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Background: Spur, a structure capable of producing and storing nectar, not only plays a vital role in the pollination process but also promotes the rapid diversification of some plant lineages, which is considered a key innovation in plants. Spur is the focus of many studies, such as evolution and ecological hypothesis, but the current understanding of spur development is limited. High-throughput sequencing of Impatiens uliginosa was carried out to study the molecular mechanism of its spur development, which is believed to provide some insights into the spur development of Impatiens., Results: Transcriptomic sequencing and analysis were performed on spurs and limbs of I. uliginosa at three developmental stages. A total of 47.83 Gb of clean data were obtained, and 49,716 unigene genes were assembled. After comparison with NR, Swiss-Prot, Pfam, COG, GO and KEGG databases, a total of 27,686 genes were annotated successfully. Through comparative analysis, 19,356 differentially expressed genes were found and enriched into 208 GO terms and 146 KEGG pathways, among which plant hormone signal transduction was the most significantly enriched pathway. One thousand thirty-two transcription factors were identified, which belonged to 33 TF families such as MYB, bHLH and TCP. Twenty candidate genes that may be involved in spur development were screened and verified by qPCR, such as SBP, IAA and ABP., Conclusions: Transcriptome data of different developmental stages of spurs were obtained, and a series of candidate genes related to spur development were identified. The importance of genes related to cell cycle, cell division, cell elongation and hormones in spur development was clarified. This study provided valuable information and resources for understanding the molecular mechanism of spur development in Impatiens., (© 2022. The Author(s).)

Impatiens is rich in germplasm resources, with more than 260 species in China. A study on the pollen micromorphology of Impatiens by scanning electron microscopy (SEM) showed that the pollen characteristics were richly diverse, and there was some correlation among the characteristics. In addition, the micromorphological index can be used for an effective cluster analysis of Impatiens. However, there was high interspecific similarity in some Impatiens, and the classification of Impatiens cannot be accurate to the species using pollen characteristics. Based on the classification conditions of Impatiens, the characteristics of the pollen structure were found to be useful to classify Impatiens into subgenera or smaller groups. The macroscopic characteristics and the number of sepals (NS) were used as references, which enabled the conclusion that there were 11 indices in the pollen micromorphological index, and the taxonomic effect was greater than the NS. In summary, the pollen micromorphology of Impatiens plays an important role in the classification of Impatiens. The purpose of this study was to explore this characteristic of Impatiens, which has some reference significance to supplement the pollen characteristics and palynological classification of Impatiens. The goal for this research was to aid in the interspecific identification and genetic breeding of Impatiens.