Hydrogen peroxide promotes seed germination, but the molecular mechanisms underlying this process are unclear. This study presents the results of eggplant (Solanum melongena) germination analyses conducted at two different temperatures and follows the effect of hydrogen peroxide treatment on seed germination and the seed proteome. Hydrogen peroxide was found to promote eggplant germination in a way not dissimilar to that of increased temperature stimuli. LC-MS profiling detected 729 protein families, 77 of which responded to a temperature increase or hydrogen peroxide treatment. These differentially abundant proteins were found to be involved in a number of processes, including protein and amino acid metabolism, carbohydrate metabolism, and the glyoxylate cycle. There was a very low overlap between hydrogen peroxide and temperature-responsive proteins, highlighting the differences behind the seemingly similar outcomes. Furthermore, the observed changes from the seed proteome indicate that hydrogen peroxide treatment diminished the seed endogenous hydrogen peroxide pool and that a part of manifested positive hydrogen peroxide effect might be related to altered sensitivity to abscisic acid.

• Keywords
• eggplant, germination, hydrogen peroxide, proteomics, seed, temperature,
• MeSH
• Chromatography, Liquid MeSH
• Stress, Physiological drug effects   MeSH
• Mass Spectrometry MeSH
• Germination drug effects   MeSH
• Carbohydrate Metabolism drug effects   MeSH
• Hydrogen Peroxide pharmacology   MeSH
• Gene Expression Regulation, Plant drug effects   MeSH
• Plant Proteins metabolism   MeSH
• Solanum melongena drug effects   physiology   MeSH
• Temperature MeSH
• Gene Expression Regulation, Developmental drug effects   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Hydrogen Peroxide MeSH
• Plant Proteins MeSH

Cytokinins (CKs) are phytohormones regulating plant growth and development as well as response to the environment. In order to evaluate their function in heat stress (HS) responses, the effect of CK elevation was determined during three types of HS - targeted to shoots, targeted to roots and applied to the whole plant. The early (30min) and longer term (3h) responses were followed at the hormonal, transcriptomic and proteomic levels in Arabidopsis transformants with dexamethasone-inducible expression of the CK biosynthetic gene isopentenyltransferase (ipt) and the corresponding wild-type (Col-0). Combination of hormonal and phenotypic analyses showed transient up-regulation of the CK/abscisic acid ratio, which controls stomatal aperture, to be more pronounced in the transformant. HS responses of the root proteome and Rubisco-immunodepleted leaf proteome were followed using 2-D gel electrophoresis and MALDI-TOF/TOF. More than 100 HS-responsive proteins were detected, most of them being modulated by CK increase. Proteome and transcriptome analyses demonstrated that CKs have longer term positive effects on the stress-related proteins and transcripts, as well as on the photosynthesis-related ones. Transient accumulation of CKs and stimulation of their signal transduction in tissue(s) not exposed to HS indicate that they are involved in plant stress responses.

• Keywords
• Abscisic acid, Arabidopsis thaliana, cytokinin, heat stress, isopentenyltransferase, proteome.,
• MeSH
• Alkyl and Aryl Transferases physiology   MeSH
• Arabidopsis drug effects   metabolism   physiology   MeSH
• Cytokinins physiology   MeSH
• Dexamethasone pharmacology   MeSH
• Plant Roots metabolism   physiology   MeSH
• Abscisic Acid physiology   MeSH
• Proteomics MeSH
• Heat-Shock Response physiology   MeSH
• Gene Expression Regulation, Plant physiology   MeSH
• Plant Growth Regulators physiology   MeSH
• Signal Transduction drug effects   physiology   MeSH
• Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization MeSH
• Gene Expression Profiling MeSH
• Plant Shoots metabolism   physiology   MeSH
• Hot Temperature MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• adenylate isopentenyltransferase MeSH Browser
• Alkyl and Aryl Transferases MeSH
• Cytokinins MeSH
• Dexamethasone MeSH
• Abscisic Acid MeSH
• Plant Growth Regulators MeSH

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 KAR(1) 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 KAR(1) (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 KAR(1) 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.

• Keywords
• Acclimatization, Asparagaceae, Conservation, Medicinal plants, Plant growth regulators, UHPLC,
• MeSH
• Acclimatization * MeSH
• Asparagaceae drug effects   growth & development   physiology   MeSH
• Biomass MeSH
• Cytokinins analysis   metabolism   MeSH
• Furans pharmacology   MeSH
• Plant Roots drug effects   growth & development   physiology   MeSH
• Smoke MeSH
• Naphthaleneacetic Acids metabolism   MeSH
• Plants, Medicinal MeSH
• Poaceae MeSH
• Plant Leaves drug effects   growth & development   physiology   MeSH
• Pyrans pharmacology   MeSH
• Plant Growth Regulators analysis   metabolism   MeSH
• Water chemistry   MeSH
• Plant Shoots drug effects   growth & development   physiology   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• 1-naphthaleneacetic acid MeSH Browser
• Cytokinins MeSH
• Furans MeSH
• karrikinolide MeSH Browser
• Smoke MeSH
• Naphthaleneacetic Acids MeSH
• Pyrans MeSH
• Plant Growth Regulators MeSH
• Water MeSH