胁迫导致CBH的胞间CO2浓度上升,气孔限制值则明显下降,这与JYH在重度胁迫下的变化趋势一致。而JYH的胞间CO2浓度在轻度、中度胁迫降低,气孔限制值则呈上升趋势。3)烟草赤星病胁迫下,2个品种的初始荧光(F0)、非光化学猝灭系数(NPQ)均有所增加。重度胁迫下,JYH、CBH的F0分别比对照增加16.5%、34.48%,NPQ分别上升95.54%、137.45%,差异均达到显著水平。而各品种的最大荧光(Fm)、可变荧光(Fv)、PSⅡ最大光化学效率(Fv/Fm)、PSⅡ潜在活性(Fv/F0)、光化学淬灭系数(qp)、PSⅡ实际光化学效率(ΦPSⅡ)在烟草赤星病胁迫下均呈下降趋势,降幅表现为JYHCBH。研究结果表明,JYH的光合色素、光合作用和叶绿素荧光特性受烟草赤星病胁迫影响小于CBH,维持较高的光合性能是对烟草赤星病具有较强抗性的生理基础。     

外源甜菜碱对盐胁迫下枸杞光合功能的改善

研究了外源甜菜碱对盐胁迫下枸杞扦插苗叶片光合功能的影响。结果表明,外源甜菜碱能使盐胁迫下的枸杞叶片叶绿素荧光动力学参数Fo、Fm、Fv、Fv／Fm、Fm／Fo和Fv／Fo增高,使光合色素叶绿素a(Chla)、叶绿素b(Chlb)和类胡萝卜素(Car)含量明显增加,叶绿素a与b的比值(Chla／Chlb)升高,类胡萝卜素与叶绿素的比值(Car／Chl)降低,说明外源甜菜碱有利于植物对光能的捕获、吸收、传递和转换,提高叶片的光合活性,降低盐胁迫对植物的抑制作用。     

盐胁迫下CO2加倍对春小麦一些光合功能的影响

 研究了在盐胁迫下CO2浓度加倍对春小麦(Triticum aestivum)青323光合色素含量和一些光合功能的影响。结果表明,盐胁迫降低春小麦叶片单位鲜重叶绿素(Chl)和类胡萝卜素(Car)的含量、叶绿体对光能的吸收能力,Mg2+对两个光系统(PSⅡ和PSⅠ)之间激发能分配的调节能力,以及荧光猝灭速率(△FV/T)。然而,CO2加倍有提高上述各参数的作用,表明高CO2浓度能减轻盐胁迫对光合功能的不利效应。     

外源NO对增补UV-B辐射下兴安落叶松幼苗叶片光合色素和叶绿素荧光特性的影响

在增强UV-B辐射下,以3年生兴安落叶松幼苗为实验材料,研究了外源NO供体硝普钠(Sodium nitroprusside,SNP)对幼苗的光合色素（Chla、Chlb和Car）和叶绿素荧光参数的影响。方差分析结果表明0.5 mmol·L^-1的SNP对增补UV B胁迫下的兴安落叶松幼苗产生显著影响。0.5 mmol·L^-1的SNP能够显著抑制增补UV-B辐射后光合色素、F_v/F_m、Φ_PSⅡ、F_v′/F_m′和qP的明显下降以及Chla /Chlb、F_o和NPQ的升高。表明了外源NO能够减轻UV-B辐射胁迫下兴安落叶松幼苗光合反应中心的生理损伤,从而增强兴安落叶松幼苗对增补UV-B辐射胁迫环境的适应能力。     

减氮运筹对甘薯光合作用和叶绿素荧光特性的影响

光合性能是决定作物产量形成的关键,氮肥的合理施用是调控作物光合特性和产量形成的重要措施.于2016—2017年开展盆栽试验,研究了减氮和施肥方式对甘薯叶片光合作用和叶绿素荧光特性的影响.试验以常规习惯基施氮肥100 kg·hm^-2为对照(FP),在常规施氮量的基础上减氮20%,同时设置3种氮肥运筹方式:100%基施(JS)、100%移栽后35 d追施(KS)、50%基施+50%移栽后35 d追施(FS).结果表明:与常规基施氮肥100 kg·hm^-2相比,减氮条件下氮肥全部基施显著降低了全生育期甘薯光合性能,但追施处理显著提高了块根膨大期净光合速率(P_n)、气孔导度(g_s)、胞间CO₂浓度(C_i)和叶绿素(Chl a+b)含量.不同处理下,P_n、g_s、C_i和Chl a+b均以50%基施+50%追施处理最高.减氮分施处理甘薯块根膨大期的PSⅡ实际光化学效率(Φ_PSⅡ)、光化学淬灭系数(q_P)、PSⅡ最大光化学效率(F_v/F_m)和PSⅡ潜在活性(F_v/F_o) 提高,而初始荧光(F_o)和非光化学淬灭系数(NPQ)则降低.氮肥分施通过提高PSⅡ的光化学效率和电子传递速率,降低光能的热耗散,提高了甘薯块根膨大期功能叶的光合速率.2个品种不同年际间表现相同.表明氮肥一次性基施或追施均不利于提高甘薯叶片光合性能.减氮20%水平下,50%基施+50%追施可减缓叶片早衰,延长叶片功能期,提高甘薯的光合生产能力和生物量,有利于产量形成.     

不同形态氮素对高蛋白小麦幼苗叶绿素荧光特性的影响

不同形态的氮素 (NO- 3 和 NH+ 4 )培养对 2组产量水平相近而蛋白质含量有较大差异的 4个小麦品种幼苗叶绿素荧光特性在不同的测定光强下产生不同的影响 :低光强下 ,NH+ 4和 NO- 3 培养的幼苗 Fv/Fm在品种间和处理间均无明显差异。饱和光强下 Fv/Fm下降 ,下降程度 CK>NH+ 4 >NO- 3 ,NH+ 4 处理中的 Fv/Fm与 CK差异达到显著性水平 ;NO- 3 处理达到极显著水平 ,对同产量水平的品种来说 ,Fv/Fm下降的程度低蛋白品种高于高蛋白品种。低光强下各品种的 ΦPS CK>NH+ 4 >NO- 3 ,而强光下的变化趋势正好相反 ,NO- 3 处理的 ΦPS 最高。在这两种光强下 ,NH+ 4 处理的 ΦPS 与对照相比 ,差异达到显著性水平 ,而 NO- 3 处理达极显著水平。差异显著性分析表明 ,不同形态的氮素对光系统的影响和作用是不同的     

水分胁迫对牛心朴子叶片光合色素及叶绿素荧光的影响

研究了水分胁迫对牛心朴子叶片光合色素及叶绿素荧光动力学参数的影响。结果表明,在长期的水分胁迫中,牛心朴子叶片的叶绿素a(Chl a)、叶绿素b(Chl b)和类胡萝卜素(Car)含量没有下降或下降不明显。直到处理末期才显著下降;叶片叶绿素荧光动力学参数Fo、Fm、Fv、Fv／Fm变化不大,在处理末期各处理Fo降低,轻度、重度水分胁迫的Fm、Fv、Fv／Fm升高。说明K期水分胁迫后牛心朴子的光合功能受到影响,但牛心朴子仍表现出较强的适应干旱的能力。     

水淹对水芹叶片结构和光系统Ⅱ光抑制的影响

通过探讨在水淹条件下水芹（Oenanthe javanica）叶片结构的变化以及出水对其光系统II功能和光抑制的影响,阐明水芹光合机构在水淹条件下及出水后死亡的可能原因。结果表明：水淹条件下新生沉水功能叶光系统Ⅱ（PSⅡ）最大光化学效率（Fv/Fm）、电子传递活性与对照叶片差异很小,但水淹使气生功能叶的Fv/Fm显著降低;植株总生物量呈负增长趋势;活体弱光条件下,沉水叶出水后2小时叶片相对含水量（RWC）和Fv/Fm无显著变化;中等光强和强光条件下其RWC和Fv/Fm迅速降低;离体条件下,5小时的中等光强对沉水叶的Fv/Fm影响不显著,在随后的弱光下能恢复到出水时的初始状态;强光能使沉水叶的Fv/Fm大幅降低,且弱光下不能恢复到出水时的初始水平;在解剖结构上,水芹沉水叶的叶片总厚度、上下表皮厚度和气孔大小都显著低于气生叶,而且沉水叶没有明显的栅栏组织分化,但是沉水叶上表皮的气孔密度显著高于气生叶。研究结果表明,水淹使水芹原气生叶PSⅡ功能迅速衰退,但对新生沉水叶片影响很小。水芹植株出水后,沉水叶片结构变化使其在光下保水能力下降,而强光导致了光合机构的光抑制和反应中心失活。田间条件下两者共同作用则加剧了对叶片光合机构的破坏,进而致使其死亡。     

Plant regeneration from protoplasts of sugar beet (Beta vulgaris)

Mesophyll protoplasts from two of five sugar beet lines tested were regenerated into plants. Mesophyll protoplasts of all lines showed high plating efficiencies up to 4.0% developed hard compact callus, and two of the lines also developed white, soft and friable callus consisting of starch grain-containing cells. Whereas the compact callus never regenerated into plants, the white friable ones frequently developed globular structures, which became green in the light and formed adventitious shoots after cytokinin (BAP or thidiazuron) treatment. Genetic analysis by PCR-fingerprinting and flow cytometry showed uniformity and unchanged ploidy levels in 15 independently regenerated plantlets in line NF. but altered ploidy level (from diploid to triploid) in a regenerated plantlet of clone VRB.     

Cadmium effects on leaf transpiration of sugar beet (Beta vulgaris)

Seedlings of sugar beet ( Beta vulgaris L. cv Monohill) were cultivated for 4 weeks in nutrient solution containing different concentrations of CdCl₂ (0 to 10 μ M ). The effects of Cd on appearance and function of stomata and leaf cuticle were investigated by water loss measurements and microscopy. The leaf transpiration rate increased with increasing Cd concentrations while the sum total of stomatal aperture area per unit leaf area decreased. Already at low Cd levels. an increase of defective and undeveloped stomata was found in Cd treated plants. These stomata are closed or have small apertures and probably lack a functional closing mechanism. The number of intact stomata per unit leaf area was lower in leaves of Cd treated plants than in controls, and Cd induced closure of intact stomata. The total number of stomata per leaf area slightly increases with increasing Cd concentration. as does the percentage of small stomata. Furthermore. specific leaf area increased, while the density of leaf structure was decreased by Cd. From this observation we conclude that the increase in transpiration rate caused by Cd is primarily due to effects on the permeability of the leaf cuticle to water.     

外源ATP对NaCl胁迫下菜豆叶片叶绿素荧光特性的调节

盐胁迫是影响植物生长的主要逆境因子之一,外源ATP被发现可作为信号分子参与植物对逆境胁迫生理反应的调节。为了探明外源ATP在植物盐胁迫响应中的作用,以增强植物对土壤盐渍化的耐性,更好地应用于土壤盐渍化修复。该研究以菜豆( Phaseolus vulgaris)为材料,通过叶绿素荧光技术探讨了外源ATP 对菜豆叶片在NaCl胁迫下叶绿素荧光特性的变化规律。结果表明：在NaCl胁迫下,叶片光系统Ⅱ( PSⅡ)潜在最大光化学量子效率( Fv/Fm)、光适应下最大光化学效率( Fv′/Fm′)、PSⅡ光适应下实际光化学效率[ Y (Ⅱ)]、光化学荧光猝灭( qP)、电子传递速率( ETR)与对照组相比均有显著性下降,而非光化学猝灭( NPQ)和( qN)较对照组有显著性增加,这表明NaCl胁迫导致菜豆叶片光系统Ⅱ光化学效率的下降和光能耗散的增加。而外源ATP(eATP)的处理能有效缓解NaCl胁迫所造成的Fv/Fm、Fv′/Fm′、Y(Ⅱ)、qP、ETR下降和NPQ、qN的上升。该研究结果表明在NaCl胁迫下外源ATP可以有效地提高菜豆幼苗光系统Ⅱ( PSⅡ)的光化学反应效率。     

Polymorphic microsatellite markers for inferring diversity in wild and domesticated sugar beet (Beta vulgaris)

Eight microsatellite loci were characterized within two cultivated beet (Beta vulgaris ssp. vulgaris) accessions and one accession of the wild progenitor of domesticated sugar beet, Beta vulgaris ssp. maritima. Allele diversity was high, yielding two to 11 alleles per locus. Polymorphism information content (PIC) values obtained for these eight loci where also high and indicate the highly informative nature of the microsatellites presented here. These described markers add to a small set of publicly available microsatellite markers for beet and will be instrumental in identifying patterns of genetic diversity and origins of domestication.     

Selection in vitro for UV-tolerant sugar beet (Beta vulgaris) somaclones

With a reduced stratospheric ozone concentration, the generation of UV-tolerant plants may be of particular importance. Among different crop plants there is large variation in sensitivity to UV-B radiation. This study was undertaken to investigate the possibilities of using somaclonal variation and selection in vitro for improving UV-B tolerance in sugar beet (Beta vulgaris L.). Sugar beet callus was exposed to UV radiation (280–320 nm, 0.863–5.28 kJ m^-2 day^-1, unweighted) and resultant shoots were selected from surviving cells. After establishment of the plants, they were grown under either visible radiation (114 μmol m^-2 s^-1 PAR) or with the addition of UV radiation (6.3 kJ m^-2 day^-1 biologically effective UV-B). Screening of regenerants in vivo for tolerance to UV radiation was undertaken 10 months after termination of the UV selection pressure. Screening was done visually and by using a number of physiological parameters, including chlorophyll fluorescence induction, ultraweak luminescence, pigment analysis and total content of UV-screening pigments. A clear difference between the unselected and the UV-selected somaclones was observed when visually studying the UV damage and other leaf injury. The observations were supported by the ultraweak luminescence measurements. Unselected plants showed significantly greater damage when subjected to subsequent UV radiation as compared to the selected plants. The clones subjected to UV selection pressure displayed a significantly higher concentration of UV-screening pigments under subsequent UV radiation. The unselected plants under subsequent UV treatment showed a lower carotenoid concentration when compared to selected plants. However, no significant difference between treatments was found for chlorophyll a/b, or F/F_max, a measure of photosynthetic quantum yield.     

Improvement of protoplast culture protocols for Beta vulgaris L. (sugar beet)

Summary The effects of NaCl, feeder cells and the embedding of protoplasts in calcium alginate have been investigated in an attempt to improve culture conditions of recalcitrant sugar beet (Beta vulgaris L.) mesophyll protoplasts. While the use of NaCl in all instances proved detrimental to protoplast development, the other two treatments had clear beneficial effects. Minimum plating densities, necessary to sustain cell division, could be reduced to <5% (<4000 protoplasts / ml) of the control levels and plating efficiencies could be significantly enhanced by approx. 10 fold. Plants could still be regenerated from soft calli derived from mesophyll protoplasts cultured under the modified conditions at a frequency of 20–30 %. In particular, the use of alginate is considered of potentially great importance for the further application of beet protoplasts for other aims e.g. asymmetric hybridization.     

Genetic approaches to sustainable pest management in sugar beet (Beta vulgaris)

Sugar beet (Beta vulgaris) is an important arable crop, traditionally used for sugar extraction, but more recently, for biofuel production. A wide range of pests, including beet cyst nematode (Heterodera schachtii), root‐knot nematodes (Meloidogyne spp.), green peach aphids (Myzus persicae) and beet root maggot (Tetanops myopaeformis), infest the roots or leaves of sugar beet, which leads to yield loss directly or through transmission of beet pathogens such as viruses. Conventional pest control approaches based on chemical application have led to high economic costs. Development of pest‐resistant sugar beet varieties could play an important role towards sustainable crop production while minimising environmental impact. Intensive Beta germplasm screening has been fruitful, and genetic lines resistant to nematodes, aphids and root maggot have been identified and integrated into sugar beet breeding programmes. A small number of genes responding to pest attack have been cloned from sugar beet and wild Beta species. This trend will continue towards a detailed understanding of the molecular mechanism of insect–host plant interactions and host resistance. Molecular biotechnological techniques have shown promise in developing transgenic pest resistance varieties at an accelerated speed with high accuracy. The use of transgenic technology is discussed with regard to biodiversity and food safety.     

Direct and indirect effects of Cd2+ on photosynthesis in sugar beet (Beta vulgaris)

Sugar-beet plants ( Beta vulgaris L. cv. Monohill) were cultivated for 4 weeks in a complete nutrient solution. Indirect effects of cadmium were studied by adding 5, 10 or 20 μ M CdCl₂ to the culture medium while direct effects were determined by adding 1, 5, 20, 50 or 2 000 μ M CdCl₂ to the assay media. The photosynthetic properties were characterized by measurement of CO₂ fixation in intact plants, fluorescence emission by intact leaves and isolated chloroplasts, photosystem (PS) I and PSII mediated electron transport of isolated chloroplasts, and CO₂-dependent O₂ evolution by protoplasts. When directly applied to isolated leaves, protoplasts and chloroplasts. Cd²⁺ impeded CO₂ fixation without affecting the rates of electron transport of PSI or PSII or the rate of dark respiration. When Cd²⁺ was applied through the culture medium the capacity for, and the maximal quantum yield of CO₂ assimilation by intact plants both decreased. This was associated with: (1) decreased total as well as effective chlorophyll content (PSII antennae size), (2) decreased coupling of electron transport in isolated chloroplasts, (3) perturbed carbon reduction cycle as indicated by fluorescence measurements. Also, protoplasts isolated from leaves of Cd²⁺-cultivated plants showed an increased rate of dark respiration.     

In vitro culture of petioles and intact leaves of sugar beet (Beta vulgaris)

Methods are described for obtaining explants which produce adventitious shoots, for subsequent stimulation of rooting and then transplanting using six commercial sugar-beet cultivars. The rate of adventitious shoot regeneration from petioles or intact leaf explants was affected by the source of donor plants, cytokinin type (BAP or Kin) and concentration and cultivar. Increasing the sucrose concentration of the medium from 3% to 5% or 8% had no apparent effect. Adventitious shoots could be produced directly from callus formed on the base of the petioles. In general adventitious shoots were produced on either the concave surface of the petiole or from the callus, occasionally simultaneously on both, and on the convex surface of the petiole in intact leaf explants. The highest rooting rate with 3% sucrose and 1.0 mg l^–1 NAA was obtained using half-strength MS medium. There was considerable variation in the propagules from petioles or callus indicating that this system may provide valuable somaclonal variation.Abbreviations BAP benzylaminopurine - IBA indole-3-butyric acid - GA₃ gibberellic acid - MS Murashige and Skoog medium - NAA naphthaleneacetic acid Author for correspondence