Empress trees are native to China. It is mainly found in the low-elevation regions of Anhui, Hebei, Henan, Hubei, Jiangsu, Shaanxi, Shandong, and Shanxi Provinces. Empress trees have significant economic and ornamental value because of its fast growth rate, the quality of its timber (Jiménez et al., 2005; López et al., 2011; Melhuish et al., 1990), its attractive flowers, and its high nitrogen levels, which allow it to serve as a fertilizer and as fodder (Zhu et al., 1986). Empress tree seeds are light-induced seeds with physiologic dormancy, and their dormancy can be broken by gibberellic acid (GA3), cold stratification, and dry storage (Liu et al., 2017). We have tested the seed germination of three species of Paulownia [empress tree, princess tree (P. tomentosa), and foxglove tree (P. fortunei)] harvested in Nanjing, China. The germination of freshly harvested seeds in princess trees and foxglove trees was more than 85%, but that of empress tree seed was only 0% to 50%. Breaking seed dormancy and increasing germination of empress trees are important for production and breeding.
NO is a signal molecule involved in physiologic processes (Delledonne, 2005; Lamotte et al., 2005; Romero-Puertas et al., 2004). NO induces seed germination in the absence of red light (Beligni and Lamattina, 2000), breaks seed dormancy, and affects growth (Beligni and Lamattina, 2001; Durner and Klessig, 1999). Giba et al. (1998) suggested the involvement of NO in the phytochrome-controlled germination of princess tree seeds by using different NO-releasing compounds and appropriate controls. A rapid accumulation of NO induces an equally rapid decrease in abscisic acid and promotes GA3 biosynthesis in arabidopsis (Arabidopsis thaliana) seeds (Debeaujon and Koornneef, 2000; Liu and Zhang, 2009; Liu et al., 2010).
Plants mainly produce endogenous NO through nitric oxide synthase (NOS), nitrate reductase (NR), xanthine oxidoreductase, horseradish peroxidase, and other enzymatic pathways as well as through the nitrification/denitrification cycle via reduction of nitrate and nitrogen dioxide (del Río et al., 2004).
In this study, seeds were treated with sodium nitroprusside (an NO-releasing compound) to investigate the effects of exogenous NO on dormancy and germination of empress tree seeds to determine whether NO-releasing compounds can be used to break seed dormancy. c-PITO [a direct NO scavenger (Bethke et al., 2004)], L-NAME (a nonselective inhibitor of NO synthase, and sodium tungstate [a specific NR inhibitor (Rockel et al., 2002)] were used at different hours during imbibition to investigate the effects of endogenous NO on seed dormancy and germination.
Association of Official Seed Analysts2010Tetrazolium testing handbook. Assn. Official Seed Analysts Washington DC
BeligniM.V.LamattinaL.2000Nitric oxide stimulates seed germination and de-etiolation, and inhibits hypocotyls elongation, three light-inducible responses in plantsPlanta210215221
BethkeP.C.GublerF.JacobsenJ.V.JonesR.L.2004Dormancy of arabidopsis seeds and barley grains can be broken by nitric oxidePlanta219847855
CalvoA.P.NicolásC.O.LorenzoG.NicolásD.DodríguezR.2004Evidence for positive regulation by gibberellins and ethylene of ACC oxidase expression and activity during transition from dormancy to germination in Fagus sylvatica L. seedsPlant Growth Regulat.234453
DebeaujonI.KoornneefM.2000Gibberellin requirement for arabidopsis seed germination is determined both by test characteristics and embryonic abscisic acidPlant Physiol.122415424
GibaZ.GrubišićD.TodorovićS.SajcL.StojakovićĐ.KonjevićR.1998Effect of nitric oxide-releasing compounds on phytochrome-controlled germination of empress tree seedsPlant Growth Regulat.26175181
GniazdowskaA.DobrzyńskaU.BabańczykT.BogatekR.2007Breaking the apple embryo dormancy by nitric oxide involves the stimulation of ethylene productionPlanta22510511057
JiménezL.RodríguezA.FerrerJ.L.PérezA.AnguloV.2005Paulownia, a fast-growing plant, as a raw material for paper manufacturingAfinidad62100105
LamotteO.CourtoisC.BarnavonL.PuginA.WendehenneD.2005Nitric oxide in plants: The biosynthesis and cell signaling properties of a fascinating moleculePlanta22114
LindermayrC.SaalbachG.BahnwegG.DurnerJ.2006Differential inhibition of arabidopsis methionine adenosyl transferases by protein S-nitrosylationBiol. Chem.28142854291
LiuJ.XueT.T.ShenY.B.2017Seed dormancy and germination of Paulownia elongata in response to light, temperature, cold stratification, after-ripening and GA3Seed Sci. Technol.45708713
LiuY.YeN.LiuR.ChenM.ZhangJ.2010H2O2 mediates the regulation of ABA catabolism and GA biosynthesis in Arabidopsis seed dormancy and germinationJ. Expt. Bot.6129792990
LiuY.ZhangJ.2009Rapid accumulation of NO regulates ABA catabolism and seed dormancy during imbibition in ArabidopsisPlant Signal. Behav.4905907
LópezF.PérezA.GarcíaJ.C.FeriaM.J.GarcíaM.M.FernándezM.2011Cellulosic pulp from Leucaena diversifolia by soda-ethanol pulping processChem. Eng. J.1662229
MelhuishJ.H.GentryC.E.BeckjordP.R.1990Paulownia tomentosa seedling growth at different levels of pH, nitrogen and phosphorusJ. Environ. Hort.8205207
NicolásG.NicolásD.DodríguezR.1996Antagonistic effects of ABA and gibberellic acid on the breaking of dormancy of Fagus sylvaticaPhysiol. Plant.96244250
RockelP.StrubeF.RockelA.WildtJ.KaiserW.M.2002Regulation of nitric oxide (NO) production by plant nitrate reductase in vivo and in vitroJ. Expt. Bot.53103110
Romero-PuertasM.C.PerazzolliM.ZagoE.D.DelledonneM.2004Nitric oxide signalling functions in plant-pathogen interactionsCell. Microbiol.6795803
YamasakiH.SakihamaY.TakahashiS.1999An alternative pathway for nitric oxide production in plants: New features of an old enzymeTrends Plant Sci.4128129
ZhuZ.H.ChaoC.J.LuX.Y.XiongY.G.1986Paulownia in China: Cultivation and utilization. Intl. Dev. Res. Ctr. Ottawa Canada