אסיף מאגר המחקר החקלאי

Dynamic interactions between root influx and long-distance N translocation in rice: Insights into feedback processes

Year:

1998

Source of publication :

Authors :

Volume :

39

Co-Authors:

Kronzucker, H.J., Department of Plant Sciences, University of Western Ontario, London, Ont. N6A 5B7, Canada, International Rice Research Institute (IRRI), P.O. Box 933, 1099 Manila, Philippines
Schjoerring, J.K., Plant Nutrition Laboratory, Royal Veterinary and Agricultural University, DK-1871 FC, Copenhagen, Denmark
Enter, Y., Department of Citriculture, ARO the Volcani Center, Bet-Dagan 50250, Israel
Kirk, G.J.D., International Rice Research Institute (IRRI), P.O. Box 933, 1099 Manila, Philippines
Yaeesh Siddiqi, M., Department of Botany, University of British Columbia, Vancouver, B.C. V6T 1Z4, Canada
Glass, A.D.M., Department of Botany, University of British Columbia, Vancouver, B.C. V6T 1Z4, Canada

Facilitators :

Link :

Abstract:

Ammonium influx into roots and N translocation to the shoots were measured in 3-week-old hydroponically grown rice seedlings (Oryza sativa L., cv. IR72) under conditions of N deprivation and NH4/+ resupply, using 13NH4/+ as a tracer. Root NH4/+ influx was repressed in plants continuously supplied with NH4/+ (at 0.1 mM), but a high proportion of absorbed N (20 to 30%) was translocated to the shoot in the form of N assimilates during the 13-min loading and desorption periods. Interruption of exogenous NH4/+ supply for periods of 1 to 3 d caused NH4/+ influx to be de-repressed. This same treatment caused N translocation to the shoot to decline rapidly, until, by 24 h, less than 5% of the absorbed 13N was translocated to the shoot, illustrating a clear priority of root over shoot N demand under conditions of N deprivation. Upon resupplying 1 mM NH4/+ root NH4/+ influx responded in a distinct four-phase pattern, exhibiting periods in which NH4/+ influx was first enhanced and subsequently reduced. Notably, a 25 to 40% increase in root influx, peaking at ~2 h following re-exposure was correlated with a 4- to 5-fold enhancement in shoot translocation and a repression of root GS activity. The transient increase of NH4/+ influx was also observed in seedlings continuously supplied with NO3/- and subsequently transferred to NH4/+. Extended exposure to NH4/+ caused root NH4+ influx to decrease progressively, while shoot translocation was restored to ~30% of incoming NH4/+. The nature of the feedback control of NH4/+ influx as well as the question of its inducibility are discussed.

Note:

Related Files :

תוכן קשור

More details

You may also be interested in