Male cone development and microsporogenesis in Pinus radiata

D. Y. Wang, D. R. Smith, H. A. Outred, R. E. Rowland, D. W. Fountain

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

The developmental timing and cytological detail of male cone development and microsporogenesis in Pinus radiata D.Don (radiata or Monterey pine) growing in the central North Island of New Zealand were studied. Potential male cone primordia were formed by mid-January, and microsporophylls were initiated in late February, the late New Zealand summer. Unlike northern temperate pine species, development of microsporophylls and differentiation of the microsporogenous tissue progressed continuously from late February to early July without a break for dormancy. Meiosis, as inferred by nuclear changes prior to tetrad formation, occurred in late May and was completed by the beginning of July. Pollen was shed in July. Electron microscopy showed major ultrastructural changes during microsporogenesis. Early in development, well-developed plasmodesmata connected all the sporogenous cells and tapetal cells which contained vacuoles, plastids, mitochondria, dictyosomes, an extensive rough endoplasmic reticulum (RER) network, and an abundance of ribosomes. As the pollen mother cells differentiated, the number of plastids, mitochondria, and ribosomes remained abundant but, in contrast, the plasmodesmata between these adjoining cells became blocked and putative autophagic vacuoles appeared. The tapetal cells became radially flattened, their nuclei and cytoplasm were intensely basophilic, and the RER system became highly dilated to form wide channels containing fibrillar material. As development progressed further, a thick callosic wall isolated the pollen mother cells from the tapetal cells. Invagination of the pollen mother cell plasmalemma became prominent along with a reduction in the numbers of plastids and mitochondria.

Original languageEnglish (US)
Pages (from-to)285-307
Number of pages23
JournalNew Zealand Journal of Forestry Science
Volume30
Issue number3
StatePublished - 2000

Keywords

  • Male cone development
  • Microsporogenesis
  • Pinus radiata

ASJC Scopus subject areas

  • Forestry
  • Chemical Engineering(all)
  • Ecology
  • Plant Science

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