Redifferentiation of leaflet tissues during midrib gall development in Copaifera langsdorffii (Fabaceae)

The tree Copaifera langsdorffii is a superhost for galling herbivores. This plant species has great morphogenetic potential, and responds differently to the stimuli of more than 20 gall-inducing insects. Among these, an undescribed species of Cecidomyiidae induces a midrib gall in which a radial cecidogenetic field is generated and the leaflet tissues redifferentiate. Our objectives were to assess the amplitude of this cecidogenetic field, in which the leaflet tissues were influenced by the feeding action of the cecidomyiid; how the final gall shape was generated; and if tissue redifferentiation conferred any adaptive value on the galling herbivore. Leaflet morphogenesis followed the pattern described in the literature for simple leaves, resulting in a mesophytic arrangement. Tissue redifferentiation due to gall formation revealed that in a midrib gall, abaxial epidermal cells divided to enlarge the gall; spongy parenchyma cells originated the storage tissue, secretory structures, and vascular bundles; palisade parenchyma cells became homogeneous; and adaxial epidermis originated the nutritive tissue. Cell elongation, a necessary step towards cell redifferentiation, is triggered by an increase in water transport to the gall site and vacuole pressure due to neoformed xylem bundles. The generation of the final shape of the midrib gall involved repetitive histological steps in response to the amplitude of the cecidogenetic field. The largest impact of the cecidomyiid feeding action occurred in gall tissues redifferentiated from protoderm and adaxial ground meristem, which provided advantages to the gall maker of the C. langsdorffii midrib gall in terms of nutritional value, microenvironment, and protection against natural enemies.     

Mechanisms of hydraulic conductivity in the leaf galls of Meunieriella sp. (Cecidomyiidae) in Avicennia schaueriana (Acanthaceae): does vascularization explain the preferred sites of induction?

• Intralaminar galls of Meunieriella result from ground tissue proliferation in leaves of Avicennia schaueriana, a typical halophytic mangrove. We tested if the preferred sites of gall induction were the midribs and secondary veins (SV) at the basal leaf portion, where the galls were expected to be largest; and if the vascular system in galls and adjacent regions was altered to favour water supply in galls, thus increasing their growth.
• Gall induction sites and gall sizes were quantified according to leaf portions and regions. Anatomical and histometric analyses in vascular and ground tissues of galls and adjacent regions were compared to equivalent regions of non-galled leaves.
• The galls were largest at basal sites on leaves, the midrib and SV. More galls occurred on the apical portion of the leaf, and on the leaf blade and secondary vein regions. Changes in shape and vascular system area, number and diameter of vessel elements were detected in both galls and adjacent regions. Fewer and smaller-sized vessel elements were observed in regions proximal to the galls and inside them.
• Gall size is not related with preferred induction sites, which could be explained by factors such as thermal balance. Alterations in the vascular system indicate reduced hydraulic conductivity in the xylem in the proximal region and inside galls, leading to water leakage to gall parenchyma cells. This compensatory mechanism explains the expansion and proliferation of water storage and spongy parenchyma cells in the galls, explaining the higher growth in more vascularized regions.

     

ANATOMY OF SOME LEAF GALLS OF ROSA WOODSII (ROSACEAE)

Infection of Rosa woodsii by some members of the order Hymenoptera results in neoplasmic outgrowths on the leaves. One type of outgrowth produces a spherical swelling (leaf gall) while the other has extensive hair-like proliferations (hairy gall). The anatomy and ultrastructure of these galls were examined by light microscopy and transmission electron microscopy. The leaf gall cells were considerably larger than normal cells, lacked well-developed chloroplasts and were loosely arranged with prominent intercellular spaces. Vascular bundles were scattered throughout the gall tissue. The upper three cell layers of the leaf gall tissue resembles a periderm, having many suberin lamellae. The suberin lamellae were often traversed by pores which may represent incomplete plasmodesmata. Phenolic compounds were commonly seen both in the normal and gall cells. A layer of internal cells of the hairy galls have remarkably thickened cell walls, presumably due to the deposition of cellulosic substances. Unlike leaf galls, the epidermal cells of the hairy galls were not heavily cuticularized and no periderm was found. The hair-like outgrowths present on the outer surface of these galls had a central vascular bundle. The epidermis of the outgrowths also had thickened cell walls, and trichomes occurred on the outer surface. The structural modifications brought about by the insect invasion in these two galls are compared and their roles in gall formation are discussed.     

Damage on 'Hass' avocado leaves, webbing and nesting behaviour of Oligonychus perseae (Acari: Tetranychidae)

The damage of Oligonychus perseae Tuttle, Baker and Abbatiello on 'Hass' avocado trees occurs mainly on the underside of the leaves along the midrib, main veins and leaf depressions. The lower epidermal, spongy parenchyma and palisade parenchyma cells of the leaf tissues are destroyed. Large necrotic areas on the underside of the leaves result from feeding when high population levels occur. Feeding and reproduction takes place in 'nests' of silken webbing, which also provide protection from some predator mites and other natural enemies. Oligonychus perseae shows a modification of the earlier defined life-type web nest (WN-c). The greatest number of nests built by a female was 12.17 at 20°C and the greatest number of eggs per female per nest was 5.20 at 25°C.     

石蒜属12 种植物叶片比较解剖学研究

 对石蒜属( Lycoris Herb. ) 12 种植物叶片的比较解剖学研究表明: (1) 石蒜属植物叶片横切面的端部、中部及基部的轮廓基本呈浅“W”或“V”字型, 有些种的表皮细胞上具有明显的尖刺状乳突; ( 2)石蒜属植物均为异面叶, 叶肉组织有一定的栅栏组织和海绵组织分化, 但二者的厚度、叶肉中所占比例及栅栏组织的细胞层数在种间有一定的差异; (3) 海绵组织发达、具有大而明显的薄壁细胞或细胞裂溶后形成空腔(分泌腔或气腔); (4) 叶片中维管束数目大多为奇数, 叶脉维管束鞘由薄壁细胞组成; (5) 石蒜属植物横切面上叶缘的形状分为圆弧形和楔形两种类型。石蒜属植物叶的解剖结构具有许多相似特征; 同时又具有一定的种间差异, 可为石蒜属植物的种间关系和开发利用提供有价值的信息。     

Transcriptomic characterization of gall tissue of Japanese elm tree (Ulmus davidiana var. japonica) induced by the aphid Tetraneura nigriabdominalis

Insect galls are abnormal plant tissues induced by parasitic insect(s) for use as their habitat. In previous work, we suggested that gall tissues induced by the aphid Tetraneura nigriabdominalis on Japanese elm trees are less responsive than leaf tissues to jasmonic acid (JA), which is involved in the production of volatile organic compounds as a typical defensive reaction of plants against attack by insect pests. A comprehensive analysis of gene expression by RNA sequencing indicated that the number of JA responsive genes was markedly lower in gall tissues than in leaf tissues. This suggests that gall tissues are mostly defective in JA signaling, although JA signaling is not entirely compromised in gall tissue. Gene ontology analysis sheds light on some stress-related unigenes with higher expression levels in gall tissues, suggesting that host plants sense aphids as a biotic stress but are defective in the JA-mediated defense response in gall tissues.     

Plant organ abscission and the green island effect caused by gallmidges (Cecidomyiidae) on tropical trees

Plants exhibit a wide array of inert and induced responses in defense against herbivore attack. Among these the abscission of organs has been argued to be a highly effective mechanism, depending, however, on the herbivore’s feeding mode. While consisting of plant tissues, insect induced galls are seen as the extended phenotype of the gall inducer which might circumvent many or most of the plant defenses. There is very little information whether and how far beyond the gall tissue gall inducers might affect plant tissues. A localized impact is likely to leave the abscission of galled organs as a viable defense although at a cost. Here, we report on an instance where the host plant, Neea madeirana (Nyctaginaceae) abscises leaves galled by two species of Bruggmannia (Diptera: Cecidomyiidae), more frequently than ungalled leaves in a rain forest in Amazonia, Brazil. Once on the forest floor the leaves decay quickly, while both gall types show signs of localized maintenance of healthy tissues for a while (the green island effect). However, on the forest floor galls are exposed to a new set of potential natural enemies. Both gall types show a minimum of a five-fold increase in mortality due to pathogens (fungi and bacteria) compared to galls that were retained on the host tree. We discuss the adaptive nature of plant organ abscission as a plant defense against gallers and as a gall inducer adaptive trait. Handling editor: Graham Stone.     

Developmental Ultrastructure of Glandular Trichomes of <Emphasis Type="Italic">Rosmarinus officinalis</Emphasis>: Secretory Cavity and Secretory Vesicle Formation

Glandular trichomes in the leaf lamina of Rosmarinus officinalis L. were examined by scanning and transmission electron microscopy. The leaves were characterized by an abundance of two types of glandular trichomes—small capitate and large peltate glandular trichomes. In addition to the glandular trichomes, numerous non-glandular trichomes were present on the abaxial surface of the leaf. These trichomes mainly predominated on the midrib, whereas glandular trichomes occurred on non-vein areas. At the initial phase of secretory cavity formation, hyaline areas were abundant in periclinal walls of head cells, while they were not observed in the anticlinal walls. The hyaline areas gradually increased in size, fusing with other areas throughout the wall. Loose wall material adjacent to hyaline areas was released from the head cell walls and migrated into the secretory cavities. As the secretory cavities continued to enlarge, the new vesicles emerging into the secretory cavities from the walls of head cells became surrounded with the surface of a typical membrane. They developed a round shape, but the contours of the vesicle surfaces appeared polygonal when tightly packed inside a cavity. These vesicles varied in size; small vesicles often possessed electron-dense contents, while large vesicles contained electron-light contents.     

Factors affecting components of fitness in a gall-making wasp (Cynips divisa Hartig)

Summary The galls of the agamic generation of the cynipid gall-wasp Cynips divisa were studied; these galls are found only on the main veins of the leaf. Galls are concentrated on the middle veins of leaves, and generally occur closer to the midrib than to the edge of the leaf. Survival of the gall-maker and fecundity of the energing wasp depend on wasp size and position of the gall. There is a striking pattern in gall size according to the number of galls on the vein. The number of galls on a vein appears therefore to have a strong effect on potential fecundity.     

Tentacles of in vitro-grown round-leaf sundew (<Emphasis Type="Italic">Drosera rotundifolia</Emphasis>L.) show induction of chitinase activity upon mimicking the presence of prey

Induction of plant-derived chitinases in the leaves of a carnivorous plant was demonstrated using aseptically grown round-leaf sundew (Drosera rotundifolia L.). The presence of insect prey was mimicked by placing the chemical inducers gelatine, salicylic acid and crustacean chitin on leaves. In addition, mechanical stirring of tentacles was performed. Chitinase activity was markedly increased in leaf exudates upon application of notably chitin. Application of gelatine increased the proteolytic activity of leaf exudates, indicating that the reaction of sundew leaves depends on the molecular nature of the inducer applied. In situ hybridization of sundew leaves with a Drosera chitinase probe showed chitinase gene expression in different cell types of non-treated leaves, but not in the secretory cells of the glandular heads. Upon induction, chitinase mRNA was also present in the secretory cells of the sundew leaf. The combined results indicate that chitinase is likely to be involved in the decomposition of insect prey by carnivorous plants. This adds a novel role to the already broad function of chitinases in the plant kingdom and may contribute to our understanding of the molecular mechanisms behind the ecological success of carnivorous plants in nutritionally poor environments.     

Bud formation in leaves,leaf fragments and midrib pieces of Heloniopsis orientalis (Liliaceae)

Summary Isolated leaves, leaf fragments and pieces of the midrib portion devoid of lamina, of Heloniopsis orientalis were grown on an inorganic nutrient medium without organic nutrients and growth regulators in order to investigate their regenerative ability. Bud formation in intact, attached leaves occurs only at the tip, in isolated leaves at the tip and the base, whereas leaf fragments cut transversely at a distance from the tip and isolated midrib pieces form numerous shoot buds in a random distribution. Lamina fragments lacking midrib frequently fail to regenerate even after a long time of culture. It is suggested that endogeneous growth regulators in the leaf, especially the vascular tissues, play an important role in bud initiation. Very young leaves of Heloniopsis are capable forming buds and roots when isolated from the mother plants.     

Anatomy of the vegetative organs and secretory structures of Rhaponticum carthamoides (Asteraceae)

Roots, stems, rhizomes and leaves of Rhaponticum carthamoides (Willd.) Iljin (a Siberian adaptogenic plant, originating from the Altai and Saian Mountains) of different ages were investigated by means of light and electron microscopy. Schizogenous secretory reservoirs occurred in every organ, and were located within the secondary xylem (adventitious roots and rhizome of young plants), at the interface of endodermis/cortical parenchyma (roots and hypocotyl), along phloem and primary xylem (older rhizome), around the vascular bundles (inflorescence stem, petiole and leaf midrib veins) and along phloem (cotyledonary and leaf veins). At the interface of endodermis/inner parenchyma, secretion accumulated in the intercellular spaces prior to the formation of proper epithelial cells. The secretion as observed by transmission electron microscopy comprised three components: soluble (i.e. absent from sections; probably phenolic), insoluble and strongly osmiophilic (probably phenolic) and insoluble, moderately osmiophilic (probably lipidic). Numerous osmiophilic oil droplets, similar to the lipidic secretion inside the reservoirs, local proliferation of rough endoplasmic reticulum and numerous multivesicular bodies characterized epithelial cells in all organs. Leucoplasts (in subterranean organs) with osmiophilic inclusions and peroxisomes with crystalloid inclusions were specific for parenchyma cells. Peltate glandular hairs were formed on leaf blades.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 207–233.     

中国芸香科植物叶分泌囊比较解剖学研究

利用整体透明、石腊和薄切片方法对芸香科22属,40种和2变种植物叶分泌囊的形态结构和分 布进行了比较研究。成熟分泌囊都由鞘细胞和一层上皮细胞围绕圆形腔隙构成,上皮细胞扁平,细胞壁 薄、完整,故分泌囊属裂生方式发生。鞘细胞1～5层,不同种类的层数有变化,个别种缺乏。内层鞘细 胞为扁平的薄壁细胞,外层的细胞壁较厚。分泌囊的形态结构、着生位置和分布密度等在不同属或不同 种间存在一定差异。根据分泌囊在叶中的分布位置和形态结构特点,可将其划分为:叶缘齿缝分泌囊, 叶肉分泌囊和两者混合型。叶肉分泌囊又可分海绵组织分泌囊和栅栏组织分泌囊。在此基础上对该科各类型分泌囊的形态演化关系以及各亚科或各属间的亲缘关系进行了探讨。     

GLANDULAR LEAF STRUCTURE OF TRIPHYOPHYLLUM PELTATUM (DIONCOPHYLLACEAE): A “FLY-PAPER” INSECT TRAPPER

Certain leaves of Triphyophyllum peltatum (Hutch. & Dalz.) Airy Shaw (Dioncophyllaceae) have an extended, erect midrib covered with stalked and sessile glands exhibiting insect-trapping ability. The stalked glands secrete a sticky, acid mucilage to which numerous insects in various stages of decay were observed adhering. The morphology and anatomy of the glandular leaves were investigated with light and scanning electron microscopy. The midrib and the lamina in the lowermost part of the leaf bear stomata. Those of the midrib are transitional between actinocytic and cyclocytic in type. Parenchyma cells in mature and immature portions of the midrib and in the glands contain numerous crystals and amyloplasts. The anatomy of the stalked and sessile glands is remarkably similar to that of Drosophyllum lusitanicum (L.) Link. (Droseraceae). A distinct cuticle covers the gland head, but no pores are visible. Three distinct layers underlie the cuticle: a definite epidermal layer with irregularly thickened cell walls, and two layers of more loosely arranged cells. A fourth layer, endodermoid in nature with radially thickened cell walls, connects the head and stalk of the stalked glands and the head and midrib parenchyma of the sessile glands. Vascular elements (including helical and scalariform tracheary elements) reach the endodermoid layer. According to recent studies, Triphyophyllum and Drosophyllum have different phylogenetic origins; the morphological and anatomical similarities in the insect-trapping glandular leaves show more support for their convergent evolution rather than for an alliance of the Dioncophyllaceae with the Droseraceae.     

The volumes of anatomical components in leaves oftypha angustifolia L. andtypha latifolia L.

The volumes of tissues in leaves of two species ofTypha with different habitus were measured. It was found that air cavities occupy more than 50%, parenchyma about 20% and photosynthetic tissue about 10% of the total volume of the leaf. If the cavities are omitted, parenehyma amounts to approximately 50% and photosynthetic tissue to little more than 20% of the total volume of tissues. The relative volumes of tissues vary continuously from the base to the tip of the leaf. The differences between the two species studied were not large. Besides the relative volumes, the real ones of leaves and tissues were calculated.     

Characterisation of the effects of leaf galls of Clusiamyia nitida (Cecidomyiidae) on Clusia lanceolata Cambess. (Clusiaceae): Anatomical aspects and chemical analysis of essential oil

Galls develop in different plant organs and are induced by the activity of various organisms. Some studies have investigated the ecological interactions between species of Clusia and gall-inducing insects. The goal of our study is to characterise changes in leaf anatomy caused by the activity of gall insects in Clusia lanceolata. Additionally, we also investigated the chemical composition of volatile compounds of normal leaves and those with galls to detect possible effects on the host plants. For anatomical studies, we used botanical material fixed in FAA₅₀. Transversal sections of the leaf blade were obtained from samples of leaves located on the third and fourth nodes from both male and female individuals. Material was studied from both sexes both with unaffected leaves and leaves containing galls. Fresh leaves of C. lanceolata were used for the extraction of volatile compounds, which were submitted to stem distillation using a modified Clevenger apparatus determining the oil yields subsequently (w/w). The unaffected leaves of female and male individuals of C. lanceolata exhibit similar anatomical structures. However, galls on leaves of both sexes show anatomical differences. The activity of the gall insect Clusiamyia nitida induces several changes in the foliar anatomy and the distribution of metabolic compounds in new tissues during gall development. However, the larvae are not able to induce significant changes in the volatile compounds of inflected leaves from male and female individuals.     

The role of the parenchyma sheath and PCD during the development of oil cavities in Pterodon pubescens (Leguminosae-Papilionoideae)

Pterodon pubescens cavities are constituted by lumen and uniseriated epithelium surrounded by multiseriate parenchyma sheath. We studied the development of secretory cavities, including the role of parenchyma sheath, using light and transmission electron microscopy. A Tunel assay was performed to verify whether programmed cell death (PCD) occurs during the process. The lumen is formed by schizogeny and lysigeny occur in later developmental stages of the secretory cavities. Ultrastructurally, epithelial cells in later developmental stages become dark and with sinuous walls; the protoplast becomes retracted and the cytoplasm shows low organelle definition. Degenerated cells are released toward the lumen. Our results showed that PCD occurs during later developmental stages of cavities and plays a critical role in functioning of these glands. New cells originated from the parenchyma sheath differentiate into secretory cells and replace those degenerated ones. This fact associated to PCD guarantees epithelium renovation during the secretory cycle and the maintenance of secretory activity of cavities.     

Growth and development of larvae and galls of Urophora cardui (Diptera,Tephritidae) on Cirsium arvense (Compositae)

Summary The tephritid fly Urophora cardui induces a large multi-chambered gall within the stems of Cirsium arvense. Three distinct phases of gall development have been identified as initiation, growth, and maturation. During initiation the insect gains control of tissue development and during the gall's growth phase parenchyma cells proliferate rapidly surrounding the larvae with thick layers of cells. Patches of primary nutritive cells appear along the surface of larval chambers during the growth phase but few of these cells are consumed. In the gall's maturation phase, thick layers of secondary nutritive cells appear around the surface of larval chambers and the remaining gall parenchyma lignifies. Secondary nutritive cells are the primary food of U. cardui.The gall expands rapidly during the growth phase then abruptly slows at the beginning of the maturation phase. Rate of gall growth is dependent upon the number of larvae per gall but the number of larvae does not affect duration of this phase.Larvae remain in the second instar throughout the growth phase and grow slowly. Once the gall enters the maturation phase and the secondary nutritive cells appear, the larvae moult to the third instar and grow quickly. Larvace attain over 98% of their final weight during the maturation phase and consume all secondary nutritive cells.It is postulated that larvae do not feed extensively on primary nutritive cells since these cells play a key role in gall morphogenesis. The appearance of secondary nutritive cells stimulates larval feeding at a time when gall growth and development is finished.     

Developmental anatomy and immunocytochemistry reveal the neo-ontogenesis of the leaf tissues of Psidium myrtoides (Myrtaceae) towards the globoid galls of Nothotrioza myrtoidis (Triozidae)

Key message

The temporal balance between hyperplasia and hypertrophy, and the new functions of different cell lineages led to cell transformations in a centrifugal gradient that determines the gall globoid shape.

Abstract

Plant galls develop by the redifferentiation of new cell types originated from those of the host plants, with new functional and structural designs related to the composition of cell walls and cell contents. Variations in cell wall composition have just started to be explored with the perspective of gall development, and are herein related to the histochemical gradients previously detected on Psidium myrtoides galls. Young and mature leaves of P. myrtoides and galls of Nothotrioza myrtoidis at different developmental stages were analysed using anatomical, cytometrical and immunocytochemical approaches. The gall parenchyma presents transformations in the size and shape of the cells in distinct tissue layers, and variations of pectin and protein domains in cell walls. The temporal balance between tissue hyperplasia and cell hypertrophy, and the new functions of different cell lineages led to cell transformations in a centrifugal gradient, which determines the globoid shape of the gall. The distribution of cell wall epitopes affected cell wall flexibility and rigidity, towards gall maturation. By senescence, it provided functional stability for the outer cortical parenchyma. The detection of the demethylesterified homogalacturonans (HGAs) denoted the activity of the pectin methylesterases (PMEs) during the senescent phase, and was a novel time-based detection linked to the increased rigidity of the cell walls, and to the gall opening. Current investigation firstly reports the influence of immunocytochemistry of plant cell walls over the development of leaf tissues, determining their neo-ontogenesis towards a new phenotype, i.e., the globoid gall morphotype.