SbLAV1, a member of the B3 transcription factor family in sorghum, plays a key regulatory role in starch biosynthesis during grain development through transcriptional activation of starch biosynthesis-related genes.
Keywords: B3 transcription family, SbLAV1, Sorghum (Sorghum bicolor L.), starch biosynthesis, transcriptional regulation
Starch, a major plant carbohydrate, is essential for food, feed, and industrial applications. Despite advances in synthetic biology, plant-based starch production remains dependent on photosynthesis and tightly controlled biochemical pathways. In cereal crops such as sorghum, transcriptional regulation is a critical mechanism governing grain starch biosynthesis. Scientists from Southwest University performed a genome-wide identification of B3 transcription factor (TF) family members in sorghum, revealing 76 genes grouped into four conserved subfamilies: ARF, LAV, RAV, and REM. These subfamilies exhibited distinct domain architectures and regulatory elements, suggesting functional divergence. Promoter analysis revealed the presence of cis-elements responsive to light, phytohormones, development, and stress, implicating B3 TFs in multifaceted regulatory networks. Expression profiling showed that while many B3 genes are broadly expressed across tissues, members of the SbLAV subfamily—particularly SbLAV1 and SbLAV5—were preferentially expressed in developing grains, pointing to roles in nutrient accumulation.
Functional characterization of SbLAV1 suggested its direct involvement in starch biosynthesis in sorghum grains. Co-expression analysis demonstrated that SbLAV1 correlates with multiple starch biosynthesis-related genes (SBRGs), and transactivation assays confirmed its ability to activate their promoters. Drawing parallels with other cereals, where LAV subfamily members regulate seed development and starch accumulation, the study proposed a transcriptional pathway mediated by SbLAV1 that modulates grain filling and starch deposition in sorghum. This research not only expands the understanding of B3 TF family evolution and function in plants but also highlights SbLAV1 as a promising regulatory hub for future efforts to enhance starch yield in sorghum breeding programs.
SorghumBase example:
Reference:
Gong X, Li J, Yan Z, Sun A, Zheng Y, Yin M, Xiao Q, Liu Z. Genome-Wide Dissection of Sorghum B3 Transcription Factor Family Identifies SbLAV1 as a Critical Transcriptional Regulator of Starch Biosynthesis in Developing Sorghum Grains. Plants (Basel). 2025 Jun 3;14(11):1701. PMID: 40508375. doi: 10.3390/plants14111701. Read more