Newly Discovered Alleles of the Tomato Antiflorigen Gene <i>SELF PRUNING</i> Provide a Range of Plant Compactness and Yield
In tomato cultivation, a rare natural mutation in the flowering repressor antiflorigen gene <i>SELF-PRUNING</i> (<i>sp-classic</i>) induces precocious shoot termination and is the foundation in determinate tomato breeding for open field production. Heterozygous <i>singl...
| Main Authors: | , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2022-06-01
|
| Series: | International Journal of Molecular Sciences |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1422-0067/23/13/7149 |
| Summary: | In tomato cultivation, a rare natural mutation in the flowering repressor antiflorigen gene <i>SELF-PRUNING</i> (<i>sp-classic</i>) induces precocious shoot termination and is the foundation in determinate tomato breeding for open field production. Heterozygous <i>single flower truss</i> (<i>sft</i>) mutants in the florigen <i>SFT</i> gene in the background of <i>sp-classic</i> provide a heterosis-like effect by delaying shoot termination, suggesting the subtle suppression of determinacy by genetic modification of the florigen–antiflorigen balance could improve yield. Here, we isolated three new <i>sp</i> alleles from the tomato germplasm that show modified determinate growth compared to <i>sp-classic,</i> including one allele that mimics the effect of <i>sft</i> heterozygosity. Two deletion alleles eliminated functional transcripts and showed similar shoot termination, determinate growth, and yields as <i>sp-classic</i>. In contrast, amino acid substitution allele <i>sp-5732</i> showed semi-determinate growth with more leaves and sympodial shoots on all shoots. This translated to greater yield compared to the other stronger alleles by up to 42%. Transcriptome profiling of axillary (sympodial) shoot meristems (SYM) from <i>sp-classic</i> and wild type plants revealed six mis-regulated genes related to the floral transition, which were used as biomarkers to show that the maturation of SYMs in the weaker <i>sp-5732</i> genotype is delayed compared to <i>sp-classic,</i> consistent with delayed shoot termination and semi-determinate growth. Assessing <i>sp</i> allele frequencies from over 500 accessions indicated that one of the strong <i>sp</i> alleles (<i>sp-2798</i>) arose in early breeding cultivars but was not selected. The newly discovered <i>sp</i> alleles are potentially valuable resources to quantitatively manipulate shoot growth and yield in determinate breeding programs, with <i>sp-5732</i> providing an opportunity to develop semi-determinate field varieties with higher yields. |
|---|---|
| ISSN: | 1661-6596 1422-0067 |