ABSTRACT
Controlling organ size in plants is a complex biological process influenced by various factors, including gene expression, genome ploidy and environmental conditions. Despite its importance for plant growth and development, the mechanisms underlying organ size regulation remain unknown. Here, we investigated the role of RAN1, a member of the Ras-related nuclear GTPase family, in regulating pollen size. A RAN1 knockdown mutant (ran1-1) exhibited a significant reduction in pollen size, accompanied by impaired germination and reduced pollen tube growth. RAN1 mutation caused disruptions in actin filament organization, such as aberrant structure of actin collar due to the dysregulation of expression of actin-binding proteins. Furthermore, we identified that mutation of the transcription activator SHORT HYPOCOTYL UNDER BLUE1 (SHB1) showed similar but milder phenotypes in pollen compared to ran1-1. Genetic evidence suggested that SHB1 acts downstream of RAN1. Transient expression assays in leaves showed that SHB1 was largely retained in the cytoplasm of the ran1-1 mutant, potentially affecting the expression of actin-binding proteins. These findings highlight the pivotal role of RAN1 in modulating pollen size and development, providing valuable insights into cell size regulation.
Footnotes
Author contributions
Conceptualization: P.L., H.R.; Methodology: Y.L., P.L., H.R.; Investigation: Y.L., Y.Z., P.L.; Data curation: Y.L., Y.Z., H.Z.; Writing - original draft: Y.L., P.L.; Writing - review & editing: Y.L., Y.Z., P.L., H.R.; Visualization: H.Z., P.L.; Supervision: P.L., H.R.
Funding
This work was supported by grants from the National Natural Science Foundation of China (92254303 and 32170335 to H.R.; 32270808 to P.L.), Taishan Scholar Foundation of Shandong Province (tsqnz20231208 to P.L.) and Department of Science and Technology of Shandong Province (2024HWYQ-052 to P.L.).
Data availability
All relevant data can be found within the article and its supplementary information.
