Variation in the degree of pectin methylesterification during the development of Baccharis dracunculifolia kidney-shaped gall.

Insect galls may be study models to test the distribution of pectins and arabinogalactan-proteins (AGPs) and their related functions during plant cell cycles. These molecules are herein histochemically and immunocitochemically investigated in the kidney-shaped gall induced by Baccharopelma dracunculifoliae (Psyllidae) on leaves of Baccharis dracunculifolia DC. (Asteraceae) on developmental basis. The homogalacturonans (HGAs) (labeled by JIM5) and the arabinans (labeled by LM6) were detected either in non-galled leaves or in young galls, and indicated stiffening of epidermal cell walls, which is an important step for cell redifferentiation. The labeling of HGAs by JIM7 changed from young to senescent stage, with an increase in the rigidity of cell walls, which is important for the acquaintance of the final gall shape and for the mechanical opening of the gall. The variation on the degree of HGAs during gall development indicated differential PMEs activity during gall development. The epitopes recognized by LM2 (AGP glycan) and LM5 (1-4-β-D-galactans) had poor alterations from non-galled leaves towards gall maturation and senescence. Moreover, the dynamics of pectin and AGPs on two comparable mature kidney-shaped galls on B. dracunculifolia and on B. reticularia revealed specific peculiarities. Our results indicate that similar gall morphotypes in cogeneric host species may present distinct cell responses in the subcelular level, and also corroborate the functions proposed in literature for HGAs

Transverse sections of non-galled leaves of <i>Baccharis dracunculifolia</i> and galls induced by <i>Baccharopelma dracunculifoliae</i> immunolabeled with the monoclonal antibodies LM2, LM5, and LM6.

<p>(a–d) LM2. (a) Non-galled leaf. Weak labeling in the cell walls of epidermis and vascular system, and moderate labeling in the cell walls of parenchyma. (b) Young galls. Weak labeling in the cell walls of the parenchyma, epidermis and vascular bundles. (c) Mature galls. Weak labeling in the cell walls of parenchyma and vascular bundles, and moderate labeling in the cells walls of the epidermis. (d) Senescent gall. Weak labeling in the cell walls of the vascular bundle. (e–h) LM5. (e) Non-galled leaf. Weak labeling in cell walls of epidermis, parenchyma, and vascular bundle. (f) Young and (g) mature gall. Weakly labeling in the cell walls of epidermis and parenchyma. (h) Senescent gall. Moderate labeling in the cell walls of epidermis and parenchyma. (i–l) LM6. (i) Non-galled leaf. Weak labeling in the cell walls of epidermis, and moderate labeling in the cell walls of the parenchyma. (j) Young, (k) mature, and senescent gall (l). Moderate labeling in the cell walls of epidermis and parenchyma. E = epidermis; LC = larval chamber; P = parenchyma; VB = vascular bundles.</p

Histochemistry of pectins on transverse sections of non-galled leaves of <i>Baccharis dracunculifolia</i> and on galls induced by <i>Baccharopelma dracunculifoliae</i>.

<p>(a–d) Coriphosphine. (e–h) Ruthenium red. (a) Non-galled leaf. Positive reaction for pectins in cell walls of epidermis, collenchyma, and phloem cells. (b) Young gall. Positive reaction for pectins in epidermis, parenchyma and phloem cells. (c) Mature gall. Intense reaction in the cells near the larval chamber and in phloem cells (arrows). (d) Weak staining at the epithelium (arrow) of a secretory cavity. (e) Non-galled leaf. Intense staining in all tissues. (f) Young gall. Moderate staining. (g) Mature gall. Weak staining. (h) Senescent gall. Moderate staining. E = epidermis; LC = larval chamber; P = parenchyma; SC = secretory cavities; VB = vascular bundles.</p

Recognition of the monoclonal antibodies to the different epitopes.

<p>Recognition of the monoclonal antibodies to the different epitopes.</p

Binding of the antibodies to the pectin epitopes in the non-galled leaves and galls (young, mature and senescent stages) of <i>Baccharopelma dracunculifoliae</i> on <i>Baccharis dracunculifolia</i>.

<p>The number of signals indicates the intensity of the reaction (+) weak, (++) moderate, and intense (+++).</p

Shoot of <i>Baccharis dracunculifolia</i> (Asteraceae) with non-galled leaves and galls of <i>Baccharopelma dracunculifoliae</i> (Psyllidae).

<p>Shoot of <i>Baccharis dracunculifolia</i> (Asteraceae) with non-galled leaves and galls of <i>Baccharopelma dracunculifoliae</i> (Psyllidae).</p

Transverse sections of non-galled leaves of <i>Baccharis dracunculifolia</i> and galls induced by <i>Baccharopelma dracunculifoliae</i> immunolabeled with the monoclonal antibodies JIM5 amd JIM7.

<p>(a–d) JIM5. (a) Non-galled leaf. Moderate labeling in cell walls of epidermis and vascular bundles, and intense labeling in cell walls of parenchyma. (b) Young galls. (b) Detail of the labeling in a vascular bundle. (c) Mature gall. Intense labeling in cell walls of epidermis and parenchyma. (d) Senescent gall. Weak labeling in the cell walls of epidermis and parenchyma. (e–h) JIM7. (e) Non-galled leaf. Moderate labeling in the cell walls of epidermis, parenchyma and vascular system. (f) Young gall and (g) Mature galls. Weak labeling in cell walls of epidermis and parenchyma. (h) Senescent gall. Intense labeling in cell walls of the epidermis and parenchyma. E = epidermis; LC = larval chamber; P = parenchyma; VB = vascular bundles.</p

Relações entre o teor de fenóis totais e o ciclo das galhas de Cecidomyiida e em Aspidosperm a spruceanum Müll. Arg. (Apocynaceae) Relationships between phenolic contents and a Cecidomyiidae gall cycle in Aspidosperma spruceanum Müll. Arg. (Apocynaceae)

Alterações morfológicas detectadas em diversas espécies vegetais em função da indução de galhas são comumente acompanhadas de mudanças químicas importantes para o estabelecimento e manutenção do sistema galhador-planta hospedeira. O estudo da variação do teor de fenóis totais e sua relação com o desenvolvimento das galhas no sistema Aspidosperma spruceanum-Cecidomyiidae foi realizado ao longo de um ano, no qual foram detectados pelo menos dois ciclos de vida dos insetos indutores. O nível de infestação foliar foi alto, atingindo 87%, e os Cecidomyiidae tiveram a região internervural como sítio preferencial de oviposição. A variação sazonal no conteúdo de fenóis totais nas amostras de folhas sadias e galhadas foi primariamente relacionada às condições abióticas e muito embora este teor tenha atingido o máximo de 10 mg EAT g-1, indicando um ambiente químico celular não favorável à indução e a sua sobrevivência, o indutor de A. spruceanum supera esta barreira química, podendo ainda ser favorecido pela proteção contra inimigos naturais propiciada pelos fenólicos.<br>Morphological alterations detected in several plant species due to gall induction are commonly followed by chemical changes fundamental to the establishment and maintenance of the host plant-gall maker system. The study of phenolic contents variation and its relation to gall development in Aspidosperma spruceanum-Cecidomyiidae system through a year-time detected two insect life cycles. The level of infestation was high, getting up to 87%, and the Cecidomyiidae preferentially oviposited in internervural region. Seasonal variation in phenolic contents in healthy and galled leaves detected in A. spruceanum was primarily related to abiotic conditions. Even though the levels of phenolic contents might get a maximum of 10 mg EAT g-1, which indicated a non stimulating cell chemical environment to gall induction and herbivore survivorship, A. spruceanum gall maker surpassed this chemical barrier, and might also be favored by the chemical protection against its natural enemies, that phenolic contents might confer