Abstract:In order to understand the expression patterns in different tissues and under abiotic stress of ascorbate peroxidase (APX) gene family in Phyllostachys edulis, seven PeAPXs were obtained from the genomic database of P. edulis. PeAPXs could be divided into three subfamilies, including cytoplasmic, peroxisome and chloroplast/mitochondrion types based on the predictions of subcellular localizations. There were drought, cold, and light responses elements in promoter sequences of each gene, such as Box-4 and G-Box. The expression of PeAPXs were different among seven tissues, showing tissue specificity. qRT-PCR revealed that there were great differences in the expression pattern of each gene under drought, salt and low temperature stress. The expression of PeAPX2 was maintained at high level under three stresses. The expression of PeAPXs were induced by low temperature stress. Under drought stress, the expression of PeAPX1 was down-regulated, while the expression of PeAPX3, PeAPX6 and PeAPX7 were not detected. Under salt stress, all of PeAPXs were up-regulated except PeAPX3 and PeAPX5. Therefore, PeAPXs may be involved in different abiotic stress processes and play an important role in the growth and development stage of P. edulis.

Abstract:To understand the regulation function of peroxidase genes in kiwifruit, two members of POD gene family (AdPOD27 and AdPOD64) were cloned from Actinidia deliciosa ‘Miliang-1’ by using reverse transcription PCR, the bioinformations of AdPOD27 and AdPOD64 were analyzed, and the correlation between their expression and POD activity were also studied. The results showed that the length of open read frame of AdPOD27 and AdPOD64 was 984 and 957 bp, encoding 327 and 318 amino acids, respectively, which GenBank accession No.were MF774100 and MF774101. AdPOD27 and AdPOD64 were hydrophilic and alkaline proteins belonging to class Ⅲ of the plant heme-dependent peroxidase superfamily. The two proteins had signal peptide, transmembrane structure and phosphorylation sites. AdPOD27 and AdPOD64 located in mitochondrion and extracellular region, respectively. qRT-PCR analysis showed that the expression of AdPOD27 was up-regulated greatly treated with abscisic acid (ABA) and under 4℃, while AdPOD64 expression only enhanced treated with ABA. Moreover, the AdPOD27 expression had significant correlations with POD activity and AdPOD64 expression. Therefore, AdPOD27 and AdPOD64 would be involved in fruit softening, low temperature response and ABA induction of A. deliciosa.

Abstract:In order to rapidly identify the tolerance to low temperature of Desmodium intortum, the physiological response to low temperature stress (4℃) was studied by comparing with Macroptilium atropurureum, a high quality forage widely planted in southern provinces in China. The results showed that under low temperature stress, the effective quantum yield (Yield) and electron transfer rate (ETR) from the 2nd to 8th day decreased significantly in M. atropurureum than those in D. intortum (P<0.05). The superoxide dismutase (SOD) activity increased and catalase (CAT) activity decreased significantly (P<0.05) for both D. intortum and M. atropurureum under low temperature stress. Specifically, the decrease of CAT activity in D. intortum was lower than that in M. atropurureum. The peroxidase (POD) activity of D. intortum did not change (P>0.05) under low temperature, while POD activity in M. atropurureum decreased by 47.11%. The contents of free proline (Pro) and soluble sugar were significantly higher in D. intortum than those in M. atropurureum (P<0.05) under low temperature. According to regression analysis, resistance index and nutrient composition analysis, D. intortum was superior to M. atropurureum in cold resistance and nutritional value. Furthermore, Yield, ETR, CAT, Pro and soluble sugar of D. intortum could be used asimportant physiological indexes for identification of cold tolerance.

Abstract:Selenium metabolic fate and accumulation of molecular mechanism are briefly reviewed in plants. Key enzymes involved in the pathway are discribed. Trends in selenium metabolism research are provided.

Abstract:Contents of soluble sugar, starch，free prolines and crude proteins were determined in functional leaves and flower buds of different diameters (<0.4 mm, 0.4-1.2 mm and >1.2 mm) in ramie (Boehmeria nivea (L.) Gaud) male sterile lines C26 and C4 and the restoration lines B8 and B16, as well as peroxidase (POD) activity．The soluble sugar content of flower buds of each size was higher in C26 and C4 than in their restoration lines, especially in flower buds ( diameter >1.2 mm ) (C26 and C4 were 0.58% and 0.83% higher than B8 and B16, respectively). In flower buds ( diameter in 0.4-1.2 mm ) and big bud, starch and free proline contents of C26 and C4 were 1.31-1.81 and 2.72-7.37 times higher than B8 and B16, respectively. In flower buds of all sizes, POD activity was slightly lower in C26 and C4 than in their restoration lines. Variations in soluble sugar content of lines C26 and C4 were not consistent with their restoration lines. Those features could be related to male sterility in ramie．

Abstract:Peroxidase(POD) from pericarp of litchi(Litchi chinensis Sonn.) was purified by 12.5-fold and a 1.9% yield using ammonium sulfate, DEAE-Sepharose and Sephadex G-75. The enzyme was determined to be homogenous by SDS-PAGE, which was relatively heat stable with a optimum temperature of 35℃, requiring a time of at least 30 min at 75℃ for 50% loss of the activity. Litchi POD had a optimum pH at 6.5, but it was stable within a range of pH 4.0-8.0. The apparent Km values with guaiacol, catechol and pyrogallol as substrates were 2.75, 12.4 and 12.8 mmol/L at 25oC and pH 7.0，respectively．The presence of Fe3+ and Cu2+ enhanced POD activity．L-cysteine，citrate acid,FeSO4，SDS，GSH and ZnS04 partially inhibited POD activity,but it was completely inhibited by dithiothreitol and ascorbate.

Abstract:Under drought condition, the drought-tolerant riee cultivar Xiangzhongxian No.2 showed lower relative plasmalemma permeability and less reduction in chlorophyllcontent as compared with drought-sensitive cultivar Xiangzaoxian No. 12 , whichindicated that the drought-tolerant cultivar was less demaged by drought stress. Ascorbate-peroxidase (AsA-POD) activity decreased in both cultivars, but less decreased in drought-tolerant one. The glutathione reductase (GR) activity increased at the beginning of drought in drought-tolerant cultivar，but that did not change obviously in drought-sensitive one．The results also showed that GR activity could be induced by paraquat(0.01 mmol／L)andH202(0.1 mmol／L)in drought-tolerant cultivar，but they had no effects on drought_sensitive one，which indicated that the increase of GR activity in drought-tolerant cultivar under drought stress might result from the induction by oxidative stress．In addition，the contents of ascorbate (AsA) and reduced glutathione (GSH) showed a tendency of being increased at first，then decreased in both cultivars，but with greater increase in the drought-tolerant cultivar．The results suggested that drought_tolerant cultivar had better protection system in chloroplasts against drought stress than the drought-sensitive cultivar.

Abstract:A common litchi cultivar Huaizhi was used to investigate how the application of Pro-long coating affects the browning of litchi peel and relevant enzymes during 4 t storage. The Hunter L and b values in both the control and treated fruits decreased continuously with storage time, indicating that the peel became darker and had less yellow characteristics. The Hunter L and b values in the control decreased faster than those in treated fruits. The Hunter a values ifl both the control and treated fruits were relatively stable during the first 20 days of storage and then significantly decreased during the remaining days, implying that stored litchi fruits maintained basically red characteristics during the first 20 days of storage and then became less red, corresponding to the changes in contents of anthocyanin, flavonoid and total phenolics. Hunter a values in the control decreased faster than those in treated fruits after the 21st day of storage. These correspond to a visible change to a dark red and brown during storage and changes in polyphenol oxidase (PPO) and peroxidase (POD), which indicate that polyphenol oxidase plays a definitive role in postharvest browning, and peroxidase is partially involved in the browning process. The increase in POD activities of treated fruits was slower than that of the control, and the peaks in PPO activities of treated fruits were delayed slightly compared to that of the control. There was no significant difference between 1.5% and 2.5% Pro-long treatments. Therefore, we suggest that the application of Pro-long coating to litchi fruits partially inhibits PPO and POD activities, and influences the breakdown of anthocyanin and the changes in contents of flavonoid and total phenolics, thereby delaying browning progress.