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

Abstract

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.

Acknowledgements

This work was supported by National Natural Science Foundation of China (32060364 to M.J.H. and 32060366 to H.Q.H.); Major Science and Technology Projects in Yunnan Province (202102AE090052 to H.Q.H. and M.J.H.); Doctoral Tutor Team for Genetic Improvement and High-efficient Propagation of Landscape Plants in Yunnan Province (503210103 to H.Q.H. and M.J.H.).

Author contributions

Y.L. and H.Q.H. conceived and designed this study. Y.L. carried out the SEM experiment, VIGS experiment, data analysis, and manuscript writing. W.L.H. carried out the sample collection, phylogenetic analyses, qRT-PCR experiment and manuscript revision. X.Y.L. carried out hormone measurement experiments. Y.D.Z. carried out histology experiments. D.C.M. and C.M.W. assisted in the VIGS experiment. M.J.H. and H.Q.H. provided guidance on all the experiments and manuscripts revision. All authors have reviewed and approved the final submission.

Data availability

The data underlying this article are available in the article and its online supplementary material.

Conflict of interest

The authors declare that they have no competing interests.

Supplementary data

Supplementary data is available at Horticulture Research online.

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