Melon short internode (CmSi) encodes an erecta-like receptor kinase regulating stem elongation through auxin signaling

Authors: YANG, SEN - Henan Agricultural University; ZHANG, KAIGI - Henan Agricultural University; ZHU, HUAYU - Henan Agricultural University; ZHANG, XIAOJIN - Henan Agricultural University; YAN, WENKAI - Henan Agricultural University; XU, NANA - Henan Agricultural University; LIU, DONGMIN - Henan Agricultural University; HU, JIANBIN - Henan Agricultural University; WU, YUEFENG - Henan Agricultural University; Weng, Yiqun; YANG, LUMING - Henan Agricultural University

Submitted to: Horticulture Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2020
Publication Date: 12/1/2020
Citation: Yang, S., Zhang, K., Zhu, H., Zhang, X., Yan, W., Liu, D., Hu, J., Wu, Y., Weng, Y., Yang, L. 2020. Melon short internode (CmSi) encodes an erecta-like receptor kinase regulating stem elongation through auxin signaling. Horticulture Research. 7. Article 202. https://doi.org/10.1038/s41438-020-00426-6.
DOI: https://doi.org/10.1038/s41438-020-00426-6

Interpretive Summary: Plant height or vine length is an important trait that directly determines plant architecture and yield. The compact or dwarfing plant can increase planting density and land use, increase lodging resistance and thus yield. Several dwarf/semi-dwarf mutants have been identified, but none of the underlying genes has been cloned. Little is known about the molecular mechanisms of internode elongation in melon. Major findings characterization of the first semi-dwarf gene short internode (CmSI) in melon. This gene encodes an ERECTA-like receptor kinase regulating internode elongation. CmSI has high expression in the vascular bundle of main stems during internode elongation. Transgenic Arabidopsis and cucumber plants of this gene suggest CmSI as a positive regulator for internode elongation. Transcriptome analysis and phytohormone measurement indicate involvement of auxin signaling pathway for stem elongaiton. Protein-protein interaction studies identified a melon polar auxin transport, CmPIN2 that physically interacts with CmSI to modulate auxin signaling. The expression of CmSI is positively correlated with the vine length in different melon varieties examined. Thus CmSI functions in an auxin-dependent regulation pathway in controlling internode elongation in melon. Results from this study are of interest to plant breeders and geneticists to understand the molecular mechanism of dwarf plant architecture in melon. Melon breeders may take advantage of the findings for more efficient use of this mutant gene.

Technical Abstract: Plant height is one of the most important agronomic traits that directly determines plant architecture, and the compact or dwarfing plant can increase density and land utilization as well as increase lodging resistance and economic yield. At least four dwarf/semi-dwarf genes have been identified in different melon varieties, while none of them has been cloned and little is known about the molecular mechanisms underlying internode elongation in melon. Here, we reported map-based cloning and functional characterization of the first semi-dwarf gene short internode (CmSI) in melon, which encodes an ERECTA-like receptor kinase regulating internode elongation. Spatial-temporal expression analyses revealed that CmSI exhibited high expression in the vascular bundle of main stems during internode elongation. Ectopic expression of CmSI in Arabidopsis and cucumber suggested CmSI as a positive regulator for internode elongation in both species. Transcriptome analysis and phytohormone quantitation showed that the auxin content and expression level for a number of genes involving in auxin signaling pathway were altered in the dwarf mutant, including several well-known auxin transporters such as the members of ABCB family and PIN-FORMED genes. Protein-protein interaction studies identified a melon polar auxin transport, CmPIN2 that physically interacts with CmSI to modulate auxin signaling. Moreover, the expression level of CmSI was positively correlated with the vine length in different melon varieties examined. Thus CmSI functions in an auxin-dependent regulation pathway in controlling internode elongation in melon. Our finding revealed that ERECTA family gene regulates stem elongation in melon through auxin signaling, which can directly interact with polar auxin transport.