Proteomic analysis of the effects of exogenous calcium on hypoxic-responsive proteins in cucumber roots

Abstract

BackgroundHypoxia acts as a plant stress factor, particularly in cucumbers plants under hydroponic culture. Calcium is involved in stress signal transmission and in the growth of plants. To determine the effect of exogenous calcium on hypoxic-responsive proteins in cucumber (Cucumis sativus L. cv. Jinchun No.2) roots, proteomic analysis was performed using two-dimensional electrophoresis (2-DE) and mass spectrometry.ResultsCucumber roots were used to analyze the influence of hypoxia on plants. The expressions of 38 protein spots corresponding to enzymes were shown to change in response to hypoxia. Of these, 30 spots were identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF/TOF MS analysis). The proteins were categorized according to functional groups, including glycolysis, the tricarboxylic acid (TCA) cycle, fermentative metabolism, nitrogen metabolism, energy metabolism, protein synthesis and defense against stress. Exogenous calcium appeared to alleviate hypoxic stress via these metabolic and physiological systems. Western blotting was used to analyze the accumulation of alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC); calcium further increased the expression of ADH and PDC under hypoxia. In addition, semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to assess the transcript levels of differentially expressed proteins.ConclusionsExogenous calcium enhanced the expression of enzymes involved in glycolysis, the TCA cycle, fermentative metabolism, nitrogen metabolism, and reactive oxygen species (ROS) defense in plants under hypoxia. Calcium appears to induce hypoxic tolerance of cucumber seedlings. These phenomena have prompted us to further investigate the mechanisms by which cucumbers respond to exogenous calcium under hypoxia.

The effect of exogenous calcium on cucumber fruit quality, photosynthesis, chlorophyll fluorescence, and fast chlorophyll fluorescence during the fruiting period under hypoxic stress

“…The involvement of calcium in hypoxia responses has been observed in many plants such as rice, wheat, and cucumber [10, 11]. This hypoxia-mediated elevation of Ca 2+ is fundamental for the activation of genes and synthesis of proteins required for acclimation responses at the cellular, tissue, and organismal levels [6, 12].…”

Comparative proteomic analysis of gamma-aminobutyric acid responses in hypoxia-treated and untreated melon roots

“…It was found to be a single-copy gene within the genome of netted and smooth melon varieties, and highly homologous to other Cucurbitaceous anionic POD (Keren-Keiserman et al, 2004). It has also been reported that hypoxia-induced stress causes cucumber roots to increase the expression level of POD, and calcium treatment further enhanced this (He et al, 2012). However, netting-associated POD expression (spot 13) was down-regulated in melon roots under hypoxia treatment, and exogenous GABA (1) further decreased its expression level, which is similar to the trend of GSH expression.…”

Proteomic Analysis Reveals the Positive Roles of the Plant-Growth-Promoting Rhizobacterium NSY50 in the Response of Cucumber Roots to Fusarium oxysporum f. sp. cucumerinum Inoculation

“…Briefly, 11 μg protein samples were transferred to a 0.45 μm PVDF membrane at 10 V for 1.5 h and were washed with TBST three times; then, the PVDF membrane was blocked with 5% nonfat dry milk for 2 h, washed with TBST three times, and incubated with monoclonal antibodies against S-adenosylmethionine synthase and enolase (produced in rabbit; Univ-bio, Shanghai, China) for 2 h. The membrane was washed with TBST and incubated at room temperature for 1 h with a Goat Anti-Rabbit IgG HRP-conjugate. The membrane was then washed with TBST three times and developed using diaminobenzidene (DAB) and H 2 O 2 (He et al, 2012). …”