Aluminium toxicity targets PIN2 in Arabidopsis root apices： Effects on PIN2 endocytosis, vesicular recycling, and polar auxin transport

• Published in: Chinese science bulletin 2008-08, Vol.53 (16), p.2480-2487
• Main Authors: Shen, Hong, Hou, NingYan, Schlicht, Markus, Wan, YingLang, Mancuso, Stefano, Baluska, Frantisek
• Format: Article
• Language: English
• Subjects: Arabidopsis; Chemistry/Food Science; Earth Sciences; Engineering; Humanities and Social Sciences; Life Sciences; multidisciplinary; Physics; Science; Science (multidisciplinary); 生长素; 胞吞作用
• ISSN: 1001-6538; 2095-9273; 1861-9541; 2095-9281
• DOI: 10.1007/s11434-008-0332-3

The most obvious symptom of AI toxicity is the inhibition of root growth. However, the mechanism of AI-inhibiting root growth remains to be elucidated. In this study, auxin transport and vesicle movement of an auxin-efflux carrier （PIN2） were investigated in Arabidopsis roots in response to AI stress. Results indicated that AI inhibited the apical transport of auxin in root tips of Arabidopsis significantly. The severe inhibition was localized in the cells of transition zone, where the concentration of auxin was only 34% that of the control. Brefeldin A （BFA）, an inhibitor of vesicle transport, induced the dot-like structure of PIN2 vesicle significantly. AI decreased the size of dot-like structure of PIN2 vesicles. Resuits of real-time RT-PCR and Western-blotting analysis showed that AI increased the transcript level of PIN2 and the accumulation of PIN2 protein in horizontal direction of plasma membrane, but decreased its distribution in endosomes, suggesting that AI inhibited the transport of PIN2 vesicles from plasma membrane to endosomes. Results of cytoskeleton-depolymering drugs indicated that it was via the pathway of disruption of actin microfilaments that AI inhibited the transport of PIN2 vesicles. Exposed to AI stress, the cells of elongation zone had less AI uptake and less transport frequency of vesicles than cells of transition zone. Taken together, our results suggested that AI inhibited root growth mainly by modulating the transport of PIN2 vesicles between plasma membrane and endosomes, thus blocking auxin transport and root growth.