The role of pectic composition of cell walls in the determination of the new shape-functional design in galls of Baccharis reticularia (Asteraceae)

Abstract

The pectic composition of cell wall is altered during the processes of cell differentiation, plant growth, and development. These alterations may be time-dependent, and fluctuate in distinct regions of the same cell or tissue layer, due to the biotic stress caused by the activity of the gall inducer. Among the roles of the pectins in cell wall, elasticity, rigidity, porosity, and control of cell death may be crucial during gall development. Galls on Baccharis reticularia present species-specific patterns of development leading to related morphotypes where pectins were widely detected by Ruthenium red, and the pectic epitopes were labeled with specific monoclonal antibodies (LM1, LM2, LM5, LM6, JIM5, and JIM7) in distinct sites of the non-galled and the galled tissues. In the studied system B. reticularia, the epitopes for extensins were not labeled in the non-galled tissues, as well as in those of the rolling and kidney-shaped galls. The high methyl-esterified homogalacturonans (HGA) were labeled all over the tissues either of non-galled leaves or of the three gall morphotypes, while the intense labeling for arabinogalactans was obtained just in the rolling galls. The pectic composition of non-galled leaves denotes their maturity. The kidney-shaped gall was the most similar to the non-galled leaves. The pectic dynamics in the gall tissues was particularly altered in relation to low methyl-esterified HGA, which confers elasticity and expansion, as well as porosity and adhesion to cell walls, and are related to the homogenization and hypertrophy of gall cortex, and to translocation of solutes to the larval chamber. Herein, the importance of the pectic dynamics of cell walls to the new functional design established during gall development is discussed for the first time. The repetitive developmental patterns in galls are elegant models for studies on cell differentiation.

Immunocytochemical demonstration of cell wall components related to tissue compartments in the globoid galls induced by Clinodiplosis sp. (Cecidomyiidae) on Croton floribundus Spreng. (Euphorbiaceae)

“…During gall development, de-methylesterification of the HGAs may occur, as reported for mature to senescent phases in galls on P. cattleianum (Carneiro et al 2015). However, in three gall morphotypes induced on B. reticularia (Formiga et al 2013), the kidney-shaped gall induced on B. dracunculifolia , and dracunculifolia . Maintenance of the methylesterified status has been associated with the conservation of juvenile features in some tissue compartments of Clinodiplosis galls.…”

“…AGPs have been commonly related to the growth and differentiation of Arabidopsis roots (Ding and Zhu 1997). For some Neotropical galls, AGPs have been labeled by LM2 in either young or senescent galls (Formiga et al 2013. Therefore, for…”

“…Formiga et al (2013) related the extensins to the reinforcement of cell walls of mature pocket galls in B. reticularia, due to their large size and orientation of axis growth. Therefore, labeling of extensins with LM1 is D r a f t 13 expected in mature galls after cessation of growth, as proposed by Cassab (1998) for other plant organs, and is true for Clinodiplosis galls in the senescent phase.…”

“…Studies on cell wall composition during the development of plant galls revealed a reorganization of cellulose microfibrils (Magalhães et al 2014;Suzuki et al 2015), protein, and pectin components (Formiga et al 2013;Carneiro et al 2015). Changes in the pectin composition of cell walls, especially in the degree of methyl esterification, may be related to the age of plant organs or to the functional profiles of cells and tissues (Dolan et al 1997).…”

Compartmentalization of Metabolites and Enzymatic Mediation in Nutritive Cells of Cecidomyiidae Galls on Piper Arboreum Aubl. (Piperaceae)

“…Furthermore, this enzyme provides substrate (UDP-glucose) for the formation of cell wall polysaccharides (Nolte & Koch, 1993;Salnikov, Grimson, Seagull, & Haigler, 2003), whose dynamics, together with the carbohydrates metabolism, have crucial roles in the development of the gall structure (Formiga et al, 2013, and consequently in the survival of the galling herbivore.…”