Energetics of acclimation to NaCl by submerged, anoxic rice seedlings.
Our aim was to elucidate how plant tissues under a severe energy crisis cope with imposition of high NaCl, which greatly increases ion fluxes and hence energy demands. The energy requirements for ion regulation during combined salinity and anoxia were assessed to gain insights into ion transport processes in the anoxia-tolerant coleoptile of rice.



We studied the combined effects of anoxia plus 50 or 100 mm NaCl on tissue ions and growth of submerged rice (Oryza sativa) seedlings. Excised coleoptiles allowed measurements in aerated or anoxic conditions of ion net fluxes and O2consumption or ethanol formation and by inference energy production.



Over 80 h of anoxia, coleoptiles of submerged intact seedlings grew at 100 mm NaCl, but excised coleoptiles, with 50 mm exogenous glucose, survived only at 50 mm NaCl, possibly due to lower energy production with glucose than for intact coleoptiles with sucrose as substrate. Rates of net uptake of Na+and Cl-by coleoptiles in anoxia were about half those in aerated solution. Ethanol formation in anoxia and O2uptake in aerobic solution were each increased by 13-15 % at 50 mm NaCl, i.e. ATP formation was stimulated. For acclimation to 50 mm NaCl, the anoxic tissues used only 25 % of the energy that was expended by aerobic tissues. Following return of coleoptiles to aerated non-saline solution, rates of net K+uptake recovered to those in continuously aerated solution, demonstrating there was little injury during anoxia with 50 mm NaCl.



Rice seedlings survive anoxia, without the coleoptile incurring significant injury, even with the additional energy demands imposed by NaCl (100 mm when intact, 50 mm when excised). Energy savings were achieved in saline anoxia by less coleoptile growth, reduced ion fluxes as compared to aerobic coleoptiles and apparent energy-economic ion transport systems.
School of Plant Biology and tuti_b@ugm.ac.id.
Budiastuti
B
Kurniasih
School of Plant Biology and.
Hank
H
Greenway
School of Plant Biology and.|Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
Timothy David
TD
Colmer
D000064:Acclimatization / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology; D000431:Ethanol / Q000378:metabolism; D018525:Germination / Q000502:physiology; D000860:Hypoxia; D012275:Oryza / Q000378:metabolism* / Q000502:physiology; D010101:Oxygen Consumption; D055049:Salt Tolerance / Q000502:physiology; D036226:Seedlings / Q000378:metabolism* / Q000502:physiology; D012965:Sodium Chloride
D000431:Ethanol; D012965:Sodium Chloride
Anoxia tolerance; NaCl ×; Oryza sativa; anaerobic catabolism; anoxia interaction; anoxia plus NaCl; coleoptile; complete submergence; energetics; energy crisis; energy efficient transport; ethanolic fermentation; germination; salinity tolerance
Physiol Plant. 2013 Oct;149(2):222-33
23379468
Microbiol Mol Biol Rev. 1999 Jun;63(2):334-48
10357854
New Phytol. 2015 Dec;208(4):1114-25
26094736
Plant Physiol. 1994 Nov;106(3):1131-1136
12232395
Plant Cell Environ. 2014 Mar;37(3):589-600
23937055
Plant J. 1996 Sep;10(3):451-8
8811859
J Exp Bot. 2012 Mar;63(5):1969-83
22174442
Planta. 1988;176:109-16
11539804
J Biol Chem. 1951 Nov;193(1):265-75
14907713
J Exp Bot. 2012 Jul;63(12):4389-402
22585748
Plant Physiol. 2011 Jul;156(3):1006-15
21562330
Annu Rev Plant Physiol Plant Mol Biol. 1997 Jun;48:223-250
15012263
Ann Bot. 2009 Jan;103(2):197-209
19001425
Ann Bot. 2005 Sep;96(4):519-32
16024558
Plant Physiol. 1995 Nov;109(3):735-742
12228628
J Exp Bot. 2005 Sep;56(419):2453-63
16061509
Funct Plant Biol. 2003 Feb;30(1):1-47
32688990
Biochim Biophys Acta. 1980 Jul 8;591(2):224-33
6446935
Plant Physiol. 1991 Mar;95(3):760-7
16668051
Plant Physiol. 1990 Dec;94(4):1561-7
16667890
Plant Physiol. 2013 Jun;162(2):940-52
23624857
Plant Physiol. 1983 Jan;71(1):30-4
16662793
New Phytol. 1985 Sep;101(1):25-77
33873830
Funct Plant Biol. 2013 Aug;40(9):759-774
32481149
New Phytol. 2008;177(4):918-926
18086222
New Phytol. 2015 Apr;206(1):36-56
25472708
Plant Cell Physiol. 2006 Mar;47(3):401-9
16418229
Plant Physiol. 1991 Jan;95(1):242-50
16667959
New Phytol. 2009;183(2):243-246
19453430
Ann Bot. 2016 May;117(6):1083-97
27063367
Annu Rev Plant Biol. 2008;59:651-81
18444910
J Exp Bot. 2011 Jan;62(1):39-57
20847100
J Exp Bot. 2003 Oct;54(391):2363-73
14504303
Biochem J. 1954 Jul;57(3):508-14
13181867
J Exp Bot. 2001 Jul;52(360):1507-17
11457911
Plant Cell Environ. 2010 Apr;33(4):566-89
19895402
Planta. 2004 Feb;218(4):615-22
14663584
Science. 1986 Jan 17;231(4735):234-41
2417316
Talanta. 1984 Apr;31(4):235-40
18963579