long-distance signalling
No description yet. This curated deck is ready for daily study.
Card preview (9)
What are the primary modes of long-distance signaling in plants?
• Hormones • Nutrients • Gases (oxygen and carbon dioxide) • Metabolites (e.g., sugars) • RNA and proteins
How does abscisic acid (ABA) function in long-distance signaling?
• ABA is synthesized in roots under water stress and transported to leaves via the xylem to induce stomatal closure. • Split root experiments and ABA radiolabelling show that ABA and conjugates move through the symplast and apoplast, with transport via the xylem being rate-limiting.
How does auxin function in long-distance signaling?
• Auxin is produced in the apex and moves to the base of the plant, playing a crucial role in gravitropism. • The flow of auxin and calcium ions to the lower side of horizontal roots inhibits cell elongation, causing roots to grow downward.
How does nutrient feedback regulate signaling between shoots and roots?
• Nitrate uptake is feedback-regulated based on internal nitrogen levels. • NH4+, glutamine, and other amino acids may mediate feedback inhibition of nitrate transporters in roots. • Hormones, peptides, proteins, and RNA likely play a role in this signaling.
How does oxygen function in long-distance signaling in plants?
• Oxygen is vital for ATP production. Depletion in roots triggers a reduced metabolism in leaves and oxygen transport to roots. • Ethylene plays a role in oxygen signaling, and plants can adapt to hypoxia by inducing enzymes for ethanol fermentation.
What is the role of carbon dioxide (CO2) in long-distance signaling?
• CO2 affects stomatal movement and stomatal density. • High CO2 concentrations decrease stomatal density and interact with sugar signalling pathways. • Jasmonic acid signalling regulates stomatal density in response to elevated CO2.
How do sugars function in long-distance signaling in plants?
• Sugars such as sucrose and glucose are key signaling molecules for growth and flowering. • Sucrose regulates flowering and gene expression, while glucose interacts with hormones and stress responses. • Trehalose affects root elongation, starch accumulation, and photosynthesis.
How do RNA and proteins contribute to long-distance signaling?
• Proteins and RNA move through plasmodesmata (PD), membrane-lined pores between cells. • Large proteins (>50 kDa) and messenger RNA can cross PD. • Movement proteins can dilate PD, enhancing protein and RNA transport. • RNA movement has been observed in the phloem.
How does long-distance signaling coordinate plant responses?
• It enables coordinated growth, development, metabolism, and environmental responses across different plant parts. • This is facilitated by signaling molecules such as hormones, gases, sugars, and RNA/proteins.