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991.
为研究水稻蜡质基因(waxy)5'上游调控区中存在的顺式作用元件,我们将水稻waxy基因翻译起始声、(ATG)5'上游3.4kb(-2118~+1291bP)片段经外切核酸酶ExoⅢ部分酶解,得到一系列5'端缺失的片段。将这些缺失片段分别与gus基因编码区连接,构建成融合质粒,经PEG介导引入水稻原生质体,26℃培养48h后,定量测定GUS酶活力,并以同时导入的由35S启动子指导的荧光素酶(LUC)基因表达的酶活力作为内对照。结果表明,GUS酶活性随5’上游调控区长度的减少而逐渐减弱。由─861bp缺失至─640bP时,gus基因表达水平有较明显的降低,推测在该区域中可能存在一个顺式作用元件区。 相似文献
992.
渗透胁迫下稻苗中铁催化的膜脂过氧化作用 总被引:12,自引:0,他引:12
在-0.7MPa渗透胁迫下,水稻幼苗体内和H2O2大量产生,Fe2+积累,膜脂过氧化作用加剧。水稻幼苗体内Fe2+含量与膜脂过氧化产物MDA含量呈极显著的正相关。外源Fe2+、Fe3+、H2O2、Fe2++H2O2、DDTC均能刺激膜脂过氧化作用,而铁离子的螯合剂DTPA则有缓解作用。OH的清除剂苯甲酸钠和甘露醇能明显地抑制渗透胁迫下Fe2+催化的膜脂过氧化作用。这都表明渗透胁迫下水稻幼苗体内铁诱导的膜脂过氧化作用主要是由于其催化Fenton型Haber-Weiss反应形成OH所致。 相似文献
993.
A genomic hsp70 gene was isolated from a rice IR36 genomic library and 4 794 bp of the gene have been sequenoed. The 5' flanking region of the gene contained a putative TATA box and a typical heat shock element sequence 5'-CTcgGAAccTTCgAG-3'. The amino acid sequence of the rice HSP70 deduced from the coding region shared 84%-92% homologies with those of HSP70s from other plant species. An intron 1939bp long was identified in the coding region at the codon specifying amino acid 72 (Asp), the similar position introns occurring in other intron-containing hsp70 genes. In addition, another intron of 57 bp was found in the 3'-untranslated region in the rice hsp70 gene. Southern blot hybridization showed that rice hsp70 gene family contained at least three members. Analysis of the RNA leveis with the gene-specific and non-specific probes revealed that the rice hsp70 gene expressed at normal temperature and the expression was enhanced by heat shock treatment. 相似文献
994.
The kinetic properties of photosynthesis (both transient and steady-state) were monitored using three non-invasive techniques to evaluate limitations on triose-phosphate (triose-P) conversion to carbohydrate in rice. These included analyzing the O2 sensitivity of CO2 fixation and the assimilatory charge (AC) using gas exchange (estimate of the ribulose 1,5- bisphosphate pool) and measuring Photosystem II activity by chlorophyll fluorescence analysis under varying light, temperature and CO2 partial pressures. Photosynthesis was inhibited transiently upon switching from 20 to 2 kPa O2 (reversed O2 sensitivity), the degree of which was correlated with a terminal, steady-state suppression of low O2 enhancement of photosynthesis. Under current ambient levels of CO2 and moderate to high light, the transient pattern was more obvious at 18 °C than at 26 °C while at 34 °C no tra nsient response was observed. The transient inhibition at 18 °C ranged from 15% to 31% depending on the pre-measurement temperature. This pattern, symptomatic of feedback, was observed with increasing light and CO2 partial pressures with the degree of feedback decreasing from moderate (18 °C) up to high temperature (34 °C). Under feedback conditions, the rate of assimilation is shifted from being photorespiration limited to being triose-P utilization limited. Transitory changes in CO2 assimilation rates (A) under low O2 indicative of feedback coincided with a transitory drop in assimilatory charge (AC) and inhibition of electron transport. In contrast to previous studies with many C3 species, our studies indicate that rice shows susceptibility to feedback inhibition under moderate temperatures and current atmospheric levels of CO2. 相似文献
995.
Chemical induction of disease resistance in rice is correlated with the expression of a gene encoding a nucleotide binding site and leucine-rich repeats 总被引:13,自引:0,他引:13
Sakamoto Koji Tada Yuichi Yokozeki Yumi Akagi Hiromori Hayashi Nagao Fujimura Tatsuhito Ichikawa Norio 《Plant molecular biology》1999,40(5):847-855
Probenazole (3-allyloxy-1,2-benzisothiazole-1,1-dioxide) is an agricultural chemical primarily used to prevent rice blast disease. Probenazole-treated rice acquires resistance to blast fungus irrespective of the rice variety. The chemical is applied prophylactically, and is thought to induce or bolster endogenous plant defenses. However, the mechanisms underlying this effect have not been established. To understand the mode of the chemical's action, we screened for novel probenazole-responsive genes in rice by means of differential display and identified a candidate gene, RPR1. RPR1 contains a nucleotide binding site and leucine-rich repeats, thus sharing structural similarity with known disease resistance genes. The expression of RPR1 in rice can be up-regulated by treatment with chemical inducers of systemic acquired resistance (SAR) and by inoculation with pathogens. RPR1-related sequences in rice varieties seem to be varied in sequence and/or expression, indicating that RPR1 itself is not a crucial factor for induced resistance in rice. However, Southern blot analysis revealed the existence of homologous sequences in all varieties examined. While the role of RPR1 has yet to be clarified, this is the first report of the identification of a member of this gene class and its induction during the systemic expression of induced disease resistance. 相似文献
996.
Rice seedlings with the mesocotyl and coleoptile (the undeveloped leaves enclosed in the coleoptile) are here referred to as MC type seedlings and are considered to be suitable for deep sowing. We investigated the effects of abscisic acid (ABA) and several of its related compounds on the occurrence of MC type seedlings and on rice mesocotyl growth. Rice (Oryza sativa L. cv. JC 91) seedlings were grown on 0.8% agar medium in the presence or absence of various kinds of ABAs under aseptic conditions at 30 °C in the dark for 14 days. The activity of the R isomer of ABA (R-ABA) was slightly less than that of the naturally occurring S form (S-ABA) concerning the occurrence of MC type rice seedlings and the growth of the rice mesocotyl. In addition, the racemate of R-and S-ABA (RS-ABA) is less effective than R-ABA and S-ABA alone.Trans-ABA had no activity in relation to both percent occurrence of MC type seedlings and mesocotyl growth. The results of the present study suggest that the occurrence of MC type rice seedlings and the growth of rice mesocotyls were closely related to structure-activity relationships with analogs of ABA. 相似文献
997.
Takehiro Ohki Hideki Matsui Atsushi Nagasaka Toshihito Yoshioka Akiyoshi Watanabe Shigeru Satoh 《Plant Growth Regulation》1999,28(2):123-127
Exposure to ozone at 1 µl l–1 for 6 h induced ethylene production in rice (Oryza sativa L. cv. Hitomebore) leaves. The stimulation of ethylene production was detectable 2 h after the start of the exposure to ozone, and lasted for 6 h after the exposure. A 429-bp cDNA fragment encoding ACC oxidase was obtained by RT-PCR from ozone-treated rice leaves. Its nucleotide sequence and deduced amino-acid sequence had 97.2% and 94.4% identity, respectively, to those of OS1A1COX, which was previously obtained from deepwater rice. The abundance of the cDNA increased in accordance with the induction of ethylene production by the exposure to ozone. 相似文献
998.
In the Xinjiang province of western China, conventional methods of iodine (I) supplementation (i.e, goiter pills and iodinated
salt) used to mitigate I deficiencies were ineffectual. However, the recent addition of KIO3 to irrigation waters has proven effective. This study was conducted to determine the effects of I form and concentration
on rice (Oryza sativa L.) growth, I partitioning within the plant, and ultimately to assist in establishing guidelines for
incorporating I into the human food chain. We compared IO3
− vs. I− in order to determine how these chemical species differ in their biological effects. Rice was grown in 48 L aerated tubs
containing nutrient solution and IO3
− or I− at 0, 1, 10, or 100 μM concentrations (approximately 0, 0.1, 1, and 10 mg kg−1 I). The IO3
− at 1 and 10 μM had no effect on biomass yields, and the 100 μM treatment had a small negative effect. The I− at 10 and 100 μM was detrimental to biomass yields. The IO3
− treatments had more I partitioning to the roots (56%) on average than did the I− treatments (36%), suggesting differences in uptake or translocation between I forms. The data support the theory that IO3
− is electrochemically or biologically reduced to I− prior to plant uptake. None of the treatments provided sufficient I in the seed to meet human dietary requirements. The I
concentration found in straw at 100 μM IO3
− was several times greater than seed, and could provide an indirect source of dietary I via livestock feeding on the straw.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
999.
Phosphorus nutrition of rice in relation to flooding and temporary loss of soil-water saturation in two lowland soils of Cambodia 总被引:1,自引:1,他引:0
In the rainfed lowlands, temporary loss of soil-water saturation during crop growth is a common factor limiting rice (Oryza
sativa L.) yield but its effects on phosphorus (P) availability are poorly understood. Rice plants were transplanted into
pots containing soils that were either continuously flooded, maintained at field capacity or flooded and then dried to field
capacity for 3 weeks during the vegetative stage. A black clay soil (Kandic Plinthaquult) and a sandy soil (Plinthustalf)
from south-east Cambodia were compared with or without amendments by rice straw and P fertilizer.
Under continuously flooded conditions, the growth of rice was vigorous without straw addition and there was a strong response
of rice growth to the addition of P fertilizer. The soil underwent reduction, which increased pH from 4.2 to 5.5 or 6.0, in
the black clay or sandy soil, respectively. By contrast, a loss of soil-water saturation 3 weeks before panicle initiation
(PI) markedly impaired the growth of rice. This was not through any effect of water stress, and the growth reductions were
not as strong as with continued loss of soil-water saturation from transplanting to PI. Fluctuations in soil pH and Eh corresponded
closely to changes in soil-water regimes. Growth reductions were attributed to reduced shoot P levels resulting from the decline
in P availability during the loss of soil-water saturation. The addition of rice straw stimulated soil reduction and lessened
changes in soil pH and Eh during the loss of soil-water saturation in both soils. Straw addition enhanced P uptake by the
rice plants during loss of soil-water saturation, but its beneficial effects could not be attributed to the direct addition
of P, N or K to the soils. Thus the application of rice straw may be effective in lessening the effects of temporary loss
of soil-water saturation on rice growth in lowland rice soils by minimising the decline in P availability.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
1000.
Whitbread Anthony Blair Graeme Naklang Kunnika Lefroy Rod Wonprasaid Sodchol Konboon Yothin Suriya-arunroj Duangjai 《Plant and Soil》1999,207(1):29-36
The maintenance of soil organic matter (SOM) and the balancing of nutrient flows into and out of the rainfed rice cropping
systems in Northeast Thailand is of paramount importance to arresting the decline in soil fertility and crop yields. A system
where small applications of leaf litters from locally grown trees are applied annually to rice paddy soils prior to transplanting
is described. The annual application of 1500 kg/ha of Cajanus cajan, Acacia auriculiformis, Phyllanthus taxodifolius and Samanea
saman for five seasons resulted in increases in rice grain yield of 48, 35, 32 and 23% above the no-leaf litter control, respectively.
Average annual nutrient inputs from the leaf litters, in kg/ha, ranged from 62.7 N, 3.9 P, 17.9 K, and 3.5 S for Cajanus cajan
to 24.5 N, 1.5 P, 8.1 K and 2.0 S for Acacia auriculiformis. Nutrient balances, determined by the difference between the inputs
(fertiliser and added leaf litters) and outputs (grain and straw) indicated net positive N and P balances of up to 457 and
60 kg/ha. respectively, after five seasons of leaf litter applications. Sulfur and potassium balances resulted in net deficits
of up to −3 and −52 kg S and K/ha, respectively, where no leaf litter was applied and rice straw was removed following harvest.
Calculated apparent nutrient recoveries reflected the decomposition rate of the added residues and were highest for P and
K, reflecting their higher soil residual value than mobile nutrients such as N and S. Sustainable farming systems will require
that crop yields are stable through the maintenance of soil fertility and the balance of nutrients in the system.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献