Shoot elongation patterns and regulatory genes controlling grapevine (Vitis vinifera L.) internode elongation

The robust growth of grape shoots often results in diminished grape quality and increased labor costs in grape production. Investigating the patterns of shoot elongation and the underlying mechanisms is beneficial for simplifying cultivation processes and enhancing fruit quality. However, there is limited research on this topic. In this study, we found that lateral growth and elongation growth occurred simultaneously in each grape internode, and exhibited a similar sigmoid growth curve model. The dissection of the internode structure revealed that elongation of the cells in the middle of the stem was the primary reason for the rapid elongation of grape shoots, while the sharp increase in the xylem area significantly contributed to the lateral growth of the internodes. Transcriptome analysis indicated that genes associated with cell cycle organization, cell wall organization, and phytohormone activity play important roles in regulating the growth of grape internodes. One candidate gene, VvSAUR72, which is related to auxin signaling components, was characterized to promote internode elongation by overexpression in Arabidopsis. These results provide a foundation for further investigation into the regulatory mechanisms related to the internode elongation in grapevine.