The interplay between P uptake pathways in mycorrhizal peas: a combined physiological and gene‐silencing approach. Issue 2 (15th March 2013)

• Record Type: Journal Article
• Authors: Grønlund, Mette; Albrechtsen, Merete; Johansen, I. Elisabeth; Hammer, Edith C.; Nielsen, Tom H.; Jakobsen, Iver
• Is Part Of: Physiologia plantarum. Volume 149:Issue 2(2013:Oct.)
• Page Start: 234
• Page End: 248
• Publication Date: 2013-03-15
• Subjects: Plant physiology -- Periodicals; 571.2
• DOI: 10.1111/ppl.12030
• Languages: English
• ISSNs: 0031-9317

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>Arbuscular mycorrhizal fungi (AMF) have a key role in plant phosphate (Pi) uptake by their efficient capture of soil phosphorus (P) that is transferred to the plant via Pi transporters in the root cortical cells. The activity of this mycorrhizal Pi uptake pathway is often associated with downregulation of Pi transporter genes in the direct Pi uptake pathway. As the total Pi taken up by the plant is determined by the combined activity of mycorrhizal and direct pathways, it is important to understand the interplay between these, in particular the actual activity of the pathways. To study this interplay we modulated the delivery of Pi via the mycorrhizal pathway in <italic>Pisum sativum</italic> by two means: (1) Partial downregulation by virus‐induced gene silencing of <italic>PsPT4</italic>, a putative Pi transporter gene in the mycorrhizal pathway. This resulted in decreased fungal development in roots and soil and led to reduced plant Pi uptake. (2) Changing the percentage of AMF‐colonized root length by using non‐, half‐mycorrhizal or full‐mycorrhizal split‐root systems. The combination of split roots, use of <sup>32</sup>P and <sup>33</sup>P isotopes and partial silencing of <italic>PsPT4</italic> enabled us to show that the expression of <italic>PsPT1</italic>, a putative Pi transporter gene in the direct pathway, was negatively correlated with increasing mycorrhizal uptake capacity of the plant, both locally and systemically. However, transcript changes in <italic>PsPT1</italic> were not translated into corresponding, systemic changes in actual direct Pi uptake. Our results suggest that AMF have a limited long‐distance impact on the direct pathway.</p> </abstract>