Guard cell starch metabolism at the intersection of environmental stimuli and stomatal movements - presented by Diana Santelia

Guard cell starch metabolism at the intersection of environmental stimuli and stomatal movements

Diana Santelia

Diana Santelia
Slide at 04:23
Distinct pathway of starch degradation in guard cells BAM1 = B-amylase 1 Distinct End of night AMY3 = a-amylase 3 pathways 1 h light BAM1 BAM1 BAM1 bam1 amy3 amy3bam1 AMY3 AMY3 End of night 1 h light Glucose Starch granule End of day AMY3 BAM1 Starch End of night Horrer et al. (2016), Curr Biol Flütsch et al. (2020), Plant Cell bam1 amy3 amy3bam1 Santelia and Lunn (2017), Plant Physiol
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References
  • 1.
    D. Horrer et al. (2016) Blue Light Induces a Distinct Starch Degradation Pathway in Guard Cells for Stomatal Opening. Current Biology
  • 2.
    S. Flütsch et al. (2020) Guard Cell Starch Degradation Yields Glucose for Rapid Stomatal Opening in Arabidopsis. The Plant Cell
  • 3.
    D. Santelia and J. E. Lunn (2017) Transitory Starch Metabolism in Guard Cells: Unique Features for a Unique Function. Plant Physiology
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Summary (AI generated)

Starch in the cell is broken down by two glucanases, BAM1 and AMY3, working together in a distinct pathway. While these enzymes are not typically needed for starch degradation in the leaf, they are crucial in guard cells. A double mutant lacking both BAM1 and AMY3 shows significantly higher levels of starch at the end of the night, which cannot be broken down efficiently as light transitions. This delayed starch degradation leads to a delayed opening of stomata in response to light, as demonstrated in a kinetic experiment showing an increase in opening time of approximately 14 units. This delay is substantial and affects the overall response of the guard cells to light.