Fig. 6: Gene manipulation to mitigate nodule senescence in soybean.

Comparison of ureide export rate (a) and gene expression levels (b) in SULTR overexpression lines. Soybean nodules at 25 dpi from wild-type (WT) and stable transgenic overexpression lines were transplanted to H-N (20 mM total N) for 3 d, and harvested for determination of N export rate and gene expression. Three promoters (pCYP15a, pVPE1, and pEF1α) were used to drive the overexpression of SULTR2;1 or/and SULTR3;5. Relative expression levels were determined by real-time RT-PCR. EF-1α was used as an internal standard. c DAF-2DA staining of NO in nodules after H-N supply. Soybean nodules from WT and overexpression lines at 25 dpi were treated with H-N (20 mM total N) for 3 d, and incubated in 12.5 μM DAF-2DA for 1 h before being imaged by confocal microscopy. Cyan shows signals from cell wall; Green shows signals from DAF-2DA; Red shows signals from mCherry-tagged rhizobia. d Relative NO intensity. The value represents the ratio of green to cyan signals from (c). e The mCherry-tagged rhizobia in infected cells. The value represents the percentage of red signals in the infected cells from (c). f S concentration in symbiosome. Soybean nodules were harvested for symbiosome isolation and S were determined by ICP-AES. The boxes in (a, b, d–f) indicate the first and third quartiles, and the whiskers indicate the minimum and maximum values. The lines within the boxes indicate the median values. n = 6 (a), 4–6 (b), 8 (d), 20 (e) or 3 (f) biologically independent replicates. The P values in (a) were calculated using two-sided t test. The different letters in (b, d–f) indicate significant differences (adjusted P ≤ 0.05) in multiple comparisons tests following two-sided Tukey tests. Source data are provided as a Source Data file.