Morphology, structure and development of glandular prickles in the genus Rosa

Prickles in genus Rosa are mainly classified into two categories, non-glandular prickles (NGPs) and glandular prickles (GPs). At present, researchers at home and abroad lack a clear and unified understanding of the morphological development and organizational structure of the Rosa prickles, especially in GPs. Understanding the origin and development of NGPs and GPs is of great significance for elucidating the relationship between them, which helps to reasonably manipulate the trait of prickles. Here, detailed morphological, anatomical and histological analysis of GPs on the stems were performed among three representative genotypes. The development of GPs consists of 5 stages, including initiation, morphogenesis, rapid growth stage, maturation and senescence, which was accompanied by the accumulation of lignin and cellulose. Notably, well-developed plasmodesmata on the adjacent wall of the outer epidermal cells of the glandular head were observed, suggesting its roles in transportation of substances specifically secreted by gland cells in GPs. We also discussed the similarities and difference between GPs and NGPs, and propose that they have independent developmental progress with different cell fate determination and genetic regulation. These results provide new perspective and theoretical basis for further exploring the molecular mechanism of the formation of prickles in the genus Rosa.