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Soybean (Glycine max (L.) Merr.) is an important nutritional crop with high seed protein content. Production of high protein concentrations relies on sufficient nutrient supplies, especially of nitrogen (N) and phosphorus (P). Although the genetic basis for seed quality traits has been well studied, little information exists on any genetic connections between seed quality and nutrient supplies in soybean. Here, a recombinant inbred line (RIL) population of 179 progeny was generated using HC6 and JD17 as parents contrasting in seed quality and N and P translocation efficiencies. Seed protein and N and P translocation efficiencies were higher in HC6 than in JD17. Meanwhile, positive correlations were observed between seed protein content and translocation efficiency of N and P in RILs, implying that high N and P translocation efficiencies might facilitate seed protein accumulation. A genetic map was constructed using 5250 SNP markers covering a genetic distance of 3154.83 cM. A total of 6 loci for quality and 13 loci for N and P translocation efficiency were detected. Among them, two fragments on chromosome 6 and chromosome 20 contained multiple significant markers for both quality and N and P translocation efficiencies, with the respective observed LOD values ranging from 2.98 to 5.61, and 3.01 to 11.91, while the respective PVE values ranged from 8.2% to 13.9%, and 8.3% to 28.0%. Interestingly, one significant locus on chromosome 20 appears to be the product of a transposable element (TE) InDel in Glyma.20G085100, with progeny lacking the TE also exhibiting higher N and P translocation efficiencies, along with higher seed protein contents. Taken together, these results provide genetic evidence that increasing N and P translocation efficiencies may lead to increasing protein contents in soybean seeds. Furthermore, a TE InDel may be used as a genetic marker for breeding elite soybean cultivars with high protein content and N and P translocation efficiencies. [ABSTRACT FROM AUTHOR]

MYB-CC transcription factors (TFs) are essential for plant growth and development. Members of the MYB-CC subfamily with long N terminal domains, such as phosphate starvation response 1 (PHR1) or PHR1-like TFs, have well documented functions, while those with short N terminal domains remain less understood. In this study, we identified a nodule specific MYB-CC transcription factor 1 (GmPHR1) in soybean that is different from other canonical PHR family genes in that GmPHR1 harbors a short N terminal ahead of its MYB-CC domain and was highly induced by rhizobium infection. The overexpression of GmPHR1 dramatically increased the ratio of deformed root hairs, enhanced subsequent soybean nodulation, and promoted soybean growth in pot experiments. The growth promotion effects of GmPHR1 overexpression were further demonstrated in field trails in which two GmPHR1-OE lines yielded 10.78% and 8.19% more than the wild type line. Transcriptome analysis suggested that GmPHR1 overexpression led to global reprogramming, with 749 genes upregulated and 279 genes downregulated, especially for genes involved in MYB transcription factor activities, root growth, and nutrient acquisition. Taken together, we conclude that GmPHR1 is a key gene involved in the global regulation of nodulation, root growth, and nutrient acquisition in soybeans, and is thus a promising candidate gene to target for soybean yield enhancement. [ABSTRACT FROM AUTHOR]

Soybean (Glycine max L.) is a major crop providing important source for protein and oil for human life. Low phosphate (LP) availability is a critical limiting factor affecting soybean production. Soybean plants develop a series of strategies to adapt to phosphate (Pi) limitation condition. However, the underlying molecular mechanisms responsible for LP stress response remain largely unknown. Here, we performed a label-free quantification (LFQ) analysis of soybean leaves grown under low and high phosphate conditions. We identified 267 induced and 440 reduced differential proteins from phosphate-starved leaves. Almost a quarter of the LP decreased proteins are involved in translation processes, while the LP increased proteins are accumulated in chlorophyll biosynthetic and carbon metabolic processes. Among these induced proteins, an enolase protein, GmENO2a was found to be mostly induced protein. On the transcriptional level, GmENO2a and GmENO2b, but not GmENO2c or GmENO2d, were dramatically induced by phosphate starvation. Among 14 enolase genes, only GmENO2a and GmENO2b genes contain the P1BS motif in their promoter regions. Furthermore, GmENO2b was specifically induced in the GmPHR31 overexpressing soybean plants. Our findings provide molecular insights into how soybean plants tune basic carbon metabolic pathway to adapt to Pi deprivation through the ENO2 enzymes. [ABSTRACT FROM AUTHOR]