A nodule‐localized phosphate transporter GmPT7 plays an important role in enhancing symbiotic N₂ fixation and yield in soybean

Abstract

Summary Symbiotic nitrogen (N2) fixation plays a vital role in sustainable agriculture. Efficient N2 fixation requires various materials, including phosphate (Pi); however, the molecular mechanism underlying the transport of Pi into nodules and bacteroids remains largely unknown. A nodule‐localized Pi transporter, GmPT7, was functionally characterized in soybean (Glycine max) and its role in N2 fixation and yield was investigated via composite and whole transgenic plants. GmPT7 protein was localized to the plasma membrane and showed transport activity for Pi in yeast. Altered expression of GmPT7 changed 33Pi uptake from rhizosphere and translocation to bacteroids. GmPT7 was mainly localized to the outer cortex and fixation zones of the nodules. Overexpression of GmPT7 promoted nodulation, and increased plant biomass, shoot nitrogen and phosphorus content, resulting in improved soybean yield by up to 36%. Double suppression of GmPT5 and GmPT7 led to nearly complete elimination of nodulation and over 50% reduction in plant biomass, shoot nitrogen and phosphorus content, indicating that both GmPT7 and GmPT5 contribute to Pi transport for N2 fixation. Taken together, our results indicate that GmPT7 is a transporter responsible for direct Pi entry to nodules and further to fixation zones, which is required for enhancing symbiotic N2 fixation and grain yield of soybean.

Celebrating 20 Years of Genetic Discoveries in Legume Nodulation and Symbiotic Nitrogen Fixation

“…Low soil phosphate is an important limiting factor of nodule initiation and growth (Le Roux et al, 2009). PHOSPHATE STARVATION RESPONSE25 (GmPHR25)-regulated phosphate transporters GmPT5 (PHOSPHATE TRANSPORTER5) and GmPT7, which likely control phosphorus uptake into nodules, control nodule number and size (Qin et al, 2012;Xue et al, 2017;Chen et al, 2019). Sulfate is also important for SNF.…”

Gene Expression in Nitrogen-Fixing Symbiotic Nodule Cells in Medicago truncatula and Other Nodulating Plants

“…The NPDs in the IRLCs and the MBP-1 and CAP peptides in the Dalbergioids are encoded by multigene families including nodule-specific subsets as well as subsets with constitutive expression (Trujillo et al, 2019). Other examples are the many small metabolite transporter genes that are essential for the formation of functional nodules (Figure 1F; Sugiyama et al, 2017;Frare et al, 2018;Senovilla et al, 2018;Chen et al, 2019). These genes belong to small multigene families, with one copy having nodule-specific or nodule-enhanced expression.…”

Genome-wide survey of soybean papain-like cysteine proteases and their expression analysis in root nodule symbiosis

“…The expression level of Glyma.04G190700, ENOD40, Nodulin35, Calmodulin and Lb1 in pGlyma.04G190700-RNAi or control was determined by qPCR using the primers listed in Table S5 and the procedure as described previously [71,72]. Nitrogenase activity was determined by the acetylene reduction assay (ARA) as described by gas chromatography (GC-14, Japan) [73].…”