<i>Arabidopsis</i> kinesins KCH3 and KCH7 promote root gravitropism through actin bundling in the stele
Abstract
Root gravitropism is essential for plant adaptation to the environment. The cytoskeleton is known to play a critical role in gravitropism, but the underlying mechanisms remain unclear. In this study, we demonstrate that the Arabidopsis kinesins KCH3 and KCH7 (KCH3/7) are expressed and functionally active in the root stele. The kch3 kch7 ( kch37 ) double mutant exhibits delayed gravitropic responses, while stele-specific expression of either KCH3 or KCH7 rescues this defect. Both the calponin homology (CH) and motor domains of KCH3/7 are essential for mediating gravitropism. In vitro and in vivo assays reveal that KCH3/7 promotes actin filament (F-actin) bundling and its turnover in the root stele. Mutation of KCH3/7 results in altered PIN protein abundance and polarity in the root stele, leading to impaired acropetal auxin transport within the stele and reduced auxin accumulation in the root tip’s columella cells. This ultimately causes defective auxin redistribution during gravistimulation. Collectively, our findings highlight the importance of cytoskeletal organization and dynamics in the root stele for maintaining the auxin gradient in the root tip and for gravistimulation-induced auxin asymmetry.
Article Details
Journal Info
Proceedings of the National Academy of Sciences
National Academy of Sciences
Authors (14)
Yingzhi Niu
Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, Department of Plant Cell Biology and Biological Breeding, School of Life Sciences, Lanzhou University
Shuyuan Chen
Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, Department of Plant Cell Biology and Biological Breeding, School of Life Sciences, Lanzhou University
Zhaoguo Deng
Center for Plant Biology, State Key Laboratory of Green Biomanufacturing, School of Life Sciences, Tsinghua University
Juan Du
College of Chemical and Pharmaceutical Engineering
Yangyang Zhou
State Key Laboratory of Chemo and Biosensing, College of Chemistry and Chemical Engineering, Advanced Catalytic Engineering Research Center of the Ministry of Education
Ni Fan
State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, College of Life Science, Northwest A&F University, Yangling, Shaanxi, China.
Dingding Zhou
Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, Department of Ornamental Horticulture, College of Horticulture, China Agricultural University
Yue Niu
Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, Department of Plant Cell Biology and Biological Breeding, School of Life Sciences, Lanzhou University
Yang Yang
Lizhe An
Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, Department of Plant Cell Biology and Biological Breeding, School of Life Sciences, Lanzhou University
Siyi Chen
Center for Plant Biology, State Key Laboratory of Green Biomanufacturing, School of Life Sciences, Tsinghua University
Yun Xiang
Key Laboratory of Luminescence Analysis and Molecular Sensing, Ministry of Education, School of Chemistry and Chemical Engineering
Haodong Chen
Center for Plant Biology, State Key Laboratory of Green Biomanufacturing, School of Life Sciences, Tsinghua University
Dong Qian