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United States Department of Agriculture

Agricultural Research Service

Title: Expression Patterns and Mutant Phenotype of Teosinte Branched1 Correlate with Growth Suppression in Maize and Teosinte

Authors
item Hubbard, Lauren - ARS-UCB PLNT GENE EXP CTR
item Mcsteen, Paula - ARS-UCB PLNT GENE EXP CTR
item Doebley, John - UNIV WISCONSIN MADISON
item Hake, Sarah

Submitted to: Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 1, 2002
Publication Date: December 1, 2002
Citation: HUBBARD, L., MCSTEEN, P.C., DOEBLEY, J., HAKE, S.C. EXPRESSION PATTERNS AND MUTANT PHENOTYPE OF TEOSINTE BRANCHED1 CORRELATE WITH GROWTH SUPPRESSION IN MAIZE AND TEOSINTE. GENETICS. 2002. 162:1927-1935.

Interpretive Summary: The evolution of domesticated maize from its wild ancestor teosinte is a dramatic example of the effect of human selection on agricultural crops. Maize has one dominant axis of growth, whereas teosinte is highly branched. The axillary branches in maize are short and feminized whereas the axillary branches of teosinte are long and end in a male inflorescence under normal growth conditions. Previous QTL and molecular analysis suggested that the teosinte branched1 (tb1) gene of maize contributed to the architectural difference between maize and teosinte. tb1 mutants of maize resemble teosinte in their overall architecture. We analyzed the tb1 mutant phenotype in more detail and showed that the highly branched phenotype was due to the presence of secondary and tertiary axillary branching, as well as to an increase in the length of each node, rather than to an increase in the number of nodes. Double-mutant analysis with anther ear1 and tassel seed2 revealed that the sex of the axillary inflorescence was not correlated with its length. RNA in situ hybridization showed that tb1 was expressed in maize axillary meristems and in stamens of ear primordia, consistent with a function of suppressing growth of these tissues. Expression in teosinte inflorescence development suggests a role in pedicellate spikelet suppression. Our analysis of tb1 provides support for a role for tb1 in growth suppression and reveal the specific tissues where suppression may occur.

Technical Abstract: The evolution of domesticated maize from its wild ancestor teosinte is a dramatic example of the effect of human selection on agricultural crops. Maize has one dominant axis of growth, whereas teosinte is highly branched. The axillary branches in maize are short and feminized whereas the axillary branches of teosinte are long and end in a male inflorescence under normal growth conditions. Previous QTL and molecular analysis suggested that the teosinte branched1 (tb1) gene of maize contributed to the architectural difference between maize and teosinte. tb1 mutants of maize resemble teosinte in their overall architecture. We analyzed the tb1 mutant phenotype in more detail and showed that the highly branched phenotype was due to the presence of secondary and tertiary axillary branching, as well as to an increase in the length of each node, rather than to an increase in the number of nodes. Double-mutant analysis with anther ear1 and tassel seed2 revealed that the sex of the axillary inflorescence was not correlated with its length. RNA in situ hybridization showed that tb1 was expressed in maize axillary meristems and in stamens of ear primordia, consistent with a function of suppressing growth of these tissues. Expression in teosinte inflorescence development suggests a role in pedicellate spikelet suppression. Our results provide support for a role for tb1 in growth suppression and reveal the specific tissues where suppression may occur.

Last Modified: 10/25/2014
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