Plant growth in relation to ontogenetic changes in productive characteristics of individual leaves I. growth and productive characteristics ofHelianthus annuus andZinnia elegans leaves

Growth and productive characteristics of successive leaves were ontogenetically examined using sunflower and zinnia plants grown in the field. For the purpose of more advanced comprehension, ontogenetic behavior of productive characteristics was formulated with the schematic leaf growth model. The largest leaf in zinnia appeared around the middle leaf order, but did not show the highest photosythetic rate. The decreasing pattern of relative leaf area expansion rate did not significantly differ among individual leaves, and seemed inherent to species. The ontogenetic changes in net photosynthetic rate per unit leaf area showed convex curves, while those in dark respiratory rate per unit leaf area rapidly decreased with leaf development and then became constant. In part, the rapid increase of photosynthetic rate in young leaves was supported by enhancement of light utilization efficiency, along with increase of chlorophyll content. The approach of leaf angle to the horizontal was more or less accompanied by photosynthetic development and leaf expansion. It was suggested that photosynthetic maturation in leaves of the sun-leaf type appears at leaf age equivalent to 0.35 to 0.46 of leaf life span. Ontogenetic pattern of all productive characteristics basically differed little among successive leaves.     

Salicylic acid-induced adaptive response to copper stress in sunflower (Helianthus annuus L.)

The ameliorative effect of salicylic acid (SA: 0.5 mM) on sunflower (Helianthus annuus L.) under Cu stress (5 mg l⁻¹) was studied. Excess Cu reduced the fresh and dry weights of different organs (roots, stems and leaves) and photosynthetic pigments (chlorophyll a, b and carotenoids) in four-week-old plants. There was a considerable increase in Chl a/b ratio and lipid peroxidation in both the roots and leaves of plants under excess Cu. Soluble sugars and free amino acids in the roots also decreased under Cu stress. However, soluble sugars in the leaves, free amino acids in the stems and leaves, and proline content in all plant organs increased in response to Cu toxicity. Salicylic acid (SA) significantly reduced the Chl a/b ratio and the level of lipid peroxidation in Cu-stressed plants. Under excess Cu, a higher accumulation of soluble sugars, soluble proteins and free amino acids including proline occurred in plants treated with 0.5 mM SA. Exogenous application of SA appeared to induce an adaptive response to Cu toxicity including the accumulation of organic solutes leading to protective reactions to the photosynthetic pigments and a reduction in membrane damage in sunflower.     

Bacterial antagonists of Sunflower (Helianthus annuus L.) fungal pathogens

Bacteria isolated on nutrient agar and King's medium B from sunflower leaves, crown and roots inhibited in vitro growth of the leaf spot and wilt pathogens Alternaria helianthi, and Sclerotium rolfsii, respectively, and also the root rot pathogensRhizoctonia solani and Macrophomina phaseolina. Antagonistic bacteria from leaves were mainly actinomycetes and pigmented Gram-positive bacteria, while those from roots and crowns were identified asPseudomonas fluorescens-putida, P. maltophilia, P. cepacia, Flavobacterium odoratum andBacillus sp. In soil bioassays, when used as seed inoculum in the presence ofS. rolfsii, P. cepacia strain N24 increased significantly the percentage of seedling emergence. Bacterial strains which exhibited broad spectrum in vitro antagonistic activity were tested for colonisation of sunflower roots, when used as a seed inoculum. Good colonisers (10⁴ to 10⁶ bacteria/g root) were consistent in their ability to reduce disease and fungal wilt. A seedling having a primary root length < 5 cm with fewer lateral roots, necrosed cotyledons or crown and a wilted shoot indicated its diseased status. On an average, only 30% of seedlings were diseased when treated with the antagonistic strains, in the presence of the pathogen, while 60% of the seedlings were diseased in the presence of the pathogen alone. In microplots treated with strain N24, only 1 to 3% of the seedlings were wilted, while 14% of the seedlings were wilted in the presence of the pathogen alone. The results obtained show that bacterial antagonists of sclerotial fungi can be used as seed inocula to improve plant growth through disease suppression     

一株具有脱胶功能大麻内生真菌的分离和鉴定

采用组织块法对大麻(Cannabis sativa)根、茎、叶等组织中的内生真菌进行分离,利用平板透明圈法筛选具有脱胶功能的菌株,对获得的脱胶菌菌株进行形态学鉴定和分子生物学鉴定。结果表明:(1)从大麻根、茎、叶的组织部位共分离得到内生真菌16株,茎部分离到9株真菌,叶部5株,根部2株。(2)编号为DM6的内生真菌具有较强的果胶分解能力,其透明圈直径为2.49cm。(3)形态学鉴定发现,内生真菌DM6不能产生孢子,菌丝较为粗壮、分支较少、有明显的隔;分子学鉴定表明,内生真菌DM6与Phoma aliena(KC311486)序列的相似性最高,为99%,并且在系统发育树上位于同一分支上。因而内生真菌DM6可以鉴定为茎点霉属一种(Phomasp.)。     

The ecological significance of the coarse soil fraction for Picea abies (L.) Karst. seedling nutrition

Elsholtzia splendens is a Cu-tolerant plant growing in copper mine areas in the south of China. In this study, X-ray absorption spectroscopy (XAS) was used to investigate the Cu speciation and biotransformation in E. splendens with 300 μM Cu treatment from 10 days to 60 days. The results showed that 300 μM Cu was phytotoxic to E. spendens. The Cu K-edge X-ray absorption near edge structure (XANES) revealed that most copper in roots, stems and leaves exists as divalent Cu. Cu speciation changed depending on the treatment time, but there was no unidirectional trend in roots, stems, and leaves. The percentages of potential Cu ligands in all samples were estimated by fitting the XANES spectra with linear combinations. Most Cu in roots, stems and leaves was bound with cell wall and histidine (His)-like ligands, while a minor proportion of the Cu was bound to oxalate and glutathione-like ligands. The fitting results of Cu K-edge extended X-ray absorption fine structure (EAXFS) showed that nitrogen/oxygen (N/O) ligands were dominant in roots, stems and leaves of the plant, while S ligands were rare. All these results suggest that Cu bound by N/O ligands plays a key role in Cu detoxification of E. splendens, and a role for classical metal-detoxifying S ligands, such as metallothioneins and phytochelatins, in Cu detoxification of E. splendens is not supported in the present study. Due to the phytotoxicity of 300 μM Cu to E. splendens, the question of whether S ligands play a significant role in Cu detoxification in E. splendens exposed to lower levels of Cu should be further studied.     

Effect of copper excess on superoxide dismutase,catalase, and peroxidase activities in sunflower seedlings (<Emphasis Type="Italic">Helianthus annuus</Emphasis> L.)

The changes in lipid peroxidation, antioxidative and lignifying enzyme activities were studied in leaves and stems of Cu-stressed sunflower seedlings. In both organs, membrane lipid peroxidation was enhanced by copper treatment. Additionally, catalase (EC 1.11.1.6) and superoxide dismutase (EC 1.15.1.1) activities were modulated: The activity of superoxide dismutase was enhanced in both plant organs. Differently, catalase activity was not affected in leaves but significantly reduced in stems. Peroxidase (EC 1.11.1.7) activities were also changed. Guaiacol peroxidase activity was increased in leaves and stems. In the same way, electrophoretic analysis of the anionic isoperoxidases involved in lignification (syringaldazine peroxidase) revealed qualitative and quantitative changes on the isoenzyme patterns. These modifications were accompanied by the increase of the NADH-oxidase activity in ionically cell wall bound fraction. It appeared that the growth delay caused by copper excess could be related to the activation of lignifying peroxidases.     

Volatiles from different organs of Unxia camphorata L. f. growing wild in the Amazon

The essential oils obtained from fresh leaves, flowers, roots and stems of Unxia camphorata collected in the rainy and dry seasons in the state of Pará, were examined by GC and GC/MS. The highest oil yields were observed from the samples collected at the dry season (flowers: 0.6%, leaves: 0.6%, stems: 0.3%, roots: 0.4%). All parts of the plant were rich in α-phellandrene, with non-significant changes during the rainy and dry seasons (flowers: 61.9–53.7%, leaves: 18.3–17.4%, stems: 68.3–72.8%, roots: 51.9–48.3%). In the leaf oil, the monoterpenoid camphor was the largest component (rainy season: 28.5%, dry season: 28.8%). In the leaf oil, the high amount of α-phellandrene was followed by methylthymol (rainy season: 14.1%, dry season: 13.1%). Depending on the plant part studied, these oils can be characterized by α-phellandrene, camphor/α-phellandrene/camphene, or α-phellandrene/methylthymol type.     

Effect of flooding and temperature regime on growth and stomatal resistance ofBetula platyphylla var.japonica seedlings

Summary Both flooding and low temperature reduced height and stem diameter growth; leaf initiation; growth of leaves, stems, and roots; and lowered root-shoot ratios of 112-dayoldBetula platyphylla var.japonica seedlings. Flooding also induced leaf scorching and abscission. Growth was reduced much more by flooding than by low temperature. Interactive effects of flooding and temperature were shown on height growth, leaf initiation and expansion, and dry weight increment of leaves, stems and roots. The amount of growth reduction by flooding and low temperature was greater when based on analysis of dry weight increment of leaves, stems, and roots, than on their relative growth rates. The greater reduction of growth by flooding than by low temperature was associated with fewer and smaller leaves, more leaf injury, more stomatal closure, and greater decay of roots in flooded plants. Flooding and low temperature appeared to reduce growth by somewhat different physiological mechanisms. Research supported by the College of Agricultural and Life Sciences, University of Wisconsin, Madison, WI, USA and by Yamagata University, Tsuruoka, Japan. McIntyre-Stennis Project 2599.     

基于广泛靶向代谢组学分析黑老虎不同部位成分差异

为提高黑老虎(Kadsura coccinea)资源的综合利用率，采用广泛靶向代谢组学技术鉴定并分析了根、茎、叶代谢组分差异及高度富集成分。结果表明，在根、茎和叶中分别鉴定出642、650和619个代谢物，以酚酸、脂质、类黄酮和有机酸为主；叶与根、茎与根的共有成分分别为566和650个，显著差异成分有442和393个，主要为酚酸、类黄酮和脂质，差异代谢物在苯丙烷生物合成、黄酮与黄酮醇生物合成通路中显著富集。代谢物总丰度和次生代谢物丰度均表现为叶>根>茎，叶中酚酸、类黄酮和脂质及茎中酚酸积累量显著高于根，而氨基酸及其衍生物、萜类、木脂素、香豆素、生物碱的丰度在根中显著上调。因此，黑老虎根、茎、叶有大量共有成分，叶和茎中酚酸、叶中类黄酮和脂质高度富集，含有新绿原酸、绿原酸、槲皮素等多个丰度较高且具有重要生物活性化合物，具有较高利用价值。     

Protein and Peroxidase Modulations in Sunflower Seedlings (Helianthus annuus L.) Treated with a Toxic Amount of Aluminium

The aim of this study is to investigate the effect of aluminium treatment on peroxidases activities and protein content in both soluble and cell-wall-bound fractions of sunflower leaves, stems and roots. Fourteen-day-old seedlings, grown in a nutrient solution, were exposed to a toxic amount of aluminium (500 μM AlNO₃) for 72 h. Under stress conditions, biomass production, root length and leaf expansion were significantly reduced. Also, our results showed modulations on soluble and ionically cell-wall-bound peroxidases activities. In soluble fraction, peroxidases activities were enhanced in all investigated organs. This stimulation was also observed in ionically cell-wall-bound fraction in leaves and stems. Roots showed a differential behaviour: peroxidase activity was severely reduced. Lignifying peroxidases activities assayed using coniferyl alcohol and H₂O₂ as substrates were also modulated. Significant stimulation was shown on soluble fraction in leaves, stems and roots. In ionically cell-wall-bound fraction lignifying peroxidases were enhanced only in stems but severely inhibited in roots. Also, aluminium toxicity caused significant increase on cell wall protein content in sunflower roots.     

不同铅水平下紫茎泽兰细胞内铅的分布和化学形态的分析

该研究运用差速离心法和化学试剂逐步提取法,分析了重金属铅在紫茎泽兰亚细胞内的分布和主要化学形态。结果表明:随着Pb浓度的升高,紫茎泽兰的叶、根、茎中各亚细胞组分Pb含量逐渐增加;紫茎泽兰中的Pb在叶片分布于可溶性部分和细胞壁中,两者占总量的75.34%~84.63%;茎也主要分布于可溶性部分和细胞壁中,占总量的36.10%~57.14%和20.07%~36.52%;而在根中则富集于细胞壁和可溶性部分,分别占39.2%~49.78%和28.27%~37.62%,其他细胞器中的Pb含量均较少。紫茎泽兰叶中的Pb以盐酸提取态和水提取态为主,两者占总量的58.74%~73.04%;茎中的Pb以醋酸提取态和氯化钠提取态为主;而根中的Pb则以醋酸提取态和盐酸提取态占优势,两者占总量的39.15%~52.91%。     

Relative importance of nodal roots and apical buds in the control of branching in Trifolium repens L.

Clonal species are characterised by having a growth form in which roots and shoots originate from the same meristem so that adventitious nodal roots form close to the terminal apical bud of stems. The nature of the relationship between nodal roots and axillary bud growth was investigated in three manipulative experiments on cuttings of a single genotype of Trifolium repens. In the absence of locally positioned nodal roots axillary bud development within the apical bud proceeded normally until it slowed once the subtending leaf had matured to be the second expanded leaf on the stem. Excision of apical tissues indicated that while there was no apical dominance apparent within fully rooted stems and very little in stems with 15 or more unrooted nodes, the outgrowth of the two most distal axillary buds was stimulated by decapitation in stems with intermediate numbers of unrooted nodes. Excision of the basal branches from stems growing without local nodal roots markedly increased the length and/or number of leaves on 14 distally positioned branches. The presence of basal branches therefore prevented the translocation of root-supplied resources (nutrients, water, phytohormones) to the more distally located nodes and this caused the retardation in the outgrowth of their axillary buds. Based on all three experiments we conclude that the primary control of bud outgrowth is exerted by roots via the acropetal transport of root-supplied resources necessary for axillary bud outgrowth and that apical dominance plays a very minor role in the regulation of axillary bud outgrowth in T. repens.     

Studies onCabomba aquatica (Cabombaceae)

Cabomba aquatica has been found for the first time in India. Both, submerged and floating leaves are epistomatic. The stomata are anomocytic and perigenous in their development. The metaxylem vessel elements have simple perforation plates and spiral side wall thickening. Vessel elements are found in roots, rhizomes and aerial stems. The venation pattern is of two types like the dimorphic leaves. On the basis of these and other featuresCabomba deserves family rank.     

Inoculation and colonization of coffee seedlings (Coffea arabica L.) with the fungal entomopathogen Beauveria bassiana (Ascomycota: Hypocreales)

The fungal entomopathogen Beauveria bassiana became established as an endophyte in coffee seedlings grown in vitro and inoculated with B. bassiana suspensions in the radicle. The fungus was recovered as an endophyte 30 and 60 days postinoculation, from stems, leaves, and roots, and at 60 days postinoculation one of the isolates was also recovered as an epiphyte. Fusarium sp., Rhodotorula sp., and four bacterial morpho-species were also detected, indicating these were present as endophytes in the seed.     

向日葵(Helianthus annuus L.)对133Cs、88Sr的吸收和分布

通过盆栽试验研究了向日葵(Helianthus annuus L.)对土壤中不同处理浓度¹³³Cs和⁸⁸Sr的吸收,以及¹³³Cs和⁸⁸Sr在向日葵不同部位的分布。结果表明：随着处理浓度的增加,植物中¹³³Cs或⁸⁸Sr的含量增加。同一处理浓度下,⁸⁸Sr含量约比¹³³Cs含量高一个数量级。¹³³Cs和⁸⁸Sr在植物不同部位分布不同。根部中¹³³Cs含量高于植物的其他部位（茎、叶、花）。不同于¹³³Cs在植物中的分布,⁸⁸Sr除在根中的分布外,主要转运到了叶片。¹³³Cs和⁸⁸Sr在向日葵体内的分布与目前对放射性¹³⁷Cs和⁹⁰Sr的研究结果相似,所以¹³³Cs和⁸⁸Sr可分别预测¹³⁷Cs和⁹⁰Sr的运转。向日葵是治理大面积低放核素污染土壤的较佳植物种类。     

NaCl处理对西伯利亚白刺幼苗生长及离子平衡的影响

以1年生西伯利亚白刺水培幼苗为材料,研究了不同浓度NaCl(0、200、400mmol·L~(-1))处理对幼苗生长及不同器官(根、茎、叶)中Na~+、K~+、Ca~(2+)、Mg~(2+)的吸收、运输与分配的影响,探讨西伯利亚白刺的盐适应机制。结果表明:(1)200mmol·L~(-1) NaCl处理促进了西伯利亚白刺幼苗的生长及叶片肉质化程度,400mmol·L-1 NaCl处理显著抑制其生长。(2)随着NaCl处理浓度的升高,西伯利亚白刺幼苗根、茎、叶中Na~+含量显著增加,且叶中Na~+含量显著高于茎和根中;根系中K~+含量显著增加;根、茎、叶中Ca~(2+)、Mg~(2+)含量在200mmol·L~(-1) NaCl处理下保持平稳或上升,而在400mmol·L-1 NaCl处理下显著下降。(3)各器官中K~+/Na~+、Ca~(2+)/Na~+和Mg~(2+)/Na~+比值总体随NaCl处理浓度的升高呈下降趋势,且根部离子比值始终高于叶片和茎。(4)随着NaCl处理浓度的升高,西伯利亚白刺幼苗根-茎SK,Na显著下降,而根-茎SCa,Na、SMg,Na及茎-叶SK,Na、SCa,Na、SMg,Na逐渐提高。研究发现,西伯利亚白刺的盐适应机制主要是通过植株的补偿生长效应及叶片对Na~+的聚积作用实现的,同时也与根系对K~+的扣留及茎叶对K~+、Ca~(2+)、Mg~(2+)选择性运输能力增强有关。     

干旱胁迫下红砂幼苗非结构性碳水化合物动态变化特征

该试验以荒漠区主要建群种红砂幼苗为研究对象,设置适宜水分(CK)、轻度干旱(MD)、中度干旱(SD)和重度干旱(VSD)4个胁迫处理(即田间持水量的80%、60%、40%和20%),采用盆栽控水试验,分别测定干旱胁迫15、30、45和60 d时红砂幼苗的叶、茎、粗根和细根中非结构碳水化合物(NSC)及其组分的含量,分析不同胁迫强度下不同干旱持续时间红砂幼苗NSC的动态变化及各组分差异,以揭示红砂NSC对干旱胁迫的响应机制。结果表明:(1)干旱胁迫强度和胁迫持续时间对红砂幼苗不同器官NSC及其组分均有显著影响,其中胁迫持续时间对NSC动态变化的影响尤为显著。(2)干旱胁迫初期,红砂叶中的NSC含量呈下降趋势,而茎中的NSC含量呈上升趋势,粗根和细根中NSC含量在各胁迫处理下基本保持稳定。(3)干旱胁迫后期,红砂叶和茎中的可溶性糖、淀粉和NSC含量逐渐增加,而粗根和细根中的淀粉和NSC含量呈下降趋势(中度干旱除外),且这一时期重度干旱处理下各器官可溶性糖和NSC的含量明显高于CK。研究发现,重度干旱胁迫能显著诱导提高红砂幼苗不同器官中的NSC含量,并通过分解根中淀粉和增加叶片中可溶性糖含量的方式来调节细胞渗透势平衡,以维持细胞活力,进而保持红砂在干旱胁迫后期的存活。