Genome-wide analysis of the B3 transcription factors reveals that RcABI3/VP1 subfamily plays important roles in seed development and oil storage in castor bean (Ricinus communis)

The B3 transcription factors (TFs) in plants play vital roles in numerous biological processes. Although B3 genes have been broadly identified in many plants, little is known about their potential functions in mediating seed development and material accumulation. Castor bean (Ricinus communis) is a non-edible oilseed crop considered an ideal model system for seed biology research. Here, we identified a total of 61 B3 genes in the castor bean genome, which can be classified into five subfamilies, including ABI3/VP1, HSI, ARF, RAV and REM. The expression profiles revealed that RcABI3/VP1 subfamily genes are significantly up-regulated in the middle and later stages of seed development, indicating that these genes may be associated with the accumulation of storage oils. Furthermore, through yeast one-hybrid and tobacco transient expression assays, we detected that ABI3/VP1 subfamily member RcLEC2 directly regulates the transcription of RcOleosin2, which encodes an oil-body structural protein. This finding suggests that RcLEC2, as a seed-specific TF, may be involved in the regulation of storage materials accumulation. This study provides novel insights into the potential roles and molecular basis of B3 family proteins in seed development and material accumulation. Copyright ?? 2021 Kunming Institute of Botany, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY

Automated summary

This study identified 61 B3 genes in the castor bean genome, classified into five subfamilies. The RcABI3/VP1 subfamily genes were found to be significantly up-regulated in the middle and later stages of seed development, potentially associated with the accumulation of storage oils. The seed-specific transcription factor RcLEC2 was shown to directly regulate the transcription of RcOleosin2, suggesting its involvement in the regulation of storage material accumulation.