Plant Galls Research Articles

GallOnt: An ontology for plant gall phenotypes.

Galls are novel plant structures that develop in response to select biotic stressors. These structures, extended phenotypes of the inducer, usually serve to protect and feed the inducer or its progeny. This life history strategy has evolved dozens of times, and tens of thousands of species - including many bacteria, fungi, nematodes, mites and insects - are capable of manipulating plants in this way. The variation in gall phenotypes is extraordinary across species but usually predictable for each species of inducer. We introduce here a new ontology, GallOnt, that facilitates consistent descriptions and the semantic representation of and reasoning over plant gall phenotype data. GallOnt was largely developed from ontologies in the Open Biological and Biomedical Ontology (OBO) Foundry and stands to connect plant gall phenotypes to knowledge derived from model plant systems, including genotype-phenotype and agricultural research. We also introduce the idea of a new gall data standard - Minimum Information for the Description of Galls (MIDG version 0.1) - as a starting point for discussions regarding cecidology best practices.

What shapes galling insect–parasitoid interaction networks on closely related host plants?

Abstract Ecological networks describe community structure by focusing on how nodes are connected by links (interactions). Related species have higher probabilities of sharing links if interactions depending on phylogeny and/or species are functionally similar; however, if and how this modularity impacts higher trophic levels is still an open question. We aimed to evaluate the effect of different structuring factors on an observed bipartite network of galling insects and associated parasitoids on a system with two closely related and recently diverged plants, where host‐tracking could be underway. We hypothesized that gall structure, galler taxonomy and host plant identity could contribute, from a higher to a lower degree respectively, to network modularity by generating a selective pressure on parasitoids. Samples were collected between May 2015 and June 2017 in the forest areas of Porto Alegre, southern Brazil. Overall, we found 4629 galls of three monophagous and four oligophagous galling species; 664 parasitoid individuals were obtained and classified into 37 morphospecies. We constructed four networks with the collected data by organising nodes according to the tested factors, that is, gall structure, galler taxonomy, host plant identity and gall–plant interaction. All networks were significantly modular, and for three out of four analysed factors (gall structure, galler taxonomy and gall–plant interaction), modularity levels were at least intermediate (at about Q = 0.4). Barriers to or preferences for certain interactions appear to be responses to multiple concomitant factors. However, galler taxonomy and host plant identity are somehow stronger determinants for the parasitoids in terms of attacked hosts.

The Chalcidoidea bush of life: evolutionary history of a massive radiation of minute wasps.

Chalcidoidea are mostly parasitoid wasps that include as many as 500 000 estimated species. Capturing phylogenetic signal from such a massive radiation can be daunting. Chalcidoidea is an excellent example of a hyperdiverse group that has remained recalcitrant to phylogenetic resolution. We combined 1007 exons obtained with Anchored Hybrid Enrichment with 1048 ultra-conserved elements (UCEs) for 433 taxa including all extant families, >95% of all subfamilies, and 356 genera chosen to represent the vast diversity of the superfamily. Going back and forth between the molecular results and our collective knowledge of morphology and biology, we detected bias in the analyses that was driven by the saturation of nucleotide data. Our final results are based on a concatenated analysis of the least saturated exons and UCE datasets (2054 loci, 284 106 sites). Our analyses support an expected sister relationship with Mymarommatoidea. Seven previously recognized families were not monophyletic, so support for a new classification is discussed. Natural history in some cases would appear to be more informative than morphology, as illustrated by the elucidation of a clade of plant gall associates and a clade of taxa with planidial first-instar larvae. The phylogeny suggests a transition from smaller soft-bodied wasps to larger and more heavily sclerotized wasps, with egg parasitism as potentially ancestral for the entire superfamily. Deep divergences in Chalcidoidea coincide with an increase in insect families in the fossil record, and an early shift to phytophagy corresponds with the beginning of the "Angiosperm Terrestrial Revolution". Our dating analyses suggest a middle Jurassic origin of 174 Ma (167.3-180.5 Ma) and a crown age of 162.2 Ma (153.9-169.8 Ma) for Chalcidoidea. During the Cretaceous, Chalcidoidea may have undergone a rapid radiation in southern Gondwana with subsequent dispersals to the Northern Hemisphere. This scenario is discussed with regard to knowledge about the host taxa of chalcid wasps, their fossil record and Earth's palaeogeographic history.

Antioxidant Effects of Methanolic Extract of Quercus infectoria as a Supplement against Oxidative Stress Induced by Sub-acute Exposure to Arsenic; An in vivo Study

Background: Exposure to arsenic through drinking water is a global health problem that causes multisystem toxicity, mainly by inducing oxidative stress and impairing cellular energy. Objective: We aimed to evaluate the effect of Quercus infectoria gall extract (Qi) against oxidative stress induced by sub acute exposure to arsenic. Methods: The plant galls were extracted with methanol and were used for the determination of total phenolic content using Folin-Cio calteu reagent. Male Wistar rats were randomly divided into 8 groups of 6 animals and treated for 30 days. Negative and positive control groups received, respectively, normal saline and sodium arsenite (5.5 mg/kg) by gavage. Treatment groups received three doses of Qi (200, 400, and 600 mg/kg/day) by intraperitoneal injection 2 h. after oral administration of normal saline or sodium arsenite (5.5 mg/kg) (As-Qi). After 30 days, all animals were anesthetized with ketamine/xylasine and 2 mL of blood was taken for measurement of total antioxidant capacity (TAC) using ferric reducing antioxidant power (FRAP), lipid peroxidation (measurement of malondialdehyde (MDA)) and protein carbonylation of plasma. Results: Total phenolic content of the plant was determined to be 5.78 ± 0.23 mg gallic acid equivalent/g dried extract. The results of pharmacological studies indicated that in arsenic treated animals, a significant decrease in TAC, increase in lipid peroxidation and protein carbonylation happens compared to control group. Co-administration of Qi (600 mg/kg) with arsenic significantly increased TAC compared with arsenic group (0.245 ± 0.007 versus 0.183 ± 0.027 for arsenic) (p < 0.05), while the serum MDA level (1.880 ± 0.499 versus 2.795 ± 0.112 for arsenic) and protein carbonylation were decreased in this group compared with arsenic treated animals (0.128 ± 0.007 versus 0.159 ± 0.009 for arsenic) (p <0.01). In non-treated arsenic animals (NTAS), all three doses of Qi improved oxidative stress markers. Conclusion: Arsenic disrupt cellular antioxidant defense through overproduction of reactive oxygen species (ROS) and the Qi galls are able to revert some of these oxidant activities of arsenic. Previous studies have reported antioxidants in the plant and the present work can conclude that antioxidant effect of Qi is useful against happened oxidative stress in arsenic treated animals.

Effect of Biosynthesized Nanoselenium on Controlling Tomato Root-Knot Nematode Meloidogyne incognita

Tomato is a globally important fruit crop, which is easily susceptible to infection by plant-parasitic nematodes during growth. In this study, selenium nanoparticles were biosynthesized through the selenite reduction pathway in a wild-type Pseudomonas stutzeri BB19 and were characterized by uniform nanostructured needle-like forms with an average size of 95.2 nm. The nematicidal effect of biosynthesized selenium nanoparticles (BioSeNPs) at different concentrations (2, 6, and 10 ppm) during the pre- or post-infection of tomato root-knot nematode (RKN), Meloidogyne incognita, was assessed under greenhouse conditions. The BioSeNPs were applied as a foliar spray or a soil drench, compared to ethoprophos nematicide (100 mL/pot). The results showed that the ethoprophos nematicide significantly reduced the number of galls, egg mass, and eggs/egg mass of M. incognita by 94.2, 92.8, and 49.8%, respectively. BioSeNPs, as foliar sprays, significantly reduced the number of galls in post-treated infected tomato plants at 10 ppm and in pre-treated infected tomato plants at 2 ppm by 91.9 and 91.4%, respectively. Concerning the egg mass, BioSeNPs significantly reduced it in pre-treated infected tomato plants at 2 ppm as a foliar spray by 90.9%. Moreover, BioSeNPs significantly reduced the eggs/egg mass in pre-treated infected tomato plants at 2 ppm as a soil drench by 43.3%. On the other hand, the BioSeNPs considerably improved tomato growth, chlorophyll a and b, carotenoid content, and enzymes (i.e., catalase and peroxidase) activity compared to untreated infected tomato plants (negative control). Hence, the BioSeNPs show a significant application potential as a cost-effective and environmentally friendly biocontrol agent for RKN management in tomato plants.

Plant Gall Diversity in Burned Semi-natural Grasslands in Japan

We surveyed woody plants, including oaks and chestnuts (Quercus L. and Castanea Mill.), and recorded the inhabiting galls induced by oak gall wasps (Hymenoptera: Cynipidae: Cynipini) at seven Japanese semi-natural grassland sites maintained by traditional regular burning with two of the seven abandoned grassland areas. Woody plants were established in all burned and abandoned grasslands. Oak species were found at four of the seven sites. In total, 15 types of cynipid galls were recorded at all four sites where oak species were found. However, the occurrence of species was site-specific for host trees and cynipid galls. Although a few ecological studies of oak gall wasps inhabiting grassland environments, which have rapidly decreased in recent decades, have been conducted, this study suggests that semi-natural grasslands may be potential habitats for oak gall wasps and their host trees, and we provide a checklist of oak gall wasps with host oak records in semi-natural grasslands throughout Japan.

Ecology and Diversity of Aphids: A Review

Plant lices are tiny, soft-bodied arthropod insects which feed on sap of plants. Aphids are another name for these insects. They are members of the Aphidinae subfamily. Aphids fall into 60 genera and have roughly 400 species globally. In India, there are 25 genera with 125 species of aphids, while Uttarakhand (plains to very high altitudes) has 4 genera with 125 species of aphids. There are 65 different types of aphids, with the genus Aphidius having the most species overall. Aphids are greatly harming horticulture fruits and vegetables as well as agricultural crops. Temperature, humidity, and other environmental conditions affect its outbreak. Aphids are tiny, soft-bodied, viviparous, parasitic insects that lack wings and have wax secreting tubes on their abdomens. They can stunt plant growth, create plant galls, spread viral diseases to plants, and deform leaves, buds, and flowers. They have an impact on both plants, such as roses, lilies, and marigolds, as well as fruits and vegetables including mustard, cabbage, peas, potatoes, and beans. The mountainous area lacks data on the variety, ecology, and inventory of aphids. So an effort has been made to review the aphids diversity in India.

Decolourization of Methylene Blue in Aqueous Solution by Photocatalytic Oxidation, Fenton Oxidation and Biosorption

The aim of the study was to investigate decolourization of Methylene Blue (MB) in aqueous solution using advanced oxidation processes (AOPs) and biosorption comparatively. Photocatalytic decolourization of MB was studied using TiO2 as catalyst. The photocatalytic decolourization of MB by direct UV irradiation alone, only TiO2 and TiO2/UV processes was investigated. It was found that decolourization by photocatalytic process of MB increased with decreasing pH, and decolourization rate also increased in the presence of TiO2/UV when compared to UV irradiation alone. Decolourization of MB was also studied with using the Fenton process (Fe(II)/H2O2). Concentrations of Fe(II) and H2O2 on decolourization ratio were investigated. The optimum catalyst to H2O2 ratio was found 1:3 at pH 4.0. In the second part of the study, the biosorption process was conducted with using plant gall immobilised alumina. The removal percentages were calculated with both plant gall immobilised alumina and alumina alone. The immobilisation of plant gall increased the removal percentages from 60-70% to 90-95%. The proposed methods (AOPs and biosorption) have both advantages and disadvantages compared to each other.

Can Molecularly Engineered Plant Galls Help to Ease the Problem of World Food Shortage (and Our Dependence on Pollinating Insects)?

The world faces numerous problems and two of them are global food shortages and the dwindling number of pollinating insects. Plant products that do not arise from pollination are plant galls, which as in the case of oak apples, can resemble fruits and be the size of a cherry. It is suggested that once research has understood how chemical signals from gall-inducing insects program a plant to produce a gall, it should be possible to mimic and to improve nature and "bioengineer" designer galls of different sizes, colorations and specific contents to serve as food or a source of medicinally useful compounds. To achieve this objective, the genes involved in the formation of the galls need to be identified by RNA-sequencing and confirmed by gene expression analyses and gene slicing. Ultimately the relevant genes need to be transferred to naïve plants, possibly with the aid of plasmids or viruses as practiced in crop productivity increases. There is then even the prospect of engineered plant galls to be produced by plant tissue culture via genetic manipulation without the involvement of insects altogether.

A New Stomatosema from the Australian Tropics - The First Species of Stomatosematidi (Diptera: Cecidomyiidae) Known to Cause a Plant Gall

Stomatosematidi are by far the smallest of the four supertribes of Cecidomyiinae (Diptera: Cecidomyiidae) containing 56 species. The life history of only one species has been known previously: adults of Stomatosema nemorum Kieffer were reared from larvae feeding on a mushroom, Lactarius sp. (Fungi: Russulaceae). Here we describe the larva and adults of a new species, Stomatosema gagnei Kolesik, that was found inducing pustulate leaf galls on Causonis trifolia (Vitaceae) plants in Cape York Peninsula, Australia. Stomatosema gagnei is the first Stomatosematidi with a described larva and the first known to cause a gall. The fact that a species of Stomatosematidi, a supertribe hypothesized to be the sister group to all remaining Cecidomyiinae, was found inducing a plant gall suggests that the first of the transitions from the ancestral fungus-feeding habit to plant-feeding occurred in Cecidomyiidae at the base of the Cecidomyiinae clade more than 100–110 million years ago, during the lower Cretaceous.

Enigma moth parasitoid: a new Australian cyclostome genus and species, Ovaustra aurantia Tetley, Glatz & Fagan Jeffries, gen. et sp. nov. (Hymenoptera: Braconidae) from Kangaroo Island

AbstractOvaustra aurantia Tetley, Glatz & Fagan‐Jeffries, gen. et sp. nov. (Mesostoinae) is described from Kangaroo Island. South Australia, Australia, and is a solitary, koinobiont, egg‐larval parasitoid of the enigma moth, Aenigmatinea glatzella Kristensen & Edwards, 2015, in the monotypic family Aenigmatineidae Kristensen & Edwards, 2015 (Lepidoptera). Female parasitoids oviposit into the eggs of A. glatzella soon after female moths place them beneath minute adpressed leaves at the growing foliar tips of the larval host plant Callitris gracilis R.T. Baker (Cupressaceae). Adult parasitoids emerge from A. glatzella larval chambers located directly beneath the bark of small branches, some way from the growing tip. Adults can be seen on or near foliage of C. gracillis primarily during October and coinciding with the presence of adult host moths. Morphological and preliminary molecular evidence place Ovaustra Glatz, Fagan‐Jeffries & Tetley, gen. nov. within Mesostoinae s.l. and indicate that its closest relatives are likely to reside within a group of genera from Australia and New Zealand whose hosts and biology are not well defined but are apparently quite broad, including lepidopteran, coleopteran and dipteran larvae, as well as primary plant gall induction.

Molecular Phylogenetic Characterization of Anguina Tritici (Steinbuch, 1799) Filipjev, 1936 (Rhabditida: Anguinidae) on Barley from Iraq.

During a nematological survey in Iraq, in the Bashika area, Ninevah province, an anguinid nematode population was isolated from galls of infected barley plants. The morphological characteristics indicated that the recovered species is identical to Anguina tritici. The barley population of A. tritici was molecularly characterized by sequencing two ribosomal regions (ITS and 18S rRNA genes), and their phylogenetic analyses revealed the newly generated sequences are in sister relation to corresponding sequences of A. tritici from wheat in the Bayesian tree, providing further evidence that the host plant can contribute to the separation of new isolates of plant parasitic nematodes.

Anatomical profiles validate gall morphospecies under similar morphotypes.

Plant galls are generated by the stimuli of gall-inducing organisms on their hosts, creating gall morphotypes that vary in color, shape, size, and tissue organization. Herein, we propose to compare the structural features of gall morphotypes on the superhost Croton floribundus (Euphorbiaceae) in order to recognize gall morphospecies, i.e., galls with similar shapes but different internal structures. Non-galled leaves and galls were analyzed macroscopically, histologically, and histochemically for the detection of primary metabolites, and the results obtained were used for statistical analyses of similarity. Among the eight gall morphospecies, four are globoid, two are lenticular, one is fusiform and one is marginal leaf rolling. Stomatal differentiation and the occurrence of different types of trichomes were impaired in some gall morphospecies. Three patterns of organization of the ground system are recognized, ranging from the maintenance of mesophyll cells that differentiate into palisade and spongy cells dorsiventrally to the formation of a complex cortex with three morphofunctional layers. The marginal leaf rolling galls have the simplest anatomical structures, quite similar to those of the non-galled host leaf, while lenticular, globoid (types I to IV), and fusiform galls are anatomically more complex. Herein, we report on eight gall morphospecies occurring on C. floribundus, which are distinguished by morpho-anatomical attributes and show the disruption of the morphogenetic patterns of the host leaf toward the morphogenesis of unique gall features.

Gene Structure-Based Homology Search Identifies Highly Divergent Putative Effector Gene Family.

Homology of highly divergent genes often cannot be determined from sequence similarity alone. For example, we recently identified in the aphid Hormaphis cornu a family of rapidly evolving bicycle genes, which encode novel proteins implicated as plant gall effectors, and sequence similarity search methods yielded few putative bicycle homologs in other species. Coding sequence-independent features of genes, such as intron-exon boundaries, often evolve more slowly than coding sequences, however, and can provide complementary evidence for homology. We found that a linear logistic regression classifier using only structural features of bicycle genes identified many putative bicycle homologs in other species. Independent evidence from sequence features and intron locations supported homology assignments. To test the potential roles of bicycle genes in other aphids, we sequenced the genome of a second gall-forming aphid, Tetraneura nigriabdominalis and found that many bicycle genes are strongly expressed in the salivary glands of the gall forming foundress. In addition, bicycle genes are strongly overexpressed in the salivary glands of a non-gall forming aphid, Acyrthosiphon pisum, and in the non-gall forming generations of H. cornu. These observations suggest that Bicycle proteins may be used by multiple aphid species to manipulate plants in diverse ways. Incorporation of gene structural features into sequence search algorithms may aid identification of deeply divergent homologs, especially of rapidly evolving genes involved in host-parasite interactions.

Observations on the Population Genetic Structure of the Leaf Galling Nematode, Ditylenchus gallaeformans.

Ditylenchus gallaeformans is a plant parasitic nematode that induces galls on aboveground parts of Melastomataceae plants. It differs from most gall-inducing nematodes in that it is not an endoparasite and has been considered as a possible biological control agent against invasive species of Miconia. Little is known about D. gallaeformans biology, genetic differences among populations, and host preferences. This study examined the genetic differences among D. gallaeformans populations from different locations and host species and the phylogenetic relationships among them. Nematodes were collected from galls in plants from Costa Rica, Dominica, and Trinidad. The Cytochrome c oxidase 1 (cox1) region was sequenced from a total of 33 individual nematodes isolated from 33 different plant individuals, representing 21 species of Melastomataceae. Phylogenetic reconstructions, haplotype networks, and analysis of molecular variance showed that the species is monophyletic and has three major clades, which were mostly consistent with geographic location but not with host species. The first clade was composed by two subclades, one with individuals from Costa Rica and one with individuals from Dominica. The second and third clades comprised nematodes only from Trinidad. Overall, there is no evidence of host-species specialization in D. gallaeformans. Biocontrol efforts using the nematode against invasive Miconia could focus on geographical location matching but likely will not need to match host species.

Symbiotic bacteria of the gall-inducing mite Fragariocoptes setiger (Eriophyoidea) and phylogenomic resolution of the eriophyoid position among Acari

Eriophyoid mites represent a hyperdiverse, phytophagous lineage with an unclear phylogenetic position. These mites have succeeded in colonizing nearly every seed plant species, and this evolutionary success was in part due to the mites' ability to induce galls in plants. A gall is a unique niche that provides the inducer of this modification with vital resources. The exact mechanism of gall formation is still not understood, even as to whether it is endogenic (mites directly cause galls) or exogenic (symbiotic microorganisms are involved). Here we (i) investigate the phylogenetic affinities of eriophyoids and (ii) use comparative metagenomics to test the hypothesis that the endosymbionts of eriophyoid mites are involved in gall formation. Our phylogenomic analysis robustly inferred eriophyoids as closely related to Nematalycidae, a group of deep-soil mites belonging to Endeostigmata. Our comparative metagenomics, fluorescence in situ hybridization, and electron microscopy experiments identified two candidate endosymbiotic bacteria shared across samples, however, it is unlikely that they are gall inducers (morphotype1: novel Wolbachia, morphotype2: possibly Agrobacterium tumefaciens). We also detected an array of plant pathogens associated with galls that may be vectored by the mites, and we determined a mite pathogenic virus (Betabaculovirus) that could be tested for using in biocontrol of agricultural pest mites.

A geographic mosaic of coevolution between Eurosta solidaginis (Fitch) and its host plant tall goldenrod Solidago altissima (L.).

A geographic mosaic of coevolution has produced local reciprocal adaptation in tall goldenrod, Solidago altissima (L.), and the goldenrod ball-gall fly, Eurosta solidaginis (Fitch 1855). The fly is selected to induce gall diameters that minimize mortality from natural enemies, and the plant is selected to limit gall growth that reduces plant fitness. We conducted a double reciprocal transplant experiment where S. altissima and E. solidaginis from three sites were grown in gardens at each site to partition the gall morphology variation into fly genotype, plant genotype, and the environment components. The host plant gall diameter induced by each E. solidaginis population was adapted to inhibit local natural enemies from ovipositing on or consuming enclosed larvae. Reciprocally, increasing the gall size induced by the local fly population increased the resistance of the local plant host population to gall growth. Differences among sites in natural enemies produced a mosaic of hotspots of coevolutionary arms races between flies selecting for greater gall diameter and plants for smaller diameters, and coldspots where there is no selection on plant or fly for a change in gall diameter. In contrast, the geographic variations of gall length and gall shape were not due to coevolutionary interactions.

Tissue-specific gene expression shows a cynipid wasp repurposes oak host gene networks to create a complex and novel parasite-specific organ.

Every organism on Earth depends on interactions with other organisms to survive. In each of these interactions, an organism must utilize the limited toolbox of genes and proteins it possesses to successfully manipulate or cooperate with another species, but it can also co-opt the genome machinery of its partner to expand its available tools. Insect-induced plant galls are an extreme example of this, wherein an insect hijacks the plant's genome to direct the initiation and development of galls consisting of plant tissue. However, previous transcriptomic studies have not evaluated individual tissues within a gall to determine the full extent to which a galling insect manipulates its host plant. Here we demonstrate that the cynipid wasp Dryocosmus quercuspalustris creates a complex parasite-specific organ from red oak tissue via massive changes in host gene expression. Our results show that the gall wasp is not merely modifying oak leaf tissue but creating extensive changes in gene expression between galled and ungalled tissue (differential expression in 28% of genes) and distinct gall tissue types (20% of genes). The outer gall tissue shows increases in various plant defence systems, which is consistent with its predicted functional role of protecting the wasp larva. The inner larval capsule shows suppression of large parts of the plant innate immune system and evidence for the wasp utilizing the plant's RNA interference mechanisms, which may be a potential mechanism for the wasp's control on gall growth.

First record of Aceria granati (Canestrini et Massalongo, 1894) in Slovakia

Plant galls of Aceria granati (Canestrini et Massalongo 1894) were observed on the leaves of Punica granatum (Lythraceae) in a private garden in Nitra in July, 2017. Aceria granati is a monophagous gall mite damaging the leaves of Punica granatum. This gall mite was present in one locality in Nitra only and was probably imported from Hungary via the plant trade. This is the first observation of an Aceria granati occurrence in Slovakia.

On the phytoscreening potential of insect-induced plant galls

On the phytoscreening potential of insect-induced plant galls