Fungal Association and Utilization of Phosphate by Plants

Flashcards about fungal associations and phosphate utilization by plants.

What is the primary role of phosphorus (P) in plant health and development?

It is a major macronutrient.

Why is available P generally low in the rhizosphere?

Because a major proportion of applied phosphate fertilizers become fixed into insoluble, unavailable forms.

What are the two modes of P uptake by plant roots?

Direct and indirect uptake.

How does direct P uptake occur?

It is facilitated by the plant's own Pi transporters.

How does indirect P uptake occur?

Via mycorrhizal symbiosis, where the host plant obtains P primarily from the fungal partner.

What is the primary benefit for fungi in mycorrhizal symbiosis?

They benefit from plant-derived reduced carbon.

Why is it difficult to exploit the Pi transporter network of arbuscular mycorrhizal fungi for large-scale sustainable agriculture?

Because arbuscular mycorrhizal fungi cannot be cultured axenically.

What is a benefit of using the root-colonizing endophytic fungus Piriformospora indica?

It can grow axenically and provides strong growth-promoting activity during its symbiosis with a broad spectrum of plants.

What is the role of the PiPT transporter in P. indica?

It is a high affinity Pi transporter involved in improving Pi nutrition levels in the host plant under P limiting conditions.

What does the genetic manipulability of P. indica offer?

New vistas to be used in P deficient fields.

Why do plants perform morphological and physiological changes in the roots when they are unable to acquire sufficient amounts of Pi?

To increase soil exploration and the total absorptive surface area.

What are some typical features of roots under Pi limitation?

Enhanced acid and phosphatase secretion and expression of a new kind of Pi transporter.

What is the range of P concentration in plants based on dry weight?

0.05 to 0.5%

What cation complexes is Pi present as under acidic conditions?

Aluminum and iron.

How much of supplied Pi is fixed in insoluble complexes?

Up to 80%

What forms of P are taken up by the roots?

Monovalent H2PO4 − or to a lesser extent as secondary HPO4 2−

What is the function of poly Pi in the cytoplasm or vacuoles?

For short term P security, plants store P as poly Pi in the cytoplasm or vacuoles.

How does AMF increase the absorptive area of plants?

The fine and thinner structure of the fungal hyphae have better access to soil pores and can explore larger soil volumes.

The existence of high- and low-affinity Pi transport systems have been reported in?

Plants, bacteria, yeast, AMF, endophytic fungi and animals.

What is the function of the Pht1 family of plant Pi transporters?

Contains high-affinity transporters