Histocytological aspects of four types of ambrosia galls on Machilus zuihoensis Hayata (Lauraceae)

Four types of prosoplasmatic galls induced by Daphnephila midges are found on leaves of Machilus zuihoensis, a species endemic to Taiwan: urn- and small urn-shaped, obovate, and hairy oblong galls. In addition to containing nutritive tissues, these galls are lined with fungal hyphae. The objective of this study was to describe and compare the structural organization of the various gall morphologies and to examine the ultrastructure of the nutritive and fungal cells lining the gall chambers. The morphology and ultrastructure of mature-stage galls were examined by light, scanning electron, and transmission electron microscopy. Diverse epidermal cell shapes and wax textures were observed in the leaves and galls of M. zuihoensis. In small urn-shaped, obovate, and hairy oblong galls vascular bundles extend from the gall base to near the centre of the gall top. In contrast, vascular bundles in urn-shaped galls are distributed in the gall wall and extend to close to the outer gall top. Trichomes were present only abaxially on leaves and on hairy oblong gall surfaces. Starch granules, tannins, and mucilage were distributed differently among the four gall types. Further, fungal mycelia spread in the interior gall wall and partially passed through the intercellular spaces of nutritive cells and reached the sclerenchyma. Histological analyses revealed that the surface structure of galls differs from that of the leaf and that the epidermal organization differs among the four gall types. Different types of leaf galls on the same plant have different patterns of tissue stratification and contain different ergastic substances. The results of this study will contribute to the understanding of tritrophic relationships and the complex interactions among parasitic gall-inducing insects, mutualistic fungi, and host plants.     

Plant development reprogramming by cynipid gall wasp: proteomic analysis

An insect–plant interaction induced gall formation is where gall wasps change the plant development towards formation of new units to shield and nourish the evolving larvae. The targets of the insect signals and the mechanism of gall development are unknown. To show the molecular pathways that are responsive to the gall wasp, the proteomic approach was used to compare the gall with non-gall plant tissues. We studied three oak gall species (Cynips quercusfolii, Cynips longiventris, and Neuroterus quercusbaccarum) and the host plant (Quercus robur). Among the 21 identified proteins, 18 increased and three decreased in abundance in gall tissue, in comparison to the leaf tissues. Ten proteins were C. quercusfolii responsive, two only with this gall inducer, while seven increased in abundance. Eleven proteins were C. longiventris responsive, and two only with this gall inducer. Sixteen proteins were associated with gall formation by the N. quercusbaccarum and, in this, eight only with this gall inducer. A similar effect on protein abundance occurred as galls in leaf veins (for five proteins). For leaf blades, such a relation was not found. The role of each protein is discussed according to its involvement in the gall formation. Moreover, S-adenosyl methionine synthase, flavone 3-hydroxylase, stress- and pathogenesis-related proteins, and gamma carbonic anhydrase are associated with developmental regulation of plant tissue into a gall.     

Morphometric analysis of young petiole galls on the narrow-leaf cottonwood, <Emphasis Type="Italic">Populus angustifolia</Emphasis>, by the sugarbeet root aphid, <Emphasis Type="Italic">Pemphigus betae</Emphasis>

An insect-induced gall is a highly specialized structure resulting from atypical development of plant tissue induced by a reaction to the presence and activity of an insect. The insect induces a differentiation of tissues with features and functions of an ectopic organ, providing nutrition and protection to the galling insect from natural enemies and environmental stresses. In this anatomical and cytological study, we characterized how the gall-inducing aphid Pemphigus betae reshapes the leaf morphology of the narrow-leaf cottonwood Populus angustifolia to form a leaf fold gall. Young galls displayed a bend on one side of the midvein toward the center of the leaf and back to create a fold on the abaxial side of the leaf. This fold was formed abaxially by periclinal and anticlinal divisions, effectively eliminating intercellular spaces from the spongy parenchyma. Galls at this stage exhibited both cell hypertrophy and tissue hyperplasia. Cells on the adaxial surface were more numerous and smaller than cells near the abaxial surface were, creating the large fold that surrounds the insect. Mesophyll cells exhibited some features typical of nutritive cells induced by other galling insects, including conspicuous nucleolus, reduced and fragmented vacuole, smaller and degraded chloroplasts, and dense cytoplasm compared to ungalled tissue. Even though aphids feed on the contents of phloem and do not directly consume the gall tissue, they induce changes in the plant vascular system, which lead to nutrient accumulation to support the growing aphid numbers in mature galls.     

Histological Comparisons of Fergusobia/Fergusonina-Induced Galls on Different Myrtaceous Hosts

The putative mutualism between different host-specific Fergusobia nematodes and Fergusonina flies is manifested in a variety of gall types involving shoot or inflorescence buds, individual flower buds, stems, or young leaves in the plant family Myrtaceae. Different types of galls in the early-to-middle stages of development, with host-specific species of Fergusobia/Fergusonina, were collected from Australian members of the subfamily Leptospermoideae (six species of Eucalyptus, two species of Corymbia, and seven species of broad-leaved Melaleuca). Galls were sectioned and histologically examined to assess morphological changes induced by nematode/fly mutualism. The different gall forms were characterized into four broad categories: (i) individual flower bud, (ii) terminal and axial bud, (iii) ''basal rosette'' stem, and (iv) flat leaf. Gall morphology in all four types appeared to result from species-specific selection of the oviposition site and timing and number of eggs deposited in a particular plant host. In all cases, early parasitism by Fergusobia/Fergusonina involved several layers of uninucleate, hypertrophied cells lining the lumen of each locule (gall chamber where each fly larva and accompanying nematodes develop). Hypertrophied cells in galls were larger than normal epidermal cells, and each had an enlarged nucleus, nucleolus, and granular cytoplasm that resembled shoot bud gall cells induced by nematodes in the Anguinidae.     

Gall distribution as a compromise between the optimal gall-site selection and the synchrony to host-plant phenology in the aphid Kaltenbachiella japonica

Gall-site selection by the aphid Kaltenbachiella japonica was evaluated in relation to leaf position in a shoot, and gall positions within a leaf. First-instar fundatrices induce closed galls on the midribs of host leaves, and several galls were often induced on one leaf. Leaves with many galls were often withered before emergence of sexuparae from the galls. Within a leaf, gall volume was positively correlated with the sum of lateral-vein length in the leaf segment at which the gall was induced. The observed pattern in gall volume among the leaf segments corresponded with that in the lateral-vein length. These results show that a foundatrix selects the most vigorous position within a leaf to produce more offspring. Although distal leaves grew faster than did basal leaves, gall density was highest on leaves at the middle order when a shoot has more than seven leaves. Optimal gall-site selection seems to be constrained by the asynchrony in timing between the hatching of fundatrices and leaf growth within a shoot. These results suggest that the observed gall distribution is affected by both the distribution of suitable galling sites within a leaf and the synchrony with leaf phenology of the host plant.     

Genetic and ecological differences between <Emphasis Type="Italic">Asphondylia yushimai</Emphasis> and the ivy gall midge, <Emphasis Type="Italic">Asphondylia</Emphasis> sp. (Diptera: Cecidomyiidae), with a new distribution record of the former from Hokkaido and South Korea

The soybean pod gall midge, Asphondylia yushimai, is known to utilize Laurocerasus zippeliana (Rosaceae) and Osmanthus heterophyllus (Oleaceae) as autumn–spring hosts. In addition, ivy, Hedera rhombea (Araliaceae), was thought to be a candidate for an additional autumn–spring host. However, our genetic analysis indicated that no haplotypes of the ivy fruit gall midge, Asphondylia sp., were identical to any of the haplotypes of A. yushimai. Furthermore, the life-history traits of the ivy fruit gall midge, such as voltinism, host-plant range, lower development threshold temperature (LDT), and developmental speed, were clearly different from those of A. yushimai. Thus, the results from genetic analysis and life-history traits revealed that the ivy fruit gall midge was not identical to A. yushimai and that H. rhombea is not an additional autumn–spring host plant for A. yushimai. We also discovered through morphological observation and genetic analysis that A. yushimai is distributed in Hokkaido and South Korea, and that the ivy fruit gall midge exhibits host plant alternation, utilizing both the fruit of Phytolacca americana (Phytolaccaceae) and the flower buds of Paederia foetida (Rubiaceae) as spring–autumn hosts.     

Leaf gall polymorphism and molecular phylogeny of a new Bruggmanniella species (Diptera: Cecidomyiidae: Asphondyliini) associated with Litsea acuminata (Lauraceae) in Taiwan,with ecological comparisons and a species description

Two types of cecidomyiid leaf galls, cup‐shaped and umbrella‐shaped, occur on Litsea acuminata (Lauraceae) in Taiwan. Based on the concept of gall shapes as “extended phenotypes” of gall inducers, these two types could be induced by different gall midge species. However, galls with intermediate shapes between the two types were recently discovered, which implies that possible genetic exchanges occur between the gall inducers of both types. To clarify the taxonomic status of gall midges responsible for the two types of galls on L. acuminata, we undertook taxonomic, molecular phylogenetic and ecological studies. Our findings show that the two gall types are induced by the same Bruggmanniella species and the species is new to science. We describe the species forming this range of galls as Bruggmanniella litseae sp. n. , and compare their geographical distribution, galling position and morphometry. Based on our results, a possible evolutionary scenario of B. litseae sp. n. is discussed.     

The foliar chemical profile of criollo avocado, Persea americana var. drymifolia (Lauraceae), and its relationship with the incidence of a gall-forming insect, Trioza anceps (Triozidae)

The role of phytochemical diversity in plant defense was studied using the specialist herbivore Trioza anceps Tuthill (avocado gall-forming insect), and the volatile fraction of the foliar chemicals of its host, the creole avocado (Persea americana var. drymifolia (Schect. &; Cham.) Blake). Two hypotheses were tested: a) plant defense is determined by phytochemical diversity, and b) plant defense is determined by single compounds or specific blends of compounds. Simple and multiple regressions and a size and shape analysis (which considers the compounds relative and absolute concentrations within the leaf blend) were used to test these hypotheses. Simple regressions of gall incidence and chemical diversity and the tree origin elevation and latitude were very weak. The linear multiple regression to explain gall incidence with 33 foliar compounds and geographical data produced a model with low predictive power (R² = 0.13). The size and shape analysis showed intraspecific variation in leaf chemical profiles among five tree groups, classified by the number of galls per 10 cm² of leaf. Discriminant analysis separated clearly the tree groups’ chemical profiles through specific compounds. These results suggest that the gall incidence is associated with specific chemical profiles, rather than to high or low foliar phytochemical diversity.     

In situ occurrence of a gall midge (Insecta,Diptera, Cecidomyiidae) on fossilized angiosperm leaf cuticle fragments from the Pliocene sediments of eastern India

In situ preservation of fossil insect damage in plant fossils is an excellent tool to study the coevolution of flora and fauna through geological time, but finding both damage and the insect causing that damage in the same specimen is a very rare phenomenon. Galling is a common form of angiosperm leaf damage, which can be regarded as a kind of extended phenotype of the causal insects, essentially the gall midges, but galls usually lack remains of the insects themselves. Here we report the in situ occurrence of a gall midge (Insecta, Diptera, Cecidomyiidae) as well as its pupal exuviae on the abaxial cuticular surface of fossilized leaf cuticle fragments of Fabaceae leaves (cf. Albizia) that also bear galls, recovered from the latest Neogene (Rajdanda Formation, Pliocene) sediments of the Chotonagpur Plateau, Jharkhand, northeastern India. This Pliocene gall midge features well-preserved legs, segmented antenna with distinct and enlarged scape, elongate curved setae, and longer than broad terminal plate of the ovipositor lamellae. The in situ presence of a gall midge on a host fabaceous leaf cuticle indicates the existence of a host-ectoparasite relationship in the ancient warm and humid tropical monsoon-influenced forests of eastern India during the Pliocene. This is the first authentic fossil record of an in situ phytophagous insect of Cecidomyiidae from India, as well as southeast Asia. Although the identification of the recovered phytophagous insect associated with the fossil leaf cuticle is only possible to family level, this find reveals that such plant-insect relationships existed in the Pliocene of eastern India.     

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.     

Floral-like destiny induced by a galling Cecidomyiidae on the axillary buds of Marcetia taxifolia (Melastomataceae)

The galls induced by Cecidomyiidae, Diptera, are very diverse, with conspicuous evidence of tissue manipulation by the galling herbivores. Bud galls, as those induced by an unidentified Cecidomyiidae species on Marcetia taxifolia, Melastomataceae, can be considered as one of the most complex type of prosoplasma galls. The gall-inducer manipulate the axillary meristem of the plant in a way that gall morphogenesis may present both vegetative and reproductive features of the host plant. Herein, we analyzed traces of determinate and indeterminate growth in the bud gall of M. taxifolia, looking for parallels between the features of the leaves and flowers, natural fates of the meristematic cells. The bud galls are induced by the cecidomyiid fly, and are formed by the connation of eight leaf primordia, a common process in ovary morphogenesis. The bud gall corresponds to a pistil-shaped gall morphotype, with anatomical features similar to those of an hypanthium and sepals. The gall mimics an ovary, which has protective barriers at the apex, and a nutritive tissue (with storage of lipids and proteins) or a placenta, respectively, at the basal portion. The redifferentiation of the promeristem into a nutritive tissue at the base of the gall confers a determinate destiny to the axillary bud. Comparatively, the gradients of cell expansion and of accumulation of primary metabolites also indicate that the gall and the ovary are convergent structures. Some constraints of the host plant cells, such as the absence of lignification, and the accumulation of polyphenols, lipids and terpenoids, are not altered and may confer chemical protection for plant tissues and the larva against oxidative stress.     

Effects of Temperature,Shoot Age,and Medium on Gall Induction by Subanguina picridis in Vitro

The influence of temperature, shoot age, and medium on gall induction by Subanguina picridis on Russian knapweed (Acroptilon repens) was examined in vitro. The optimal temperature for gall formation was 20 C. Gall induction was delayed as the temperature decreased, and decreased as shoot age increased. Bud primordia (0-day-old shoots and 5-day-old shoots) with an average length of 4.2 mm and 7.9 mm were the most suitable tissues for nematode development and gall formation. Gall formation was more effective on B5G medium than on MSG. Young shoots under slow growth were most suitable for mass rearing of S. picridis.     

Physiological and proteomic characterization of manganese sensitivity and tolerance in rice (Oryza sativa) in comparison with barley (Hordeum vulgare)

Background and Aims

Research on manganese (Mn) toxicity and tolerance indicates that Mn toxicity develops apoplastically through increased peroxidase activities mediated by phenolics and Mn, and Mn tolerance could be conferred by sequestration of Mn in inert cell compartments. This comparative study focuses on Mn-sensitive barley (Hordeum vulgare) and Mn-tolerant rice (Oryza sativa) as model organisms to unravel the mechanisms of Mn toxicity and/or tolerance in monocots.

Methods

Bulk leaf Mn concentrations as well as peroxidase activities and protein concentrations were analysed in apoplastic washing fluid (AWF) in both species. In rice, Mn distribution between leaf compartments and the leaf proteome using 2D isoelectic focusing IEF/SDS–PAGE and 2D Blue native BN/SDS–PAGE was studied.

Key Results

The Mn sensitivity of barley was confirmed since the formation of brown spots on older leaves was induced by low bulk leaf and AWF Mn concentrations and exhibited strongly enhanced H₂O₂-producing and consuming peroxidase activities. In contrast, by a factor of 50, higher Mn concentrations did not produce Mn toxicity symptoms on older leaves in rice. Peroxidase activities, lower by a factor of about 100 in the rice leaf AWF compared with barley, support the view of a central role for these peroxidases in the apoplastic expression of Mn toxicity. The high Mn tolerance of old rice leaves could be related to a high Mn binding capacity of the cell walls. Proteomic studies suggest that the lower Mn tolerance of young rice leaves could be related to Mn excess-induced displacement of Mg and Fe from essential metabolic functions.

Conclusions

The results provide evidence that Mn toxicity in barley involves apoplastic lesions mediated by peroxidases. The high Mn tolerance of old leaves of rice involves a high Mn binding capacity of the cell walls, whereas Mn toxicity in less Mn-tolerant young leaves is related to Mn-induced Mg and Fe deficiencies.     

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.     

Description of a New and Two Known Species of the Free-living Nematode Paroigolaimella Paramonov, 1952 (Diplogastridae) from India

This paper describes a new and two known species of Paroigolaimella collected from India. Paroigolaimella helalii n. sp. is characterized by having conspicuous sexual dimorphism in the stoma and pharynx, ovaries with a sphincter separating the mature oocyte from developing ones, a vagina leading to a strong ovijector, a pore-like vulva with cuticular flap; males with slender strongly arcuate spicules with dilated capitula; the gubernaculum slender with expanded plate-like distal end and nine pairs of genital papillae, and four to five pairs of copulatory muscle bands. P. coprophila (Sudhaus and Rehfeld, 1990) Sudhaus and Fürst von Lieven, 2003 collected from leaf litter from a farmyard has been redescribed with reassessment of its distinguishing characters from P. bernensis. P. bodamica (Micoletzky, 1922) n. comb. has been described and its status has been discussed with context to P. bernensis.     

Differential accumulation of proteinase inhibitor I in normal and crown gall tissue of tobacco, tomato, and potato

A proteinase inhibitor (inhibitor I) is induced in crown gall tumors of tobacco (Nicotiana tabacum) initiated through infection with the tumorinducing bacterium, Agrobacterium tumefaciens, strains B6 or CG-14. Uninfected tissues do not contain immunologically detectable quantities of inhibitor I. Inhibitor I synthesis in tobacco crown gall tumors paralleled tumor growth at the average rate of about 4.5 μg of inhibitor I per 200 mg of fresh tissue per day. Infection of variegated tobacco mutant Dp-I with A. tumefaciens strain CG-14 produced tumors with 25% more inhibitor than tumors induced with strain B6. Unlike tobacco, tumors induced by either bacterial strain on potato (Solanum tuberosum) and on tomato (Lycopersicum esculentum) did not accumulate inhibitor I. Consequently, inhibitor I accumulation is modulated by the type of plant host used in spite of familial relatedness (Solanaceae) and the strain of A. tumefaciens used for infection.     

Effect of gall formation by a cynipid wasp, Andricus symbioticus, on the development of the leaves and shoots of Quercus dentata

The sexual generation of a cynipid wasp, Andricus symbioticus Kovalev, forms its leaf galls most frequently near and on the leaf petiole of Quercus trees. I examined the effect of gall formation by A. symbioticus on the leaf development of a host plant, Quercus dentata Thunberg, by comparing the size and shape of galled and ungalled leaves. I also examined the effect of gall formation on shoot development by comparing the length of shoots with and without galled leaves. Three of seven Q. dentata trees surveyed were heavily infested with A. symbioticus. Leaf size did not differ between galled and ungalled leaves. However, the ratio of leaf width to length was greater in galled leaves, which is regarded to be a result of gall formation by A. symbioticus inhibiting the growth in length of Q. dentata leaves. Shoot length did not differ significantly between shoots with and without galled leaves. These results suggest that galls of A. symbioticus act as a sink that competes with leaves for reserved photoassimilates.     

A synopsis of gall midges associated with conifers,with description of a new species of the genus <Emphasis Type="Italic">Kaltenbachiola</Emphasis> Hedicke (Diptera,Cecidomyiidae: Lasiopterinae) from Yakutia,damaging cones of the Siberian spruce (<Emphasis Type="Italic">Picea obovata</Emphasis>)

The world fauna comprises 134 species from 52 genera of gall midges associated with plants of the order Pinales (3 families, 16 genera and 74 species); 14 genera are specific to Pinales. The distribution of genera and species of gall midges over host plant taxa is described. The Holarctic genus Kaltenbachiola comprises four species all developing in the spruce (Picea spp.) cones. Earlier, K. strobi (Winnertz), widely distributed in Europe, was the only species known in the Palaearctic. A new species Kaltenbachiola anastasiae sp. n. is described, which damages cones of Picea obovata in Central Yakutia. The phylogenetic relationships of Kaltenbachiola with close genera specific to Pinales are characterized, and an updated diagnosis of the genus with additional morphometric parameters and keys to the pine-specific genera of the tribe Dasineurini and to species of the genus Kaltenbachiola are given. The host associations and specific traits of biology and distribution of Kaltenbachiola species are considered.