Comparative morphoanatomic and histochemical characterization of Cucurbita pepo L. specimens

Cucurbita pepo L. is popularly known as pumpkin or zucchini. Compared to the others of the genus, it presents the greatest genetic variability. Thus, given its nutritional and medicinal benefits, it results in many widely cultivated and economically important specimens. Due to this, differentiation between specimens becomes necessary, mainly pumpkin and zucchini which have different characteristics, however they receive the same scientific nomenclature (C. pepo). It is noteworthy that the anatomical knowledge of the specimens helps with taxonomy. Furthermore, due to the economic value, when it comes to vegetative propagation, the identification of structural aspects is important for the success of propagation, which depends on the regeneration of plant tissues. This study aimed to characterize and differentiate two specimens of C. pepo through morphoanatomy and histochemistry. For anatomical study, usual methods in plant anatomy were used to prepare and analyze, under an optical microscope, semi-permanent slides containing transverse sections of the roots, stems, leaves, and paradermic sections of the leaf blades of C. pepo specimens. Histochemical tests were performed on cross-sections of the specimens' leaf blades to locate chemical compounds. The optical microscopic evaluation enabled the anatomical characterization, revealing distinct characters among the specimens. For example, the zucchini shows crystals in the root. Meanwhile, the pumpkin shows sclerenchymatic pericycle in the stem and secretory ducts in the stem and leaves. Histochemical techniques showed the presence of different compounds, differentiating in the presence of starch in the zucchini and triterpenes and steroids in the pumpkin. Correct characterization provides important information for quality control of the plant drug and taxonomic differentiation of the specimens since diagnostic characters vary.