Cytokinin profiles in ex vitro acclimatized Eucomis autumnalis plants pre-treated with smoke-derived karrikinolide
The current evidence of regulatory effect of smoke–water (SW) and karrikinolide (KAR 1 ) on the concentrations of endogenous cytokinins in plants partly explain the basis for their growth stimulatory activity.
Karrikinolide (KAR1) which is derived from smoke–water (SW) is involved in some physiological aspects in the life-cycle of plants. This suggests a potential influence on the endogenous pool (quantity and quality) of phytohormones such as cytokinins (CKs). In the current study, the effect of SW (1:500; 1:1000; 1:1500 v/v dilutions) and KAR1 (10−7; 10−8; 10−9 M) applied during micropropagation of Eucomis autumnalis subspecies autumnalis on the ex vitro growth and CKs after 4 months post-flask duration was evaluated. The interactions of SW and KAR1 with benzyladenine (BA), α-naphthaleneacetic acid (NAA) or BA+NAA were also assessed. Plants treated with SW (1:500) and KAR1 (10−8 M) demonstrated superior growth in terms of the rooting, leaf and bulb sizes and fresh biomass than the control and plants treated with BA and BA+NAA. However, plant growth was generally inhibited with either SW (1:500) or KAR1 (10−8 M) and BA when compared to BA (alone) treatment. Relative to NAA treatment, the presence of KAR1 (10−7 M) with NAA significantly increased the leaf area and fresh biomass. Both SW and KAR1-treated plants accumulated more total CKs, mainly isoprenoid-type than the control and NAA-treated plants. The highest CK content was also accumulated in SW (1:500) with BA+NAA treatments. Similar stimulatory effects were observed with increasing concentrations of KAR1 and BA. The current findings establish that SW and KAR1 exert significant influence on the endogenous CK pools. However, the better growth of plants treated with SW and KAR1 treatments was not exclusively related to the endogenous CKs.
KeywordsAcclimatization Asparagaceae Conservation Medicinal plants Plant growth regulators UHPLC
Analysis of variance
Multiple reaction monitoring
Murashige and Skoog medium
Plant growth regulator
Photosynthetic photon flux density
Plant tissue culture
Ultra high performance liquid chromatography
We thank the two anonymous reviewers and editor for their effort in improving our manuscript. Financial support from the University of KwaZulu-Natal (UKZN) and the National Research Foundation (98028), South Africa is gratefully appreciated. This work was co-financed by the Ministry of Education, Youth and Sports, Czech Republic (Grant LO1204 from the National Program of Sustainability) and IGA of Palacký University (Grant IGA_PrF_2015_024). O.N. thanks the Program “Návrat” for Research, Development and Innovations (no. LK21306). We thank Mrs Alison Young of the UKZN Botanical Garden and her Staff for their help during the greenhouse experiments.
Author contribution statement
AOA conceived the research idea, designed the experiments and carried out the in vitro propagation and greenhouse experiments. LP and ON were involved in the analysis and quantification of the cytokinins. AOA and WAS prepared the draft manuscript while all authors edited and approved the final version. KD and JVS coordinated and supervised the project.
Compliance with ethical standards
Conflict of interest
We declare no conflict of interest.
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