Pollination Syndrome, Florivory, and Breeding System of Satyrium nepalense var. ciliatum (Orchidaceae) in Central Yunnan, China.

Research on Satyrium nepalense var. ciliatum (Lindl.) Hook. f. has primarily focused on populations in Northwestern Yunnan, with limited studies on pollination syndromes and insect behavior. In addition, it is geographically limited in its breeding system studies. Here, pollination syndromes, florivory, and breeding systems of S. nepalense var. ciliatum from Liangwang Mountain (Central Yunnan, China) were investigated through field work, microscope, scanning electron microscope (SEM), and parafin section. It was revealed that the pollination syndrome was possessing out-crossing, such as bright color, a developed rostellum, nectar glands in the spur, and food hairs at the lip base. The color and nectar attracted flower visitors, and florivory was observed. Some flower visitors pollinated their companion species. Ants were identified as floral visitors for the first time in Satyrium, although substantial pollination was not observed. Ants might be potential pollinators. S. nepalense var. ciliatum possessed a mixed breeding system, including selfing, out-crossing, and apomixis, with apomixis being predominant in nature. It is suggested that the pollination syndrome, florivory, and pollination competition would contribute to its mixed breeding systems, particularly leading to the occurrence of apomixis.

The cellular and molecular basis of the spur development in Impatiens uliginosa.

The nectar spur is an important feature of pollination and ecological adaptation in flowering plants, and it is a key innovation to promote species diversity in certain plant lineages. The development mechanism of spurs varies among different plant taxa. As one of the largest angiosperm genera, we have little understanding of the mechanism of spur development in Impatiens. Here, we investigated the initiation and growth process of spurs of Impatiens uliginosa based on histology and hormone levels, and the roles of AUXIN BINDING PROTEIN (ABP) and extensin (EXT) in spur development were explored. Our results indicate that the spur development of I. uliginosa is composed of cell division and anisotropic cell elongation. Imbalances in spur proximal-distal cell division lead to the formation of curved structures. Endogenous hormones, such as auxin and cytokinins, were enriched at different developmental stages of spurs. IuABP knockdown led to an increase in spur curves and distortion of morphology. IuEXT knockdown resulted in reduced spur length and loss of curve and inner epidermal papillae structures. This study provides new insights into the mechanism of spur development in core eudicots.