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Effect of mineral sulphur availability on nitrogen and sulphur uptake and remobilization during the vegetative growth of Brassica napus L

Abdallah, M., Dubousset, L., Meuriot, F., Etienne, P., Avice, J.C., Ourry, A.
Journal of experimental botany 2010 v.61 no.10 pp. 2635-2646
Brassica napus var. napus, adaptation, leaves, nitrogen, plasma membrane, roots, sulfates, sulfur, tonoplast, transporters, vegetative growth
Because it has a high demand for sulphur (S), oilseed rape is particularly sensitive to S limitation. However, the physiological effects of S limitation remain unclear, especially during the rosette stage. For this reason a study was conducted to determine the effects of mineral S limitation on nitrogen (N) and S uptake and remobilization during vegetative growth of oilseed rape at both the whole-plant and leaf rank level for plants grown during 35 d with 300 μM ³⁴SO₄²⁻ (control plants; +S) or with 15 μM ³⁴SO₄²⁻ (S-limited plants; -S). The results highlight that S-limited plants showed no significant differences either in whole-plant and leaf biomas or in N uptake, when compared with control plants. However, total S and ³⁴S (i.e. deriving from S uptake) contents were greatly reduced for the whole plant and leaf after 35 d, and a greater redistribution of endogenous S from leaves to the benefit of roots was observed. The relative expression of tonoplast and plasmalemma sulphate transporters was also strongly induced in the roots. In conclusion, although S-limited plants had 20 times less mineral S than control plants, their development remained surprisingly unchanged. During S limitation, oilseed rape is able to recycle endogenous S compounds (mostly sulphate) from leaves to roots. However, this physiological adaptation may be effective only over a short time scale (i.e. vegetative growth).