A crucial role for a node‐localized transporter, HvSPDT, in loading phosphorus into barley grains

Abstract

Grains are the major sink of phosphorus (P) in cereal crops, accounting for 60-85% of total plant P, but the mechanisms underlying P loading into the grains are poorly understood.We functionally characterized a transporter gene required for the distribution of P to the grains in barley (Hordeum vulgare), HvSPDT (SULTR-like phosphorus distribution transporter).HvSPDT encoded a plasma membrane-localized Pi/H + cotransporter. It was mainly expressed in the nodes at both the vegetative and reproductive stages. Furthermore, its expression was induced by inorganic phosphate (Pi) deficiency. In the nodes, HvSPDT was expressed in both the xylem and phloem region of enlarged and diffuse vascular bundles. Knockout of HvSPDT decreased the distribution of P to new leaves, but increased the distribution to old leaves at the vegetative growth stage under low P supply. However, knockout of HvSPDT did not alter the redistribution of P from old to young organs. At the reproductive stage, knockout of HvSPDT significantly decreased P allocation to the grains, resulting in a considerable reduction in grain yield, especially under P-limited conditions.Our results indicate that node-based HvSPDT plays a crucial role in loading P into barley grains through preferentially distributing P from the xylem and further to the phloem.

Milestones in understanding transport, sensing, and signaling of the plant nutrient phosphorus

“…These findings indicate that SPDT functions as a switch in the rice node to allocate Pi to the grains preferentially. Likewise, barley HvSPDT, mainly expressed in the nodes, also plays an essential role in loading P into grains ( Gu et al . 2022 ).…”

Molecular membrane separation: plants inspire new technologies

“…For example, loss of rice SPDT function resulted in a 20% reduction of P in the grain (Yamaji et al ., 2017). A barley ( Hordeum vulgare ) Pi/H + cotransporter HvSPDT, observed to be localised in nodes of reproductive and vegetative tissues, was recently identified as the primary mechanism responsible for distribution of P to grains (Gu et al ., 2022). In arsenic hyperaccumulator plants like Pteris vittate , there are P transporter encoding genes that were reported to specifically influence P transport, such as PvPht1;2 , and other P transporter genes encoding mechanisms that transport both P and arsenic, such as PvPht1;3 and PvPht1;4 (Cao et al ., 2018; Han et al ., 2022).…”