KATANIN promotes cell elongation and division to generate proper cell numbers in maize organs

Microtubule severing is essential for proper eukaryotic cell elongation and division. Here we show that the microtubule severing protein, KATANIN, is encoded by two genes in Zea mays (maize) called Discordia3a (Dcd3a) and Dcd3b. Loss of function allele combinations contribute to reduced microtubule severing and decreased cell elongation. The latter results in reduced cell number by slowing entry into mitosis. KATANIN is important for preprophase band (PPB) formation and positioning, and nuclear positioning in symmetric cell divisions. A combination of these defects contribute to generating mutant plants with small size and aberrant shape.