The isolation of leaf protoplasts from the submerged aquatic angiosperm Potamogeton lucens L.

Abstract. A method for isolating protoplasts from leaves of the submerged aquatic angiosperm Potamogeton lucens L. is described. The protoplasts are produced enzymatically from leaf strips using 1.5% (w/v) Cellulysin, 0.3% (w/v) Macerozyme R10, and 2.5% (v/v) β-glucuronidase at 27°C in the dark. Subsequently the protoplasts are purified on a discontinuous Ficoll gradient. The yield obtained is approximately 20% of the starting material on a chlorophyll basis. The viability is high, namely more than 90% as estimated with Evans Blue. Cells of the intact leaves of P. lucens can use HCO₃⁻ for photosynthesis. ¹⁴CO₂ fixation experiments at pH 6.0 and 8.5 suggest that these isolated protoplasts can also use bicarbonate as a carbon source.     

Stomatal responses to humidity in air and helox

Abstract. Stomatal responses to humidity were studied in several species using normal air and a helium: oxygen mixture (79:21 v/v, with CO₂ and water vapour added), which we termed 'helox'. Since water vapour diffuses 2.33 times faster in helox than in air, it was possible to vary the water-vapour concentration difference between the leaf and the air at the leaf surface independently of the transpiration rate and vice versa. The CO₂ concentration at the evaporating surfaces ( c_i ), leaf temperature and photon flux density were kept constant throughout the experiments. The results of these experiments were consistent with a mechanism for Stomatal responses to humidity that is based on the rate of water loss from the leaf. Stomata apparently did not directly sense and respond to either the water vapour concentration at the leaf surface or the difference in water vapour concentration between the leaf interior and the leaf surface. In addition, stomatal responses that caused reductions in transpiration rate at low humidities were accompanied by decreases in photosynthesis at constant c_i , suggesting heterogeneous (patchy) stomatal closure.     

早花百子莲叶片器官发生和胚胎发生再生体系的建立

以早花百子莲(Agapanthus praecox)叶片为外植体, 建立了器官发生和胚胎发生离体再生体系, 并对移栽驯化基质进行了初步筛选。结果表明, 毒莠定(PIC)对叶片愈伤组织诱导效果良好, 最适培养基为MS+2.0 mg·L ^-1 PIC; 叶片组织分生能力决定愈伤组织诱导效果, 1-2片新叶基部愈伤组织诱导率可达85.71%, 叶片分生区0-0.5 cm愈伤组织诱导率为66.48%, 叶片横切面中部诱导效果优于边缘。不定芽诱导最适培养基为MS+1.5 mg·L ^-1 PIC+0.3 mg·L ^-1 6-BA, 诱导率达80.27%。体细胞胚诱导培养基为MS, 0.05 mg·L ^-1多效唑或1.0 mg·L ^-1 ABA均对体胚诱导具有显著促进作用。1.0 mg·L ^-1 6-BA对幼苗增殖有利, 器官发生和胚胎发生途径幼苗增殖系数分别为2.23和2.93。草炭:珍珠岩:蛭石=1:1:1 (v/v/v)为早花百子莲移栽驯化的最佳基质, 成活率达100%。该研究建立了早花百子莲叶片外植体再生体系, 丰富了百子莲快繁技术体系, 可为其它单子叶植物离体再生体系建立提供参考。     

Isolation of photorespiratory mutants from Lotus japonicus deficient in glutamine synthetase

A mutagenesis programme using ethyl methanesulphonate (EMS) was carried out on Lotus japonicus (Regel) Larsen cv. Gifu in order to isolate photorespiratory mutants in this model legume. These mutants were able to grow in a CO₂-enriched atmosphere [0.7% (v/v) CO₂] but showed stress symptoms when transferred to air. Among them, three mutants displayed low levels of glutamine synthetase (GS; EC 6.3.1.2) activity in leaves. The mutants accumulated ammonium in leaves upon transfer from 0.7% (v/v) CO₂ to air. F₁ plants of back crosses to wild type were viable in air and F₂ populations segregated 3 : 1 (viable in air : air-sensitive) indicative of a single Mendelian recessive trait. Complementation tests showed that the three mutants obtained were allelic. Chromatography on DEAE-Sephacel used to separate the cytosolic and plastidic GS isoenzymes together with immunological data showed that: (1) mutants were specifically affected in the plastidic GS isoform, and (2) in L. japonicus the plastidic GS isoform eluted at lower ionic strength than the cytosolic isoform, contrary to what happens in most plants. The plastidic GS isoform present in roots of wild type L. japonicus was also absent in roots of the mutants, indicating that this plastidic isoform from roots was encoded by the same gene than the GS isoform expressed in leaf tissue. Viability of mutant plants in high-CO₂ conditions indicates that plastidic GS is not essentially required for primary ammonium assimilation. Nevertheless, mutant plants did not grow as well as wild type plants in high-CO₂ conditions.     

A Multiple-Pathogen System for Bioherbicidal Control of Several Weeds

A novel system using four host-specific fungal plant pathogens applied in a single, postemergent spray to control pigweed, sicklepod, and showy crotalaria was tested under greenhouse conditions. The four pathogens were Phomopsis amaranthicola (a pathogen of pigweed species), Alternaria cassiae (a pathogen of sicklepod and showy crotalaria), Colletotrichum dematium f. sp. crotalariae and Fusarium udum f. sp. crotalariae (pathogens of showy crotalaria). Spore suspensions of each pathogen alone (10⁶ spores mL^-1) or a mixture of the four pathogens (1:1:1:1, v/v, 2.5×10⁵ spores mL^-1 of each pathogen, total 10⁶ spores mL^-1) were tested on four- to six-leaf stage seedlings of the three weed species grown together in pots. One week after inoculation (WAI), all sicklepod and showy crotalaria seedlings were killed, and all pigweed seedlings were killed by 6 WAI when inoculated with their respective pathogen(s) alone or a mixture of the pathogens. None of the weeds inoculated with the root-infecting pathogen F. udum developed wilt disease by the time the experiment was completed (6WAI). The results demonstrate the feasibility to control three weeds simultaneously with different fungi without loss of efficacy or alterations in host-specificity of each fungus in the given mixture. Scanning electron microscopy showed visual differences in the appearance or germination and further development of conidia of each pathogen on its respective host leaf surface compared to nonhost leaf surfaces, whether the pathogen was applied alone or in a mixture with the other pathogens studied. Application of several host-specific fungal pathogens in a bioherbicide mixture as a multi-component bioherbicide system may be advantageous for further development of simultaneous, broad-spectrum weed control.     

Root zone calcium modulates the response of potato plants to heat stress

Potato plant growth and development are known to be severely impacted by heat stress. Here plants grown in a chemically inert medium of 1 : 1 quartzite : perlite (v : v) were subjected to either 35/25°C (stress) or 20/15°C (control) day/night air temperatures and four concentrations of root zone calcium (5, 25, 125 and 600 µ M Ca) for 3 weeks. We report for the first time that potato plant growth under heat stress can persist at specific levels of Ca²⁺ in the root zone and that the Ca²⁺ level required for growth under heat stress exceeds that required for growth under normal temperatures. We also provide strong, initial evidence that the ability of high Ca²⁺ levels to mitigate heat stress effects results from shifts in meristematic activity. Total foliar mass and leaf area were essentially unaffected by Ca²⁺ level under control temperatures. Under heat stress, leaf area was reduced to about 5% of the control at 5 and 25 µ M Ca but to only 70% of the control at 125 and 600 µ M Ca. Likewise, total foliar mass was reduced under heat stress to about 30% of the control at 5 and 25 µ M Ca but total foliar mass was greater under heat stress than control conditions at 125 and 600 µ M Ca. This increase at higher Ca²⁺ concentrations was due primarily to axillary shoot growth. Anatomical studies of leaves grown under heat stress show that cell expansion was impaired by heat stress and this impairment was overcome by increasing root zone calcium levels. These results provide insight into the mechanism by which root zone Ca²⁺ may modulate plant response to heat stress.     

华西雨屏区麻栎-喜树人工混交林林冠对降雨中钾和钠离子再分配的影响

2016年12月—2017年11月研究了都江堰灵岩山麻栎-喜树人工混交林林冠对不同物候期(无叶期、展叶期、盛叶期和落叶期)雨水中K⁺和Na⁺的再分配作用.结果表明: 大气降雨中K⁺和Na⁺浓度分别为1.87和1.46 mg·L^-1,穿透雨中分别为5.78和1.39 mg·L^-1,雨水中的K⁺浓度在展叶期最高,盛叶期最低,Na⁺在无叶期和展叶期较高,盛叶期和落叶期较低;大气降雨中K⁺和Na⁺的输入量分别为25.47和21.60 kg·hm^-2·a^-1;降雨对林冠中K⁺的淋溶量为13.64 kg·hm^-2·a^-1,无叶期、展叶期、盛叶期和落叶期的淋溶量分别为1.67、6.23、2.28和3.46 kg·hm^-2,在展叶期淋溶量最大;林冠对Na⁺的截留量为11.26 kg·hm^-2·a^-1,无叶期、展叶期、盛叶期和落叶期的截留率分别为32.6%、18.0%、44.9%和31.5%,盛叶期时截留量最大.可见,麻栎-喜树人工混交林林冠对大气降雨中K⁺和Na⁺的再分配作用随物候期而变化,这为深入了解华西雨屏区森林生态系统的K⁺和Na⁺循环提供了基础数据.     

New Uses for Calcium Chloride Solution as a Mounting Medium

Fresh cross sections of stems [Psilotum nudum, Coleus blumei, and Pelargonium peltatum] and roots (Setcreasea purpurea) 120 μm thick were fixed in FPA₅₀ (formalin: propionic acid: 50% ethanol, 5:5:90, v/v) for 24 hr and stored in 70% ethanol. The sections were transferred to water and then to 1% phloroglucin in 20% calcium chloride solution plus either hydrochloric, nitric, or lactic acid in the following ratios of phloroglucin-CaCl₂ solution:acid: 25:4, 20:2, or 15:5. The sections were mounted on slides either in one of the three mixtures or in fresh 20% calcium chloride solution. A rapid reaction of the acid-phloroglucin with lignin produced a deep red color in tracheary elements and an orange-red color in sclerenchyma. Fixed and stored leaf pieces from Nymphaea odorata were autoclaved in lactic acid, washed in two changes of 95% ethanol, transferred to water, and treated with the three acid-phloroglucin-calcium chloride mixtures. The abundant astrosclereids stained an orange-red color similar to that of sclerenchyma in the sections. In addition, a new method is reported for specifically staining lignified tissues. When sections or leaf pieces are stained in aqueous 0.05% toluidine blue O, then placed in 20% calcium chloride solution, all tissues destain except those with lignified or partially lignified cell walls. Thus, toluidine blue O applied as described becomes a reliable specific test for lignin comparable to the acid-phloroglucin test.     

大花银莲花愈伤组织诱导及再生体系的建立

为建立野生大花银莲花(Anemone silvestris)组培再生体系,分别以无菌苗上、下胚轴、叶片和叶柄为外植体,探讨不同浓度植物生长调节剂对不同外植体的愈伤组织诱导、不定芽分化、增殖与生根的影响。结果表明, 4种外植体均可诱导出不定芽,其中上胚轴诱导效果最佳,其在1/2MS+2.0mg·L^–1 6-BA+0.1mg·L^–1 NAA培养基中诱导率最高,为86.67%;最适增殖培养基为1/2MS+1.0mg·L^–1 6-BA+0.05mg·L^–1 NAA,增殖系数为3.67;最佳生根培养基为1/2MS+0.3mg·L^–1 IBA,生根率为100%;在草炭:蛭石=2:1(v/v)的栽培基质中,组培苗的移栽成活率最高,为98.33%。该研究有效解决了野生大花银莲花在园林及药用生产上的种质资源紧缺难题,为工厂化育苗提供了技术支撑。     

Development of leaf thickness for Plectranthus parviflorus – Influence of photosynthetically active radiation

Photosynthetically active radiation (PhAR) is apparently the environmental factor having the greatest influence on leaf thickness for Plectranthus parviflorus Henckel (Labiatae). A four-fold increase in leaf thickness from 280 to 1170 μm occurred as the PhAR was raised from 1.3 to 32.5 mol m⁻² day⁻¹. Compared to a constant PhAR of 2.5 mol m⁻² day⁻¹, a PhAR of 32.5 mol m⁻² day⁻¹ for one week during the first week (with return to 2.5 mol m⁻² day⁻¹ during the second and third weeks) led to an increase in final leaf thickness by 323 μm (to 802 μm). When increased PhAR was applied during the second week the increase in final thickness over the control was 217 μm, and when increased PhAR was applied during the third week it was 99 μm. However, leaf thickness was not simply responding to total daily PhAR, since a leaf 450 μm thick could occur at a low instantaneous PhAR for a long daytime (total daily PhAR of 1.5 mol m⁻² day⁻¹) and at a high PhAR for a short daytime (4.5 mol m⁻² day⁻¹). Total daily CO₂ uptake (net photosynthesis) was approximately the same in the two cases, suggesting that this is an important factor underlying the differences in leaf thickness. Leaf thickness is physiologically important, since thicker leaves tend to have greater mesophyll surface area per unit leaf area ( A ^mes/ A ) and hence higher photosynthetic rates.     

Dominant Gene cplsr1 Corresponding to Premature Leaf Senescence Resistance in Cotton (Gossypium hirsutum L.)

Cotton (Gossypium hirsutum L.) premature leaf senescence-resistant inbred XLZ33 and senescencesusceptible inbred lines XLZ13 were selected and crossed to produce F1,F1-reciprocal,F2 and BC1 generations...     

鬼箭锦鸡儿叶片和土壤碳稳定同位素特征及其影响因素

为探究高海拔地区的植物碳(C)循环过程与其生境的关系,以生长在高山地区的豆科灌木鬼箭锦鸡儿为研究对象,沿着横跨我国东西部山区的样带采集35个样点的鬼箭锦鸡儿叶片和土壤样品,分析了鬼箭锦鸡儿叶片碳稳定同位素组成(δ13C)、土壤δ13C、叶片和土壤δ13C差值(Δδ13C)在不同采样点的特征及其与气候因子、叶片和土壤元素...     

玉米叶形相关性状的Meta-QTL及候选基因分析

叶长、叶宽、叶面积及叶夹角不仅影响玉米(Zea mays)光合效率, 也是株型的重要构成因素。通过对620个叶形QTL进行整合, 构建不同遗传背景下的叶形QTL整合图谱, 利用元分析发掘出22个叶长、22个叶宽、12个叶面积以及17个叶夹角mQTL; 进一步运用生物信息学手段, 确定44个与叶片发育密切相关的候选基因。分析发现, 仅有NAL7-like、YABBY6- like和GRF2等13个基因位于mQTL区间内, 而玉米中已克隆的KNOTTED1、AN3/GIF1、rgd1/lbl1、mwp1及SRL2-like、HYL1-like和CYCB2;4-like等水稻(Oryza sativa)和拟南芥(Arabidopsis thaliana)叶形同源基因位于未被整合的QTL内; 对44个候选基因在叶片长、宽、厚发育过程中基部-末端、中央-边缘、远轴-近轴的调控机理进行归纳分析, 发现玉米中仅有少数几个候选基因被报道, 揭示了叶形发育的部分分子机理。因此, 对玉米叶形相关mQTL/QTL及基因进行全面深入的分析, 不仅有助于增加对其遗传结构的了解, 发掘更多候选基因, 阐明叶形发育和形成的分子机制, 还可为耐密理想株型的分子标记辅助选择提供依据。     

Endogenous abscisic acid levels are linked to decreased growth of bush bean plants treated with NaCl

This paper studies the relative importance of endogenous ABA and ion toxicity in the leaf growth inhibition caused by NaCl in salt-adapted and unadapted bush beans. Adaptation to salt-stress was achieved by germination of seeds in 75 m M NaCl, while unadapted plants were germinated in tap water. The adaptation process caused a transitory increase in leaf ABA, Na⁺ and Cl⁻ concentrations, while leaf expansion was inhibited. However, when grown for 8 or 13 days in 75 m M NaCl-containing nutrient solution, primary and first trifoliolate leaves of salt-adapted plants had greater areas than those of unadapted plants. Concentrations of ABA, Na⁺ and Cl⁻ in these leaves were lower in adapted plants, and a strong negative correlation between leaf expansion growth and either leaf Na⁺, Cl⁻ or ABA concentrations could be established. However, in the second trifoliolate leaves only the ABA, but not the Na⁺ or Cl⁻, concentrations were significantly correlated with leaf expansion. Our results suggest that salt-induced inhibition of leaf expansion growth in bush beans is mediated by ABA rather than Na⁺ or Cl⁻ toxicity. Moreover, the increase of ABA, induced by the salt-pretreatment, seems to play an important role in limiting the accumulation of Na⁺ and Cl⁻ in the leaves, leading to adaptation of bush beans to salt-stress.     

Repellent Activity of n-Hexane, Ethylacetate, n-Butanol, and Water Extracts of Native Plants against Aedes albopictus

ABSTRACT n -Hexane, ethyl acetate, n -butanol, and water extracts of seventeen native plants (Taraxacum Platycarpum leaf, Artemisia prinseps leaf, Artemisia keiskeana whole, Chrysanthemum zawadskii whole, Petasites japonicus leaf, Allium tuberosom leaf, Lonicera japonica stem and leaf, Cassia obtussifolia whole, Hydrangea macrophylla leaf, Clivia miniata leaf, Pinus densiflora leaf, Taxus cuspidatas fruit, Thuja orientalis leaf, Juniperus chinensis stem, Zanthoxylum schinifolium peel, leaf, Citrus unshiu and Picrasma quassioides stem and leaf) were tested for repellent activity against Aedes albopoctus. The extracts of T. Platycarpum leaf ( n -hexane, BuOH, H₂O), A. prinseps leaf ( n -hexane, BuOH, H₂O), A. keiskeana whole ( n -hexane, BuOH, H₂O), L. japonica stem (BuOH, H₂O), L. japonica flower (H₂O), H. macrophylla leaf (BuOH, H₂O), C. miniata leaf (EtOAC), P. densiflora leaf ( n -hexane, BuOH), Z. schinifolium peel (EtOAC), Z. schinifolium leaf (EtOAC BuOH, H₂O) and P. quassioides leaf ( n -hexane, H₂O) exhibited excellent repellent activity against Aedes albopitus.     

不同灌水量对干旱区枸杞叶片结构、光合生理参数和产量的影响

宁夏枸杞是我国重要的药用植物资源.为确定宁夏枸杞的适宜灌溉量,在人工控水条件下,研究了不同月灌溉定额对宁夏枸杞叶片结构、光合生理以及果实产量的影响.结果表明：月灌水定额＜900 m³·hm^-2时,随着灌水量的增加,枸杞的叶面积、叶片厚度、栅栏组织厚度和叶片结构紧密度、叶片光合速率、瞬时水分利用效率、气孔限制值和枸杞果实产量显著增加,而气孔密度和胞间CO₂浓度则呈下降趋势;月灌水定额＞900 m³·hm^-2以后,叶片胞间CO₂浓度随月灌溉定额的增加呈上升趋势, 而叶面积、气孔密度和枸杞果实产量变化不显著,其他指标均呈相反的变化趋势.枸杞叶片蒸腾速率和气孔导度值以450 m³·hm^-2处理最高,分别达8.02和324 mmol·m^-2·s^-1;其他处理均低于对照.在节水条件下,900 m³·hm^-2的月灌溉定额较适合枸杞的灌溉.     

Variations and interrelationships of foliar hydraulic and photosynthetic traits for Larix gmelinii

Aims Variations and potential trade-offs of leaf hydraulic and photosynthetic traits are essential for assessing and predicting the effect of climate change on tree survival, growth and distribution. Our aims were to examine variations and interrelationships of leaf hydraulic and photosynthetic traits in response to changes in site conditions for Dahurian larch (Larix gmelinii)—a dominant tree species in Chinese boreal forests.Methods This study was conducted at the Maoershan Forest Ecosystem Research Station. A transect of 27 year-old Dahurian larch plantation was established that consisted of five plots extending from the valley to the ridge of a slope. The predawn leaf water potential (Ψ_pre), area- and mass-based leaf hydraulic conductance (K_area and K_mass, respectively), resistance to embolism capacity (P₅₀), leaf mass per area (LMA), net photosynthetic rate (A), and leaf nitrogen content (N) were measured in August 2016.Important findings The Ψ_pre, K_area, K_mass, P₅₀, A, LMA, and N all varied significantly among the plots (p < 0.05), indicating significant intra-specific variations in these traits in response to the changes in site conditions. The P₅₀ was significantly (p < 0.05) correlated with Ψ_pre, K_area or K_mass, suggesting that a trade-off between hydraulic efficiency and safety exist within the species to some degree. There were significant (p < 0.05) pairwise correlations between A, LMA, and N. Nevertheless, there was no significant (p < 0.05) correlation between the measured photosynthetic traits and hydraulic traits. We concluded that the intra-specific variations and multiple interrelationships of the leaf hydraulic and photosynthetic traits for the larch reflect the plasticity of its leaf traits and strategies of its survival and growth as a result of its acclimation to diverse site conditions.     

Changes in water relations and in some physiological functions of bean under very light osmotic shock induced by polyethylene glycol

Bean plantlets ( Phaseolus vulgaris L. cv. Topcrop) were stressed at the age of 16–18 days by gradual (2–8%) or abrupt addition of 6% (w/v) polyethylene glycol Mw 6000 (PEG 6000) to Hoagland solution. Leaf conductance, photosynthesis, internal CO₂ partial pressure (C_i), relative water content (RWC), water content/dry weight (H₂O/DW), apoplastic PEG concentrations and weight of leaves, stems and roots were determined. Leaf conductance, photosynthesis and C_i were determined on non-detached primary leaves, and leaf potentials (water, osmotic and turgor potentials) were investigated in freshly detached (non-rehydrated) primary leaves, both in treated and control plants; RWC and osmotic potential were also assessed at the null turgor point. Low PEG 6000 concentrations induced early and evident decrease in leaf conductance and photosynthesis, whereas C_i decreased only moderately and tended to recover during advanced stress. There were moderate though significant decreases in RWC and H₂O/DW, no change or increases in water potential, no significant changes in osmotic potential and a moderate but significant increase in turgor potential. Even when referred to null turgor point, RWC significantly decreased and osmotic potential was unchanged. It was concluded that apoplastic PEG 6000 accumulation at evaporating sites would account for the early decrease in conductance which would also justify the unchanged or the prevalent increase in water potential and turgor potential. The subsequent PEG diffusion and concentration in the leaf apoplastic water would have induced the RWC and H₂O/DW decrease and the final turgor flexion documented.     

异源过表达水稻OsSAPP3基因促进拟南芥叶片衰老

蛋白磷酸酶催化的蛋白质可逆磷酸化反应是叶片衰老的关键环节。该研究筛选并克隆了1个新的参与水稻(Oryza sativa)叶片衰老调控的PP2C基因OsSAPP3。研究表明, OsSAPP3的启动子在Pro_OsSAPP3-GUS转基因拟南芥(Arabidopsis thaliana)的莲座叶中有活性, 并且活性以依赖叶龄方式增加。利用CaMV 35S启动子驱动组成型异源过表达OsSAPP3导致转基因拟南芥无法正常生长。用可诱导型启动子GVG系统驱动OsSAPP3异源过表达导致转基因拟南芥出现莲座叶变小、数量增加、叶片早衰及抽薹开花提前等早衰表型。外源诱导OsSAPP3基因异源过表达后, 利用实时荧光定量PCR检测到SAG12、WRKY6和NAC2等衰老标志基因显著上调表达。研究结果表明, OsSAPP3是参与水稻叶片衰老的正向调控因子。