In reproduction

The life-cycle of multicellular plants alternates between the sporophyte (the long-lived conspicuous phase of angiosperms) and the gametophyte generation (Gifford and Foster 1988). Cell degeneration occurs during formation both of female and of male gametes (Wu and Cheun 2000). Development of the female gametophyte of angiosperms (megagametogenesis) typically begins with the four haploid megaspores produced by meiotic division of the megaspore mother cell within the ovule (Yadegari and Drews 2004). The three megaspores towards the micropylar end degenerate by what is believed to be a programmed cell death process leaving the surviving megaspore to undergo three successive mitotic divisions to produce an eight-nucleate megagametophyte (Punwani and Drews 2007). Selective cell senescence also occurs during microsporogenesis (McCormick 2004) where the tapetum that surrounds the microsporocytes dies and disintegrates during pollen formation.

References

• Gifford, E.M. and Foster, A.S. (1988) Morphology and Evolution of Vascular Plants, 3rd edn, New York: W.H. Freeman.
• McCormick? S (2004) Control of male gametophyte development. Plant Cell, 16(Suppl.): S142–S153?.
• Punwani JA, Drews GN (2007) Development and function of the synergid cell. Sexual Plant Reproduction 21:7-15.
• Wu HM, Cheun AY (2000) Programmed cell death in plant reproduction. Plant Molecular Biology 44: 267–281.
• Yadegari R, Drews GN (2004) Female gametophyte development. Plant Cell, 16(Suppl.): S133–S141?.