Classification of inheritance of trichomes in different organs in zucchini (Cucurbita pepo L.)

Plant trichomes are specialized structures that develop from epidermal cells and are widely present on the surface of the aboveground tissues in plants. Trichomes play a significant role in plant development, the biotic and abiotic adaptations, and some of them have important commercial value. Trichome micromorphology of the aboveground parts of zucchini germplasm resources was observed, and the results showed that zucchini trichomes are multicellular, and they consist of head, stem, and basal cells. Zucchini trichomes were classified into seven types: type I, II, III, and VII trichomes were nonglandular, and type IV, V, and VI trichomes were glandular. Each type had a unique structure and morphology, and type I and II trichomes were long and pointy, which could easily be observed. According to the presence of type I and II trichomes, the zucchini germplasm resources were divided into long dense trichome (LDT) groups (presence of type I and II trichomes) and sparse micro trichome (SMT) groups (absence of type I and II trichomes). The F-2 population derived by crossing typical LDT 16 and typical SMT 63 was constructed, and the density of type I and type II petiole trichomes was found significantly different. Petiole trichome density exhibited quantitative characteristic inheritance and was controlled by multiple genes. A study of the structure and morphology of zucchini trichomes can deepen the understanding of multicellular trichomes and lay the foundation for the morphological development of zucchini trichomes and the identification of trichome density genes, which could have important theoretical and practical application value for the selection of new zucchini varieties in the future.