Ultrastructure of microsporogenesis and microgametogenesis in Brachypodium distachyon

Abstract

Brachypodium distachyon has emerged as a model system for forage grass and cereal grain species. Here, we report B. distachyon pollen development at the ultrastructural level. The process of microsporogenesis and microgametogenesis in B. distachyon follows the typical angiosperm pollen development sequence. Pronounced evaginations of the nuclear envelope are observed prior to meiosis, indicating active nucleocytoplasmic exchange processes. The microspore mother cells undergo meiosis and subsequent cytokinesis, forming isobilateral tetrads. Following dissolution of the callose wall and release of free and vacuolated microspores, mitotic divisions lead to the formation of mature, three-celled ..