花粒期光照对夏玉米光合特性和叶绿体超微结构的影响

在大田条件下,以夏玉米品种‘登海605’为试验材料,研究花粒期不同光照强度(正常光照、开花至收获期遮阴和开花至收获期增光)对夏玉米叶片光合、荧光性能和叶绿体超微结构的影响.结果表明:与对照相比,花粒期遮阴影响叶绿体排布及内部结构发育,基粒个数和基粒片层数均有不同程度减少,叶片的净光合速率、蒸腾速率、气孔导度、叶绿素含量下降,PSⅡ反应中心的实际光化学效率和最大光化学效率降低,非光化学淬灭系数数值增加,导致产量降低;增光后叶绿体结构良好,基粒片层排列紧致、清晰且数量增加,PSⅡ反应中心的实际光化学效率增加,净光合速率、蒸腾速率、气孔导度、叶绿素含量上升,叶片光合性能增强,产量增加.即花粒期遮阴破坏了夏玉米叶片叶绿体超微结构,降低了叶片光合能力,产量下降;花粒期增光增加了叶肉细胞中叶绿体的基粒和基粒片层,导致基粒片层排列紧密有序,有利于增加作物产量潜力.     

生长调节物质和可溶性糖含量对丹参中丹酚酸类物质积累的影响

采用盆栽实验研究了生长调节物质水杨酸（SA）、茉莉酸甲酯（MeJA）、赤霉素（GA3）对不同生长时期丹参植株中非结构糖含量、碳/氮比及根中丹酚酸类物质积累的影响;并进一步测定培养基中不同浓度蔗糖、葡萄糖、果糖对丹参毛状根中丹酚酸类物质积累的影响,对盆栽实验的结论进行了验证。结果显示,SA处理的丹参幼苗及花后期植株中蔗糖含量有增加趋势,而MeJA处理的丹参幼苗及花后期植株及GA3处理的丹参花后期植株中蔗糖积累均有降低趋势;且SA、MeJA和GA3处理对花后期植株地上和地下部分碳/氮比的影响不同。然而,SA和MeJA处理的丹参幼苗及花后期植株地上部分和根中还原糖含量、GA3处理的花后期植株根中还原糖含量均显著增加;同时,SA和MeJA处理的丹参幼苗根中迷迭香酸含量,以及SA、MeJA、GA3处理的花后期植株根中迷迭香酸含量和丹酚酸类总量显著增加。毛状根培养结果进一步证明,葡萄糖促进毛状根中迷迭香酸的产生,增加丹酚酸类总量,毛状根中迷迭香酸、丹酚酸B的积累及丹酚酸类总量与培养基中蔗糖浓度不相关。可见,丹参（植株）根中丹酚酸类物质的产生和积累受SA、MeJA和GA3的诱导,其与碳/氮比及植株中蔗糖含量没有相关性,推测植株中葡萄糖含量的增加促进根中丹酚酸类物质的积累。     

外源GA3对紫斑牡丹幼苗叶片解剖结构与光合特性及内源激素含量的影响

以1年生紫斑牡丹幼苗为试验材料,采用不同浓度(0、100、300、500 mg/L)赤霉素(GA_3)喷施叶片处理,通过透射电镜、扫描电镜、光学显微镜观察幼苗叶片解剖结构,光合仪测定幼苗光合参数并以酶联免疫吸附法测叶片内源激素含量,探究外源GA_3对紫斑牡丹幼苗叶片解剖结构、光合特性和内源激素水平的影响。结果表明:(1)低浓度GA_3处理的紫斑牡丹叶肉细胞增大,栅栏组织外层细胞中叶绿体数量增加,高浓度GA_3处理则与之相反;GA_3处理叶片的栅栏组织/海绵组织比值(P/S)、组织结构紧密度(CTR)均下降,而其组织结构疏松度(SR)增加;GA_3处理的幼苗叶片的叶肉细胞内各叶绿体大小显著大于对照,随着GA_3处理浓度增加,紫斑牡丹叶肉细胞内叶绿体的体积趋于增大,类囊体垛叠凝聚逐渐松散,叶绿体上淀粉颗粒在300 mg/L GA_3处理中较明显;叶片气孔长度、宽度、气孔器大小、气孔开度和气孔密度随着GA_3浓度升高先升高后下降,同时叶片上表皮角质层厚度随GA_3浓度的升高而增加。(2)紫斑牡丹叶片净光合速率(P_n)、气孔导度(Cond)、蒸腾速率(T_r)、水分利用率(WUE)在100和300 mg/L GA_3处理下大都显著高于对照,且300 mg/L GA_3处理显著高于其余处理,而其在500 mg/L GA_3处理下显著低于对照。(3)紫斑牡丹叶片脱落酸(ABA)和吲哚乙酸(IAA)含量均在500 mg/L GA_3下显著高于对照,而在其余浓度处理下不同程度低于对照,叶片内源玉米素核苷(ZR)和GA_3含量均在300 mg/L GA_3处理下显著高于其余处理和对照,而其余处理相比对照均无显著变化;叶片的ZR/ABA、ZR/IAA、ZR/GA_3和(IAA+GA_3+ZR)/ABA比值都在300 mg/L GA_3处理下显著高于其他处理,叶片的IAA/ABA和ABA/GA_3比值均在500 mg/L GA_3处理下显著高于其他处理。研究发现,适宜浓度外源GA_3处理,能显著提高紫斑牡丹幼苗叶片光合速率、水分利用效率及蒸腾速率,调节植物体内源激素的含量及平衡,从而使叶片能合成较多有机物,促进幼苗生长。     

信号分子水杨酸减缓干旱胁迫对紫御谷光合和膜脂过氧化的副效应

为研究信号分子水杨酸(SA)对干旱胁迫下紫御谷光合和膜脂过氧化的影响,为SA应用于紫御谷抗旱育苗提供理论依据,测定分析了SA处理对干旱胁迫下紫御谷幼苗叶片光合和膜脂过氧化相关指标的变化。结果表明:(1)干旱胁迫破坏了紫御谷叶绿体的膜结构,使基粒数量明显减少,垛叠不明显,排列比较松散,而SA处理能在一定程度上保护叶绿体的膜结构。(2)干旱胁迫降低了紫御谷幼苗叶片的叶绿素b和总叶绿素含量,而SA处理能提高干旱胁迫下紫御谷幼苗叶片的叶绿素a、叶绿素b、总叶绿素和胡萝卜素含量。(3)干旱胁迫降低了叶片的净光合速率、气孔导度、蒸腾速率、光饱和点和暗呼吸速率,增加了叶片的光补偿点、CO₂饱和点、CO₂补偿点和光呼吸速率,而SA处理则增加了紫御谷幼苗叶片的净光合速率、气孔导度、光饱和点和暗呼吸速率,降低了紫御谷幼苗叶片的光补偿点、CO₂饱和点、CO₂补偿点和光呼吸速率。(4)干旱胁迫降低了紫御谷幼苗叶片的F_v/F_m和Φ_PSⅡ,显著增加了叶片的相对电导率和丙二醛含量,而SA处理则增加了幼苗叶片的F_v/F_m和Φ_PSⅡ,降低了叶片的相对电导率和丙二醛含量。表明:信号分子水杨酸能够有效减缓干旱胁迫对紫御谷光合和膜脂过氧化的影响。     

模拟大气硫酸铵污染对香樟幼苗生长及光合特性的影响

通过室内盆栽实验研究了大气颗粒污染物硫酸铵对香樟幼苗生长及光合特性的影响。结果表明,香樟幼苗叶片涂抹硫酸铵处理对植物生长无显著影响;低浓度硫酸铵(2 g·L^-1)提高了叶片叶绿素含量,而高浓度(4 g·L^-1)却降低了叶片叶绿素含量;与对照相比,低浓度处理的香樟叶片净光合速率、气孔导度、胞间二氧化碳浓度与蒸腾速率无显著差异;高浓度处理的香樟叶片净光合速率与蒸腾速率高于对照,而气孔导度与胞间二氧化碳浓度与对照无显著差异。机理分析表明,硫酸铵颗粒物主要通过影响叶片气孔导度来影响植物光合特性。     

光质对番茄和莴苣幼苗生长及叶绿体超微结构的影响

采用发光二极管(LED)精确调制不同光谱能量分布,以荧光灯光照为对照,研究光质对番茄和莴苣幼苗生长及叶绿体超微结构的影响.结果表明：红光下番茄、莴苣幼苗的可溶性糖、淀粉和碳水化合物含量均显著高于对照,叶片叶绿体中淀粉粒膨大显著;蓝光极显著抑制了番茄下胚轴伸长,显著提高了莴苣和番茄幼苗叶片叶绿素a和类胡萝卜素含量;红蓝光下莴苣幼苗叶片的可溶性糖、淀粉、碳水化合物、蔗糖含量和C/N均达到最大值且显著高于红光处理,番茄和莴苣幼苗的主根显著伸长,幼苗叶片中叶绿体形态正常,基粒增多,基质片层清晰,淀粉粒体积明显小于红光处理.光质对植物幼苗的光形态建成、生长、碳氮代谢及叶绿体发育有显著影响;红光下光合产物积累显著但运输受阻严重,在红光中添加适量蓝光更有利于莴苣幼苗的碳水化合物积累,并可促进幼苗根系生长,有利于同化产物输出.     

茉莉酸甲酯和水杨酸对丹参幼苗中蔗糖代谢和酚酸类物质积累的影响

以丹参幼苗为材料,研究了茉莉酸甲酯(MeJA)和水杨酸(SA)对其地上地下部分蔗糖代谢和根系中酚酸类物质积累的影响.结果显示:(1)外源施用MeJA能够显著增强幼苗叶片和根中酸性蔗糖转化酶活性,促进蔗糖降解,减少根系中蔗糖含量;同时根中丹参素(来源于酪氨酸-衍生物支路)、原儿茶酸(类苯丙烷支路的中间产物)、咖啡酸(来源于类苯丙烷支路)、迷迭香酸(来源于类苯丙烷支路和酪氨酸-衍生物支路)、丹酚酸B(丹参素、咖啡酸、迷迭香酸的衍生物)以及总酚酸含量均显著增加.(2)外施SA可显著降低幼苗叶片和根中酸性蔗糖转化酶活性及叶片中性蔗糖转化酶活性,抑制蔗糖降解,显著增加地上部分蔗糖含量,根中蔗糖含量和对照相比差异不显著;同时根中丹参素含量减少,但原儿茶酸、咖啡酸以及迷迭香酸含量增加,丹酚酸B和总酚酸类物质含量与对照相比差异不显著.因此推测,植物中蔗糖代谢影响丹参素合成的酪氨酸-衍生物支路,而不影响原儿茶酸、咖啡酸及迷迭香酸等合成的类苯丙烷支路.     

不同叶色水稻叶绿体密度及基粒结构的计算机图象分析

水稻叶绿体计算机图象分析表明,随着叶片色级的提高,叶绿体表面积密度、体积密度以及两者的比值都相应增加。深色稻叶基粒堆直径与高度、类囊体垛叠数与类囊体厚度、叶绿素与类胡萝卜素含量、气孔导度与净光合率均大于浅色叶片。深色叶片基粒堆密集,有些基粒类囊体出现沿叶绿体长轴方向排列整齐现象;浅色叶片基粒堆稀疏,其中较大的基粒类囊体与长轴呈倾斜排列。     

岳桦幼苗光合特性和非结构性碳水化合物积累对干旱胁迫的响应

以长白山林线树种岳桦为对象,利用生长控制试验进行干旱处理,研究干旱对岳桦幼苗光合特性及非结构性碳水化合物(NSC)积累的影响.结果表明:干旱显著降低了岳桦幼苗的净光合速率和气孔导度,提高了其水分利用效率;干旱显著增加了岳桦幼苗叶、皮、干和根中的可溶性糖和总NSC的含量,但显著降低了淀粉含量;随着干旱的持续,叶片的气孔导...     

He-Ne激光对增强UV-B辐射小麦叶片显微结构及光合特性的影响

采用低剂量(5 mW·mm-2)He-Ne激光辐照经增强UV-B辐射处理(10.08 kJ·m-2·d-1)后的晋麦47号小麦幼苗,用常规石蜡切片法,观察各处理组小麦幼苗叶片组织显微结构特征;同时对幼苗光合特性、水分利用及色素含量状况进行测定分析.结果显示:(1)与对照(CK)相比,UV-B辐射处理(B)与复合处理(BL)的表皮细胞及腺毛排列致密,气孔稀疏、缩小且下陷;叶肉组织细胞均明显加厚,细胞略小且排列紧密,维管束相对面积减小,BL的以上性状均介于CK与B之间.(2)B组净光合速率、气孔导度、蒸腾速率均显著降低.与B相比,BL气孔导度及光合速率偏高,蒸腾速率差异不明显.就水分利用率而言,L最大,略高于CK,B组最小,略低于BL,各组间差异显著.(3)增强UV-B辐射可使小麦幼苗叶绿素含量显著降低,经He-Ne激光辐照处理后可以使叶绿素含量得到一定程度恢复性升高,并且Chla变化的幅度大于Chlb.结果表明:低剂量He-Ne激光辐照能够对小麦幼苗组织显微结构以及光合器官的UV-B辐射损伤起到促进修复的作用.     

Leaf shape,stomata density and photosynthetic rate of the common oak leaves

Leaf shape and size, stomata dimensions and density, chlorophyll content and photosynthetic rate of the common oak leaves were investigated in shoots of various growth phases (polycyclic growth). Mean and maximal daily net photosynthetic rates, shoot length, leaf area, stomatal density and chlorophyll contents were significantly higher in shoots of the second growth phase. Intraspecific differences in leaf shape were found within each shoot growth phase.     

Study on Leaf Anatomy and Photosynthesis of Cymbidium sinense

The leaf surface of Cymbidium sinense(Andr.) Willd was covered with cuticle and wax. The stomata were distributed in the dorsum of the leaf, the density being 100–130 mm-2 There was a stomatal cover on each stoma. The mesophyll was not differentiated into spongy tissue and palisade tissue. No chloroplast was observed in the vascular bundle sheath cells. The chloroplast in the mesophyll cells had well developed grana, with lightly stacked thylakoids and osmiophilic granules. The highest quantum yield of functional leaf was 0.082. The light compensation point of photosynthesis was about 5 μE·m-2·s-1, the light saturation point was about 200 μE·m-2·s-1. The photosynthetic ra,e of Cymbidium sinense was very low, generally 2.0–2.6 μmol CO2· m-2·s-1. The optimum temperature of photosynthesis of one-year-old leaf was 25℃. The photosynthe,ic rate of the three-year-old leaf declined with temperature rise. The ratio of chlorophyll a/b was about 2.7. The CO2 compensation point of photosynthesis was 105–220 ppm. All these data show that Cymbidium sinense belongs to the typical shade plants with low photosynthetic rate and high CO2 compensation point that explains that the growth of Cymbidium sinense is slow in nature.     

Influence of Potassium Deficiency on Photosynthesis,Chlorophyll Content,and Chloroplast Ultrastructure of Cotton Plants

In cotton (Gossypium hirsutum L.) grown in controlled-environment growth chamber the effects of K deficiency during floral bud development on leaf photosynthesis, contents of chlorophyll (Chl) and nonstructural saccharides, leaf anatomy, chloroplast ultrastructure, and plant dry matter accumulation were studied. After cotton plants received 35-d K-free nutrient solution at the early square stage, net photosynthetic rate (P _N) of the uppermost fully expanded main-stem leaves was only 23 % of the control plants receiving a full K supply. Decreased leaf P _N of K-deficient cotton was mainly associated with dramatically low Chl content, poor chloroplast ultrastructure, and restricted saccharide translocation, rather than limited stomata conductance in K-deficient leaves. Accumulation of sucrose in leaves of K-deficient plants might be associated with reduced entry of sucrose into the transport pool or decreased phloem loading. K deficiency during squaring also dramatically reduced leaf area and dry matter accumulation, and affected assimilate partitioning among plant tissues.     

Influence of exogenous sucrose on the greening of oat

The greening of roots and leaves has been studied in whole oat seedlings grown on White's medium either with or without 2% sucrose. The added nutrient promotes chlorophyll synthesis and chloroplast differentiation in the roots. Yet it manifests a negative effect in the foliar tissues where it accelerates the decline in chlorophyll as well as the chloroplast ultrastructural alterations usually associated with senescence. The negative effect of the nutrient in the leaves is probably a consequence of the addition of exogenous sucrose to the endogenous sugars produced by photosynthesis. The foliar tissues would therefore be in the presence of high sucrose concentrations, which are known to be harmful for the photosynthetic apparatus. SDS-PAGE analysis of thylakoid polypeptides from root and leaf chloroplasts has revealed organ-specific differences in the electrophoretic patterns.     

The leaf anatomy of a broad-leaved evergreen allows an increase in leaf nitrogen content in winter

In temperate regions, evergreen species are exposed to large seasonal changes in air temperature and irradiance. They change photosynthetic characteristics of leaves responding to such environmental changes. Recent studies have suggested that photosynthetic acclimation is strongly constrained by leaf anatomy such as leaf thickness, mesophyll and chloroplast surface facing the intercellular space, and the chloroplast volume. We studied how these parameters of leaf anatomy are related with photosynthetic seasonal acclimation. We evaluated differential effects of winter and summer irradiance on leaf anatomy and photosynthesis. Using a broad-leaved evergreen Aucuba japonica , we performed a transfer experiment in which irradiance regimes were changed at the beginning of autumn and of spring. We found that a vacant space on mesophyll surface in summer enabled chloroplast volume to increase in winter. The leaf nitrogen and Rubisco content were higher in winter than in summer. They were correlated significantly with chloroplast volume and with chloroplast surface area facing the intercellular space. Thus, summer leaves were thicker than needed to accommodate mesophyll surface chloroplasts at this time of year but this allowed for increases in mesophyll surface chloroplasts in the winter. It appears that summer leaf anatomical characteristics help facilitate photosynthetic acclimation to winter conditions. Photosynthetic capacity and photosynthetic nitrogen use efficiency were lower in winter than in summer but it appears that these reductions were partially compensated by higher Rubisco contents and mesophyll surface chloroplast area in winter foliage.     

建兰水晶艺叶片的超微结构和转录组学分析

水晶艺建兰(Cymbidium ensifolium)因其叶片上呈现出白色透明状,犹如水晶而得名,观赏价值高,但是其形成机理不明确。该研究以建兰‘铁骨水晶’为试验材料,通过对水晶叶片和绿色叶片进行显微结构和超微结构观察,并结合转录组测序等方法,探索建兰水晶艺叶片形成的原因。结果表明:(1)建兰‘铁骨水晶’水晶叶片比绿色叶片薄,叶肉细胞数量减少,形状不规则,且叶绿体含量少;水晶叶片的表皮气孔数量较绿色叶片显著减少;水晶叶片的叶肉细胞中叶绿体结构发育不良,叶绿体双膜和类囊体膜模糊,细胞中存在着大量的嗜锇颗粒。(2)转录组数据分析显示,水晶叶片中与光合作用-天线蛋白、光合作用等代谢途径相关的基因表达量显著下降,而与色素合成代谢途径相关的基因表达量上升。研究推测,建兰水晶艺叶形成的原因可能是由于与光合作用相关的基因表达量降低,导致叶绿体发育不良,叶绿素合成受阻,从而形成白色透明状叶片。     

高粱、紫苏叶脉密度与光合特性的关系

叶脉是植物叶片光合作用水分输送的重要结构。为阐述叶脉与光合特性之间的关系,以C4植物高粱(Sorghum bicolor)、C3植物紫苏(Perilla frutescens)为实验材料研究了叶脉密度和光合特性之间的关系。结果表明,与紫苏相比,高粱叶片叶脉密度大,导水能力强,蒸腾速率高,但气孔密度小。进一步分析表明,高粱叶片近轴侧气孔密度占总气孔的比例明显高于紫苏。叶脉密度大的高粱具有较高的净光合速率;而紫苏叶脉密度小,净光合速率也较低。由此表明,较高的叶脉密度有利于支持较高的光合速率,但研究表明叶脉密度和气孔密度可能不存在严格的协同变异关系。研究结果对理解植物光合作用适应有重要意义。