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Remobilization of leaf S compounds and senescence in response to restricted sulphate supply during the vegetative stage of oilseed rape are affected by mineral N availability

Author:
Dubousset, L., Abdallah, M., Desfeux, A.S., Etienne, P., Meuriot, F., Hawkesford, M.J., Gombert, J., Ségura, R., Bataillé, M.P., Rezé, S., Bonnefoy, J., Ameline, A.F., Ourry, A., Dily, F. Le, Avice, J.C.
Source:
Journal of experimental botany 2009 v.60 no.11 pp. 3239-3253
ISSN:
0022-0957
Subject:
Brassica napus var. napus, gene expression, leaves, senescence, shoots, sulfates, sulfur, transporters, vegetative growth
Abstract:
The impact of sulphur limitation on the remobilization of endogenous S compounds during the rosette stage of oilseed rape, and the interactions with N availability on these processes, were examined using a long-term ³⁴SO[Formula: see text] labelling method combined with a study of leaf senescence progression (using SAG12/Cab as a molecular indicator) and gene expression of the transporters, BnSultr4;1 and BnSultr4;2, involved in vacuolar sulphate efflux. After 51 d on hydroponic culture at 0.3 mM ³⁴SO[Formula: see text] (1 atom% excess), the labelling was stopped and plants were subject for 28 d to High S-High N (HS-HN, control), Low S-High N (LS-HN) or Low S-Low N (LS-LN) conditions. Compared with the control, LS-HN plants showed delayed leaf senescence and, whilst the shoot growth and the foliar soluble protein amounts were not affected, S, ³⁴S, and SO[Formula: see text] amounts in the old leaves declined rapidly and were associated with the up-regulation of BnSultr4;1. In LS-LN plants, shoot growth was reduced, leaf senescence was accelerated, and the rapid S mobilization in old leaves was accompanied by decreased ³⁴S and SO[Formula: see text], higher protein mobilization, and up-regulation of BnSultr4;2, but without any change of expression of BnSultr4;1. The data suggest that to sustain the S demand for growth under S restriction (i) vacuolar SO[Formula: see text] is specifically remobilized in LS-HN conditions without any acceleration of leaf senescence, (ii) SO[Formula: see text] mobilization is related to an up-regulation of BnSultr4;1 and/or BnSultr4;2 expression, and (iii) the relationship between sulphate mobilization and up-regulation of expression of BnSultr4 genes is specifically dependent on the N availability.
Agid:
501259