RESUMO
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.
Assuntos
Fabaceae , Tumores de Planta , Folhas de PlantaRESUMO
The development of plant organs depends on cell division, elongation, structural and chemical changes, and reorganization of cell wall components. As phenotype manipulators, galling insects can manipulate the structure and metabolism of host tissues to build the gall. The gall formation depends on the rearrangement of cell wall components to allow cell growth and elongation, key step for the knowledge regarding gall development, and shape acquisition. Herein, we used an immunocytochemical approach to investigate the chemical composition of the cell wall during the development of galls induced by Bystracoccus mataybae (Eriococcidae) on leaflets of Matayba guianensis (Sapindaceae). Different developmental stages of non-galled leaflets (n = 10) and of leaflet galls (n = 10) were collected from the Cerrado (Brazilian savanna) for anatomical and immunocytochemical analysis. We found that the epitopes of (1 â 4) ß-D-galactans and (1 â 5) α-L-arabinans were evident in the tissues of the young and senescent galls. These epitopes seem to be associated with the mechanical stability maintenance and increased gall porosity. As well, the degree of methyl-esterification of pectins changed from the young to the senescent galls and revealed the conservation of juvenile cell and tissue features even in the senescent galls. The extensins detected in senescent galls seem to support their rigidity and structural reinforcement of these bodies. Our results showed a disruption in the pattern of deposition of leaflet cell wall for the construction of M. guianensis galls, with pectin and protein modulation associated with the change of the developmental gall stages.
Assuntos
Parede Celular/química , Imuno-Histoquímica , Tumores de Planta , Sapindaceae/citologiaRESUMO
The galls can offer shelter, protection, and an adequate diet for the gall-inducing organisms. Herein, we evaluated the structure of Manihot esculenta leaves and galls induced by Iatrophobia brasiliensis in order to identify metabolic and cell wall composition changes. We expected to find a complex gall with high primary metabolism in a typical nutritive tissue. Non-galled leaves and galls were subjected to anatomical, histochemical, and immunocytochemical analyses to evaluate the structural features, primary and secondary metabolites, and glycoproteins, pectins, and hemicelluloses in the cell wall. The gall is cylindric, with a uniseriate epidermis, a larval chamber, and a parenchymatic cortex divided into outer and inner compartments. The outer compartment has large cells with intercellular spaces and stocks starch and is designated as storage tissue. Reducing sugars, proteins, phenolic compounds, and alkaloids were detected in the protoplast of inner tissue cells of galls, named nutritive tissue, which presents five layers of compact small cells. Cell walls with esterified homogalacturonans (HGs) occurred in some cells of the galls indicating the continuous biosynthesis of HGs. For both non-galled leaves and galls, galactans and xyloglucans were broadly labeled on the cell walls, indicating a cell growth capacity and cell wall stiffness, respectively. The cell wall of the nutritive tissue had wide labeling for glycoproteins, HGs, heteroxylans, and xyloglucans, which can be used as source for the diet of the galling insect. Manihot esculenta galls have compartments specialized in the protection and feeding of the galling insect, structured by nutritive tissue rich in resource compounds, in the cell walls and protoplast.
Assuntos
Dípteros , Euphorbiaceae , Manihot , Transtornos Fóbicos , Animais , Protoplastos , Glicoproteínas/metabolismo , Parede Celular , Tumores de Planta , Folhas de Planta/metabolismoRESUMO
Gall formation impacts the development of plant species by altering the structure and mobilization of reserves, and the functional and physiological patterns of the host organ. The current study aimed to evaluate the impact generated by the Neolithus fasciatus galling insect (Hemiptera: Triozidae) in Sapium glandulosum leaves (Euphorbiaceae) at the cytological, histological, histochemical, and biochemical levels. Non-galled leaves and galls in the young, mature, and senescent stages were evaluated. The non-galled leaf has a uniseriate epidermis, stomata only on the abaxial side, a dorsiventral mesophyll, and parenchyma cells with thin primary walls containing chloroplasts with plastoglobules. The gall has a parenchymatous compartmentalized cortex. The young and mature galls already have a dense cytoplasm, especially in the inner cells of the cortex, with chloroplasts, mitochondria, Golgi complex, and large and evident nuclei. In senescent galls, there are signs of organelle degradation and cell digestion. Carbohydrates occur in greater amounts in the mature gall, mainly in the starch grain form, while proteins and lipids predominate in non-galled leaves. Secondary metabolites occur mainly in the young gall and may be related to its protection and to the signaling of its development. Sapium glandulosum galls have histological and cytological compartmentalization of the cortex with a large amount of carbohydrates, which supply energy to maintain the development of the structure.
Assuntos
Hemípteros , Sapium , Animais , Cloroplastos , Carboidratos , Tumores de Planta , Folhas de Planta/metabolismoRESUMO
Infection by the root-knot nematode (RKN), Meloidogyne incognita, impacts crop productivity worldwide, including parsley cultures (Petroselinum crispum). Meloidogyne infection involves a complex relationship between the pathogen and the host plant tissues, leading to the formation of galls and feeding sites that disorganize the vascular system, affecting the development of cultures. Herein, we sought to evaluate the impact of RKN on the agronomic traits, histology, and cell wall components of parsley, with emphasis on giant cell formation. The study consisted of two treatments: (i) control, where 50 individuals of parsley grew without M. incognita inoculation; and (ii) inoculated plants, where 50 individuals were exposed to juveniles (J2) of M. incognita. Meloidogyne incognita infection affected the development of parsley, reducing the growth of some agronomical characteristics such as root weight and shoot weight and height. Giant cell formation was noticed at 18 days after inoculation, promoting disorganization of the vascular system. Epitopes of HGs detected in giant cells reveal the continuous capacity of giant cells to elongate under the stimulus of RKN, essential processes for feeding site establishment. In addition, the detection of epitopes of HGs with low and high methyl-esterified groups indicates the PMEs activity despite biotic stress.
Assuntos
Petroselinum , Tylenchoidea , Humanos , Animais , Parede CelularRESUMO
Root-knot nematodes are endoparasites whose mature females lodge and grow inside the root of some cultivated plants, leading to losses in productivity. Herein, we investigated if the infection of okra, Abelmoschus esculentus (Malvaceae), promoted by the root-knot nematode Meloidogyne incognita (Meloidogynidae) changes some agronomic traits of the host plant, as well as the cell wall composition of the root tissues. The okra Santa Cruz 47® cultivar was infected with a suspension of 5000 M. incognita juveniles. The inoculated and non-inoculated okra plants were then submitted to morphological analysis at the end of experiment, as well as histological (at 4, 11, 18, 39, ad 66 days after inoculation) and immunocytochemical analysis (control and 66 days after inoculation). Root-knot nematode infection reduced the dry weight of the stem system but, unexpectedly, the number and weight of fruits increased. At 11 days after inoculation, we detected the presence of giant cells that increased in number and size until the end of the experiment, at 66 days after inoculation. These cells came from the xylem parenchyma and showed intense and moderate labeling for epitopes recognized by JIM5 and JIM7. The presence of homogalacturonans (HGs) with different degrees of methyl esterification seems to be related to the injuries caused by the nematode feeding activity and to the processes of giant cell hypertrophy. In addition, the presence of HGs with high methyl-esterified groups can increase the cell wall porosity and facilitate the flux of nutrients for the root-knot nematode.
Assuntos
Abelmoschus , Malvaceae , Tylenchoidea , Animais , Parede Celular , Doenças das Plantas , Raízes de PlantasRESUMO
Abstract Gall-inducing insects manipulate the structural, histochemical and physiological profiles of host-plant tissues to develop galls. We evaluated galls induced by Eugeniamyia dispar on the leaves of Eugenia uniflora in an attempt to answer the following questions: (i) How does this gall-inducing insect change the structural and histochemical profiles of the host-plant organ? (ii) Despite structural changes, can gall tissues maintain photosynthetic activity? Starch, proteins, reducing sugars and reactive oxygen species were detected mainly in the nutritive tissue surrounding the larval chamber. Despite structural changes, the galls induced by E. dispar on E. uniflora retain chlorophyllous tissue, although its amount and photosynthetic activity are less than that of non-galled leaves. This reduced photosynthetic activity, in association with the presence of large intercellular spaces, could improve gas diffusion and, consequently, avoid hypoxia and hypercarbia in gall tissue.(AU)
Resumen Los insectos que inducen las agallas manipulan los perfiles estructurales, histoquímicos y fisiológicos de los tejidos de la planta hospedera para su desarrollo. Nosotros evaluamos las agallas inducidas por Eugeniamyia dispar en las hojas de Eugenia uniflora en un intento de responder las siguientes preguntas: (i) ¿Cómo este insecto inductor de agallas cambia los perfiles estructurales e histoquímicos en el órgano de la planta hospedera? (ii) A pesar de las modificaciones estructurales, ¿pueden los tejidos de la agalla mantener la actividad fotosintética? El almidón, las proteínas, los azúcares reductores y las especies reactivas de oxígeno se detectaron principalmente en la capa de tejido nutritivo que rodea a la cavidad larval. A pesar de las modificaciones estructurales, las agallas inducidas por E. dispar en E. uniflora retienen su tejido clorofílico, aunque su cantidad y actividad fotosintética son menores que en las hojas no agalladas. Esta actividad fotosintética reducida, asociado a la presencia de grandes espacios intercelulares, pueden mejorar la difusión de gases y, en consecuencia, evitar la hipoxia y la hipercapnia en los tejidos de las agallas.(AU)