The tale of tapetum: from anther walls to pollen wall

Tapetum plays the most dynamic role in the development of the male germline in plants involving a time dependent shift from secretory and biosynthetic activity to its differentiation induced programmed cell death. Several genes regulating the specification of the tapetum and its subsequent impact on the cell fate of microsporocytes have been identified from genetic screening of male sterile lines and with the advent of single cells sequencing. In this review we have discussed the signaling mechanisms operational during the establishment of tapetum from the anther primordia, the biogenesis and role of miRNAs from tapetal cells in microsporogenesis, the biosynthetic and secretory functions of these specialized cells, cytomorphic changes in the tapetal cells during different stages, and finally the significance of its degradation in pollen grain development.