Olukayode, T.; Chen, J.; Zhao, Y.; Quan, C.; Kochian, L.V.; Ham, B.-K. Phloem-Mobile MYB44 Negatively Regulates Expression of PHOSPHATE TRANSPORTER 1 in Arabidopsis Roots. Plants2023, 12, 3617.
Olukayode, T.; Chen, J.; Zhao, Y.; Quan, C.; Kochian, L.V.; Ham, B.-K. Phloem-Mobile MYB44 Negatively Regulates Expression of PHOSPHATE TRANSPORTER 1 in Arabidopsis Roots. Plants 2023, 12, 3617.
Olukayode, T.; Chen, J.; Zhao, Y.; Quan, C.; Kochian, L.V.; Ham, B.-K. Phloem-Mobile MYB44 Negatively Regulates Expression of PHOSPHATE TRANSPORTER 1 in Arabidopsis Roots. Plants2023, 12, 3617.
Olukayode, T.; Chen, J.; Zhao, Y.; Quan, C.; Kochian, L.V.; Ham, B.-K. Phloem-Mobile MYB44 Negatively Regulates Expression of PHOSPHATE TRANSPORTER 1 in Arabidopsis Roots. Plants 2023, 12, 3617.
Abstract
Phosphorus (P) is an essential plant macronutrient; however, its availability is often limited in soils. Plants have evolved complex mechanisms for efficient phosphate (Pi) absorption, which are responsive to changes in external and internal Pi concentration, and orchestrated through local and systemic responses. To explore these systemic Pi responses, here, we identified AtMYB44 as a phloem-mobile mRNA, an Arabidopsis homolog of Cucumis sativus MYB44, that is responsive to the Pi-starvation stress. qRT-PCR assays revealed that AtMYB44 was up-regulated and expressed in both shoot and root in response to Pi-starvation stress. The atmyb44 mutant displayed higher shoot and root biomass, compared to wild-type plants, under Pi-starvation conditions. Interestingly, the expression of PHOSPHATE TRANSPORTER1;2 (PHT1;2) and PHT1;4 was enhanced in atmyb44 in response to a Pi-starvation treatment. A split-root assay showed that AtMYB44 expression was systemically regulated, under Pi-starvation conditions and, in atmyb44, systemic controls on PHT1;2 and PHT1;4 expression were moderately disrupted. Heterografting assays confirmed graft transmission of AtMYB44 transcripts, and PHT1;2 and PHT1;4 expression was decreased in heterografted atmyb44 rootstocks. Taken together, our findings support the hypothesis that mobile AtMYB44 mRNA serves as a long-distance Pi response signal, which negatively regulates Pi transport and utilization in Arabidopsis.
Keywords
Pi-starvation stress; mobile mRNA; phloem; systemic signaling
Subject
Biology and Life Sciences, Plant Sciences
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
