Precocious shoot termination in determinate tomatoes is partially suppressed by <i>sft/</i>

<p>+<b> mutant heterozygosity.</b> (A) Schematic diagrams showing shoot architecture of a wild type (WT) indeterminate tomato plant (left) and an <i>sp</i> determinate mutant (right). In WT M82 plants the primary shoot meristem (PSM) from the embryo gives rise to 7–9 leaves before terminating in the first flower of the first multi-flowered inflorescence (boxed). A specialized axillary meristem called a sympodial meristem (SYM) in the axil of the last leaf on primary shoot then generates three leaves before terminating in the first flower of the next inflorescence. In indeterminate tomatoes, this process continues indefinitely (left). In <i>sp</i> mutants (right), sympodial cycling accelerates progressively on all shoots causing leaf production to decrease in successive units until growth ends in two juxtaposed inflorescences (asterisks). Alternating colored groups of three ovals represent leaves within successive sympodial units numbered at right. Colored circles represent fruits and flowers within each inflorescence (red: fully ripe fruit; orange: ripening fruit; green: unripe fruit; yellow: flowers) and arrows represent canonical axillary shoots. (B) Compared to <i>sp</i> mutants alone, <i>sft/+ sp</i> plants produce more inflorescences (left) and sympodial units (right) before sympodial cycling terminates on the main shoot. Genotypes and sample sizes are shown below, and standard deviations of averages are presented. (C) Compared to <i>sp</i> alone, <i>sft/+ sp</i> plants produce more leaves in the first three sympodial units, indicating a delay in precocious termination. Colored bars indicate average leaf numbers within sympodial units with standard deviations. Statistical significance in B and C was tested by Wilcoxon rank sum test, and significance levels are indicated by asterisks (*P&lt;0.05, **P&lt;0.01, ***P&lt;0.001).