Ultrastructural characterization of microlipophagy induced by the interaction of vacuoles and lipid bodies around generative and sperm cells in Arabidopsis pollen

Kae Akita, Tomoko Takagi, Keiko Kobayashi, Kazuyuki Kuchitsu, Tsuneyoshi Kuroiwa, Noriko Nagata

Research output: Contribution to journalArticlepeer-review

Abstract

During pollen maturation, various organelles change their distribution and function during development as male gametophytes. We analyzed the behavior of lipid bodies and vacuoles involved in lipophagy in Arabidopsis pollen using serial section SEM and conventional TEM. At the bicellular pollen stage, lipid bodies in the vegetative cells lined up at the surface of the generative cell. Vacuoles then tightly attached, drew in, and degraded the lipid bodies and eventually occupied the space of the lipid bodies. Degradation of lipid began before transfer of the entire contents of the lipid body. At the tricellular stage, vacuoles instead of lipid bodies surrounded the sperm cells. The degradation of lipid bodies is morphologically considered microautophagy. The atg2-1 Arabidopsis mutant is deficient in one autophagy-related gene (ATG). In this mutant, the assembly of vacuoles around sperm cells was sparser than that in wild-type pollen. The deficiency of ATG2 likely prevents or slows lipid degradation, although it does not prevent contact between organelles. These results demonstrate the involvement of microlipophagy in the pollen development of Arabidopsis.

Original languageEnglish
Pages (from-to)129-138
Number of pages10
JournalProtoplasma
Volume258
Issue number1
DOIs
Publication statusPublished - Jan 2021

Keywords

  • ATG2
  • Lipid body
  • Lipophagy
  • Microautophagy
  • Pollen
  • Vacuole

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