Chilling Treatment Research Articles

Altered post-mortem metabolism identified in very fast chilled lamb M. longissimus thoracis et lumborum using metabolomic analysis

The aim of this experiment was to use metabolomic techniques to investigate the energy metabolism in lamb M. longissimus thoracis et lumborum subjected to very fast chilling (VFC) post-mortem. The tissue was prepared by 2 different operators and subjected to very fast chilling (less than 0°C within 1.5h of slaughter) or typical chilling regimes (Control; 0°C within 22h of slaughter). Non-targeted metabolomic analysis (1H NMR) and targeted analysis (31P NMR, HPLC-PDA and HPLC–MS/MS) were used to examine the change in muscle metabolites post-mortem. One VFC treatment, which resulted in a colder core temperature and more tender meat, had higher levels of glycolytic intermediate metabolites pre-rigor as well as more of the end-products of adenosine and nicotine nucleotide metabolism pre-rigor, relative to conventionally chilled treatments. In conclusion, VFC to less than 0°C within 1.5h of slaughter causes considerable changes in metabolism and rigor onset, which are associated with tender meat.

A Phytocystatin Gene from Malus prunifolia (Willd.) Borkh., MpCYS5, Confers Salt Stress Tolerance and Functions in Endoplasmic Reticulum Stress Response in Arabidopsis

Cystatins, or phytocystatins (PhyCys), comprise a family of plant-specific inhibitors of cysteine proteinases. They are thought to help regulate endogenous processes and protect plants against biotic or abiotic stresses, such as heat, salinity, cold, water deficit, chilling, and abscisic acid (ABA) treatment. We isolated and identified a novel cystatin gene from Malus prunifolia, MpCYS5. Its expression was typically induced by salt stress treatment; ectopic expression in Arabidopsis enhanced salt tolerance. Physiological parameters confirmed this phenotype, with the transgenics having remarkably lower electrolyte leakage (EL) values, higher chlorophyll concentrations, and lower levels of malondialdehyde (MDA) upon salt treatment. In addition, the accumulation of reactive oxygen species was markedly regulated by MpCYS5 under stress conditions, as shown by fluctuations in the concentrations of hydrogen peroxide and superoxide radicals and the activities of antioxidant enzymes. We also noted that this gene modulated tunicamycin (TM)-induced endoplasmic reticulum (ER) stress tolerance and functioned in the unfolded protein response (UPR)-signaling pathway in Arabidopsis. This was confirmed by the expression of eight ER stress-responsive genes. All marker genes examined were strongly induced in the wild type, while most of them maintained relatively stable over time in the transgenics. These results demonstrated that ectopic expression of a cystatin gene is associated with salt-tolerant and TM-tolerant phenotypes. Therefore, the discovery of MpCYS5 from M. prunifolia might establish a molecular link between the ER stress response and salt tolerance in plants.

Effect of methyl salicylate and methyl jasmonate pre-treatment on the volatile profile in tomato fruit subjected to chilling temperature

Tomato fruits exposed to chilling temperatures suffer aroma loss prior to visual chilling injury (CI) symptoms. Methyl salicylate (MeSA) and methyl jasmonate (MeJA) treatments were reported to alleviate the development of visual CI; however, it is unknown if the treatments alleviate internal CI in the form of aroma loss. In this research, ‘FL 47’ tomatoes at breaker stage were treated with MeSA or MeJA vapor prior exposure to chilling temperature. The chilling treatment did not result in visual CI; however, for internal CI it generally suppressed production of oxygen-containing heterocyclic compounds, ketones, sulfur- and nitrogen-containing heterocyclic compounds, alcohols, and aldehydes, including 13 important aroma contributors to tomato fruit. MeJA had no impact on sensory evaluation in spite of resulting in slightly altered volatile profile; however, MeSA alleviated the CI-induced reduction of a number of volatile compounds, and thereby enhanced tomato aroma.

Suaeda salsa is Adaptive to Chilling Stress under Salinity at Stages of Seed Germination and Seedling Establishment

Suaeda salsa L., a C3 euhalophytic herb, is a native of saline soils. This herb displays high resistance to salinity stress. In the present study, we investigated the interaction between low temperature and salinity on seed germination and seedling establishment. Low temperature (4 oC) conditions severely inhibited seed germination at 0 and 200 mM NaCl. The percent germination at 200 mM NaCl was higher than that at 0 mM NaCl. After 24 h of chilling stress, the fresh weight and dry weight of S. salsa seedlings at 0 mM NaCl was reduced, but the fresh weight and dry weight of S. salsa seedlings at 200 mM NaCl increased. APX and CAT activities decreased during chilling stress at both 0 and 200 mM NaCl, yet the activity of both enzymes was not affected as strongly at 200 mM NaCl compared to 0 mM NaCl. After a 12 h chilling treatment, the unsaturated fatty acid content and the double bond index (DBI) of DGDG, SQDG and PG major membrane lipids was significantly increased at 200 mM NaCl. The level of PG and the ratio of DGDG/MGDG in seedling leaves were also increased in the presence of 200 mM NaCl. These results suggest that S. salsa is more adaptive to chilling stress under 200 mM NaCl conditions at stage of seed germination and during seedling establishment.

Cloning and expression analysis of CaPIP1-1 gene in pepper (Capsicum annuum L.)

Plant aquaporins are responsible for water transmembrane transport, which play an important role on abiotic and biotic stresses. A novel plasma membrane intrinsic protein of CaPIP1-1 was isolated from the pepper P70 according to transcriptome databases of Phytophthora capsici inoculation and chilling stress library. CaPIP1-1, which is 1155bp in length with an open reading frame of 861bp, encoded 286 amino acids. Three introns, exhibited CT/AC splice junctions, were observed in CaPIP1-1. The numbers and location of introns in CaPIP1-1 were the same as observed in tomato and potato. CaPIP1-1 was abundantly expressed in pepper fruit. Increased transcription levels of CaPIP1-1 were found in the different stresses, including chilling stress, salt stress, mannitol stress, salicylic acid, ABA treatment and Phytophthora capsici infection. The expression of CaPIP1-1 was downregulated by 50μM HgCl2 and 100μM fluridone. The pepper plants silenced CaPIP1-1 in cv. Qiemen showed growth inhibition and decreased tolerance to salt and mannitol stresses using detached leaf method.

The Effect of Chilling Stress at Transplant Stage on Broccoli Development and Yield with Elements of Modeling

Abiotic stresses affect plant development in different ways depending on the phase of ontogeny. Exposure to moderate stress may induce cross-tolerance resulting in complex acclimation. The improvement of vegetable transplants able to withstand outdoor conditions is achieved by controlled stress applications. The aim of the experiment was to investigate the effects of diverse chilling treatments applied to transplants on subsequent broccoli development and yield. The evidence for a long-lasting “stress imprint” effect during plant ontogeny was investigated. Transplants were subjected to temperatures of 6, 10, and 14 °C maintained for 7 and 14 days before planting out, and to 18 °C (control). The fresh weight (FW), dry weight (DW), and chosen leaf parameters were measured five times in 10-day intervals, starting 21 days after transplanting (DAT). At first sampling, the FW and DW of control plants were slightly higher in comparison to previously chilled plants, but finally (at 61 DAT) chilling increased both the FW and DW of broccoli, particularly in the 6 °C for 7 days (FW) and 14 °C for 7 days (FW and DW) treatments. Polynomial regression models for alterations in DW content over time were developed and validated. All models showed a high accuracy of prediction, indicating that they could be useful tools for describing broccoli development. The growth rate and relative growth rate showed alterations during field cultivation, due to the chilling treatments of the transplants, up to 41 DAT. The effect of chilling on leaf number per plant was observed only after 2 months of vegetative growth, when broccoli treated with 10 °C for 7 days had the highest number of leaves. Leaf surface area and leaf perimeter were significantly influenced by chilling only at 31 DAT. Broccoli subjected to 6 °C for 14 days formed leaves with the highest surface area and largest perimeter as compared with the control. At 61 DAT, all leaf parameters of chilled plants were slightly higher than the control; however, differences for leaf surface area and perimeter were not confirmed statistically. Treatment with 10 °C for 7 days, resulted in an increase in yield, by 2.38 t ha−1, in relation to the control. A regression model including microclimatic parameters for the prediction of broccoli yield was proposed in this paper. The collected data showed the long-term effects of transplant chilling on subsequent broccoli development and yield, and the existence of “stress memory.”

Expression of an exogenous 1-aminocyclopropane-1-carboxylate deaminase gene in psychrotolerant bacteria modulates ethylene metabolism and cold induced genes in tomato under chilling stress

The role of stress induced ethylene under low temperature stress has been controversial and hitherto remains unclear. In the present study, 1-aminocyclopropane-1-carboxylate deaminase (ACCD) gene, acdS expressing mutant strains were generated from ACCD negative psychrotolerant bacterial strains Flavobacterium sp. OR306 and Pseudomonas frederiksbergensis OS211, isolated from agricultural soil during late winter. After transformation with plasmid pRKACC which contained the acdS gene, both the strains were able to exhibit ACCD activity in vitro. The effect of this ACCD under chilling stress with regards to ethylene was studied in tomato plants inoculated with both acdS expressing and wild type bacteria. On exposing the plants to one week of chilling treatment at 12/10 °C, it was found that stress ethylene, ACC accumulation and ACO activity which are markers of ethylene stress, were significantly reduced in plants inoculated with the acdS gene transformed mutants. In case of plants inoculated with strain OS211-acdS, ethylene emission, ACC accumulation and ACO activity was significantly reduced by 52%, 75.9% and 23.2% respectively compared to uninoculated control plants. Moreover, expression of cold induced LeCBF1 and LeCBF3 genes showed that these genes were significantly induced by the acdS transformed mutants in addition to reduced expression of ethylene-responsive transcription factor 13 (ETF-13) and ACO genes. Induced expression of LeCBF1 and LeCBF3 in plants inoculated with acdS expressing mutants compared to wild type strains show that physiologically evolved stress ethylene and its transcription factors play a role in regulation of cold induced genes as reported earlier in the literature.

Suppression of volatile production in tomato fruit exposed to chilling temperature and alleviation of chilling injury by a pre-chilling heat treatment

Chilling exposure of tomato fruit to 5 °C for less than 5 days at mature green stage does not cause visual symptom of chilling injury (CI), however, it is unknown whether such conditions would impact flavour quality (internal CI) after ripening, and if a pre-chilling heat treatment could alleviate internal CI. In this experiment, mature green ‘FL 47’ tomatoes were gassed with ethylene to initiate ripening before heating and/or chilling treatment, and fruits were ripened at 20 °C after short exposure to the high or low temperature. Volatile analysis of the fruits were conducted after ripening. Chilling treatment generally suppressed production of aldehyde, alcohol, ketone, ester, acid and terpene volatile compounds, including the following abundant and/or important volatiles: hexanal, trans-2-hexenal, 6-methyl-5-hepten-2-one, β-ionone, 2-methylbutanal, 2-phenylethanol, guaiacol and 2-isobutylthiazole. Heat treatment alone did not affect most volatile levels after ripening. Heat treatment prior to chilling exposure alleviated the reduction of some key volatile compounds caused by chilling exposure, which agreed with sensory panel results in that panellists perceived more tomato flavour in “heating + chilling” treated fruit than fruit that were chilled only.

A REVIEW OF TRADITIONAL HERBAL MEDICINAL PRODUCTS WITH DISEASE CLAIMS FOR ELDER (SAMBUCUS NIGRA) FLOWER

European elder (Sambucus nigra) is traditionally used as a medicinal plant by many native peoples and herbalists alike. Stem bark, leaves, flowers, fruits, and root extracts are used to treat bronchitis, cough, upper respiratory infections, and fever. Several pharmacopoeias have for centuries included Sambuci flos or dried flower of elderberry, and numerous recognized textbooks and monographs have described the medicinal use of elderberry flower. Thus in 2002, WHO (World Health Organization) published a monograph which stated that although no controlled clinical data are available, the descriptions in pharmacopoeias and traditional systems of medicine justify the use of elder flower herbal preparation “as a diaphoretic for treatment of fever and chills, and as an expectorant for treatment of mild inflammation of the upper respiratory tract; also for symptomatic treatment of the common cold”. In 2008, EMA (European Medicinal Agency) issued the Community herbal monograph on Sambucus nigra flos with the following approval: “Herbal medicinal product traditionally used for the relief of early symptoms of common cold. The product is a traditional herbal medicinal product for use in specified indications exclusively based upon long-standing use”. This review summarizes the plethora of medicinal and human disease/health claims made for elder flower.

C-1013: Cryopreservation of spermic milt in the model species Ambystoma tigrinum (Tiger salamander) for application in endangered salamanders

In the face of the amphibian extinction crisis, captive assurance colonies have been established to preserve genetic diversity. Sadly, many captive assurance colonies fail due to reproductive cues which are not entirely understood. In addition, the majority of amphibian conservation and genome banking research has focused on anurans (frogs/toads), despite the fact that caudates (salamanders/newts) face a larger threat of extinction. Therefore, it is critical that assisted reproductive technologies, such as gamete cryopreservation and artificial fertilization, be developed as conservation tools for application in genetic management of threatened caudates. It was hypothesized that a modified anuran sperm freezing protocol could be successfully used in cryopreservation of Ambystoma tigrinum (tiger salamander) sperm as a caudate model. Spermiation in male tiger salamanders was hormonally induced via injection with hCG, LHRH, or a combination of these two hormones. Average spermic milt concentrations were 2.75 × 107(±7.2 × 106)/mL. Average total motility upon collection of fresh milt was 53.6% (±17.6%). After collection and initial analysis, fresh milt samples were diluted 1:1 in chilled cryoprotectant treatment solutions. They were then frozen in 0.25 mL French straws using a stepwise slow-rate freezing process. Upon thawing, milt suspensions were diluted 1:10 with a 10% Holtfreter’s solution in order to activate the sperm for post thaw analysis. Frozen-thawed sperm in the 5% Me2SO treatment group had an average total motility of 19.1% (±15.8%) and sperm in the 5% Me2SO with 0.5% BSA treatment group had an average total motility of 21.75% (±14.8%). Early trials showed that caudate sperm are not susceptible to toxicity from several cryoprotective media. Moreover, initial fertilization trials indicate that frozen-thawed caudate sperm are capable of producing early cleavage stage embryos. Optimizing cryopreservation protocols for salamander sperm is an important step in building a global genetic resource bank for endangered caudates.

Breaking bud dormancy in Erythronium japonicum Decne. (Liliaceae) by natural and artificial chilling

This study was conducted to investigate flower bud differentiation and to determine the chilling requirements for bud dormancy breaking and sprouting in Erythronium japonicum Decne. (Liliaceae). Dormant bulbs grown in an open field were randomly selected from June 2012 to December 2013 for observation of flower bud differentiation and development. The 3–4 year-old bulbs and > 10 year-old bulbs were used for vegetative bud development and flower bud development, respectively. For natural chilling treatments, the plants were transferred from an experimental field to a growth module every month from September to February. Artificial chilling treatments were applied at 5°C for 0, 2, 4, 8, and 12 weeks in October and November. The cumulative chill unit (CCU) of low temperatures below 5°C was calculated. Flower bud initiation and differentiation in E. japonicum were observed in May, and from June to July, respectively, followed by flower bud elongation in August. Sprouting and bud break did not occur throughout the experiment when dormant bulbs were transferred from September (0 CCU) to November (450 CCU). However, all plants sprouted when the dormant bulbs were transferred after January (1,794 CCU). Prolonged cold storage also promoted sprouting of dormant E. japonicum. No cold storage or 4 weeks (672 CCU) of cold storage at 5°C in October did not induce sprouting and bud break. However, when the dormant bulbs were stored at 5°C for 12 weeks (2,061 CCU) in October, percent sprouting increased to 72.7%. Chilling treatment for 8 weeks (1,483 CCU) or 12 weeks (2,155 CCU) at 5°C in November resulted in 72.7 and 100% sprouting, respectively. In conclusion, at least 1,483–1,794 CCU may be recommended for dormancy breaking in the forcing culture of E. japonicum.

Dynamic of Campylobacter species contamination along a poultry slaughtering chain

The prevalence of Campylobacters was studied in a poultry farm and along the slaughtering chain. Fifteen swabs from a farm and 75 samples (swabs and rinsates) from its slaughterhouse were collected. All the faecal and cloacal farm swabs were contaminated by Campylobacter jejuni and C. coli against 50% for breast swabs. C. jejuni had a concentration of 6.26, 6.34 and 5.38 Log10 CFU/mL in faecal, cloacal and breast swabs respectively. Rinsates showed an almost constant concentration of Campylobacters (6 Log10 CFU/mL) with a predominance of the presumptive C. jejuni. C. lari was found in 22% of eviscerated samples. Faecal coliforms and E. coli, used as indicators, were detected in all samples (5.46 and 5.15 Log10 CFU/mL, respectively). Final chilling and chlorine (50 ppm) treatments decreased them to acceptable levels, unlike for Campylobacters. Further investigation of the dynamics of Campylobacters and their response to prevention and treatment measures is required.

Pre-rigor temperature control of Chinese yellow cattle carcasses to 12–18 °C during chilling improves beef tenderness

This study evaluates the effects of pre-rigor temperature control on quality traits of Chinese yellow cattle M. longissimus lumborum (LL). One stepwise chilling (SC) treatment was used on one half-carcass, involved a fast chilling (−11±1°C;0.5m/s) for 2h, then the refrigeration was stopped to hold a core temperature of 12–18°C until 10h postmortem, followed by a 1±1°C chilling (0.5m/s) to 48h postmortem. The other half-carcass was conventional chilled at 1±1°C (0.5m/s) until 48h as control chilling (CC). Quality attributes were evaluated at 1, 7 and 14days. The SC treatment resulted in decreased WBSF and increased myofibril fragmentation index compared with control. SC-treated LL at 7d postmortem had a lower WBSF than those of CC-treated at 14d. This pre-rigor temperature controlled chilling is a realistic alternative for the beef industry in China to ensure adequate tenderness and shorten aging time.

Growth and development of ‘Illini Hardy’ blackberry (Rubus subgenus Eubatus Focke) under shaded systems

Blackberries (Rubus subgenus Eubatus Focke) of the Eastern United States commonly grow along forest edges and in disturbed sites, though the potential for introducing improved cultivars into managed forest systems has been little explored in agroforestry literature. Bare root ‘Illini Hardy’ blackberry plants were grown under three neutral shade cloth levels (20, 50, and 70 % irradiance relative to full sunlight) and a full sun control in an orchard system over one growing season. The plants were then excavated from the shade plots and the floricanes forced to fruit in a heated greenhouse after receiving a chilling treatment consistent with data published about the cultivar. Potential yield reflected by primocane yield components was only marginally affected by the light treatments, with no significant differences in primocane counts, cane length, or the numbers of nodes. Cane diameter and attributes of primocane architecture were significant, affecting crown geometries and resulting in the highest percent light interception among plants grown at 70 % relative irradiance. Maximum net photosynthesis rates increased at higher irradiance levels with little increase above 70 % full sunlight, although no differences were observed in whole plant biomass or biomass allocation. Flowering and harvest periods were more concentrated from plants receiving 70–100 % relative irradiance during flower initiation. These results suggest that vegetative phases of ‘Illini Hardy’ blackberry may benefit from partial shading with an optimum light intensity approximating 70 % of full sunlight, but that floral bud differentiation is delayed or incomplete at lower irradiance levels produced by whole canopy or intracane shading.

Overexpression of the OsChI1 gene, encoding a putative laccase precursor, increases tolerance to drought and salinity stress in transgenic Arabidopsis

In a previous study, we identified a number of genes induced by chilling using a microarray approach. In order to investigate the molecular mechanism underlying chilling tolerance and possible crosstalk with other abiotic stresses, we selected a rice gene, OsChI1 (Os01g61160), for further analysis. The OsChI1 gene encodes a putative laccase precursor protein. In accordance with our previous results, its transcript is highly accumulated during a 12-day period of chilling treatment. Higher expression of the OsChI1 gene was also detected in roots and tissues at the vegetative and productive stages. In addition, we also observed increased transcript levels of the OsChI1 gene during dehydration and high salinity conditions. Transient expression of OsChI1 proteins tagged with fluorescence protein in rice protoplasts revealed that OsChI1 is localized in the plasma membrane. The Arabidopsis transgenic plants overexpressing OsChI1-EGFP resulted in an increased tolerance to drought and salinity stress. In silico analysis of OsChI1 suggests that several genes coexpressed with OsChI1 in the root during various abiotic stresses, such as chilling, drought and salt stress, may play an important role in the ROS signaling pathway. Potential roles of OsChI1 in response to abiotic stresses are discussed.

Molecular characterization and expression patterns ofPsSVPgenes reveal distinct roles in flower bud abortion and flowering in tree peony (Paeonia suffruticosa)

Wang, S., Xue, J., Ahmadi, N., Holloway, P., Zhu, F., Ren, X. and Zhang, X. 2014. Molecular characterization and expression patterns of PsSVP genes reveal distinct roles in flower bud abortion and flowering in tree peony (Paeonia suffruticosa). Can. J. Plant Sci. 94: 1181–1193. Container culture and flower forcing are used for off-season production of tree peony for the Chinese Spring Festival. Storage of potted tree peony for 10 d at 12°C in a refrigerator before 4°C chilling treatment can help new root growth and promote leaf development. Development from bud swelling to anthesis was divided into nine stages. Some aborted flower buds usually emerge in Stage III. Removal of two to four leaflets in an alternating pattern and applying gibberellic acid 3 (GA3) around the flower bud at Stage III can decrease the flower bud abortion rate and promote flower formation rate. Two MADS-box genes with homology to Arabidopsis SVP, designated PsSVP1 and PsSVP2, which probably caused flower-bud abortion, were isolated by reverse transcription-PCR. Sequence comparison analysis showed that PsSVP was most similar to SVP-like gene in apple. Phylogenetic analysis indicates that PsSVP was evolutionarily close to SVP-like genes from Malus domestica, SVP genes from Cruciferae and SVP-like genes from Vitis vinifera. The qRT-PCR results suggested that expression of PsSVP was high in vegetative growth phase, especially in the leaves of tree peony, and its expression was regulated by GA3. Further analysis showed that more PsSVP transcripted in the aborted flower bud, especially in the buds where leaflets grew well. It was deduced that PsSVP can promote vegetative growth and suppress flowering in tree peony. Thus, it is very important to further investigate PsSVP and decipher the mechanisms of flower-bud abortion to improve forcing culture of tree peony.

The long-term ambient storage-induced alterations in seed viability, germination and seedling vigour of Saussurea costus, a critically endangered medicinal herb of North West Himalaya

Saussurea costus (Falc.) Lipschitz (Asteraceae), an economically important medicinal herb, is categorized as critically endangered. The plant is cultivated in some parts of Lahaul (Himachal Pradesh, India) in North West Himalaya. However, in the recent past, the cultivation has declined owing to an array of reasons including a long cultivation cycle, greater profits from other cash crops (mainly pea, potato, hops) and formalities to be completed in obtaining the export permits. Therefore, the possibilities of ex situ (in areas other than Lahaul) cultivation/conservation needs to be explored. In this context, the understanding of seed physiological characteristics would be of immense help. Since there is a dearth of information concerning the storage-depenedent changes in seed physiological status of S. costus, we have analyzed these aspects for a long-term ambient storage (66 months) in a population from Lahaul. The freshly harvested seeds exhibited high viability (95%) with 65% germination that could be enhanced through GA3 and chilling pre-treatments. During storage, the seed germination increased after 12 months suggesting the seeds to be partially dormant that required an after-ripening prior to the commencement of germination. GA3 and chilling treatments appeared to substitute such requirement. Further, the seed viability was completely maintained at least for 18 months and even after 30 months storage, 82% viability retention associated with the production of healthy seedlings was evident. However, beyond 30-month-storage, both seed viability and germination declined substantially. Maintenance of reasonably high viability status, germination and seedling vigour even after substantial storage of seeds under ambient conditions suggests the suitability of seeds for regeneration/cultivation of this species.

Cloning and expression analysis of the R2R3-PsMYB1 gene associated with bud dormancy during chilling treatment in the tree peony (Paeonia suffruticosa)

Transcription factor (TF) MYB-like proteins are involved in many physiological and biochemical processes. This study isolated the full length cDNA encoding a MYB from the tree peony (Paeonia suffruticosa Andr.), whose GenBank Accession No. is KC282466. The deduced MYB-like protein sequence shares extensive sequence similarity with previously characterized plant R2R3-MYBs, and was named PsMYB1 according to the accepted nomenclature for TFs. Phylogenetic analysis showed that the deduced amino acid of PsMYB1 was closely related to VvMYB30 from grape. The PsMYB1 gene was expressed in all tissues, but it was most strongly expressed in the stem, and least expressed in the root. When exposed to chilling at 4 °C, PsMYB1 was up-regulated at 7 days and then decreased until 21 days suggesting it responded to low temperature, and it might negatively regulate dormancy release. In addition, the PsMYB1 quicker response to the temperature changes in flower buds of complete dormancy release might be that PsMYB1 involved in eco-dormancy and accelerated budbreak. These experiments enhance our knowledge of PsMYB1 and provide more information for understanding the genetic and physiological changes during the dormancy release process in the tree peony.

Differential expression proteins associated with bud dormancy release during chilling treatment of tree peony (Paeonia suffruticosa).

Endo-dormant flower buds of tree peony must have sufficient chilling duration to reinitiate growth, which is a major obstacle to the forcing culture of tree peony in winter. We used a combination of two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionisation time of flight/time of flight mass spectrometry (MALDI-TOF/TOF MS) to identify the differentially expressed proteins of tree peony after three different chilling treatments: endo-dormancy, endo-dormancy release and eco-dormancy stages. More than 200 highly reproducible protein spots were detected, and 31 differentially expressed spots (P<0.05) were selected for further analysis. Finally, 20 protein spots were confidently identified from databases, which were annotated and classified into seven functional categories: response to abiotic or biotic stimulus (four), metabolic processes (four), other binding (three), transcription or transcription regulation (two), biological processes (one), cell biogenesis (one) and unclassified (five). The results of qPCR of five genes were mainly consistent with that of the protein accumulation analysis as determined by 2-DE. This indicated that most of these genes were mainly regulated at transcriptional level. The activity of nitrate reductase and pyruvate dehydrogenase E1 was consistent with the 2-DE results. The proteomic profiles indicated activation of citrate cycle, amino acid metabolism, lipid metabolism, energy production, calcium signalling and cell growth processes by chilling fulfilment to facilitate dormancy release in tree peony. Analysis of functions of identified proteins will increase our knowledge of endo-dormancy release in tree peony.

A Comparative Proteomics Analysis of Soybean Cotyledon and Unifoliolate Leaves Under Heat (Chilling) Treatments

To understand the cold stress response of soybean, 480 soybean germplasms were used to find the tolerant and sensitivity of germplasm to cold. Then a comparative proteomic analysis between soybean seed treated at chilling and non-chilling temperature was carried out using the tolerant cold soybean germplasm. During the germination of seed, it was possible to discriminate between proteins involved in symptoms and proteins implicated in response to chilling. A proteomic approach, based on two-dimensional electrophoresis and MALDI-ToF-MS peptide mass fingerprinting experiments, was used for this purpose. The comparison of the resulting proteomic maps highlighted proteins showing quantitative variations induced by temperature treatments. Twenty-nine protein spots exhibited significant quantitative changes under at least one stress condition. Identified, differentially represented proteins belonged to two main broad functional groups, namely energy production/carbon metabolism and response to abiotic and oxidative stresses. In addition, our data seem to indicate a possible candidate to be used as a protein marker for further studies on cold stress.