Rapid N transport to pods and seeds in N-deficient soybean plants

Abstract

Non-nodulated soybean (Glycine max (L.) Merr.) plants were cultivated hydroponically under N-sufficient (5 mM NaNO(3)) or N-deficient (0.5 mM NaNO(3)) conditions. (13)N- or (15)N- labelled nitrate was fed to the cut end of the stems, and the accumulation of nitrate-derived N in the pods, nodes and stems was compared. Real-time images of (13)N distribution in stems, petioles and pods were obtained using a Positron Emitting Tracer Imaging System for a period of 40 min. The results indicated that the radioactivity in the pods of N-deficient plants was about 10 times higher than that of N-sufficient plants, although radioactivity in the stems and nodes of N-deficient versus N-sufficient plants was not different. A similar result was obtained by supplying (15)NO(3) to cut soybean shoots for 1 h. The fact that the N translocation into the pods from NO(3) fed to the stem base was much faster in N-deficient plants may be due to the strong sink activity of the pods in N-deficient plants. Alternatively, the redistribution of N from the leaves to the pods via the phloem may be accelerated in N-deficient plants. The temporal accumulation of (13)NO(3) in nodes was suggested in both N-sufficient and N-deficient plants. In one (13)NO(3) pulse-chase experiment, radioactivity in the stem declined rapidly after transferring the shoot from the (13)NO(3) solution to non-labelled NO(3); in contrast, the radioactivity in the node declined minimally during the same time period.

Non-invasive approaches for phenotyping of enhanced performance traits in bean

“…By combining MRI with PET technology, it is possible to reveal both structural traits and transport functionality of bulky organs such as sugar beets and roots hidden in soil ). Phloem and xylem transport of other short-lived radionuclides can be measured as well, such as 13 N (Kiyomiya et al 2001;Ohtake et al 2001;Gómez et al 2010), 15 O (Nakanishi et al 2002;Ohya et al 2008) or 52 Fe (Tsukamoto et al 2009). Quantitative information and physiological parameters about metabolite fluxes, however, require robust analysis that allows for both the tracer's short half-life and also its lack of equilibrium (e.g.…”

52Mn translocation in barley monitored using a positron-emitting tracer imaging system

“…Recently, positron-emitting nuclides have been used in plants to study the distribution and translocation of 18 F (Kume et al 1997), [ 11 C]methionine (Bughio et al 2001;Nakanishi et al 1999), 11 C (Fujikake et al 2003;Matsuhashi et al 2005), (Hayashi et al 1997;Matsunami et al 1999;Ohtake et al 2001), 13 N (Kiyomiya et al 2001b), (Kiyomiya et al 2001a;Mori et al 2000;Nakanishi et al 2002;Tsukamoto et al 2004) and 52 Fe, 52 Mn and 62 Zn (Watanabe et al 2001) using a positron-emitting tracer imaging system (PETIS). With this technique, γ-rays produced by positron-emitting nuclides are detected by scintillation detectors, allowing the real-time investigation of the movement of elements in intact plants.…”

Exploring the transport of plant metabolites using positron emitting radiotracers

“…While this spatial resolution is four times finer than that of the Duke prototype PET device, the imaging area is reduced by about a factor of 8. Since this original application, the PETIS device has been used to visualize translocation of 11 C-labeled methionine in barley (Nakanishi et al, 1999), 13 N-labeled nitrates in soybean plants (Ohtake et al, 2001), 13 N-labeled ammonium in rice (Kiyomiya et al, 2001b), and 15 O-labeled water in soybean plants (Nakanishi et al, 2001a). The primary limitation of the original PETIS was the small FOV.…”