Figure 6.

A hypothetical scheme showing the role of the phosphorylation of Thr-579 in NtMAP65-1 during plant cytokinesis. (Left) In this scheme, NtMAP65-1 stabilizes and maintains phragmoplast structures via its strong ability to bundle MTs during cytokinesis. During cytokinesis, in the midzone of the phragmoplast at sites where the components of the NACK–PQR pathway, including NRK1/NTF6 MAPK, are activated, NtMAP65-1 is phosphorylated by NRK1/NTF6 at Thr-579, and this phosphorylation results in localized suppression of its MT-bundling activity. (Right) Such suppression increases the instability of the organized MT-containing structure and the rate of MT turnover, which results in accelerated expansion of the phragmoplast.