Dear Colleagues,

Phosphorus (P) is one of the essential mineral macronutrients for plant growth and development. The predominant P form absorbed by plants is inorganic phosphate (Pi), which is a finite resource on the Earth derived from rocks and is also a limiting factor for crop yields. Thus, understanding the physiological and molecular mechanisms of P-uptake and utilization has been a crucial issue in the field of plant nutrition. In the past decades, great advances have been made in understanding these mechanisms of P-transport, P-metabolism, and P-signaling, with the identification of numerous P-related transporters, enzymes, and regulatory proteins. In addition, evidence for the molecular basis of the interactions between P and other nutrients (e.g., nitrogen and iron) or biological processes (e.g., root and shoot development) is emerging.

Despite these advances, a full understanding of the molecular mechanisms underlying plant P-nutrition is still a long way off. Many open questions remain to be resolved. Selected unresolved questions in each aspect of P-nutrition in plants (A. P-transport; B. P-metabolism; C. P-signaling) are listed as follows:

A1. Which transporters are responsible for the efflux of Pi from the root cell layers with the casparian strip (exodermis/endodermis) and from the mesophyll cells?

A2. How does P distribute at the cellular resolution in different organs/tissues of various plants?

A3. What is the contribution of symplastic transport to P-distribution/redistribution in aboveground source and sink organs?

B1. Do all the genes involved in P-metabolism (e.g., those encoding enzymes catalyzing reactions involving P-containing chemicals) exert roles as annotated and do they play dual/multiple roles as the ‘moonlighting proteins’ similarly to hexokinase?

B2. To what extent can the physiological P-use efficiency be maximized, namely minimizing plant requirement for P while maintaining normal or even higher productivity in different environments?

C1. Which regulatory genes are responsible for monitoring the abundance/activities of Pi transporters for P-distribution and are the known regulators for Pi uptake involved?

C2. Do the interactions between P and other elements occur within plants and affect the distribution of P at the organ/tissue and cellular/subcellular scales? If yes, what regulatory modules are involved?

C3. How do other biotic and abiotic factors, such as insects, light, temperature, pH, etc., modulate P-signaling and -homeostasis? What are the key hubs connecting these molecular interactions?

C4. How does plant sense the Pi-status of soil?

The forthcoming Special Issue aims to take another step forward to fully understand the molecular mechanisms of plant P-nutrition. Some of the aforementioned unresolved questions are not specific to P, and thus could be extended to other mineral nutrients or toxic elements. Moreover, it requires the constant efforts of this research community and the facilitation of state-of-the-art technologies.

Dr. Mian Gu
Dr. Wenyuan Ruan
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Plants is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.