Hydrogen peroxide is involved in abscisic acid\|induced adventitious root formation in cucumber under drought stress
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DOI:10.7606/j.issn.1000-7601.2018.03.29
Key Words: drought stress  adventitious root of cucumber  abscisic acid(ABA)  hydrogen peroxide(H2O2)  water balance  cell membrane stability  osmotic adjustment substances
Author NameAffiliation
LI Xue-ping College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu 730070 
JIN Xin College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu 730070 
LIAO Wei-biao College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu 730070 
HU Lin-li College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu 730070 
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Abstract:
      Cucumber (Cucumis sativus. L) was used as a test material and we used polyethylene glycol to simulate drought stress to cucumber. The effect of H2O2 and ABA on adventitious root development of cucumber (Cucumis sativus. L) under drought stress and their interrelationship were studied. The results indicated that 0.3% PEG could simulate moderate drought stress. Exogenous H2O2 and ABA had significant positive effect on adventitious root development of cucumber explants under drought stress and the effect was dose\|dependent with a maximal biological response at 800 μmol·L-1 H2O2 and 0.5 μmol·L-1 ABA treatment. The root number developed in H2O2 + ABA treatment was 19.3% and 31.3% higher than that in H2O2 or ABA single treatment, respectively. Compared with ABA single treatment, the root numbers in ABA + H2O2 scavenger (CAT) or ABA + H2O2 inhibitor (DPI) treatment decreased by 15.2% and 30.9%, respectively under drought stress. The root length decreased by 24.1% and 26%, respectively. The results showed that PEG + ABA treatment has decreased stomatal aperture, density and relative electric conductivity by 24.2%, 15.4% and 14.2% compared to the PEG treatment; while it has increased the relative water content by 25%. Moreover, PEG + ABA treatment has increased the content of osmotic adjustment substances (praline, water soluble carbohydrate and soluble protein) and the activity of the peroxidase, polyphenol oxidase and indoleacetate oxidase, while has decreased the content of malondialdehyde. However, CAT treatment significantly reversed the promoting function of ABA in adventitious root formation under drought stress. Therefore, endogenous H2O2 might be regulating water balance, cell membrane stability, osmotic adjustment substances and relative enzyme activity, involving in the signaling pathway of ABA\|induced adventitious rooting under drought stress.