13. Translocation in the Phloem 2_Lecture Note_2024.09.23

It ensures the distribution of essential nutrients to growing tissues and storage organs.

14 CO2 is used as a tracer to study carbon allocation and movement in plants during the transition from sink to source.

A model explaining how oligosaccharides are trapped in the phloem for transport.

The process by which sugars are transported through the cell walls and intercellular spaces of plant tissues.

In the phloem, particularly during the loading of sugars into the phloem sieve elements.

Source is where sugars are produced, and sink is where they are used or stored.

Oligomers are trapped in the phloem, facilitating the transport of nutrients.

They are larger molecules that cannot easily diffuse out of the phloem.

It co-transports sucrose and protons into the cell.

A model explaining how oligosaccharides are trapped in the phloem for transport.

In the root system, particularly in the uptake of water and nutrients.

The Pressure-Flow Model.

They assist in loading and unloading sugars into the phloem.

They work together to ensure efficient transport of water, nutrients, and sugars throughout the plant.

A part of the plant that produces or stores carbohydrates, such as leaves.

Symplastic and apoplastic pathways.

The process where plant tissues change from being carbon sinks (storing carbon) to sources (releasing carbon) as they mature.

They are co-transported into the cell together.

Through the interconnected cytoplasm of adjacent cells.

It explains the movement of sap in the phloem of plants.

It suggests that nutrients move from areas of high pressure to areas of low pressure.

They are the sites where nutrients are utilized or stored.

Carbon dioxide (CO2).

Sucrose is a primary form of sugar transported in plants.

It uses the energy from the proton gradient to facilitate sucrose transport.

It allows for rapid transport of nutrients and water without crossing cell membranes.

Differences in pressure between source and sink regions.

A model that explains how certain molecules are retained in the phloem during transport.

It facilitates the distribution of nutrients necessary for growth.

To transport sugars and other metabolic products downward from the leaves.

Raffinose and stachyose in addition to sucrose.

From source to sink.

A plasma-membrane sucrose-H+ symporter.

Symporter mechanism.

It is a form of secondary active transport.

A process where sugars are transported through the cytoplasm of plant cells via plasmodesmata.

Apoplastic and symplastic phloem loading.

Water and dissolved minerals from the roots to the rest of the plant.

A method of phloem loading where sugars move through the cell walls and intercellular spaces before entering the phloem.

Xylem and phloem.

Xylem provides structural support due to its lignified cell walls.

Through various transport mechanisms and physiological processes.

The process of transporting sugars into the phloem from source tissues.

The process by which sugars and other solutes are transported into the sieve elements of the phloem.

A method of phloem loading where solutes move through the cell walls and intercellular spaces before entering the sieve elements.

The process where substances move through the cell walls and intercellular spaces, bypassing the cytoplasm.

They connect plant cells, allowing for the movement of substances between them.

Xylem and phloem.

Areas where sugars are produced or stored, such as leaves.

A method of phloem loading where sugars move through the cytoplasm of cells via plasmodesmata.

The shift in the role of plant tissues from being a sink (receiving sugars) to a source (producing sugars).

Herbs and woody species.

It is related to the activity of the sucrose-H+ symporter encoded by the SUC2 gene.

A method of phloem loading where solutes move through the cytoplasm of cells via plasmodesmata.

The process by which sugars and other nutrients are loaded into the sieve elements of the phloem.

They work together to facilitate the long-distance transport of sugars in plants.

Areas where sugars are utilized or stored, such as roots or fruits.

Sugars and other nutrients.

Carbon fixation, reduction, and regeneration of RuBP.

Transporter driven.

High.

A part of the plant that consumes or stores carbohydrates, such as roots or fruits.

Higher sugar concentrations in source tissues drive the loading process into the phloem.

It influences the distribution of resources and energy within the plant, impacting overall growth and development.

In the root and leaf tissues.

Passive transport, as it relies on concentration gradients.

The process where resources move from areas of storage (sink) to areas of growth (source).

By facilitating the distribution of essential nutrients and water.

Active transport and diffusion.

In the stroma of chloroplasts.

Glucose and other carbohydrates.

Transfer cells.

They assist in the transport of sugars into the sieve tubes.

Protons (H+).

Diffusion, osmosis, and active transport.

Plasmodesmata are not involved in apoplastic loading as this process bypasses the cytoplasm.

To transport sugars and other metabolic products downward from the leaves.

The process by which sugars and other nutrients are transported from the phloem to sink tissues.

The process of transporting sugars from the phloem to sink tissues.

To transport water and minerals from the roots to the rest of the plant.

RuBP (ribulose bisphosphate) acts as the carbon dioxide acceptor.

Sieve element – companion cell complex.

The process of transporting sugars and other organic nutrients into the phloem from source tissues.

It transports sucrose into cells using the proton gradient.

A method of loading where substances move through the cytoplasm of cells via plasmodesmata.

It ensures that cells receive necessary nutrients and water for metabolic processes.

Oligomer-Trapping Model.

Pressure differences between source and sink tissues.

It enhances the efficiency of nutrient transport by retaining essential molecules.

It provides essential nutrients for growth and development.

To convert carbon dioxide into glucose.

ATP and NADPH.

Mainly herbaceous.

It involves the movement of water and nutrients over short distances within plant tissues.

Apoplastic loading involves movement through cell walls, while symplastic loading involves movement through the cytoplasm of cells.

To transport water, nutrients, and sugars throughout the plant.

How sugars and nutrients are transported through the phloem.

It describes how oligosaccharides are trapped in the phloem to facilitate transport.

Transpiration creates a negative pressure that helps pull water up through the xylem, which is essential for phloem function.

Passive symplasmic loading.

Low in apoplastic loading, high in symplasmic loading.

Mesophyll cells.

Phloem transports sugars from sources to sinks, while xylem transports water and nutrients.

They facilitate the movement of substances between plant cells.