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10 March 2006, Volume 20 Issue 2 Previous Issue    Next Issue
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研究报告
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Molecular Cloning and Expression Analysis of a New Vacuolar Na +/H + Antiporter Gene in Rice(Oryza sativa) QIU Sheng-ping ,ZHOU Guo-an ,LU Ju-fei ,HUANG Ji ,PAN Li-juan ,WANG Jian-fei ,YANG Qing ,ZHANG Hong-sheng 2006, 20(2): 119-124 .  Abstract ( )   PDF (682KB) ( )   A new vacuolar Na +/H + antiporter gene OsNHX2was isolated from rice by RT-PCR. The OsNHX2cDNA with 1726 bp in length encodes a protein of 544 amino acid residues with a calculated molecular mass of 60 kD. Hydrophobicity plot analysis showed the OsNHX2 has 11 putative transmembrane domains. Database searching results revealed the deduced amino acid sequence of OsNHX2 has 78% similarity to vacuolar Na +/H + antiporter (OsNHX1) from rice and 77% similarity to Na +/H + antiporter (AtNHX1) from Arabidopsis thaliana. Phylogenetic analysis showed that OsNHX2 clustered with other plant vacuolar Na +/H + antiporters. Semi-quantitive RT-PCR results revealed that OsNHX1 and OsNHX2expression was continuously up-regulated under NaCl stress in roots and shoots of salt-tolerant variety Jiucaiqing. However, in a salt-sensitive variety IR28, the OsNHX2 transcripts were up-regulated transiently in shoots then down-regulated immediately, and not regulated in roots under salt stress. OsNHX1 was increased transiently in both shoots and roots after exposure to salt stress in IR28. These results suggested the mRNA expression of vacuolar Na +/H + antiporter genes was diverse in rice varieties with different salt-sensitivity, and its transcriptional regulation possibly was an important factor deciding the ability of rice to cope with salt stress.

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Expression Characteristics of a Rice OsWRKY89 Gene Promoter HAO Zhong-na ,WANG Hai-hua ,GUO Ze-jian 2006, 20(2): 125-130 .  Abstract ( )   PDF (1211KB) ( )   A 1470 bp promoter fragment of a rice transcription factor WRKY89 gene(OsW89p) amplified from a rice variety (Oryza sativa L. subsp. japonica cv. Xiushui 11) by polymerase chain reaction(PCR) technique, was fused with GUS gene and transformed into rice embryos by Agrobacterium-mediated method. The results of histochemical GUS staining showed that leaves, culms and sheaths of the transformants had GUS activities at different developmental stages. In terms of flower organ and roots, lemmae and anthers had GUS activities except for pollen, and primary, adventitious and lateral roots had the activities but root tips not at the 2.5-leaf stage, and only lateral roots had the activities at the 5-leaf stage. There were GUS activities in the embryos of the germinating seeds, but not in mature seeds. The inducible expression characteristic of OsW89p in rice detected by GUS fluorometric measurement revealed that:1)Expression level of GUS was increased 4-fold by MeJA treatment, and repressed by the presence of 2,4-D, but was not influenced by salicylic acid; 2)The expression of GUS was repressed in the roots and promoted in the leaves by NaCl and PEG; 3)Ultraviolet, high temperature (42℃), low temperature(5℃) and injury treatments can increase the expression of GUS in leaves, and the induced efficiency of ultraviolet was the highest.

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Expression and Localization Analysis of Analogue for the Non-Host Bacterial Leaf Streak Resistance Gene Rxo1 in Rice CHEN Cai-hong ,TAN Ming-pu ,ZHENG Wei ,HUANG Xiao-man ,ZHANG Duan-pin ,LIN Xing-hua 2006, 20(2): 131-136 .  Abstract ( )   PDF (385KB) ( )   The main open reading frame (ORF) DNA sequence containing nucleotide binding site and leucine-rich repeats (NBS-LRR) domain of Rxo1, which was cloned from maize and found to be a non-host gene conferring resistance to rice bacterial leaf streak (BLS),was used to Blast the Genbank, and 16 resistance gene analogues (RGAs) were obtained from rice genome. One of the RGAs, RPR1, which located on chromosome 11, was found to be related to BLS resistance because, firstly, primer pairs designed based on the RPR1 sequence amplified target band only in the resistant genotypes, and secondly, the expression of RPR1 could be induced by BLS pathogen inoculation, indicating that the gene analogues came from different species may have common functions. On the other hand, the long map distance (9 cM) between RPR1 and qBLSR-11-1, a major resistance QTL identified formerly,implied that RPR1 might not be a key factor for BLS resistance in rice.

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SSR Markers on indica-japonica Differentiation of Natural Population of Oryza rufipogon in Yuanjiang, Yunnan Province LI Ya-li ,YANG Xiao-xi ,ZHAO Feng-ping ,XU Ming-hui 2006, 20(2): 137-140 .  Abstract ( )   PDF (126KB) ( )   By using 19 pairs of SSR primers which could identify indica and japonica types of cultivated rice (Oryza sativa), the indica-japonica differentiation of 56 individuals from the natural population of common wild rice (Oryza rufipogon) in Yuanjiang was analyzed. Of the 19 pairs of primers, 17 pairs (89.47%) could amplify only one kind of band type among all the individuals, but primers RM251 and RM18 could amplify polymorphic band types. The bands amplified by 16 pairs of primers (84.21 %) were similar with the indica-japonica identified bands of relevant locus in cultivated rice including 11 japonica-like loci and 4 indica-like loci, while the bands amplified by other 3 pairs of primers (RM18, RM202, RM205) were different from indica or japonica identified bands of cultivated rice. Among the 19 loci analyzed, 84.21% of them in genomic DNA of common wild rice in Yuanjiang showed indica-japonica differentiation and 13.79% of them still kept primitive, and the natural population was homogenetic in most of the detected loci.

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Improvement of Rice Salt-Tolerance by Using an Integrated Method of Gene Transformation and Traditional Breeding GUO Long-biao ,XUE Da-wei ,WANG Hui-zhong ,CHEN Shou-yi ,LU De-zhao ,ZENG Da-li ,GAO Zhen-yu ,YAN Mei-xian ,HUANG Da-nian ,QIAN Qian 2006, 20(2): 141-146 .  Abstract ( )   PDF (159KB) ( )   The genes encoding enzymes responsible for synthesizing some low-molecular weight metabolites, such as betaine, polyamines, and mannitol,were transformed into rice plants to enhance the salt- tolerance. The improvement of rice salt- tolerance with five target genes (BADH, CMO, mtlD, gutD and SAMDC) was conducted through gene transformation and traditional breeding approaches. Results indicated that the genes were successfully transformed into rice by particle bombardment or mediated by Agrobacterium tumefaciens and integrated into the genome of the transgenic plants by using PCR detections. The salt tolerance of the transgenic plants and their progenies with 1-5 genes was significantly enhanced and stably maintained in the salt-stress fields. Nine elite rice transgenic lines such as Pin 3, Pin 6 and Pin 7 from Xiushui 11 were obtained, which grew normally in the salt pool containing 0.5%-1.0% NaCl.

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Transfer of Lysozyme Gene into indica Parents of Hybrid Rice by Backcrossing YI Zi-li ,WANG Zi-xuan ,QIN Jing-ping ,JIANG Jian-xiong ,TAN Yan-ning ,ZHOU Qing-ming 2006, 20(2): 147-152 .  Abstract ( )   PDF (165KB) ( )   A lysozyme gene resistant to rice blast from the donor D2-1-2, a transgenic japonica rice line of Zhonghua 9, was transferred into the sterile line Pei′ai 64S(PA64S) and restorer line 9311 of the hybrid Liangyoupeijiu, and the restorer line Minghui 63 (MH63) of Shanyou 63 by successive backcrossing. PCR analysis confirmed that foreign lysozyme gene was segregated with the ratio of 1∶1 in backcross generations of B39311, B3MH63 and B2PA64S, and with the ratio of 3∶1 in inbred generations of B2F29311, B2F2MH63 and B1F2PA64S, indicating the foreign gene was stably inherited over successive generations as a dominant single copy gene. The resistance to rice blast of the backcross or inbred generations and corresponding testcross combinations were investigated in the years of 2003 and 2004, and the results showed that their resistance to rice blast had a greater improvement than that of the corresponding recurrent parents or the corresponding hybrid combinations, respectively. The resistance to rice blast became stronger with the generations of the transferred rice progressed. This confirmed that transferring the lysozyme gene into hybrid parents by backcrossing was a simple and effective approach to develope new hybrid combinations resistant to rice blast.

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Breeding Restorer Lines with High Resistance to Bacterial Blight in Hybrid Rice by Using Molecular Marker-Assisted Selection DENG Qi-ming ,WANG Shi-quan ,ZHENG Ai-ping ,ZHANG Hong-yu ,LI Ping 2006, 20(2): 153-158 .  Abstract ( )   PDF (241KB) ( )   Two bacterial blight(BB)resistance genes, Xa21 and Xa4,from IRBB24 were introduced into hybrid rice restorer line Mianhui 725, which is highly susceptible to BB by using hybridization and molecular marker-assisted selection technology. Four homologous restorer lines were obtained through molecular marker test for the R target genes and different parental genetic background analysis. Inoculation on the 4 lines and their hybrids were carried out with the specific Xanthomonas oryzae pv.oryzae strains, P1, P6(Philippine races) and seven representative strains of Chinese pathotype, CⅠ-CⅦ.The results indicated that all the 4 lines and their hybrids were highly resistant and showed broad resistance-spectrum to BB. The hybrids of G46A / R207-2 displayed good agronomic characters and high yield potentiality, and R207-2 was named as Shuhui 207.

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QTL Mapping of Low Temperature Germinability in Rice CHEN Liang ,LOU Qiao-jun ,SUN Zong-xiu ,XING Yong-zhong ,YU Xin-qiao ,LUO Li-jun 2006, 20(2): 159-164 .  Abstract ( )   PDF (109KB) ( )   A double haploid population (DH) with 198 lines, derived from anther culture of F 1 hybrid between indica line Zhenshan 97B and japonica perennial rice line AAV002863 was used to construct a linkage map with 140 SSR markers and to investigate the low temperature germinability (LTG). The germination rates of Zhenshan 97B and AAV002863 were 79.7% and 30.1%, respectively, and those of the DH population ranged from 0% to 100% at 15℃ for six days. Quantitative trait loci (QTLs) controlling low temperature germinability were identified on chromosomes 3 and 10. The percentage of observed phenotypic variance attributed to qLTG-3 and qLTG-10were 12.6% and 12.9%, respectively. Allele from Zhenshan 97B increases the LTG at the region of qLTG-3, while allele from AAV002863 increases the LTG at the region of qLTG-10. One pair of epistatic interaction were detected between loci on chromosomes 3 and 10. The main-effect QTL on chromosome 10 was also involved in epistatic interaction.

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Developmental Characters of Autotetraploid Rice Pollen DAI Xi-mei ,HUANG Qun-ce ,LI Guo-ping ,QIN Guang-yong 2006, 20(2): 165-170 .  Abstract ( )   PDF (183KB) ( )   The developmental characters and abortive stages of pollen in autotetraploid rice Zijing-4x were observed using a laser scanning confocal microscope. The percentage of normal pollen was only 45.5%, and the total frequency of pollen aborted during developmental process was 54.5%. Some abnormal division had been observed at microspore mother cell meiosis stage, e.g. chromosome pairing abnormally, aberrant dyad formation and asynchronous dyad division. Most pollen abortion occurred at mononuclear pollen stage and late binuclear pollen stage. Typical, spherical and stained abortive rates were 214%, 5.0% and 28.1%, respectively. The pollen abortion might be attributed to abnormal division, which resulted from the abnormal pairing of doubled chromosomes.

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Effects of Dry Cultivation with Straw Mulching on Rice Agronomic Traits and Water Use Efficiency QIN Jiang-tao ,HU Feng ,LI Hui-xin ,WANG Yi-ping ,HUANG Fa-quan ,HUANG Hua-xiang 2006, 20(2): 171-176 .  Abstract ( )   PDF (162KB) ( )   A field experiment was conducted to study water use efficiency and agronomic traits in rice cultivated under submerged conditions(SC) and dry cultivation conditions with zero mulching(ZM) and straw mulching (SM). The total amount of water used in rice under SC was 2.42 and 3.31 times as much as that under the ZM and SM treatments, respectively. The average field leakage was 13 560 m3/hm2 in the SC plots, 4 750 m3/hm2 in the ZM treatment and 4 680 m3/hm2 under the SM treatment. Rice straw mulching could decrease water evapotranspiration obviously. The evapotranspiration under the SM treatment was only 38.2% and 63.6% to the SC treatment and ZM treatment, respectively. Compared with the ZM treatment, the SM treatment significantly increased the leaf area per plant, main root length, gross root length and root dry weight per plant of rice. The highest yield under the SM treatment(6 747 kg/hm2) was close to that under the SC treatment(6 8115 kg/hm2) . However, the yield under the ZM treatment (4 716 kg/hm2) was much lower than that under the SC and SM treatments. The order of water use efficiency and irrigation water use efficiency was both as follows: SM> ZM> SC.

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Effect of Low Temperature on Photosynthetic Pigments and Thylakoid Membrane Fatty Acid in Flag Leaves of Rice at the Milky Stage WANG Jing ,ZHANG Cheng-jun ,CHEN Guo-xiang ,WANG Ping ,SHI Da-wei ,LU Chuan-gen 2006, 20(2): 177-182 .  Abstract ( )   PDF (118KB) ( )   To clarify the resistance of a new super hybrid rice (Oryza sativa) Liangyou 122 to chilling temperature at the milky stage, the contents of photosynthetic pigments, the changes of thylakoid membrane fatty acid and the activities of several enzymes in anti-oxidation system were investigated using a traditional hybrid rice Shanyou 63 as control, under the conditions of 25℃/15℃ and 25℃/20℃(day/night temperature). The contents of malondialdehyde(MDA) and superoxide anion (O2 -·) were increased remarkably, while the activities of superoxide dismutase(SOD) and catalase(CAT) were obviously dropped with the overtime of low temperature and the increased difference in temperature between daytime and night; at the same time, the index of unsaturated fatty acid (IUFA) of both varieties went up. As a result, the photosynthetic rate and the chlorophyll content were decreased obviously, the content of carotenoids increased firstly and then dropped. Of all the characteristics investigated, the changing degree of Liangyou 122 was less than that of Shanyou 63, but in the quantity the former was more than the latter, which meant that Liangyou 122 may have higher resistance to chilling temperature in milky period.

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Comparison of Tissue Transglutaminase Activity During Young Panicle Development in Honglian-Type Cytoplasmic Male Sterile Rice (Oryza sativa) CHANG Xun ,ZHANG Zai-jun ,LI Yang-sheng ,ZHU Ying-guo 2006, 20(2): 183-188 .  Abstract ( )   PDF (114KB) ( )   The leaves and young panicles at different developmental stages, being excised from the Honglian-type cytoplasmic male sterile line, Yuetai A and its maintainer line, Yuetai B, were used to investigate the changes of tissue transglutaminase activity. An ELISA (enzyme-linked immunosorbnent assay) measurement protocol for tissue transglutaminase activity detection in rice was well established. It was found that tissue transglutaminase activity was regulated positively by calcium cation, and in Yuetai A and Yuetai B the tissue transglutaminase activity in the senescent leaves was remarkably higher than that in the young leaves, but there was no distinct difference between Yuetai A and Yuetai B. Interestingly, from the tetrad to binucleate stages the tissue transglutaminase activity increased gradually with the development of the young panicles and up to maximum at binucleate stage in Yuetai A. However, no similar changes were observed in Yuetai B. It was suggested that tissue transglutaminase was involved in programmed cell death in abortive pollen.

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Different Responses to Cadmium Stress in Nitrogen Metabolism Between Weedy Rice and Cultivated Rice (Oryza sativa) SHAO Guo-sheng ,XIE Zhi-kui ,ZHANG Guo-ping 2006, 20(2): 189-193 .  Abstract ( )   PDF (102KB) ( )   Effect of cadmium stress on nitrogen uptake and activities of some enzymes related to N metabolism was compared between weedy rice and japonica rice cultivar Koshihikari with a hydroponic experiment under four Cd levels, i.e. 0, 01, 1.0 and 5.0 μmol/L with ammonium nitrate as N source. Cd concentration and accumulation in both shoots and roots of the two rices increased dramatically with increasing Cd level. However the extent of the increase varied with the rice genotypes. Under high Cd levels (1.0 and 5.0 μmol/L), weedy rice had lower Cd concentration and fewer Cd accumulation in roots than Koshihikari, while in shoots the case was just opposite, indicating that more Cd was translocated to shoots in weedy rice than in Koshihikari, and the shoots of weedy rice were more capable of detoxifying Cd than those of Koshihikari. N concentration, accumulation and the activities of nitrate reductase, glutamicoxalacetic transaminase and glutamatepyruvate transaminase decreased markedly with increasing Cd level. There was a clear difference in the extent of the decrease between the two rices. In general, the inhibition of N uptake and N metabolism-related enzymes was relatively less for weedy rice than for Koshihikari. It was proved that weedy rice had stronger tolerance to Cd toxicity than Koshihikari and there is a close association between performance of these N metabolism related enzymes and Cd toxicity tolerance.

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Changes of SOD Activity and MDA Content in Rice Exposed to Cd Stress as Affected by Genotype ZHANG Xiu-fu ,WANG Dan-ying ,CHU Kai-fu ,YANG Chun-gang ,MOU Ren-xiang ,CHEN Ming-xue ,ZHU Zhi-wei ,HE Qing-fu ,LIAO Xi-yuan 2006, 20(2): 194-198 .  Abstract ( )   PDF (75KB) ( )   A pot experiment was conducted to investigate the effects of soil cadmium (Cd) stress on superoxide dismutase (SOD) activity and malindialdehyde (MDA) content in rice plant, the correlations between SOD activity, MDA content and Cd content in plant by using four rice cultivars. SOD activity increased when plants were subjected to slight Cd stress, but was inhibited when subjected to high soil Cd concentration. There was a negative correlation between SOD activity and MDA content, and MDA content declined at low Cd level and increased at high Cd level. SOD activity varied with growth stage in the order of tillering stage> milky stage>full heading stage, while MDA content showed the constant increase in the whole growth period. There was a significant difference among the four rice cultivars in the changes of SOD activity caused by Cd stress, with the largest difference at the tillering stage. A negative correlation between SOD activity and Cd content of rice plant and brown rice was found, and the correlation was significant at the full heading stage.

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Effects of Nitrogen Application on Nitrogen Utilizationand Grain Yield and Quality in Rice under Water Saving Irrigation YOU Xiao-tao ,JING Qi ,JIANG Dong ,DAI Ting-bo ,ZHOU Dong-qin ,CAO Wei-xing 2006, 20(2): 199-204 .  Abstract ( )   PDF (40KB) ( )   The effects of nitrogen fertilization levels on rice grain yield and quality were studied under different irrigation methods by using japonica rice cultivar 9325 as material. Under water saving irrigation, number of panicles per hectare, head rice rate, protein content and gel consistency of rice decreased, while chalkiness values and amylose content of rice increased. As the increase of N level, head rice rate, protein content, chalky grain rate, chalkiness and gel consistency improved, and amylose content decreased under the same water management. Under water saving irrigation, the efficiency of N utilization and translocation after heading increased, while N productivity insensitive to water. It was found that parabolic relationship existed between N applied rates and plant accumulation and translocation in rice. Increasing of N applied rates and N utilization resulted in decreasing N productivity and N harvest index. In addition, grain yield and rice quality were significantly related to variations of N absorption and utilization in respect to water management and N applied rates.

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Relations Between Transpiration and N Uptake of Rice Grown in Elevated Air Carbon Dioxide Concentration PANG Jing ,ZHU Jian-guo ,XIE Zu-bin ,LIU Gang ,CHEN Gai-ping 2006, 20(2): 205-209 .  Abstract ( )   PDF (112KB) ( )   Correlation between transpiration and N uptake rate of rice at low N (LN, 14 mg/L) and high N (HN, 28 mg/L) in solution culture was studied under ambient air and elevated atmospheric p CO2 (Ambient+200 μmol/mol) by the China FACE (Free-Air CO2 Enrichment). Elevated p CO2 increased rice biomass and total N uptake significantly by 36% and 7% at LN, 29% and 5% at HN, respectively, while decreased total amount of transpiration by 28% at LN and 10% at HN. Elevated p CO2 stimulated average N uptake rate at the tillering stage as the result of enhanced occurrence of tillers. However, the significant effect of elevated p CO2 on average transpiration rate was only observed from the panicle initiation to late filling stage. The positive correlation between transpiration rate and N uptake rate was significant at Ambient but not elevated p CO2, indicating that declined transpiration caused by CO2 enrichment may not be the key factor affecting N uptake.

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Population Dynamics and Distribution of the Rice Water Weevil, Lissorhoptrus oryzophilus, in Direct Seeded Rice Area ZHENG Hong-hai ,HUANGFU Wei-guo ,LIN Jia-wei ,LOU Li-xing ,QIAN Wei-xing ,LAI Zhao-hui ,CHEN Hong-ming ,XU Pei-qian ,ZHOU Ding-guo 2006, 20(2): 210-215 .  Abstract ( )   PDF (82KB) ( )   The population dynamics and distribution of the rice water weevil, Lissorhoptrus oryzophilus Kuschel, was investigated in the first cropping rice field by direct sowing in a small flatland of mountainous area in Xiangshan, Zhejiang Province. The density peak of adults hibernated on hillside and field ridge occurred concurrently in early May. These adults migrated directly into rice field about 7 days after feeding on weeds and the immigrant peak of the direct seeded rice field appeared. They showed distinct preference of feeding, distributing and ovipositing for the habitat with water. In the direct seeded field, the nearer to the ridge, the higher density of the weevil population was, and the weevil density was higher in the margin than that in the middle in the same row. In the direct seeded rice field, it took the weevil about 50 days to complete its development of the first generation, the weevil multiplied 7.23-fold, which was significantly lower than that in the transplanted rice field, and mainly attributed to lower oviposition per adult in the direct seeded rice field. The weevil adults of the 1 st generation migrated back to the hillside or the ridge of the field for over-summering or over-wintering at the end of July. Some suggestions for the pest forecast and control were also brought forward based on the characteristics of the pest population dynamics and distribution in the direct seeded rice field.

研究简报

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Isolation and Analysis of Promoter of OsRacD from Photoperiod Sensitive Genic Male Sterile Rice LIANG Wei-hong ,WU Nai-hu 2006, 20(2): 216-218 .  Abstract ( )   PDF (175KB) ( )   Using OsRacD cDNA as probe to screen the genomic library of photoperiod sensitive genic male sterile rice Nongken 58S, a positive clone containing 2 kb promoter and 396 bp coding region of OsRacD was obtained. Compared with the promoter of OsRacD cloned by reverse PCR from rice variety Nongken 58N, the homology was 99.8%, and the different nucleotides were outside the predicted response elements in promoter, suggesting that the fertility difference between Nongken 58S and Nongken 58N under long day conditions was not attributed to the difference in the structure of OsRacD upstream regulation sequences, but to the developmental regulation of gene differential expression.

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Resistance to Rice Stripe in Eight Rice Varieties SUN Dai-zhen ,JIANG Ling ,ZHANG Ying-xin ,CHENG Xia-nian ,WANG Chun-ming ,ZHAI Hu-qu ,WAN Jian-min 2006, 20(2): 219-222 .  Abstract ( )   PDF (33KB) ( )   The resistance to rice stripe virus (RSV) and vector, small brown planthopper (SBPH) (Laodelphax striatellus Fallen) was studied and analyzed in eight indica rice varieties by using individual inoculation, mass inoculation, non-preference test and antibiosis test. The mechanism of resistance to RSV and vector SBPH was different in the eight rice varieties. Some rice varieties were highly resistant to RSV and vector SBPH, such as IR36, Kasalath, Zhaiyeqing 8, Daorenqiao and DV85; some others, such as Aichi 97 and Kenta Nakan were only resistant to RSV but susceptible to SBPH; and IR24 was moderately resistant to RSV and SBPH.

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Natural Antioxidants Extracted from Weeds in Paddy Field QIAO Feng-yun ,ZHOU Yong-jun ,TANG Jian-jun ,YU Liu-qing 2006, 20(2): 223-226 .  Abstract ( )   PDF (32KB) ( )   The optical density (OD) values of the extracts got with ethanol from 12 weeds in rice fields were determined using spectrophotometry. The OD values of the extracts from Echinochloa crusgall,Leptochloa chinensis,Cyperus iria and Monochoria vaginalis after 8 h extraction are 0.0165, 0.0215, 0.0235 and 0.0120, respectively,which were lower than that of tea polyphenols significantly, while equivalent to that from Elsholtzia ciliata. It suggested that the substances from the ethanol extracts were excellent antioxidants with significant antioxidation potential. By using water solution containing 0.3% antioxidant, the conditions of the ratio of solvent quantity to sample material of 12∶1, extraction of 8 h and temperature of 80℃ were the optimal parameters for collecting the antioxidants from Monochoria vaginalis.

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Hydrolysis Conditions for Porous Starch Preparation with Early-indica Rice by Compound Enzyming HE Guo-qing ,LIU Cai-qin ,CHEN Qi-he ,RUAN Hui ,WU Ying-long 2006, 20(2): 227-230 .  Abstract ( )   PDF (29KB) ( )   Porous starch is a good carrier as many functional components in food or medicine industry.The preparation methods for porous starch using α-amylase and glucoamylase to hydrolyze early indica rice starch were presented. Main hydrolyzing factors such as temperature, pH value, time and quantity of the enzymes were investigated by statistical method. In each case, the best technique conditions for preparing porous starch were different for three response values: yield rate, water absorption and adsorption capacity of ponceau 4R. Based on the water absorption of porous starch, the best condition obtained from enzymatic experiment was the enzymatic temperature 55℃,pH 4.0 and hydrolyzing time 16 h, the ratio of α-amylase to glucoamylase in volume 1∶3,enzyme active 14.00 KNU/g,90.00 AGU/g,respectively. When validated twice under the optimized conditions, the porous starch yield rate was 41.07% and 43.37%, water absorption was 148.03% and 155.61%, adsorption capacity of ponceau 4R was 9.37 mg/g and 9.38 mg/g, respectively.