菠萝PEPC基因家族生物信息学分析

磷酸烯醇式丙酮酸羧化酶（phosphoenolpyruvate carboxylase, PEPC）在C₄和景天酸代谢（CAM）光合途径吸收CO₂过程中发挥重要作用,并参与各种非光合作用过程,包括果实成熟、气孔开放、碳氮相互作用、种子形成和萌发以及调节植物对逆境胁迫的耐受性。菠萝为典型的景天酸代谢途径（CAM）植物,为了解磷酸烯醇式丙酮酸羧化酶（PEPC）在菠萝景天酸代谢途径（CAM）中的作用,本研究鉴定到3个菠萝PEPC基因,按照基因描述命名为AcPEPC1、AcPEPC3和AcPEPC4,进化树分析结果AcPEPC1和AcPEPC3为植物型PEPC（PTPCs）蛋白,序列同源性较高且基因结构、保守结构域及保守基序均一致。AcPEPC4为细菌型PEPC（BTPCs）蛋白,与AcPEPC1/AcPEPC3间的序列同源性低。组织表达分析表明AcPEPC1菠萝叶片表达量较高,而AcPEPC3和AcPEPC4在菠萝花和果实表达量较高。     

The effects of lighting conditions and food restriction paradigms on locomotor activity of common spiny mice, Acomys cahirinus

Background

An endogenous circadian clock controls locomotor activity in common spiny mice (Acomys cahirinus). However, little is known about the effects of constant light (LL) on this activity or about the existence of an additional food entrainable clock. A series of experiments were performed to investigate the effects of LL and DD on tau and activity levels.

Methods

Spiny mice were housed individually and their running wheel activity monitored. One group of mice was exposed to LD, DD and several intensities of LL. Another group was exposed to a restricted feeding (RF) paradigm in light: dark (LD) during one hour before the L to D transition. Significance of rhythmicity was assessed using Lomb-Scargle periodograms.

Results

In LD all animals exhibited nocturnal activity rhythms that persisted in DD. When animals were exposed to RF (during L), all of these animals (n?=?11) demonstrated significant food anticipatory activity as well as an increase in diurnal activity. This increase in diurnal activity persisted in 4/11 animals during subsequent ad libitum conditions. Under LL conditions, the locomotor rhythms of 2/11 animals appeared to entrain to RF. When animals were exposed to sequentially increasing LL intensities, rhythmicity persisted and, while activity decreased significantly, the free-running period was relatively unaffected. In addition, the period in LL was significantly longer than the period in DD. Exposure to LL also induced long-term changes (after-effects) on period and activity when animals were again exposed to DD.

Conclusions

Overall these studies demonstrate clear and robust circadian rhythms of wheel-running in A. cahirinus. In addition, LL clearly inhibited activity in this species and induced after-effects. The results also confirm the presence of a food entrainable oscillator in this species.     

Diurnal and seasonal patterns of leaf gas exchange in bahiagrass (Paspalum notatum Flügge) growing in a subtropical climate

The objective of this study was to evaluate the seasonal and diurnal changes in leaf gas exchange in bahiagrass (Paspalum notatum) plants grown in an irrigated lawn. Carbon dioxide assimilation, transpiration, stomatal conductance, leaf temperature and leaf‐to‐air vapour pressure difference were measured during the daylight period from April 2003 to March 2004. The monitored environmental variables were photosynthetic photon flux density, air temperature, air relative humidity, photoperiod and sunshine rate. Factor and cluster analyses were used to select variables and to group months with similar physiological and meteorological characteristics, and three distinct periods were identified: (i) May to July: with low energetic availability, low leaf temperatures and low photosynthetic activity; (ii) September to January: with high energetic availability, high leaf temperatures and high photosynthetic activity; and (iii) April–March–August: a transient period with environmental and physiological characteristics showing intermediate values. The reduced plant development and growth during the winter season was in accordance to the lower photosynthetic activity recorded from June to August, this variable being a potential indicator of reduced phytomass production. The relationships between leaf gas exchange and seasonal growth are discussed.     

Phosphoenolpyruvate carboxylase activity in ear organs is related to protein concentration in grains of winter wheat

The relationship between phosphoenolpyruvate carboxylase (PEPC) activities in flag leaf blade and ear organs (glume and grain) and protein content of grain as well as grain weight after flowering were studied in different winter wheat (Triticum aestivum L.) genotypes. Results showed higher PEPC activity in the developing grain than in flag leaf blade and glume during grain development. For 16 of the genotypes studied, the mean PEPC activity in the developing grain or glume at 15 and 25 days after flowering was significantly and positively correlated with final protein content of grain. Enzyme activities in glume and flag leaf blade were positively correlated with final grain weight but the activity in developing grain was weakly and negatively correlated with grain weight. The overall data suggest that PEPC may be involved in protein biosynthesis during grain development, and it may have an important role in regulating carbon and nitrogen metabolism in the ear of wheat.     

Myzus persicae (Sulzer) in diffuse light and dark rustic storages and resultant PLRV transmission

Population levels ofMyzus persicae (Sulzer) were studied on potato tubers in diffuse light and dark rustic storage houses in Peru. No differences in numbers of aphids/sprouted eye on potatoes infested naturally during storage in diffuse light or darkness were observed. Significantly more alate aphids were observed on tubers stored in darkness than in diffuse light storage houses. Viral transmission was occurring during the storage period. The incidence of viral transmission was not significantly influenced by storing tubers in diffuse light or dark storages. There were significantly more plants infected with virus from tubers that had not been sprayed for aphid control than from tubers that had been sprayed     

The effects of lighting conditions and food restriction paradigms on locomotor activity of common spiny mice, Acomys cahirinus

ABSTRACT: BACKGROUND: An endogenous circadian clock controls locomotor activity in common spiny mice (Acomys cahirinus). However, little is known about the effects of constant light (LL) on this activity or about the existence of an additional food entrainable clock. A series of experiments were performed to investigate the effects of LL and DD on tau and activity levels. METHODS: Spiny mice were housed individually and their running wheel activity monitored. One group of mice was exposed to LD, DD and several intensities of LL. Another group was exposed to a restricted feeding (RF) paradigm in light: dark (LD) during one hour before the L to D transition. Significance of rhythmicity was assessed using Lomb-Scargle periodograms. RESULTS: In LD all animals exhibited nocturnal activity rhythms that persisted in DD. When animals were exposed to RF (during L), all of these animals (n = 11) demonstrated significant food anticipatory activity as well as an increase in diurnal activity. This increase in diurnal activity persisted in 4/11 animals during subsequent ad libitum conditions. Under LL conditions, the locomotor rhythms of 2/11 animals appeared to entrain to RF. When animals were exposed to sequentially increasing LL intensities, rhythmicity persisted and, while activity decreased significantly, the free-running period was relatively unaffected. In addition, the period in LL was significantly longer than the period in DD. Exposure to LL also induced long-term changes (after-effects) on period and activity when animals were again exposed to DD. CONCLUSIONS: Overall these studies demonstrate clear and robust circadian rhythms of wheel-running in A. cahirinus. In addition, LL clearly inhibited activity in this species and induced after-effects. The results also confirm the presence of a food entrainable oscillator in this species.     

Effects of temperature and light on salinity tolerance during germination in two desert glycophytic grasses,Lasiurus scindicus and Panicum turgidum

The grasses Lasiurus scindicus and Panicum turgidum are among the most important forage species of the Arabian deserts. Both are ‘glycophytic’ or salt‐intolerant species, where seed germination becomes reduced by salinity effects. Here, we report experimental effects of light/darkness, temperature and NaCl salinity on seed germination and ‘recovery’ germination in these two species, after seeds had been transferred from saline solution to distilled water. Seeds were germinated in a range of salinities and incubated at a range of temperatures, in both light and darkness. Seeds of P. turgidum germinated significantly more in darkness than in light at temperatures 15–25°C, but the reverse was true at higher temperatures. Seeds of L. scindicus germinated well across a wide range of temperatures and in both light and darkness. In both species, germination decreased with the increase in salt concentration, and in P. turgidum germination was almost completely inhibited at a concentration of 200 mm . In saline solution, germination in darkness was significantly greater than in light at all the temperatures. Seeds of both species ‘recovered’ their germination capacity after transfer from saline solutions to distilled water. Germination recovery depended on both light and temperature of incubation in both species.     

Geographic distribution of mealybug wilt disease of pineapple and genetic diversity of viruses infecting pineapple in Cuba

Several species of ampeloviruses and badnaviruses infect pineapple plants around the world. Pineapple mealybug wilt-associated ampeloviruses have been associated with mealybug wilt of pineapple (MWP), the major viral disease threatening this crop. Conversely, infection by the badnaviruses Pineapple bacilliform comosus virus (PBCOV) and Pineapple bacilliform erectifolius virus (PBERV) is asymptomatic. To investigate the status of infection of the pineapple crop in Cuba, a diagnostic survey was developed in commercial areas during the period 2009–2012. Incidence of MWP disease was found in up to 100% of the plants in some fields of Central and Eastern regions of the island. Molecular assays revealed the presence of PMWaV-1 for the first time in the Caribbean basin and PMWaV-2, PMWaV-3, either as mixed infections or in combination with PBCOV throughout the country. Furthermore, they revealed for the first time the presence of PMWaV-2 in Bromelia pinguin L., a plant commonly used in Cuba as hedgerow. Sequence analysis of partial heat shock protein 70h and complete coat protein gene of Cuban isolates of PMWaV-1, -2 and -3 showed nucleotide identities above 97% with cognate sequences of viruses isolated from other countries. This work discloses the presence of a complex of viruses associated with the pineapple crop in Cuba, highlights the potential role of B. pinguin in the PMWaV-mealybug-pineapple pathosystem and makes available diagnostic tools for the detection of viruses affecting pineapple for a seed certified production system in Cuba.     

Intermittent long-wavelength red light increases the period of daily locomotor activity in mice

Background  

We observed that a dim, red light-emitting diode (LED) triggered by activity increased the circadian periods of lab mice compared to constant darkness. It is known that the circadian period of rats increases when vigorous wheel-running triggers full-spectrum lighting; however, spectral sensitivity of photoreceptors in mice suggests little or no response to red light. Thus, we decided to test the following hypotheses: dim red light illumination triggered by activity (LEDfb) increases the circadian period of mice compared to constant dark (DD); covering the LED prevents the effect on period; and DBA2/J mice have a different response to LEDfb than C57BL6/J mice.     

The impact of cutting,liming and fertilizing on characteristics of abandoned upland meadows in the Czech Republic

The responses of three upland grassland phytocoenoses to three different management treatments were studied in Southern Bohemia. The sites were at an advanced successional stage, with all three being meadows abandoned since World War II: (i) Molinion, (ii) degraded Calthion with dominant Carex brizoides and (iii) plant community with the dominant species Calamagrostis villosa. Three different treatments (cutting, liming and fertilizing) were applied to the three grassland types, and their effects on the diversity, plant cover and biomass production were investigated over a 3‐year period. Analyses showed significant differences between meadow types in time as well as response to treatments. Independent of the treatments, the biomass production and Shannon index increased significantly in all meadows by varying degrees during the investigation period, whereas the cover decreased slightly in the case of the Carex community and the Molinion and remained unchanged in the case of the Calamagrostis community. Changes in the ground cover (as percentage) in response to management treatments varied between the meadow types. Limed and fertilized plots of the Molinion and Calamagrostis communities had higher percentage cover values compared to the control, but the cover of the C. brizoides community was not affected. In contrast, cut plots of the Molinion had slightly reduced cover. The changes in biomass and species diversity showed no significant correlation with the types of treatment used.     

Evaluation of Cultivar Differences in Preharvest Sprouting of Common Buckwheat (Fagopyrum esculentum Moench)

Abstract

Preharvest sprouting of buckwheat (Fagopyrum esculentum Moench) is an important problem, but cultivar differences in preharvest sprouting and their causes have not been investigated. We detected cultivar differences under natural field conditions. Preharvest sprouting of three cultivars was significantly lower than that of the current main cultivar. Seeds collected before rainfall were threshed and incubated on a wet filter paper in a petri dish for 10 days at 10, 20, 30 and 40ºC in the dark, or at an alternating light and temperature condition of 8 h light at 30ºC and 16 h darkness at 20ºC. Germination was promoted by a higher temperature except for 40ºC, suggesting that the risk of preharvest sprouting in buckwheat is higher at a relatively higher temperature. The risk of preharvest sprouting in the field was highly correlated with germination at 20ºC (r = 0.98***) and 30ºC (r = 0.99***) in the dark, suggesting that germination test can be used to predict preharvest sprouting in the field. Preharvest sprouting was significantly correlated (r = ?0.77**) with main stem length, suggesting that ecotype is partly responsible for this phenomenon.     

外源C4二羧酸对转玉米PEPC基因水稻C4光合途径的促进作用

以转PEPC基因水稻和野生型水稻Kitaake为材料, 研究了不同基因型水稻叶片中的C4光合微循环及其功能。通过测定与光合C4途径有关的关键酶,如磷酸烯醇式丙酮酸羧化酶(PEPC)、NADP苹果酸酶(NADP-ME)、NADP苹果酸脱氢酶(NADP-MDH)和丙酮酸磷酸双激酶(PPDK),说明野生型水稻叶片中具有完整的C4光合酶体系;用外源草酰乙酸(OAA)或苹果酸(MA)饲喂叶切片或叶绿体后明显增加光合速率,证明野生型水稻中具有一个有限的光合C4微循环。将玉米的PEPC基因导入原种水稻后,可大幅度提高光合C4微循环的速率。测定不同基因型的CO2交换速率,看出水稻中C4光合微循环的增强有提高净光合速率(Pn)和降低Pr/Pn比值的作用。叶绿素荧光特性分析表明,C4光合微循环的增强伴随着PSⅡ电子传递效率(Fv/Fm)和光化学猝灭(qp)的增加,以及非光化学猝灭(qN)的降低。      

Photosynthesis, respiration and nitrogen fixation in white clover

An apparatus in which shoot and root CO₂ exchange and acetylene reduction can be simultaneously measured in specific white cloverrhizobium associations is described. In mature stolonating clover there was a fairly constant ratio between net photosynthesis, root respiration and acetylene reduction. Of the net carbon fixed daily (12 h light of 80 W m^-2, 400–700 nm; day/night temperature 15°C) 12% was lost during the dark period by the shoot and 17% by the nodulated root. Changes in the rate of acetylene reduction by nodulated root systems occurred more slowly than those in rates of root respiration in response to reduced irradiance. In 21·5 h continuous darkness the rate of acetylene reduction remained constant. Responses to increased irradiance were more immediate in both root respiration and acetylene reduction. In plants maintained at 15°C in a 12-h, 80-W m^-2 photoperiod there was no significant diurnal variation in acetylene reduction or root respiration. Acetylene depressed root respiration by 20%. Assuming the energy requirement of the nitrogenase system to be the same when reducing acetylene and N the depression can be used as an indication of the energy requirement of fixed N assimilation, metabolism and export in the nodulated root. Of the net carbon fixed daily 3·4% was utilized in this way in plants growing in a 12-h photoperiod (80 W m^-2, 400–700 nm) at 15°C.     

宁夏小麦品种（系）脂肪氧化酶基因的检测与分布

为给宁夏优质小麦育种和推广提供依据,本研究以180份宁夏小麦品种（系）为材料,利用分子标记检测脂肪氧化酶（LOX）基因在QLpx.caas-1AL和TaLOX-B1位点的组成情况,分析其分布特点。结果表明,不同等位变异及其组合类型的分布比例不同。在QLpx.caas-1AL位点,除了原有的3种等位变异Xwmc312-227、Xwmc312-235和Xwmc312-247外,还发现了2种新的等位变异。经测序分析,两种新变异条带大小分别为199 bp和223 bp,暂命名为Xwmc312-199和Xwmc312-223。该位点5种等位变异的分布比例分别为46.11%、32.78%、18.89%、1.11%和1.11%。在TaLOX-B1位点存在2种等位变异,即TaLOX-B1a和TaLOX-B1b,分别占15.56%和84.44%。宁夏小麦LOX基因位点存在8种等位变异组合类型,其中Xwmc312-227/TaLOX-B1b组合类型比例（40.56%）最高,Xwmc312-235/TaLOX-B1b次之（27.78%）,Xwmc312-199/TaLOX-B1b和Xwmc312-223/TaLOX-B1b最低（均为1.11%）。同时,在不同地区和相同地区不同来源品种（系）间,LOX基因的分布也存在差异。总体来看,宁夏小麦低活性LOX基因等位变异类型（Xwmc312-227/TaLOX-B1b）所占的比例明显高于高活性类型（Xwmc312-235/TaLOX-Ba1）。     

Alleviation of salinity stress on germination of Leymus chinensis seeds by plant growth regulators and nitrogenous compounds under contrasting light/dark conditions

The effects of plant growth regulators (PGRs) and nitrogenous compounds on alleviating salinity stress on seed germination of Leymus chinensis in light (12 h light/12 h dark) and dark (24 h dark) conditions were determined in a laboratory experiment. Seed germination was compared at various combinations of salinity and germination‐promoting compounds. Seed germination percentages were 57 and 74% under non‐saline conditions in light and dark, respectively, suggesting that germination was light‐inhibited. Germination decreased significantly with increasing salinity level in both light and dark conditions, and the reduction was greater in light than in dark at each salinity level. Seed germination percentage decreased to 22 and 7% in light but only to 51 and 27% in dark, in 100 and 200 mm NaCl solutions respectively. The influence of PGRs and nitrogenous compounds in alleviating salinity stress varied with light and salinity condition; e.g., gibberellins (GA_4 + 7) significantly increased germination percentages from 22%, 7% and 0·3% to 47%, 23% and 15% in light at 100, 200 and 300 mm NaCl, respectively, while they showed no effect on germination in darkness. In contrast, sodium nitroprusside and cytokinin significantly increased germination percentage in darkness at all salinity levels, but showed no effect on germination in light at 200 and 300 mm NaCl. Fluridone was very effective in alleviating salinity stress on germination in both light and dark; however, it was lethal to seedlings. Thiourea had no effect in alleviating salinity stress in either light or dark. Thus, alleviation of salinity stress on seed germination of L. chinensis by germination‐promoting compounds is strongly dependent on chemicals and light conditions.     

Photosynthetic Recovery of a Perennial Grass Leymus chinensis after Different Periods of Soil Drought

Abstract

The effects of rewatering after different periods of soil drought stress on the photosynthetic capacity of Leymus chinensis in pots were investigated. The plants were subjected to short-term (10-d), moderate-term (20-day) and long-term (30-d) drought each followed by rewatering. Control plants were well watered during the experimental periods. The long-term water stress without rewatering decreased the chlorophyll content, Chl a/b ratio, carbonic anhydrase (CA) activity, net photosynthetic rate (A), and leaf area compared with the control. Rewatering increased the ratio of Chl a/b, CA activity and A, but decreased the leaf area and ion leakage from the cut leaf pieces. The long-term water stress without rewatering reduced the maximal efficiency of PSII (F_v/F_m), the actual quantum yield (Φ_p), and photochemical quenching (q_p), but these values were increased by rewatering to more than the control level, though non-photochemical quenching (q_N) was decreased as compared with the control. This implied that long-term drought aggravated PSII, but rewatering improved it. The net CO₂-exchange rate showed similar diurnal changes in all treatments, but the rate in the morning was lower in long-term drought (before rewatering) than in the other treatments. These results suggest the photosynthesis of Leymus chinensis may be well adapted to episodical soil drought.     

Chemical composition of kernels from some species ofCucurbitaceae grown in Nigeria

The seeds of lesser-known species —Cucumeropsis mannii, Lagenaria sicceraria varities 1 and 2 andTelfairia occidentalis, ofCucurbitaceae family were studied. The protein content ofC. mannii was 36.1% and the varieties 1 and 2 ofL. sicceraria had 32.1% and 33.3% respectively.Telfairia occidentalis had protein content of 33.2%. The fat contents ofC. mannii, L. Sicceraria var. 1 and 2 andT. occidentalis were 44.4%, 44.6%, 46.9% and 42.3% respectively. The crude fibre content for each of the two varieties ofL. sicceraria was 3.6% andT. occidentalis had 5.5%.Cucumeropsis mannii had the lowest (2.4%) fibre content. The carbohydrate contents forL. Sicceraria var. 2,C. mannii, andT. occidentalis were 12.6%, 13.2% and 14.4% respectively.Lagenaria sicceraria var. 1 had the highest value of carbohydrate (15.8%). The species were relatively rich in potassium and magnesium with range of values of 0.56% to 0.68% and 434 ppm to 444 ppm respectively.Cucumeropsis mannii andLagenaria sicceraria var. 2 had relatively high contents of calcium (117 ppm) and iron (109 ppm) respectively. The kernels of these species exhibited lipase activity.Telfairia occidentalis showed the highest degree of lipase activity.     

Effects of temperature and light on the hatching of overwintering eggs in three Japanese Sympetrum species

The aim of the present study was to obtain quantitative information on egg hatching with respect to temperature and light to clarify the effect of cultivation methods on three Japanese Sympetrum species. Eggs of three Sympetrum species were collected on October 2005 at Akita prefecture located at north of Japan, and the eggs had been laid on soil surface of paddy field till April 2006. The eggs (3 trays with 50 eggs each) were held under four constant temperatures (8, 13, 18 and 23°C) with a photoperiod (L:D 14:10; relative light intensity 3,000 Lux) and 23°C in darkness. No S. infuscatum eggs, but 67 and 60% S. frequens and S. darwinianum hatched in constant darkness. This result suggests that S.frequens and S.darwinianum do not require light for hatching, but S.infuscatum requires light for hatching. Eggs of S. darwinianum and S. infuscatum did not hatch at 8°C. In S. frequens, some eggs hatched but the hatching rate was significantly lower at 8°C than at higher temperatures (P < 0.05). At higher temperatures, the hatching rate did not differ significantly for three Sympetrum species. At 13°C, S. infuscatum hatched fastest, 0.18 for S. infuscatum, 0.11 for S. darwinianum and 0.08 for S. frequens. The mean head width of second stadium larva of S. frequens, S. darwinianum and S. infuscatum were 0.4 ± 0.01, 0.4 ± 0.01 and 0.6 ± 0.01 mm (SD), respectively. These results suggest that S. infuscatum may have a competitive advantage over S. frequens and S. darwinianum under conditions that favor S. infuscatum through hatching speed.     

Photosynthetic Characteristics of an Amphibious C4 Plant,Eleocharis retroflexa ssp. chaetaria

Abstract

Eleocharis retroflexa (Poir.) Urban ssp. chaetaria (Roem. & Schult.) T. Koyama, an amphibious leafless sedge, grows not only under terrestrial conditions but also under completely submerged aquatic conditions. We investigated the photosynthetic traits and structural features of the culms, which are the photosynthetic organs, in the terrestrial and submerged forms of this species and compared them with those of other amphibious species of Eleocharis which are known to change the photosynthetic modes. The culms of the terrestrial form had Kranz anatomy with well-developed Kranz (bundle sheath) cells and high levels of C₄ enzyme activity typical of the NAD-malic enzyme (NAD-ME) subtype of C₄ metabolism. They also had a δ ¹³C value typical of C₄ plants, indicating that the terrestrial form fixes carbon through the C₄ pathway. The culms of the submerged form had not only a Kranz-like anatomy but also revealed anatomical traits typical of leaves of submerged aquatic plants. The activities of the C₄ enzymes in the submerged form were lower than those in the terrestrial form, but were still in the range typical of G4 plants, ¹⁴C pulse-¹²C chase experiments with the submerged form indicated that almost all of the fixed ¹⁴C was incorporated into G4 compounds, and subsequently the raioactivity was transferred into C₃ compounds and sucrose. The submerged form showed no diurnal fluctuation in malate level. These data demonstrate that a C₄ metabolism is operative even in the submerged form. This unique amphibious C₄ plant provides an intriguing example of the physiological and ecological adaptability of C₄plants.