Myosin XI is required for boron transport under boron limitation via maintenance of endocytosis and polar localization of the boric acid channel AtNIP5;1

Myosin XI plays a major role in cytoplasmic streaming and is essential for intracellular transport. Here, we investigated the physiological roles of myosin XI in nutrient transport using double (2ko) and triple (3ko) myosin XI knockout mutants of Arabidopsis thaliana. The results revealed that the mutants exhibited more severe boron deficiency phenotypes under boron-limiting conditions, and the boron concentration in the aerial parts of mutant plants was lower than that in the wild-type. Microscopic analysis demonstrated a reduction in general endocytosis and abolishment of NIP5; 1's polar localization in 2ko and 3ko plants. Overall, these results indicate that myosin XI is necessary for proper boron transport via the maintenance of the endocytic pathway and NIP5; 1's polar localization.