Figure 7.

FAS1 proteins act sequentially in male gametophyte development: (A) OsMtr1 acts in early stage of tapetum development. It is specifically expressed and secreted in microspore cells (MS) and influences the development of tapetum cells; (B) AtFla3 acts at the late stage of the formation of the cellulose- and pectin-rich intine layer of pollen cell walls; (C) RNA-Seq data of Arabidopsis thaliana at different floral stages [164,165] show that six FAS1 genes are specifically expressed in anthers at different stages of floral development. f1 indicates the first open flower. The expression patterns of AtFla20 that might be the ortholog of OsMtr1 and of AtFla3 are consistent with roles in early and late pollen development, respectively.