In plants, the control of vegetative growth involves a complex interplay of regulatory factors. A recent study highlights how the ubiquitin ligase seven in absentia1 (SINA1) and the regulatory module it forms with mammalian BTF2-like transcription factors, Drosophila synapse-associated proteins, and yeast DOS2-like proteins (BSD1) influence tomato growth. Specifically, SINA1 manages vegetative growth by regulating the plant growth hormone gibberellin (GA) through the degradation of BSD1.
Transgenic tomatoes overexpressing SINA1 (SINA1-OX) show a dwarfism phenotype similar to BSD1-knockout (BSD1-KO) plants, pointing to SINA1's role in controlling BSD1 levels. Additionally, BSD1 is found to activate the expression of the BSD1-regulated gene 1 (BRG1) by binding to a novel core BSD1 binding site (BBS) in the BRG1 promoter, indicating a direct mechanism for gene regulation in plant growth.
Knockout of BRG1 (BRG1-KO) also leads to dwarfism, underscoring its positive role alongside BSD1 in promoting growth. The study observes reduced GA levels in SINA1-OX, BSD1-KO, and BRG1-KO plants, all exhibiting dwarfism. However, applying bioactive GA3 can counteract this effect, highlighting GA's critical role in vegetative development.
Furthermore, the research shows BRG1 is necessary for expressing several GA biosynthesis genes, with BSD1 activating genes that promote GA production. This reveals the SINA1-BSD1 module's direct and indirect influence on GA biosynthesis and plant growth, offering insights into potential agricultural applications for controlling plant stature and improving crop yields.
Read more at Wiley Online Library.