The present invention relates to a new sequence of BRANCHED1a gene, the SpBRANCHED1a gene of Solanum pennellii, and to an expression product of said gene, to a vector, host cell, cell culture, recombinant expression system, or tomato plants comprising said SpBRANCHED1a gene. The present invention also refers to the heterologous use of the gene in tomato plants, to produce a plant having fewer and/or shorter axillary shoots than a control plant, and to a method for producing tomato plants having fewer and/or shorter axillary shoots than a control plant.