OsBBX19-OsBTB97/OsBBX11 module regulates spikelet development and yield production in rice

Spikelet and floral-related organs are important agronomic traits for rice grain yield. BTB (broad-complex, tram track, and bric-abrac) proteins control various developmental functions in plants; however, the molecular mechanism of BTB proteins underlying grain development and yield production is still unknown. Here, we evaluated the molecular mechanism of a previously unrecognized functional gene, namely OsBTB97 that regulates the floral and spikelet-related organs which greatly affect the final grain yield. We found that the knockdown of the OsBTB97 gene had significant impacts on the development of spikelet-related organs and grain size, resulting in a decrease in yield, by altering the transcript levels of various spikelet- and grain-related genes. Furthermore, we found that the knockout mutants of two BBX genes, OsBBX11 and OsBBX19, which interact with the OsBTB97 protein at translation and transcriptional level, respectively, displayed lower OsBTB97 expression, suggesting the genetic relationship between the BTB protein and the BBX transcription factors in rice. Taken together, our study dissects the function of the novel OsBTB97 by interacting with two BBX proteins and an OsBBX19-OsBTB97/OsBBX11 module might function in the spikelet development and seed production in rice. The outcome of the present study provides promising knowledge about BTB proteins in the improvement of crop production in plants.