杂草稻落粒粳的抗逆境特性研究

杂草稻落粒粳（Oryza sativa）发生在我国辽宁丹东.落粒粳植株明显高于当地大多数栽培品种,颖果呈中长型,成熟后容易掉粒;果壳稻草色或黄间黑灰色,小穗无芒或有芒,芒长4～12 cm;颖果千粒重235 g,种皮桔红色.落粒粳种子在13～38 ℃条件下的发芽率均大于88%,水层2.5～10 cm处理,落粒粳植株干重减少50%～69%.在幼苗期,落粒粳对无芒稗的各项影响因子均明显大于化感潜力品种I-kung-pao,表明落粒粳无化感作用.落粒粳可以忍耐0.5%的盐碱.     

A calcium- and phospholipid-dependent protein kinase from rice (Oryza sativa) leaves

Protein kinases in plants have not been examined in detail, but protein phosphorylation has been shown to be essential for regulating plant growth via the signal transduction system. A Ca²⁺- and phospholipid-dependent protein kinase, possibly involved in the intracellular signal transduction system from rice leaves, was partially purified by sequential chromatography on DE52, Phenyl Superose and Superose 12. This protein kinase phosphorylated the substrate, histone III-S, in the presence of Ca²⁺ and phosphatidylserine. The apparent molecular mass of the Ca²⁺- and phosphatidylserine-dependent protein kinase (Ca²⁺/PS PK), determined by phosphorylation in SDS-polyacrylamide gel containing histone III-S, was 50 kDa. The protein kinase differed from Ca²⁺-dependent protein kinase (CDPK) in rice leaves in that Ca²⁺/PS PK showed phospholipid dependency and the molecular mass of Ca²⁺/PS PK exceeded that of CDPK. Investigations were carried out on changes in Ca²⁺/PS PK and CDPK activity in the cytosolic and membrane fractions during germination. The maximum activity of Ca²⁺/PS PK in the cytosolic fraction was observed before imbibition and that of CDPK in the membrane fraction was noted at 6 days following imbibition. Protein kinases are likely to regulate plant growth through protein phosphorylation.     

Characteristics of floral organs related to reliable self-pollination in rice (Oryza sativa L.)

In many varieties of rice, the length of basal pores on the thecae just after anthesis is strongly correlated both with the percentage of florets receiving adequate pollen and with the number of pollen grains deposited on the stigmata and its variation (coefficient of variation). Therefore, the size of the basal pores is considered to be an important factor for the reliable self-pollination of rice. We discuss how long basal pores may facilitate self- pollination.     

Models of floral pattern in detached flowers of Silene coeli-rosa (L) Godr. (Caryophyllaceae)

Organ number per whorl was analysed in aberrant flowers of the long-day (LD) plant , Silene coeli-rosa , to test a hypothesis that organ number in a whorl takes its cue from an adjacent outer whorl and that perturbed organ number per whorl is not random but defaults to that of closely related taxa or genera of the Caryophyllaceae. When plants were grown under short-days (SD), transferred to LD and the shoot meristem excised and cultured in vitro under SD, the normal pattern of flower development was often disrupted. For example, we observed flowers which comprised floral whorls with an aberrant number of floral organs. In part, this was an effect of tissue culture; however, the over-and-above effect was the establishment of an alternative pattern of development. Our data indicate that two distinct and recurrent patterns occurred in the aberrant flowers we observed in five separate experiments. First, pairs of floral whorls were linked so that aberration in one whorl resulted in the next whorl being more aberrant than normal. Second, the number of organs in aberrant whorls was not random, but defaulted to an organ number which mimicked the flowers of closely related species of Silene or related genera in the Caryophyllaceae.  © 2002 The Linnean Society of London , Botanical Journal of the Linnean Society , 2002, 140 , 229−235.     

水稻水溶性环氧化合物水解酶的生物信息学分析

水溶性环氧化合物水解酶（Soluble Epoxide Hydrolase,SEH）是一组催化环氧化合物水解为相应邻位二醇的酶类,在哺乳动物、植物、昆虫和微生物体内广泛存在。通过BLAST对水稻基因组的蛋白质数据库进行搜索,获得10个水溶性环氧化物水解酶（Soluble Epoxide Hydrolase SEH）sEH蛋白的同源序列。经分析发现这些基因在水稻不同胁迫处理下各个部位都有所表达,而且不同成员之间的表达模式存在较大的差异。水稻sEH蛋白主要参与角质层形成,应激反应,以及病原防御等生理过程,特别在脱毒过程中扮演着重要的角色。对蛋白质多序列联配和三级结构预测结果表明：水溶性环氧化合物水解酶的核心结构域由3个催化残基Asp、His和Asp形成三位一体的催化活性构象。这类基因的表达受抗逆环境诱导,其功能与抗逆性有关,为基因工程抗逆育种提供了参考。     

Separation and characterization of proteins in rice (Oryza sativa) suspension cultured cells

Proteins extracted from suspension cultured cells of rice were separated by two-dimensional polyacrylamide gel electrophoresis. The separated proteins were electroblotted onto a polyvinylidene difluoride membrane and 103 electroblotted proteins were analyzed. The N-terminal amino-acid sequences of 20 out of 103 proteins were determined in this manner. N-terminal regions of the remaining proteins could not be sequenced and they were inferred to have a blocking group at the N-terminus. Internal amino-acid sequences of 32 proteins were determined by sequence analysis of peptides obtained by Cleveland peptide mapping. The amino-acid sequences determined here were compared with those of known plant and animal proteins. Furthermore, the concanavalin A-peroxidase method was used to determine which of the 103 proteins were glycosylated, and in vitro and in vivo phosphorylation was carried out to identify some of the phosphorylated proteins. Using this experimental approach, we could identify the major proteins involved in growth and development of rice cell suspension cultures and discuss on the physiological function of some of these identified proteins including the calcium binding protein, superoxide dismutase and rice ascorbate peroxidase. This revised version was published online in June 2006 with corrections to the Cover Date.     

Defective cell proliferation in the floral meristem of alloplasmic plants of Nicotiana tabacum leads to abnormal floral organ development and male sterility

Flowers of an alloplasmic male-sterile tobacco line, comprised of the nuclear genome of Nicotiana tabacum and the cytoplasm of Nicotiana repanda, develop short, poorly-pigmented petals and abnormal sterile stamens that often are fused with the carpel wall. The development of flower organ primordia and establishment of boundaries between the different zones in the floral meristem were investigated by performing expression analysis of the tobacco orthologs of the organ identity genes GLO, AG and DEF. These studies support the conclusion that boundary formation was impaired between the organs produced in whorls 3 and 4 resulting in partial fusions between anthers and carpels. According to the investigations cell divisions and floral meristem size in the alloplasmic line were drastically reduced in comparison with the male-fertile tobacco line. The reduction in cell divisions leads to a discrepancy between cell number and cell determination at the stage when petal and stamen primordia should be initiated. At the same stage expression of the homeotic genes was delayed in comparison with the male-fertile line. However, the abnormal organ development was not due to a failure in the spatial expression of the organ identity genes. Instead the aberrant development in the floral organs of whorls 2, 3 and 4 appears to be caused by deficient floral meristem development at an earlier stage. Furthermore, defects in cell proliferation in the floral meristem of the alloplasmic male-sterile line correlates with presence of morphologically modified mitochondria. The putative causes of reduced cell number in the floral meristem and the consequences for floral development are discussed.     

Population structure of rice (Oryza sativa) landraces under farmer management

Greater insight into the dynamics of genetic resources of crop plants is needed in order to pinpoint detrimental evolutionary patterns and draw up conservation priorities. The present study demonstrated farmer management of crop population structure and temporal evolution of rice genetic diversity in traditional production systems. The 16 STMS primers analysed for 11 rice landrace populations indicated enough polymorphism to fully differentiate the inter- and intrapopulation diversity. A total number of 98 alleles were recorded, of which 91 were common and seven were rare. The mean number of alleles per locus was 6.13 and for different groups of rice landrace populations, namely five populations of upland common landrace Jaulia, three populations of irrigated common landrace Thapachini and one population each of three distinct rare landraces were 4.37, 2.75 and 4.37, respectively. The study also compared genebank-conserved ( ex situ ) populations and on-farm-managed ( in situ ) landrace populations of same named landraces Jaulia and Thapachini, and revealed greater number of alleles per locus for on-farm-managed populations as compared to the populations under static management. A substantial number of alleles specific to populations under dynamic management could also be recorded. Further, the rare landrace populations included in the present study were more diverse than the common landrace populations. The rare landraces were distinct genetic entities largely representing locally common alleles. Investigating the population genetic structure is therefore helpful in monitoring change in diversity over time and space, and also for devising a rational plan for management of farmer landraces on-farm.     

Polyamines in various rice (Oryza sativa) genotypes with respect to sodium chloride salinity

Physiological responses of various rice genotypes were studied in relation to salt (NaCl) stress. Cultivars CSR-1 and Dular germinated well in different NaCl regimes compared to cvs Rupsail, Assam Getu and M-1–48. At 100 m M NaCl, the lowest germination was observed in cv. M-1–48. Cvs CSR-1 and Dular were relatively effective in maintaining high concentrations of polyamines as well as arginine decarboxylase (EC 4.1.1.19) activity in coleoptiles and roots in a non-stressed condition. The activities of two biodegradative enzymes, diamine oxidase (EC 1.4.3.6) and polyamine oxidase (EC 1.4.3.4), were lowest in cv. CSR-1. The polyamine content was not significantly altered when seedlings of cv. CSR-1 were exposed to 100 m M NaCl. However, in cv. M-1–48 enhancement of arginine decarboxylase activity with concomitant accumulation of polyamines was observed. Leakage of metabolites and changes in the levels of Na⁺ and Cl⁻ were prominent in cv. M-1–48 under saline conditions. The results suggest a correlation between polyamine and salt stress-induced responses in rice genotypes.     

Selection for mutants with low nitrate uptake ability in rice (Oryza sativa)

Screening for mutants deficient in the high affinity system of nitrate uptake was performed using mutagenized M₂ population of rice ( Oryza sativa , cv. Nipponbare or Kinmaze). For selecting mutants, M₂ seedlings were transferred individually to 10 ml solution containing 250 μ M potassium nitrate and 500 μ M calcium sulphate at 20 or 28°C. After 6 or 24 h, nitrate concentration of the solution was determined with a nitrate selective electrode and the seedlings showing impaired nitrate uptake were selected as nitrate uptake deficient variants. Of 74 variants, three were confirmed to be mutants with low nitrate uptake ability in the M₃ generation. Potassium uptake ability also decreased in the mutants. Three mutants were divided into two groups based on the analysis of nitrate reductase (NR, EC 1.6.6.1) activity and chlorate resistance. Two, NUE13 and NUE36 , had a lower level of NR activity than the original cultivar and were not resistant to chlorate, while the seedlings of NUE50 had the same level of NR activity as the original cultivar and were more resistant to chlorate than the original cultivar. All mutants were resistant to cesium, a toxic ion analogue for potassium, suggesting that the decreased levels of both nitrate and potassium uptake were coupled to the change of plasma membrane H⁺-ATPase activity.     

A comparison of nitrate transport in four different rice(Oryza sativa L.) cultivars

As rice can use both nitrate (NO3-) and ammonium (NH4+), we have tested the hypothesis that the shift in the pattern of cultivars grown in Jiangsu Province reflects the ability of the plants to exploit NO3- as a nitrogen (N) source. Four rice cultivars were grown in solution culture for comparison of their growth on NO3- and NH4+ nitrogen sources. All four types of rice,Xian You 63 (XY63), Yang Dao 6 (YD), Nong Keng 57 (NK) and Si You 917 (SY917), grew well and produced similar amounts of shoot biomass with 1 mmol/L NH4+ as the only N source.However, the roots of NK were significantly smaller in comparison with the other cultivars. When supplied with 1 mmol/L NO3-, YD produced the greatest biomass; while NK achieved the lowest growth among the four cultivars. Electrophysiological measurements on root rhizodermal cells showed that the NO3--elicited changes in membrane potential (ΔEm) of these four rice cultivars were significantly different when exposed to low external NO3- (＜1 mmol/L); while they were very similar at high external NO3- (10 mmol/L). The root cell membrane potentials of YD and XY63 were more responsive to low external NO3- than those of NK and SY917. The ΔEm values for YD and XY63 rhizodermal cells were almost the same at both 0.1 mmol/L and 1 mmol/L NO3-;while for the NK and SY917 the values became larger as the external NO3- increased. For YD cultivar, ΔEm was measured over a range of NO3- concentrations and a Michaelis-Menten fit to the data gave a Km value of 0.17 mmol/L. Net NO3- uptake depletion kinetics were also compared and for some cultivars (YD and XY63) a single-phase uptake system with first order kinetics best fitted the data; while other cultivars (ND and SY917) showed a better fit to two uptake systems. These uptake systems had two affinity ranges: one had a similar Km in all the cultivars (0.2 mmol/L); the other much higher affinity system (0.03 mmol/L) was only present in NK and SY917. The expression pattern of twelve different NO3- transporter genes was tested using specific primers, but only OsNRT1.1 and OsNRT2. 1 expression could be detected showing significant differences between the four rice cultivars. The results from both the physiological and molecular experiments do provide some support for the hypothesis that the more popular rice cultivars grown in Jiangsu Province may be better at using NO3- as an N source.     

Population structure of rice (Oryza sativa) landraces from high altitude area of Indian Himalayas

This study examined the genetic diversity in 20 rice landrace populations from parts of traditional farming areas of the Indian Himalayas using 11 mapped simple sequence repeats (SSR) loci. Twenty‐four individuals sampled from each of the 20 landraces (480 individuals), which were collected from farmers from Northwest to Northeast Himalaya, showed that all landraces showed within population variation and none were homogeneous. The number of polymorphic loci in a landrace population ranged from 5 to 11. A total of 71 alleles were recorded of which 58 were common and 13 were rare. Of the 71 alleles, 46 were common to both Northwest and Northeast regions, whereas 9 were unique to the former and 16 were unique to the latter. The mean number of alleles per locus was 6.45 and for landrace populations from Northwest and Northeast regions were 5.0 and 5.64, respectively. Population differentiation, as shown by a high F_ST value (0.61), was greater for Northeast populations. The unweighted pair group method with arithmetic mean (UPGMA) dendrogram classified the populations into three major clusters: cluster I comprised seven populations from the Northwest region, cluster II comprised seven populations from the Northeast region and cluster III comprised populations from both regions. Investigating the population genetic structure can help monitor change in diversity over time and space, and also help devise a rational plan for management of crop landraces on‐farm under farmer management.     

Oxygen dynamics in submerged rice (Oryza sativa)

Complete submergence of plants prevents direct O(2) and CO(2) exchange with air. Underwater photosynthesis can result in marked diurnal changes in O(2) supply to submerged plants. Dynamics in pO(2) had not been measured directly for submerged rice (Oryza sativa), but in an earlier study, radial O(2) loss from roots showed an initial peak following shoot illumination. O(2) dynamics in shoots and roots of submerged rice were monitored during light and dark periods, using O(2) microelectrodes. Tissue sugar concentrations were also measured. On illumination of shoots of submerged rice, pO(2) increased rapidly and then declined slightly to a new quasi-steady state. An initial peak was evident first in the shoots and then in the roots, and was still observed when 20 mol m(-3) glucose was added to the medium to ensure substrate supply in roots. At the new quasi-steady state following illumination, sheath pO(2) was one order of magnitude higher than in darkness, enhancing also pO(2) in roots. The initial peak in pO(2) following illumination of submerged rice was likely to result from high initial rates of net photosynthesis, fuelled by CO(2) accumulated during the dark period. Nevertheless, since sugars decline with time in submerged rice, substrate limitation of respiration could also contribute to morning peaks in pO(2) after longer periods of submergence.     

A large-scale field study of transgene flow from cultivated rice (Oryza sativa) to common wild rice (O. rufipogon) and barnyard grass (Echinochloa crusgalli)

The introgression of transgenes into wild relatives or weeds through pollen-mediated gene flow is a major concern in environmental risk assessment of transgenic crops. A large-scale (1.3–1.8 ha) rice gene flow study was conducted using transgenic rice containing the bar gene as a pollen donor and Oryza rufipogon as a recipient. There was a high frequency of transgene flow (11%−18%) at 0–1 m, with a steep decline with increasing distance to a detection limit of 0.01% by 250 m. To our knowledge, this is the highest frequency and longest distance of gene flow from transgenic rice to O. rufipogon reported so far. On the basis of these data, an adequate isolation distance from both conventional and transgenic rice should be taken for in situ conservation of common wild rice. Meanwhile, there is no evidence of transgene introgression into barnyard grass, even when it has coexisted with transgenic rice containing the bar gene for five successive years. Thus, the environmental risk of gene flow to this weedy species is of little concern.