The Interaction between DELLA and ARF/IAA Mediates Crosstalk between Gibberellin and Auxin Signaling to Control Fruit Initiation in Tomato.
Fruit initiation following fertilization in angiosperms is strictly regulated by phytohormones. In tomato (Solanum lycopersicum), auxin and gibberellin (GA) play central roles in promoting fruit initiation. Without fertilization, elevated GA or auxin signaling can induce parthenocarpy (seedless fruit production). The GA-signaling repressor SlDELLA and auxin-signaling components SlIAA9 and SlARF7 repress parthenocarpy, but the underlying mechanism is unknown. Here, we show that SlDELLA and the SlARF7/SlIAA9 complex mediate crosstalk between GA and auxin pathways to regulate fruit initiation. Yeast-two-hybrid and coimmunoprecipitation assays showed that SlARF7 and additional activator SlARFs interact with SlDELLA and SlIAA9 through distinct domains. SlARF7/SlIAA9 and SlDELLA antagonistically modulate the expression of feedback-regulated genes involved in GA and auxin metabolism, whereas SlARF7/SlIAA9 and SlDELLA coregulate the expression of fruit growth-related genes. Analysis of procera (della), SlARF7 RNAi (with downregulated expression of multiple activator SlARFs), and entire (iaa9) single and double mutants indicated that these genes additively affect parthenocarpy, supporting the notion that the SlARFs/SlIAA9 and SlDELLA interaction plays an important role in regulating fruit initiation. Analysis of the GA-deficient mutant gib1 showed that active GA biosynthesis and signaling are required for auxin-induced fruit initiation. Our study reveals how direct crosstalk between auxin- and GA-signaling components is critical for tomato fruit initiation.
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Related Subject Headings
- Solanum lycopersicum
- Signal Transduction
- Plant Proteins
- Plant Biology & Botany
- Indoleacetic Acids
- Gibberellins
- Gene Expression Regulation, Plant
- Fruit
- 3108 Plant biology
- 0607 Plant Biology
Citation
Published In
DOI
EISSN
ISSN
Publication Date
Volume
Issue
Start / End Page
Related Subject Headings
- Solanum lycopersicum
- Signal Transduction
- Plant Proteins
- Plant Biology & Botany
- Indoleacetic Acids
- Gibberellins
- Gene Expression Regulation, Plant
- Fruit
- 3108 Plant biology
- 0607 Plant Biology