Morris, V. H. | Search bioRxiv

bioRxiv2022

The localization of PHRAGMOPLAST ORIENTING KINESIN1 at the division site depends on two microtubule binding proteins TANGLED1 and AUXIN-INDUCED-IN-ROOT-CULTURES9 in Arabidopsis.

Proper plant growth and development requires spatial coordination of cell divisions. Two unrelated microtubule-binding proteins, TANGLED1 (TAN1) and AUXIN-INDUCED-IN-ROOT-CULTURES9 (AIR9), are together required for normal growth and division-plane orientation in Arabidopsis. tan1 air9 double mutants have synthetic growth and division-plane orientation defects while single mutants lack obvious defects. Here we show that the division-site localized protein, PHRAGMOPLAST-ORIENTING-KINESIN1 (POK1), was aberrantly lost from the division site during metaphase and telophase in tan1 air9 mutants. Since TAN1 and POK1 interact via the first 132 amino acids of TAN1 (TAN11-132), we assessed its localization and function in the tan1 air9 double mutant. TAN11-132 rescued tan1 air9 mutant phenotypes and localized to the division site in telophase. However, replacing six amino-acid residues within TAN11-132 that disrupts POK1-TAN1 interaction in the yeast-two-hybrid system caused loss of both rescue and division-site localization of TAN11-132 in tan1 air9 mutants. Full-length TAN1 with the same alanine substitutions had defects in phragmoplast guidance and reduced TAN1 and POK1 localization at the division site but rescued most tan1 air9 mutant phenotypes. Together, these data suggest that TAN1 and AIR9 are required for POK1 localization, and yet unknown proteins may stabilize TAN1-POK1 interactions. One sentence summarySpecific amino acids within TAN1 are required for its correct localization and function partially through interaction with POK1; both TAN1 and AIR9 mediate POK1 division site localization.

plant biology↗

bioRxiv2021

Functional characterization of TANGLED1 interaction with PHRAGMOPLAST ORIENTING KINESIN1 during mitosis in Arabidopsis

Cell division plane orientation is critical for plant and animal development and growth. TANGLED1 (TAN1) and AUXIN-INDUCED-IN-ROOT-CULTURES9 (AIR9) are division-site localized microtubule-binding proteins required for division plane positioning. tan1 and air9 Arabidopsis thaliana single mutants have minor or no noticeable phenotypes but the tan1 air9 double mutant has synthetic phenotypes including stunted growth, misoriented divisions, and aberrant cell-file rotation in the root differentiation zone. These data suggest that TAN1 plays a role in nondividing cells. To determine whether TAN1 is required in elongating and differentiating cells in the tan1 air9 double mutant, we limited its expression to actively dividing cells using the G2/M-specific promoter of the syntaxin KNOLLE (pKN:TAN1-YFP). Unexpectedly, in addition to rescuing division plane defects, pKN:TAN1-YFP rescued root growth and the root differentiation zone cell file rotation defects in the tan1 air9 double mutant. This suggests that defects that occur in the meristematic zone later affect the organization of elongating and differentiating cells. Summary StatementExpression of TAN1 in the root meristematic zone rescues cell file rotation defects in tan1 air9 mutants, suggesting defects that occur in mitosis may influence organization of nondividing cells.

plant biology↗