AUTHOR=Wei Lijie , Deng Xing-Guang , Zhu Tong , Zheng Ting , Li Peng-Xu , Wu Jun-Qiang , Zhang Da-Wei , Lin Hong-Hui 

TITLE=Ethylene is involved in brassinosteroids induced alternative respiratory pathway in cucumber (Cucumis sativus L.) seedlings response to abiotic stress

JOURNAL=Frontiers in Plant Science

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2015.00982

DOI=10.3389/fpls.2015.00982

ISSN=1664-462X

ABSTRACT=<p>Effects of brassinosteroids (BRs) on cucumber (<italic>Cucumis sativus</italic> L.) abiotic stresses resistance to salt, polyethylene glycol (PEG), cold and the potential mechanisms were investigated in this work. Previous reports have indicated that BRs can induce ethylene production and enhance alternative oxidase (AOX) pathway. The mechanisms whether ethylene is involved as a signal molecule which connected BR with AOX in regulating stress tolerance are still unknown. Here, we found that pretreatment with 1 μM brassinolide (BL, the most active BRs) relieved stress-caused oxidative damage in cucumber seedlings and clearly enhanced the capacity of AOX and the ethylene biosynthesis. Furthermore, transcription level of ethylene signaling biosynthesis genes including ripening-related <italic>ACC</italic> synthase1 (<italic>C</italic><sub><italic>S</italic></sub><italic>ACS1</italic>), ripening-related <italic>ACC</italic> synthase2 (<italic>C</italic><sub><italic>S</italic></sub><italic>ACS2</italic>), ripening-related <italic>ACC</italic> synthase3 (<italic>C</italic><sub><italic>S</italic></sub><italic>ACS3</italic>), 1-aminocyclopropane-1-carboxylate oxidase1 (<italic>C</italic><sub><italic>S</italic></sub><italic>ACO1</italic>), 1-aminocyclopropane-1-carboxylate oxidase2 (<italic>C</italic><sub><italic>S</italic></sub><italic>ACO2</italic>), and <italic>C</italic><sub><italic>S</italic></sub><italic>AOX</italic> were increased after BL treatment. Importantly, the application of the salicylhydroxamic acid (SHAM, AOX inhibitor) and ethylene biosynthesis inhibitor aminooxyacetic acid (AOA) decreased plant resistance to environmental stress by blocking BRs-induced alternative respiration. Taken together, our results demonstrated that ethylene was involved in BRs-induced AOX activity which played important roles in abiotic stresses tolerance in cucumber seedlings.</p>