The GAMYB-like gene SlMYB33 mediates flowering and pollen development in tomato

Abstract

GAMYBs are positive GA signaling factors that exhibit essential functions in reproductive development, particularly in anther and pollen development. However, there is no direct evidence of the regulation of any <i>GAMYB</i> in these biological processes in tomato (<i>Solanum lycopersicum</i>). Here, we identified a tomato <i>GAMYB-like</i> gene, <i>SlMYB33</i>, and characterized its specific roles. <i>SlMYB33</i> is predominately expressed in the stamens and pistils. During flower development, high mRNA abundance of <i>SlMYB33</i> is detected in both male and female organs, such as microspore mother cells, anthers, pollen grains, and ovules. Silencing of <i>SlMYB33</i> leads to delayed flowering, aberrant pollen viability, and poor fertility in tomato. Histological analyses indicate that <i>SlMYB33</i> exerts its function in pollen development in the mature stage. Further transcriptomic analyses imply that the knockdown of <i>SlMYB33</i> significantly inhibits the expression of genes related to flowering in shoot apices, and alters the transcription of genes controlling sugar metabolism in anthers. Taken together, our study suggests that <i>SlMYB33</i> regulates tomato flowering and pollen maturity, probably by modulating the expression of genes responsible for flowering and sugar metabolism, respectively.