Abstract The structural complexity of galls depends on species-specific interaction driven by the galling taxa. However, the host plant and environment stressors can impose limits on gall developmental patterns and impact the establishment of gall morphology. Herein, we employed qualitative and quantitative approaches in order to elucidate how cell divisions, elongation patterns, and tissue organization are determinant for the development of intralaminar gall morphology induced by Pseudophacopteron longicaudatum Malenovský, Burckhardt, Queiroz, Isaias & Oliveira (Hemiptera: Psylloidea: Phacopteronidae) on leaves of Aspidosperma tomentosum Mart. (Apocynaceae). In addition, we aimed to determine which anatomical process can discriminate the stages of gall development, plus, examine the histochemical and cytological profiles of the galls. The differentiated structures, mainly abaxial epidermis and spongy parenchyma, are associated with gall closure, with hyperplastic events concentrated in the young phase of the galls. Thus, epidermis and spongy parenchyma hypertrophy and are responsible for the determination of the nymphal chamber formation and gall shape. The mature galls do not differentiate into a typical nutritive cells and do not develop a histochemical gradient in their tissues. The cytological features of galls such as plastoglobules and multivesicular bodies are related to ROS scavenging mechanisms due the high oxidative stress.

Trichogonia cinerea é endêmica no Brasil e ocorre em áreas de Cerrado e campo rupestre. Neste estudo, foram caracterizados os tricomas glandulares e não glandulares das partes aéreas dessa espécie, determinados os principais eventos no desenvolvimento dos primeiros e identificados os principais constituintes do óleo volátil produzido em seus órgãos aéreos. Folhas completamente expandidas, entrenós, flores, brácteas involucrais e ápices caulinares foram utilizados para a caracterização dos tricomas. Folhas, entrenós, flores e brácteas involucrais foram examinados em microscópio de luz e microscópio eletrônico de varredura, enquanto ápices caulinares foram examinados somente em microscópio de luz. Ramos, em fase reprodutiva, foram usados para a extração e a determinação da composição do óleo volátil. A espécie tem três tipos de tricomas glandulares, bisseriados vesiculosos, bisseriados pedunculados e unisseriados pluricelulares, que secretam óleos voláteis e compostos fenólicos. Os principais componentes identificados no óleo volátil foram 3,5-muuroladieno (39,56%) e hidroxitolueno butilado (13,07%).

Trichogonia cinerea is endemic to Brazil and occurs in areas of cerrado and campo rupestre. In this study, we characterized the glandular and non-glandular trichomes on the aerial parts of this species, determined the principal events in the development of the former, and identified the main constituents of the volatile oil produced in its aerial organs. Fully expanded leaves, internodes, florets, involucral bracts, and stem apices were used for the characterization of trichomes. Leaves, internodes, florets, and involucral bracts were examined by light microscopy and scanning electron microscopy, whereas stem apices were examined only by light microscopy. Branches in the reproductive phase were used for the extraction and determination of the composition of the volatile oil. The species has three types of glandular trichomes, biseriate vesicular, biseriate pedunculate, and multicellular uniseriate, which secrete volatile oils and phenolic compounds. The major components identified in the volatile oil were 3,5-muuroladiene (39.56%) and butylated hydroxytoluene (13.07%).