Rapid determination of rice seed vigour by spontaneous chemiluminescence and singlet oxygen generation during early imbibition

Using a highly sensitive single photon counter, a spontaneous chemiluminescence (CL) study on rice (Oryza sativa L.) seeds stored in different years was carried out. We first observed that the degree of ageing in rice seeds was related to the intensity of spontaneous CL during early imbibition (0–30 min). Rice seeds stored for a shorter time had a stronger intensity of CL in early imbibition. The germination rate of rice seeds showed an obvious positive correlation with the intensity of spontaneous CL. Singlet oxygen (¹O₂) in rice seeds during early imbibition was investigated by a CL method using a cypridina luciferin analogue, 2‐methyl‐6‐(p‐methoxyphenyl)‐3,7‐dihydroimidazo [1,2α] pyrazin‐3‐one (MCLA), as a selective CL probe. Additional experimental evidence for the formation of ¹O₂ came from the quenching effect of sodium azide (NaN₃) on MCLA‐mediated rice seeds' CL. Analysis based on the experimental results demonstrated that spontaneous CL in rice seeds during early imbibition was mainly contributed by singlet oxygen (¹O₂). Copyright © 2002 John Wiley & Sons, Ltd.     

激素浸种对薄壳山核桃种子萌发的影响及其种子吸胀过程中SOD和POD活性变化

薄壳山核桃﹝Carya illinoinensis ( Wangenh.) K. Koch﹞为胡桃科( Juglandaceae)山核桃属( Carya Nutt.)植物,又名美国山核桃、长山核桃,是世界上著名的经济树种之一[1-2]。目前,主要采用本砧嫁接的方法培育薄壳山核桃良种嫁接苗,而培育优质实生苗作为砧木是该技术的关键环节之一,因此,了解其种子萌发特性极为重要。目前,对薄壳山核桃种子萌发特性的研究主要集中在植物激素催芽方面[3-5],而有关激素催芽过程中的适宜浸泡天数、种子吸胀过程中相关的酶活性变化等问题尚不明确。     

Transgenic rice seed synthesizing diverse flavonoids at high levels: a new platform for flavonoid production with associated health benefits

Flavonoids possess diverse health‐promoting benefits but are nearly absent from rice, because most of the genes encoding enzymes for flavonoid biosynthesis are not expressed in rice seeds. In the present study, a transgenic rice plant producing several classes of flavonoids in seeds was developed by introducing multiple genes encoding enzymes involved in flavonoid synthesis, from phenylalanine to the target flavonoids, into rice. Rice accumulating naringenin was developed by introducing phenylalanine ammonia lyase (PAL) and chalcone synthase (CHS) genes. Rice producing other classes of flavonoids, kaempferol, genistein, and apigenin, was developed by introducing, together with PAL and CHS, genes encoding flavonol synthase/flavanone‐3‐hydroxylase, isoflavone synthase, and flavone synthases, respectively. The endosperm‐specific GluB‐1 promoter or embryo‐ and aleurone‐specific 18‐kDa oleosin promoters were used to express these biosynthetic genes in seed. The target flavonoids of naringenin, kaempferol, genistein, and apigenin were highly accumulated in each transgenic rice, respectively. Furthermore, tricin was accumulated by introducing hydroxylase and methyltransferase, demonstrating that modification to flavonoid backbones can be also well manipulated in rice seeds. The flavonoids accumulated as both aglycones and several types of glycosides, and flavonoids in the endosperm were deposited into PB‐II‐type protein bodies. Therefore, these rice seeds provide an ideal platform for the production of particular flavonoids due to efficient glycosylation, the presence of appropriate organelles for flavonoid accumulation, and the small effect of endogenous enzymes on the production of flavonoids by exogenous enzymes.     

Metabolism of amino acids in germinating yellow lupin seeds. II. Pathway of conversion of aspartate to alanine during the imbibition

The incorporation of ¹⁴C-aspartate during the imbibition of yellow lupin seeds resulted in the production of ¹⁴C-alanine and ¹⁴CO₂. On the basis of tracer and enzymatic assays, conducted in vitro on the extract obtained from lupin seeds, it is postulated that aspartate can be converted to oxaloacetate, then, by phosphoenolopyruvate and pyruvate to alanine. This pathway can be catalyzed by the following enzymes: aspartate aminotransferase, phosphoenolpyruvate carboxykinase, pyruvate kinase and alanine aminotransferase.     

Influence of long-term different fertilization on soil weed seed bank diversity of a paddy soil under rice/rape rotation

A long-term fertilized paddy field under rice/ rape rotation in the Taihu Lake Region was selected to investigate the dynamics of soil weed seed diversity.Four fertilizer treatments were performed,including non-fert-ilizer (NF),chemical fertilizer only (CF),chemical fert-ilizer combined with pig manure (CMF) and chemical fertilizer plus crop stalk (CSF).We recorded the seed numbers and crop yields,estimated the weed seed bank density and identified the kinds of weed seeds in the top-soil (0-15 cm) in the study area using a stereomicroscope.Based on the records,we analyzed the effect of long-term fertilization on soil weed seed bank diversity and the rela-tionship between weed seed diversity and crop yields.Comparing the four treatments,it was found that in the cultivating seasons of both rice and rape,the density of soil weed seed bank was the lowest with the treatment of chemical fertilizer plus crop stalk.Whereas,the total num-ber of species and the weed seed bank diversity was the highest.Furthermore,the crop yields were at maximum and kept constant with this treatment.There was a def-inite correlation between fertilizer treatment and soil weed seed bank diversity and crop yields.It was concluded that balancing the fertilizer management was helpful in main-taining soil weed seed bank diversity,increasing crop yields and alleviating crop yield fluctuation.Therefore,among the four fertilizer treatments,chemical fertilizer plus rice crop stalk treatment was the best one to stimulate the productivity of agricultural ecosystems and simulta-neously protect biodiversity.     

Influence of long-term different fertilization on soil weed seed bank diversity of a paddy soil under rice/rape rotation

A long-term fertilized paddy field under rice/rape rotation in the Taihu Lake Region was selected to investigate the dynamics of soil weed seed diversity. Four fertilizer treatments were performed, including non-fertilizer (NF), chemical fertilizer only (CF), chemical fertilizer combined with pig manure (CMF) and chemical fertilizer plus crop stalk (CSF). We recorded the seed numbers and crop yields, estimated the weed seed bank density and identified the kinds of weed seeds in the topsoil (0–15 cm) in the study area using a stereomicroscope. Based on the records, we analyzed the effect of long-term fertilization on soil weed seed bank diversity and the relationship between weed seed diversity and crop yields. Comparing the four treatments, it was found that in the cultivating seasons of both rice and rape, the density of soil weed seed bank was the lowest with the treatment of chemical fertilizer plus crop stalk. Whereas, the total number of species and the weed seed bank diversity was the highest. Furthermore, the crop yields were at maximum and kept constant with this treatment. There was a definite correlation between fertilizer treatment and soil weed seed bank diversity and crop yields. It was concluded that balancing the fertilizer management was helpful in maintaining soil weed seed bank diversity, increasing crop yields and alleviating crop yield fluctuation. Therefore, among the four fertilizer treatments, chemical fertilizer plus rice crop stalk treatment was the best one to stimulate the productivity of agricultural ecosystems and simultaneously protect biodiversity. __________ Translated from Biodiversity Science, 2006, 14(6): 461–469 [译自:生物多样性]     

Antagonism between abscisic acid and gibberellins is partially mediated by ascorbic acid during seed germination in rice

The antagonism between abscisic acid (ABA) and gibberellin (GA) plays a key role in controlling seed germination,^1,2 but the mechanism of antagonism during this process is not known. In the associated study,³ we investigated the relationship among ABA, reactive oxygen species (ROS), ascorbic acid (ASC) and GA during rice seed germination. ROS production is reduced by ABA, which hence results in decreasing ASC accumulation during imbibition. GA accumulation was also suppressed by a reduced ROS and ASC level, whereas application of exogenous ASC can partially rescue seed germination from ABA treatment. Further results show that production of ASC, which acts as a substrate in GA biosynthesis, was significantly inhibited by lycorine which thus suppressed the accumulation of GA. Consequently, expression of GA biosynthesis genes was suppressed by the low levels of ROS and ASC in ABA-treated seeds. These studies reveal a new role for ASC in mediating the antagonism between ABA and GA during seed germination in rice.     

Rice calcium-dependent protein kinase isoforms OsCDPK2 and OsCDPK11 show different responses to light and different expression patterns during seed development

We investigated the spatial and temporal expression patterns of two rice calcium-dependent protein kinases (CDPKs), OsCDPK2 and OSCDPK11, using isoform-specific antisera. Bands of the expected molecular sizes for OsCDPK2 (59 kDa) and OsCDPK11 (61 kDa) were detected on western blots. OsCDPK2 and OsCDPK11 mRNA and protein levels increased in unison during flower development. However, at the onset of seed development, the protein expression profiles diverged significantly. OsCDPK2 protein was expressed at low levels during early seed development, but increased to high levels that were maintained in later stages (20 days after fertilisation, DAF). Conversely, OsCDPK11 protein levels were high at the beginning of seed development, but fell rapidly from 10 DAF onwards. This decrease in the level of OsCDPK11 protein was associated with the abundant synthesis of a truncated mRNA species. OsCDPK2 expression was also closely associated with light perception. OsCDPK2 protein was barely detectable in green leaves exposed to light, but levels increased sharply when plants were shifted to darkness. Initially, this increase reflected a rapid elevation in the levels of OsCDPK2 mRNA, which was normally located in the mesophyll. Conversely, OsCDPK11 mRNA and protein levels were unaffected by light. These data strongly indicate that two rice CDPK isoforms have different functions in seed development and in response to light in leaves.     

不同浓度氯化钙浸种处理对水稻防御酶活性和抗褐飞虱的影响

[目的]研究不同浓度氯化钙(calcium chloride,CaCl2)浸种处理对水稻防御酶活性和抗褐飞虱Nilaparvata lugens的影响.[方法]分别用10,20,30,40和50 mmol/L CaCl2溶液浸泡水稻种子48 h,以蒸馏水浸种为对照,待水稻长至分蘖期时,检测褐飞虱3龄若虫取食胁迫下各浓度...     

The effect of parent plant nutrition on seed size, viability and vigour and on germination of wheat and triticale at different temperatures

Seed was obtained from two adjacent trials of wheat (cv. Avalon) and triticale (cv. Lasko) harvested in 1990. The treatments consisted of factorial combinations of five levels of spring nitrogen (50, 100, 150, 200 and 250 kg N ha^-1) with fungicide treatments designed to control foliar diseases. Seed was graded by size into different fractions. Application of foliar fungicides to the parent plant increased the proportion of large seed in wheat but not in triticale. Fungicide application had no effect on seed vigour (quantified as the value of K; after controlled deterioration), final germination, median germination time (t₅₀) or rate of germination. Parent plant nutrition altered the proportions of seed in different size categories in triticale and wheat. In laboratory germination tests, final germination of wheat increased with seed size. Large (> 3.0 mm diameter) wheat seed from plots receiving 50 kg N ha“¹ had a lower final germination than large seed from plots which had received greater amounts of nitrogen, but t₅₀ and K; were similar for all nitrogen levels. In triticale, the higher the seed weight, the higher the final germination, the faster the rate and the higher the Ki. Final germination, t₅₀ and K;, were all positively correlated with the amount of nitrogen received by the parent plants. Parent plant nutrition had no effect on the response to temperature of final germination, t₅₀, or rate of germination for large or small seeds of both wheat and triticale.     

不同氮水平下不同种稗草对水稻产量形成的影响

以‘南粳9108’(粳稻)为材料,自移栽至成熟期分别与无芒稗、西来稗和光头稗共培养,以无稗草共培为对照,观察不同种类共培稗草在不同施氮水平下(0、120、240、360 kg N·hm^-2)对水稻产量形成的影响.结果表明:相同氮肥水平下,不同种稗草株高表现为西来稗>无芒稗>光头稗,生育期由长到短为无芒稗>西来稗>光头稗.随着氮肥施用量的增加,不同种稗草的生物量在240 kg N·hm^-2下达到最大值,然后降低,无芒稗和西来稗的生物量均显著高于光头稗.在0 kg N·hm^-2下,不同种稗草对水稻产量无显著影响;在120 kg N·hm^-2下,无芒稗和光头稗处理水稻产量与无稗草处理差异不显著,但西来稗处理产量较无稗草处理显著降低;在240 kg N·hm^-2下,无芒稗、西来稗和光头稗处理显著减产;在360 kg N·hm^-2下,无芒稗和西来稗处理产量较无稗草处理显著降低,光头稗处理与无稗草处理差异不显著.稗草和氮肥对水稻产量形成具有明显的互作效应.120 kg N·hm^-2下,西来稗处理显著降低了水稻灌浆期剑叶硝酸还原酶活性、光合速率和根系氧化力以及成熟期氮积累量和干物质量,其他稗草处理与对照差异不显著;在240和360 kg N·hm^-2下,无芒稗和西来稗处理降低了水稻上述指标;在0 kg N·hm^-2下,各处理的上述指标差异不显著.回归分析表明,稗草表型对水稻产量的影响由大到小的顺序为生物量、株高、生育期和分蘖数,推测稗草较大的生物量造成水稻剑叶光合速率、硝酸还原酶活性、根系氧化力、氮积累量和干物质积累量降低,影响了水稻的生长发育,造成水稻减产.     

Germination of Prosopis juliflora (Sw.) D.C. seeds at different osmotic potentials and temperatures

The effects of osmolytes, osmotic potential (Ψ_s), temperature, and their interactions on the germinability, germination rate, and other germination parameters of the invasive shrub Prosopis juliflora, which grows in the semiarid environmental conditions of the Caatinga in northeast Brazil, were evaluated. To study the effects of polyethylene glycol (PEG) and NaCl stress and temperature on germination, two separate experiments were carried out at the Plant Ecophysiology Laboratory of the Federal University of Pernambuco in 2011. The overall germinability decreased significantly with increases in both PEG (one‐way anova , F_4,75 = 111.21, P ≤ 0.001) and NaCl (one‐way anova , F_4,75 = 12.82, P ≤ 0.001); however, the effects were more accentuated with PEG than NaCl. The PEG‐treated seeds maintained their germinability, even when they were subjected to a Ψ_s = ?1 MPa after being rinsed and allowed to germinate on deionized water. In contrast, NaCl‐treated seeds usually lost their ability to germinate; this fact was possibly linked to the accumulation of Na⁺ and Cl^? in the cells, which may have contributed to a loss of membrane function that led to the death of the embryos. Although numerous studies describing seed germination in the presence of osmolytes have been conducted, studies that show the interactions between osmolytes, osmotic potentials, and temperature are scarce. The present study is the first to describe these interactions for P. juliflora seeds.     

Variation in the loss of seed dormancy during after-ripening of wild and cultivated rice species

BACKGROUND AND AIMS: The aim of this paper was to verify the variation in the loss of seed dormancy during after-ripening and the interspecific and interpopulation variability in the degree of dormancy of seven wild and two cultivated rice species comprising 21 populations and two cultivars. METHODS: Four wild rice species from South America, Oryza glumaepatula, O. latifolia, O. grandiglumis and O. alta, and two O. sativa cultivars were tested in one experiment. In a second experiment, five wild species, O. punctata, O. eichingeri, O.rufipogon, O. latifolia and O. glumaepatula, and one cultivated species (O. glaberrima) were evaluated. Initial germination tests were performed soon after the seeds were harvested and subsequently at 2-month intervals, for a total of six storage periods in the first experiment and three in the second. All tests were conducted in the dark at a temperature of 27 degrees C. KEY RESULTS: Different patterns of after-ripening among populations within and between species were observed. CONCLUSIONS: The cultivated species (O. sativa and O. glaberrima) and, amongst the wild species, the tetraploids O. latifolia, O. grandiglumis and the diploids O. eichingeri and O. punctata, had weak dormancy, losing it completely 2 months after harvest, while O. rufipogon and O. glumaepatula exhibited pronounced dormancy. The latter showed different patterns of after-ripening between populations indigenous to the Amazon region and those originating in the Paraguay River system. Seeds of Solimoes (Amazon) and Japura origin showed weak dormancy whereas those of Paraguay origin showed deep dormancy. Ecological differences among natural habitats may be involved in such differentiation.     

Effects of aqueous extract of rice plants (Oryza sativa L.) on seed germination and radicle elongation of Monochoria vaginalis var. plantaginea

Laboratory experiments were conducted to examine the allelopathic potentials of rice plants (Oryza sativa L.) on seed germination and radicle elongation of Monochoria vaginalis (Burm. f.) Presl var. plantaginea (Roxb.) Solms-Laubat. To compare the relative allelopathic potentials of rice plants at different growth stages, aqueous extracts of dried tissues were obtained from the seeds, husks, and seedlings harvested 10, 20, 40 and 120 days after seeding. When M. vaginalis seeds were incubated in solutions containing aqueous extracts, significant increases in the germination rate were observed for all the aqueous extracts except for the extract of 10 d-old shoots at higher dosages. When partitioned with ethyl acetate, the germination-promoter(s) in the aqueous extracts remained in the aqueous phase while some inhibitors were extracted with ethyl acetate. In contrast, aqueous shoot extracts added to the incubation media at the same dosage for promotion of seed germination inhibited radicle elongation of M. vaginalis, indicating that the sensitivity of the weed varies between these two growth stages.     

Discrimination of nitrogen isotopes during absorption of ammonium and nitrate at different nitrogen concentrations by rice (Oryza sativa L.) plants

Studies of uptake of ionic sources of N by two hydroponically grown rice (Oryza sativa L.) cultivars (paddy‐field‐adapted Koshihikari and dryland‐adapted Kanto 168) showed that the magnitude of the nitrogen isotope fractionation (?) for uptake of NH₄⁺ depended on the concentrations of NH₄⁺ and cultivar (averaging –6·1‰ for Koshihikari and –12·0‰ for Kanto 168 at concentrations from 40 to 200 mmol m^?3 and, respectively, –13·4 and –28·9‰ for the two cultivars at concentrations from 0·5 to 4 mol m^?3). In contrast, the ? for uptake of NO₃^? in similar experiments was almost insensitive to the N concentration, falling within a much narrower range (+3·2‰ to –0·9‰ for Koshihikari and –0·9‰ to –5·1‰ for Kanto 168 over NO₃^? concentrations from 0·04 to 2 mol m^?3). From longer term experiments in which Norin 8 and its nitrate‐reductase deficient mutant M819 were grown with 2 or 8 mol m^?3 NO₃^? for 30 d, it was concluded that the small concentration‐independent isotopic fractionation during absorption of this ion was not related to nitrate reductase activity.     

不同生育阶段夜温升高对双季水稻物质生产与养分吸收的影响

利用2间玻璃室内夜间不同的温度条件,研究了水稻生长期间夜温升高对双季早、晚稻物质生产和养分积累的影响.结果表明:播种-幼穗分化期夜温升高增加早稻的干物质积累,而减少晚稻的干物质积累;幼穗分化期-抽穗的夜温升高对早、晚稻的干物质积累均有一定的负作用;抽穗后的夜温升高对早稻物质生产影响较小,但降低其茎鞘物质的转运,而晚稻的干物质生产和茎鞘物质的转运均提高.在早稻幼穗分化前夜温适度升高有利于提高根系活力,促进植株养分的积累,但不利于晚稻植株养分的积累;幼穗分化-抽穗期间的夜温升高均不利于早、晚稻植株的养分积累;灌浆结实期的夜温升高会造成早稻根系早衰,不利于养分吸收,但有利于保持晚稻根系较高活力,促进养分吸收.试验证明,不同生育阶段的夜温升高对双季水稻不同生育阶段的干物质生产和养分吸收的影响是不同的.     

Lethal oxygen levels at different temperatures and the preferred temperature during hypoxia of the Atlantic cod, Gadus morhua L.

The behavioural thermoregulation of Atlantic cod Gadus morhua L. was investigated in a shuttlebox at normoxia and at three levels of hypoxia: 30, 20 and 15% oxygen saturation.
The preferred temperatures at normoxia, 30, 20 and 15% oxygen saturation were 13·9, 13·1. 10·0 and 8·8° C, respectively.
A decrease in metabolism and an increased blood oxygen affinity are among the physiological advantages of selecting a lower temperature during hypoxia. Furthermore the chances of surviving low oxygen saturations are better at low temperatures.
In natural environments, this behaviour may result in habitat shifts of fish living in heterothermal environments with changing oxygen saturations, especially in coastal areas with eutrophication, as for example the Baltic Sea.     

Effect of different carbon sources on membrane permeability,membrane fluidity,and fatty acid composition of a psychrotrophic Acinetobacter sp. HH1-1 during growth at low temperatures and after cold shock

The effect of different carbon sources on the ability of a psychrotrophic Acinetobacter sp., strain HH1-1, to grow at low temperatures and respond to cold shock was investigated by monitoring cell membrane permeability, membrane fluidity and fatty acid composition. Cells were grown in batch cultures with acetate, Tween 80 or olive oil as the sole source of carbon and incubated at 25, 5^°C or subjected to a 25 to 5 ^°C decrease in growth temperature (cold shock). Cell membrane changes were observed following cold shock for all carbon sources. Cells became leaky and membranes less fluid immediately after cold shock. The fatty acid composition of cells also varied significantly with carbon source. A higher content of oleic acid (cis-9-octadecenoic acid – 18:1) was observed in cells grown in the presence of Tween 80 and olive oil compared to cells grown in the presence of acetate. Increased content of palmitoleic acid (cis-9-hexadecenoic acid – 16:1) observed during growth at 5^°C and following cold shock indicated that this fatty acid may be important for growth at low temperatures. Acetate-grown cells responded more quickly to cold shock than did Tween 80 or olive oil-grown cells by restoring membrane fluidity and by taking K+ back into the cells. In addition, acetate-grown cells modified the content of fatty acid cis-9-hexadecenoic acid at 2h post cold shock as opposed to 24h post cold shock in cells grown in the presence of Tween 80 or olive oil. This research indicated that cells are most affected by rapid decreases in growth temperature and growth at low temperatures when cells utilized olive oil as the sole source of carbon.