Data from: A cucumber protein, Phloem Phosphate Stress Repressed 1, rapidly degrades in response to a phosphate stress condition

Under depleted external phosphate (Pi), many plant species adapt to this
stress by initiating downstream signalling cascades. In plants, the
vascular system delivers nutrients and signalling agents to control
physiological and developmental processes. Currently, limited information
is available regarding the direct role of phloem-borne long-distance
signals in plant growth and development under Pi-stress conditions. Here,
we report on the identification and characterization of a cucumber
protein, Cucumis sativus Phloem Phosphate-Stress-Repressed 1 (CsPPSR1),
whose level in the phloem translocation stream rapidly responds to imposed
Pi-limiting conditions. CsPPSR1 degradation is mediated by the 26S
proteasome; under Pi-sufficient conditions, CsPPSR1 is stabilized by its
phosphorylation, within the sieve tube system, through the action of
CsPPSR1 Kinase. Further, we discovered that CsPPSR1 Kinase was susceptible
to Pi-starvation-induced degradation, in the sieve tube system. Our
findings offer insight into a molecular mechanism underlying the response
of phloem-borne proteins to Pi-limited stress conditions.