Ornithine decarboxylase is involved in methyl jasmonate-regulated postharvest quality retention in button mushrooms (Agaricus bisporus).

BACKGROUND: In the present study, we investigated the role of ornithine decarboxylase (ODC) in the methyl jasmonate (MeJA)-regulated postharvest quality maintenance of Agaricus bisporus (J. E. Kange) Imbach button mushrooms by pretreating mushrooms with a specific irreversible inhibitor called α-difluoromethylornithine (DFMO) before exposure to MeJA vapor. RESULTS: Mushrooms were treated with 0 or 100 µmol L-1 MeJA or a combination of 120 µmol L-1 DFMO and 100 µmol L-1 MeJA, respectively, before storage at 4 °C for 21 days. Treatment with MeJA alone induced the increase in ODC activity whereas this effect was greatly suppressed by pretreatment with DFMO. α-Difluoromethylornithine strongly attenuated the effect of MeJA on decreasing cap opening, slowing the decline rate of soluble protein and total sugar, and accumulating total phenolics and flavonoids. α-Difluoromethylornithine pretreatment also counteracted the ability of MeJA to inhibit polyphenol oxidase and lipoxygenase activities, and malondialdehyde production, and to stimulate superoxide dismutase and catalase activities. It also largely downregulated MeJA-induced accumulation of free putrescine (Put). CONCLUSION: These results reveal that ODC is involved in MeJA-regulated postharvest quality retention of button mushrooms, and this involvement is likely to be associated with Put levels. © 2018 Society of Chemical Industry.

Isolation of high quality and yield of RNA from Agaricus bisporus with a simple, inexpensive and reliable method.

A method for isolating high purity and quantity RNA from Agaricus bisporus which is rich in proteins, carbohydrate, fiber and secondary metabolites, is described. RNA was extracted from mycelium, primordia, sporophores at two development stages and two post-harvest storage stages as well as from pileipellis, inner cap, gill and stipe of the mature sporophore. The A(260)/A(230) and A(260)/A(280) ratios of isolated RNA from fruiting bodies were both ~2 and the yield was about 200 µg/g fresh wt (FW). The yield of RNA from mycelium was approx. 100 µg/g FW. High quality RNA was also extracted from fruiting body tissues of Lentinus edodes, Pleurotus ostreatus, Flammulina velutipes and Pleurotus eryngii with yields from 130 to 225 µg/g FW. RNA extracted from all samples was intact, as demonstrated by gel electrophoresis and was suitable for downstream molecular applications, including RT-PCR and qPCR.

[Spectral analysis of some nutrients and minerals in Agaricus bisporus fruit bodies harvested at four different maturity stages].

The contents of nutritional elements such as Na, K, P, Ca, Mg and trace elements such as Cu, Se, Mo, Fe in Agaricus bisporus fruit bodies harvested at four different maturity stages (stage I, II, III, IV) were analyzed by ICP-AES, and the contents of some nutritional ingredients such as water, soluble protein, soluble sugar and ascorbic acid were also investigated. The results showed that the contents of Na, K, P, Mg, Cu, Se and Mo in stage I was respectively higher than those in the other three stages (alpha = 0.05), and the contents of Ca and Fe were respectively higher than those in stage II and III. The content of Se in stage IV was respectively higher than that in stage II and III, while the content f Na was respectively higher than that in stage II. The content of Cu in stage IV was respectively higher than that in stage III. The contents of K, P, Ca, Mg, Mo and Fe in stage II and III were respectively higher than those in stage IV. The content of water in stage IV was respectively higher than that in stage I and III, and had no significant differences from that in stage II. There were no significant differences in the contents of soluble protein, but the content of soluble sugar was significantly lower in stage IV. The content of ascorbic acid in stage III had no significant differences from that in stage I, but it was respectively higher than that in stage II and IV. The content of ascorbic acid in stage I and IV was respectively higher than that in stage II. The differences in the nutritional ingredients and mineral elements in the four stages of Agaricus bisporus fruit bodies provide academic data for the consumers and food industries while choosing Agaricus bisporus produces.

[Nondestructive examination of tomato chilling injury by ultraweak luminescence].

Ultraweak luminescence (UWL) is an universal phenomenon of photons emission in living organism. It is intrinsically connected with biological processes, and it closely links with biochemical, physiological and pathological conditions in organisms under stress. UWL testing is widely used in clinical medicine, agriculture, environmental protection and food industry etc. But it was not applied in testing physiological disease of agricultural product in storage. This study used tomato fruit as material to find rule of UWL in fruits under chilling stress, which is the main problem in tomato fruit storage. To obtain fruits with different chilling injury degree, before cold storage a group of fruits were treated with cold shock, the effective method to decrease chilling injury, which showed alleviative chilling injury symptom compared with untreated fruits. It was found that UWL rose with the degree of chilling injury, furthermore UWL went up remarkably (P < 0.01) before symptom of chilling injury happening. Correlation analysis between UWL and chilling injury rate and chilling injury index showed that correlation coefficient was 0. 901 6 and 0.9577 (P < 0.01)respectively. In conclusion, UWL could factually reflect the degree of chilling injury.

[Analysis of 14 minerals of mulberry fruit in different mature stage by ICP-OES method].

In the present study, the contents of nutritional elements such as Na, K, Ca, Mg, Fe, Zn, Se, Mn and Mo and heavy elements such as Cu, Cd, Pb, Cr and Co of mulberry fruits in three different mature stages were analyzed by ICP-OES. The results showed that the contents of Na, K, Ca, Mg, Fe, Zn, Mn and Cu decreased with maturation development. The contents of the above mentioned mineral elements in green stage were 2.99, 2957.49, 809.00, 559.95, 36.30, 10.07, 2.12 and 1.32 mg x kg(-1), respectively, their contents in pink stage were 169% (Zn) to 14% (Na) lower, the contents of these elements in red stage were 1.63, 2367.13, 489.30, 221.54, 19.01, 2.64, 0.40 and 0.59 mg x kg(-1), and the same changing trend remained in black stage, but the difference was much smaller. The content of Se was the highest in green stage (1.24 mg x kg(-1)), decreased in pink stage, increased in red stage (0.88 mg x kg(-1)), but decreased to 0.65 mg x kg(-1) in black stage. There was no significant change in Pb content in the first three stages, but a substantial decrease occurred in black stage, and the highest content of Pb was 0.27 mg x kg(-1) in green stage. The content of Cr increased during ripening, which was 54.07 mg x kg(-1) in red stage, but in black stage it decreased to the same level as that in pink stage. Both the Pb and Cr contents were not over allowance of Chinese National Standard. These data can be well reference for harvesting stage design and evaluation of function and safety of mulberry fruits.

[Relationship between the laccase production of Pleurotus ostreatus and the full wavelength scan for the fermentation liquid].

Laccase, widely distributed in fungi lacking high substrate specificity, plays an important role in lignin degradation in nature and environmental protection. In order to determine or estimate the laccase production during the fermentation of liquid media, the authors studied the full-length wave scan on the rough fermentation liquid of the Pleurotus ostreatus, which produces laccase high. Combined with the normal chemical method and diameter of the laccase and mycelium stain, which grew on the PDA (potato dextrose agar) plate with guaiacol added, we could get the exact information of laccase production. The result showed that the laccase activity increased in a rapid way in the first 5 days during the fermentation process, remained almost at the same level in the following 4 days, then increased rapidly until the 11 day, which was 148.7 U x L(-1), increased 17.9 times. The diameter of laccase and mycelium stain increased with the culture time. The number of the wave peaks around 300 nm had a positive correlation with the laccase production; the peak width of OD over 1.5 around 300 nm had a positive correlation with the laccase production, which ranges from 5 nm on the first day to 80 nm on the 11th day. The light absorption line between the wavelengths 300 and 400 nm had a positive correlation with the laccase production with peaks at 349, 365 and 388 nm, and at 365 the peak gets its highest. Using these parameters, the authors could get the general production of the laccase production of liquid fermentation. Compared with the normal chemical method, the full-length wave scan method is much easier, cheap and simple. Furthermore, there are no special chemical substances used. It is really a new method for the evaluation and determination of laccase.

[Analysis of some nutrients and minerals in organic and traditional cherry tomato by ICP-OES method].

In the present study, the contents of nutritional elements such as Ca, Mg, K, Zn, Fe and Mn and heavy elements such as Cu, Cd and Pb in organic and traditional cherry tomato fruit were analyzed by ICP-OES, and the contents of some nutritional ingredients such as water, total soluble solid, soluble sugar and asorbic acid were also investigated. The results showed that the contents of K, Ca and Zn in organic cherry tomato were 1.62, 71.7 and 1.34 mg x g(-1), which were 4.52%, 129.81% and 65.43% respectively higher than those in traditional tomato. There were no significant differences in the contents of Mg and Fe, which showed 73.8 and 2.05 mg x g(-1) in organic cherry tomato. But the content of Mn in organic tomato was 0.475 mg x g(-1), 11.22% lower than that in traditional one (alpha = 0.05). The contents of Cu, Cd and Pb showed no significant differences in the two kinds of tomato, which were 0.457 mg x g(-1), 4.86 ng x g(-1) and 0.127 mg x g(-1) respectively in organic cherry tomato, and all the contents were lower than the national requirement. There were no significant differences in the contents of water, soluble sugar, and asorbic acid, but the total soluble solid and the content of soluble protein were significantly higher in organic cherry tomato. The differences in the nutritional ingredients and mineral elements and safety status in the two kinds of tomato provide academic data for the evaluation of organic vegetables and traditional ones.

[Effects of exogenous nitric oxide on chlorophyll in cadmium-induced tomato seedlings].

Cadmium (Cd) is an important heavy metal pollution, and NO is a bioactive molecule, which was found to participate in the reaction of plant to Cd. Leaves from tomato seedlings pretreated with 100 micromol x L(-1) sodium nitroprusside (SNP, as NO donor) 1 day prior to being treated with 50 micromol x L(-1) Cd for 7 days were used as materials, and chloroplasts were isolated from the leaves to study the effects of NO on the spectroscopic characteristics of chlorophyll. The results of absorption spectra of chloroplasts showed that NO alleviated the effects of Cd on absorption spectra of chloroplast by raising the relative absorbance at 436 nm, 480 nm and 470 nm, which caused lower contents of carotinoid and chlorophyll. Fluorescence emission spectra of chloroplasts indicated that NO alleviated effect of Cd, and the relative absorbance at 686 nm and 734 nm decreased 17% and 10% respectively, while they decreased 33% and 23% respectively in chloroplasts treated with Cd. DCPIP analysis results showed that NO alleviated the inhibition of photosynthetic electron transport by Cd, and consequently the electron transport rate reached the same level of control.

[Effect of cultivation in zinc media on the growth of and the degree of zinc in organic form in transgenic metallothionein mushroom].

Metallothioneins (MTs) are a family of low molecular weight, cysteine-rich and metal-binding functional proteins. Transgenic MT mushroom can be used as functional food additives, but its zinc-enriching ability has not been studied systemically until now. The zinc contents in mycelia of transgenic MT mushroom (Pleurotus ostreatus) and wild type mushroom mycelia cultivated in different zinc concentration media were analyzed by ICP-OES. The growth status, zinc-enriching ability and degree of zinc in organic form (DZOF) were also analyzed. Results showed that MT mushroom mycelia grew rapidly, but the growth was inhibited when the zinc content in solid media was higher than 1.6 mmol x L(-1). MT mushroom mycelia could enrich more zinc than that of wild type, and the zinc content in MT mushroom mycelia could be 2.56-27.49 mg x kg(-1) when it was cultivated in a liquid media with 0.6-1.2 mmol x L(-1) zinc. DZOF of MT mushroom mycelia in a liquid media with 0.6 mmol x L(-1) zinc at 7 d was significantly higher (88.7%) than that in the wild type (82.1%, alpha = 0.05), but there was no significant difference in DZOF when the MT mushroom mycelia was cultivated in a liquid media with different zinc content at 7 d.

[Relationship of Zn content and Na/K ratio to the resistance to pathogen invasion in antisense ACS transgenic tomato fruit and normal tomato].

In the present work, inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to determine the content of Zn, Na and K and the ratio of Na/K in antisense ACS transgenic tomato fruit (in which the antisense ACC synthase gene construct was inserted) and in normal tomato fruit of the same variety (Lycopersicon esculentum cv. Lichun). The difference in mineral elements content between the two tomatoes and the involvement of Zn content and Na/K ratio in the disease resistance of postharvest tomato fruit were discussed. The results showed that the ethylene biosynthesis is limited in antisense ACS transgenic tomato fruit. Meanwhile, the resistance to Rhizopus nigricans invasion of this transgenic tomato was higher, the disease incidence and lesion area in transgenic tomato fruit were 20.0% and 33.3% lower than those in control fruit, respectively. In addition, the content of Zn in transgenic tomato fruit was 0.322 microg x g(-1) and was 1.5 times higher than that in Lichun tomato fruit. There was no significant difference in K content between transgenic tomato fruit and Lichun fruit, but the content of Na in transgenic tomato fruit was significant higher than that in Lichun fruit and the Na/K ratio in transgenic tomato fruit was 2.0 times higher than that in Lichun fruit. It is suggested that the content of Zn and the Na/K ratio may be involved in the resistance response to pathogen invasion and the development of antisense ACS transgenic tomato fruit.

[Determination of six mineral elements in roots, stems, leaves, flowers and seeds of Scutellaria baicalensis by FAAS].

A study was carried out on the contents of six trace elements, Ca, Cu, Fe, Mn, Zn and K, in roots, stems, leaves, flowers and seeds of planted Scutellaria baicalensis, by flame atomic absorption spectrophotometry (FAAS). The results indicated that Scutellaria baicalensis was rich in trace elements, meaning that it has a relatively high nutritive value. In stems of Scutellaria baicalensis, the content sequence of the six trace elements was found to be Fe > Mn > Zn = Cu > K > Ca. In leaves, the content sequence of the six trace elements was Fe> Mn > Zn > Cu > K > Ca. In flowers and seeds it was Ca > Fe > Mn > Zn > Cu > K, and Ca > Fe > Zn > Mn > Cu >K, separately, and in roots it was Ca > Fe > Cu > Mn > Zn > K. The stems, leaves, flowers and seeds are rich in Fe, whose content is higher than that in pork liver, Mn and Zn, but lower in Ca. The flowers, seeds and roots are especially rich in Ca, whose content is higher than that in bone, indicating that different parts of Scutellaria baicalensis may accumulate different mineral element. This study, for the first time, researched into Ca, Cu, Fe, Mn, Zn and K contents in different parts of Scutellaria baicalensis, which helps explain the multifunction of Scutellaria baicalensis and provides theoretical basis for further developing its medical and edible value.

[Comparative study on selenium and amino acids content in leaves of planted and wild Scutellaria baicalensis].

Scutellaria baicalensis is one of the most important Chinese herbs. It is widely used in Asian medicine to improve impaired brain function and to treat headaches, and used to treat prostate cancer. It is also known to be anti-inflammatory and antifungal, and also seems to have antiviral properties, including possible effectiveness against HIV. Scutellaria baicalensis tea and other products are in development. In the present study, the content of selenium (Se) in leaves of planted and wild Scutellaria baicalensis was determined by fluorescence photometer. The contents of 18 kinds of amino acids in the leaves of planted and wild Scutellaria baicalensis were determined with amino acids instruments. The results showed that the two kinds of leaves were rich in Se content, and the content of Se in planted Scutellaria baicalensis (0.051 microg x g(-1)) was not significantly different from that in wild one (0.051 microg x g(-1), alpha = 0.05). The amino acids, of which the total content was up to 14.62% and 10.25% separately, were rich in both planted and wild Scutellaria baicalensis. Among the 18 kinds of amino acids, aspartic acid, glutamic acid and leucine were comparatively high in leaves of planted and wild Scutellaria baicalensis. There are 8 kinds of amino acids essential to human body, which were higher in leaves of planted Scutellaria baicalensis than those of wild one. This study, for the first time, determined Se and amino acids content in Scutellaria baicalensis and concluded that the leaves of planted type have Se and amino acids content not lower or higher than that of wild type, and the planted type could be a good substitute of wild type in the development of Scutellaria baicalensis products. This study also provided useful data for explaining the multifunction of Scutellaria baicalensis and theological basis for developing its medical and edible value.

[Comparative study of minerals and some nutrients in organic celery and traditional celery].

Conventional cultivation pattern, integrated cultivation pattern and organic cultivation pattern are three patterns in China, and organic produce from organic cultivation pattern is considered the best one in quality and safety. Some experiments have been done on the effect of different cultivation patterns on the vegetable quality, such as the contents of Vc, total sugar, and dissoluble solid, which show the organic cultivation pattern and integrated cultivation pattern excel the conventional cultivation pattern, but there are no data that show the difference in the contents of mineral elements. In the present study, the contents of nutritional elements such as Ca, Mg, K, Zn, Fe and Mn and heavy elements such as Cu, Cd and Pb in organic celery and traditional celery were analyzed by ICP-OES, and the contents of some nutritional ingradients such as water, total soluble solid, soluble sugar and asorbic acid were also investigated. The results showed that the contents of K and Zn in organic celery were respectively 70.22% and 47.93% higher than that in traditional celery, but there was no significant difference in the contents of Ca, Mg and Fe, while the content of Mn was 47.24% lower in organic celery (alpha = 0.05). The contents of Cu, Cd and Pb showed no significant difference between the two kinds of celery, and are lower than the national requirement. The content of water and total soluble solid showed no significant difference, whereas the contents of soluble sugar and asorbic acid in organic celery were 55.04% and 118.18% higher, respectively. The difference in the nutritional ingredients and mineral elements and safety status between the two kinds of celery provides academic data for the comparison between organic vegetables and traditional ones.

[Content of trace elements and heavy metals in Chinese winter jujube fruit].

Today researchers pay more and more attention to the content of trace elements and heavy metals in food. Contents of trace elements and heavy metals in Chinese winter jujube fruit were analyzed by ICP-MS, the results showed that winter Chinese jujube contained plentiful trace elements, especially Ca (126.67 microg x g(-1) x FW), Mg (68.04 microg x g(-1) x FW), Sr (1691.39 ng x g(-1) x FW), Zn (787.26 ng x g(-1) x FW), Fe (512.84 ng x g(-1) x FW), Mn (495.42 ng x g(-1) x FW) and Mo (33.38 ng x g(-1) x FW), which is necessary for human health and can prolong the human life. But Chinese winter jujube contains little heavy metals and accords with relative national standard.

Rapid inactivation of chloroplastic ascorbate peroxidase is responsible for oxidative modification to Rubisco in tomato (Lycopersicon esculentum) under cadmium stress.

To investigate the sensitive site of antioxidant systems in chloroplast under cadmium stress and its consequence on reactive oxygen species production and action, the sub-organellar localization of chloroplast superoxide dismutases (SOD, EC 1.15.1.1) and ascorbic peroxidase (APX, EC 1.11.1.11) isoenzymes and changes of enzymes activities under cadmium stress were investigated in tomato seedlings. Two APX isoforms, one thylakoid-bound and one stromal, were detected. Cd at 50 microM induced a moderate increase of SOD activities but a rapid inactivation of both APX isoenzymes. APX inactivation was mainly related to the decrease of ascorbate concentration, as supported by in vitro treatment of exogenous ascorbate and APX kinetic properties under Cd stress. H2O2 accumulation in chloroplast, as a consequence of APX inactivation, was associated with a 60% loss of Rubisco (EC 4.1.1.39) activity, which could be partially accounted for by a 10% loss of Rubisco content. Protein oxidation assay found that the Rubisco large subunit was the most prominent carbonylated protein; the level of carbonylated Rubisco large subunit increased fivefold after Cd exposure. Thiol groups in the Rubisco large subunit were oxidized, as indicated by non-reducing electrophoresis. Treating crude extract with H2O2 resulted in a similar pattern of protein oxidation and thiols oxidation with that observed in Cd-treated plants. Our study indicates that APXs in the chloroplast is a highly sensitive site of antioxidant systems under Cd stress, and the inactivation of APX could be mainly responsible for oxidative modification to Rubisco and subsequent decrease in its activity.

[Distribution of Pb and Zn in transgenic metallothionein tobacco].

Transgenic metallothionein (MT) plant can clear the heavy metals from soil and environment, but the distribution of metals in plants has not been studied systematically. The Pb and Zn contents in different parts of transgenic MT tobacco plant of sixth generation and traditional plant (same culture variety as control) were analyzed. The Pb and Zn contents in total transgenic plant were 21.8% and 27.2% higher than control, respectively. The distribution of Pb and Zn in different organs varied in these two types of plants. The Pb and Zn contents in old leaves, stem and root in transgenic plants were significantly higher than those in wild type tobacco, while there was no significant difference in young leaves. The Pb contents in old leaves and root were 30.2% and 47.8% higher than those in the control, and the Zn contents in old leaves, stem and root were 4.7%, 29.2% and 21.6% higher than those in the control. These data showed that Pb was accumulated in old leaves and root easily, while Zn was accumulated in old leaves and stem easily.