A TCP Transcription Factor, BRANCH ANGLE DEFECTIVE 1 (BAD1), is required for normal tassel branch angle formation in Maize

FANG BAI; RENATA REINHEIMER; DIEGO DURANTINI; ELIZABETH KELLOGG; ROBERT J. SCHMIDT

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA

NATL ACAD SCIENCES

Lugar: Washington DC, USA; Año: 2012 p. 12225 - 12230

0027-8424

In grass species, the pulvinus is a structure found in the axil of inflorescence branches.  Both size and shape of the pulvinus affect the angle of the lateral branches that emerge from the main axis, and therefore have a large impact on inflorescence architecture.  Through EMS mutagenesis we have identified three complementation groups of recessive mutants in maize having defects in pulvinus formation.  All mutants showed extremely acute tassel branch angles accompanied by a significant reduction in the size of the pulvinus compared to wild type plants.  Two of the complementation groups correspond to mutations in the previously identified genes, RAMOSA2 (RA2) and LIGULESS1 (LG1).  Mutants corresponding to the third group were cloned using mapped based approaches and found to encode a new member of the plant-specific TCP family of DNA binding proteins, BRANCH ANGLE DEFECTIVE 1 (BAD1).  BAD1 is expressed in the developing pulvinus as well as in other developing tissues, such as tassels and juvenile leaves.  Both molecular and genetics studies show that RA2 is upstream of BAD1, while LG1 may function downstream of BAD1.  Our findings demonstrate that BAD1 is a TCP class II gene that functions to promote cell proliferation in a lateral organ, the pulvinus, and influences inflorescence architecture by changing lateral branch angle.