A smoke-induced alteration of the sub-testa cuticle in seeds of the post-fire recruiter, Emmenanthe penduliflora Benth. (Hydrophyllaceae)

Louise M. Egerton-Warburton*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

63 Scopus citations

Abstract

Emmenanthe penduliflora is an obligate fire-recruiter and demonstrates a prolonged seed dormancy followed by germination closely cued to the immediate post-fire environment. This study investigated, at the ultrastructure level, the causal factor(s) associated with seed dormancy and the stimulation of germination after exposure to smoke. The seed coat was responsible for the proximal regulation of dormancy-a waxy cuticular layer situated between the testa and endosperm was the primary barrier to the diffusion of water and small diameter solutes. The sub-testa cuticle in dormant seeds was partially permeable, as indicated by the presence of permeate channels. A short exposure to dry smoke (3 min) promoted a significant increase in seed germination (dormant 8±0.3%; smoke-treated 79±3%). Exposure to smoke also resulted in two major changes to the morphology of the seed. First, smoke treatment produced an intense chemical scarification at the seed surface; the external cuticle was plasticized to form numerous small spheres on the seed surface. Second, smoke significantly altered the permeability of the internal (subtesta) cuticle. A significant increase in both the number and size of permeate channels in the subtesta cuticle indicated that these modifications were directly associated with the breaking of seed dormancy. The observed changes at both the internal (subtesta) and external cuticles are consistent with the hypothesis that volatiles in smoke exert a surfactant-like reaction to break seed dormancy in E. penduliflora.

Original languageEnglish (US)
Pages (from-to)1317-1327
Number of pages11
JournalJournal of Experimental Botany
Volume49
Issue number325
DOIs
StatePublished - Aug 1998

Keywords

  • Chaparral
  • Emmenanthe penduliflora
  • Fire-recruiter
  • Seed coat dormancy
  • Smoke

ASJC Scopus subject areas

  • Physiology
  • Plant Science

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