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10 September 2006, Volume 20 Issue 5 Previous Issue    Next Issue
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研究报告
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研究报告

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Genetic Analysis and Molecular Mapping of a New Yellow-Green Leaf Gene ygl-2 in Rice WANG Jun ,WANG Bao-he ,ZHOU Li-hui ,XU Jie-fen ,GU Ming-hong ,LIANG Guo-hua 2006, 20(5): 455-459 .  Abstract ( )   PDF (419KB) ( )   A natural new rice yellow-green leaf mutant, derived from a japonica rice variety Wuyunjing 7, was crossed with the wild type variety and an indica rice variety Jiangxi 1587 to investigate the genetic model and map the referring gene(s). The yellow-green leaf mutant, named ygl-2 following the similar mutant reported before was controlled by a recessive gene ygl-2. The gene was roughly mapped between two microsatellite markers RM541 and RM30, with genetic distances of 13.1 cM and 9.1 cM, respectively. Then eight new polymorphic microsatellite markers were developed in this region. The ygl-2 was further mapped between two microsatellite markers SSR6-16 and RM7434, with genetic distances of 0.62 cM and 0.74 cM, respectively.

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Construction and Testing of Primary Microsatellite Database of Major Rice Varieties in China ZHUANG Jie-yun ,SHI Yong-feng ,YING Jie-zheng ,E Zhi-guo ,ZENG Rui-zhen ,CHEN Jie ,ZHU Zhi-wei 2006, 20(5): 460-468 .  Abstract ( )   PDF (280KB) ( )   Sixty-three major conventional varieties and parental lines of major F1 hybrids used in the commercial rice production in China were assayed with microsatellite markers screened in a previous study and additional markers on four chromosomes. A set of 24 markers was selected and proposed for its application in the variety identification of rice, which are distributed on all the 12 rice chromosomes with two markers on each chromosome. The 63 major varieties and parental lines, as well as 41 major F1 hybrids, were genotyped with the markers, and alleles detected at each marker locus were verified. By matching marker genotypes of corresponding F1 , maternal and paternal lines of hybrid rice, high reliability of the maternal lines was verified, data on paternal lines were modified, and a false hybrid was removed. A database containing genotype data of 103 major rice varieties and parental lines at the 24 marker loci was constructed and analyzed. The influence of the authenticity of rice materials on the database quality was discussed, and a threshold for microsatellite marker-based variety identification in rice and an approach for authentification of rice materials and genotype data were proposed.

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Natural Homologous Triploidization and DNA Methylation of Twin-Seedling Rice SARⅡ-628 PENG Hai ,ZHANG Hong-yu ,LI Yun ,XU Pei-zhou ,WANG Xu-dong ,WU Xian-jun 2006, 20(5): 469-474 .  Abstract ( )   PDF (544KB) ( )   A total of 5 pairs of diploid-triploid twin-seedlings were selected from 4500 pairs of SARⅡ-628 twin-seedlings. SSR analysis showed that there was no difference on 310 detected sites. A modified AFLP technique MSAP(methylation- sensitive AFLP) was employed to analyze methylation mutation. Although no methylation mutation was found in the 5 diploids, 29 methylation mutation sites were found in the corresponding triploids, which indicated that methylation mutation happened rapidly in M0 generation after natural homologous triploidization. The mutations were classified into 10 types, including 3 increased types of methylation-degree, 3 decreased types and 4 undecided types. The fragments of 22 methylation sites were sequenced and then searched through website. The results showed that the methylation mutation involved into the whole rice genome. The mutation trend was site-related and there were different mutation sites for different triploids, which foretelled that SARⅡ-628 would undergo different evolution ways after natural homologous triploidization.

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Genetic Diversity of Parental Lines in indica Hybrid Rice Based on Phenotypic Characters and SSR Cluster Analysis WANG Sheng-jun ,LU Zuo-mei ,WAN Jian-min 2006, 20(5): 475-480 .  Abstract ( )   PDF (111KB) ( )   Two methods of cluster analysis based on phenotypic characters and SSR molecular markers were compared to study the diversity of 41 parental lines popularized in commercial hybrid rice production in China. Forty-one entries were divided into two groups (i.e. early or medium-maturity group; medium or late-maturity group) and further into six subgroups based on phenotypic character cluster analysis. The early or medium-maturity group was composed of 15 maintainer lines, four early-maturity restorer lines and two thermo-sensitive genic male sterile lines. The medium or late-maturity group included 16 restorer lines and four medium or late-maturity maintainer lines. While on the basis of SSR cluster analysis, the entries were classified into two groups (i.e. maintainer line group and restorer line group) and seven subgroups. The maintainer line group consisted of all 19 maintainer lines, two thermo-sensitive genic male sterile lines, and the restorer line group was composed of all 20 restorer lines. Classifying results based on SSR analysis was basically consistent with the pedigree information. The results and the status of hybrid rice breeding indicate that SSR analysis could be a better method to study the diversity of parental lines in indica rice.

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Genetic Variation of Main Agronomic Traits in a New Germplasm Resource of Perennial Rice ZHAO Zheng-wu ,LI Shi-gui ,LEI Shu-fan 2006, 20(5): 481-486 .  Abstract ( )   PDF (109KB) ( )   The heritabilities of the overwintering ability of axillary buds were analyzed using four hybrid rice combinations, which derived from a new gramplasm resource of perennial waxy rice Nuodao 89-1 crossed with 4 different rice genotypes, and the genetic variation of main agronomic traits in F2 generation was also investigated among the three combinations. The highest heritabilities of 1000-grain weight and plant height were in main crop season, whereas the lowest were in overwintering season,and grain number per panicle and seed setting rate reached peak in ratooning season. The averages of grain number per panicle,1000-grain weight,plant height and panicle length in F2 approached to those in F1 with a nearly normal distribution,indicating there was no gametic selection from F1 to F2 generation.The variation range and coefficient were greater in main crop season and overwintering season. Though the average seed setting rate was higher in F2 generation than in F1 generation,the highest was in ratooning season, and the seed setting rate presented bimodal distribution,indicating gametic selection did exist from F1 to F2 generation, and result was in favor of gametes with a high seed setting rate.

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Fertility Expression of Thermo-Sensitive Genic Male Sterile Genes under the Backgrounds of indica Cytoplasmic Male Sterile Lines, Restorer Lines and Maintainer Lines WANG Ji-feng ,LU Zuo-mei 2006, 20(5): 487-492 .  Abstract ( )   PDF (43KB) ( )   Fertilities of generations of 51 F1 , 19 F2 and 6 BC1 derived from 3 thermo-sensitive genic male sterile lines(TGMS-lines) Pei′ai 64S, 6311S and 360S and three-lines including 7 indica cytoplasmic male sterile lines(CMS-lines) and their corresponding maintainer lines(B-lines) and 3 indica restorer lines(R-lines) were investigated to study the expression of TGMS-genes under the backgrounds of the three-line. The TGMS trait of Pei′ai 64S was governed by 2 pairs of independent recessive genes and Pei′ai 64S had stronger fertility restoring(Rf) genes for CMS-lines; The TGMS trait of 6311S was conferred by a single recessive gene and 6311S had a pair of weaker Rf-gene;the TGMS trait of 360S was controlled by a single recessive gene and 360S had no Rf-gene. After studying on the fertility of F1 plants between 5 CMS-lines and 4 TGMS generations selected from F2 plants of 4 CMS-lines/6311S, it was confirmed that the expression of TGMS-gene was controlled by Rf-gene under the background of CMS, but not affected by Rf-gene under the background of normal fertile cytoplasm. The potential breeding strategies of TGMS-lines under the background of CMS and CMS-lines with the nucleus of TGMS-genes were discussed.

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Genotypic Variation of Rice in Utilization of Sparingly Soluble Phosphate and Its Relationship with Mobilization Characteristic of Root Exudation LI Yong-fu ,LUO An-cheng ,WEI Xing-hua ,YAO Xu-guo 2006, 20(5): 493-498 .  Abstract ( )   PDF (212KB) ( )   A sand culture experiment and a hydroponic culture experiment were conducted to study genotypic variation of rice in utilization of sparingly soluble phosphates (Al-P and Fe-P) and its relationship with mobilization characteristic of root exudation. Both Al-P and Fe-P treatments significantly decreased the plant biomass, total P uptake, and plant total P concentration of eight rice genotypes in comparison with the P-sufficient treatment. There were genotypic variations in plant biomass, P uptake, and plant P concentration under Al-P or Fe-P treatments. Root exudation of either the P-sufficient plants or P-deficient plants had certain ability to mobilize P from sparingly soluble phosphate. The root exudation of P-deficient plants showed higher ability to mobilize P from Al-P or Fe-P than that of P-sufficient plants. Correlation analysis showed that P mobilization from Al-P or Fe-P by root exudation of P-deficient plants did not correlate with total P uptake from Al-P or Fe-P by rice, suggesting that genotypic variation in P mobilization from sparingly soluble phosphate by rice root exudation could not account for the genotypic variation in P uptake from sparingly soluble phosphate. Low P treatment increased secretion of malic acid and oxalic acid for most of the eight genotypes. However, the amount of malic acid and oxalic acid secretion in the root exudation was not consistent with P mobilized from sparingly soluble phosphate by root exudation.

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Photosynthetic Characteristics and Heterosis in Transgenic Hybrid Rice with Maize Phosphoenolpyruvate Carboxylase Gene (pepc) LI Ji-hang ,XIANG Xun-chao ,HE Li-bin ,ZHANG Kai-zheng ,LI Ping 2006, 20(5): 499-504 .  Abstract ( )   PDF (144KB) ( )   Rice sterile lines Gang 46A,776A and 2480A as the female parents were crossed with the improved restorer line Shuhui 881 containing maize phosphoenolpyruvate carboxylase gene(pepc) and the restorer line Shuhui 881(control). The dynamic changes of photosynthetic characteristics in leaves of the F1 with pepc gene and controls were determined at the initial tillering, maximum tillering, booting, initial heading, heading, maturity stages and other six different periods after flag leaves completely expanded. The leaf PEPCase activities and net photosynthesis rate (Pn) of the three F1s with pepc gene increased significantly as compared with the controls during the whole developmental stages, and the correlation coefficient (0.6081 ** ) between PEPCase activities and Pn in the three F1s with pepc gene was significant. The leaf photosynthetic indexes of the three F1s with pepc gene were obviously superior to the controls, being increased by 30.6%-59.7%, 29.8%-36.9% and 34.3%-40.0% in apparent quantum yield, light compensation point, carboxylation efficiency, respectively, and decreased by 23.5%-33.3% in CO2 compensation point. The Pn of the three F1 s with pepc gene at light saturated point and CO2 saturated point was also higher than that of the controls. Furthermore, there was average 37.10% competitive advantage compared with the controls for the three F1s with pepc gene on grain yield per plant. It indicated that the photosynthetic characteristics of the three F 1 s containing pepc gene have been improved to some extent as compared with their controls, which established physiological foundation for rice high production.

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Effects of Coupling Between Nitrogen Forms and Water Stress on Content and Distribution of Phosphorus in Different Parts of Rice Plants at the Seedling and Tillering Stages ZHOU Yi ,GUO Shi-wei ,GAO Ying-xu ,CHEN Gui ,SHEN Qi-rong 2006, 20(5): 505-511 .  Abstract ( )   PDF (91KB) ( )   By using the method of nutrient solution culture and simulated water stress with PEG6000, the effects of different nitrogen forms (NO3--N, NH4+-N and the mixture of NO3--N and NH4+-N) and water statuses (non-water stress and water stress conditions) on P distribution in the different parts of rice plants at the seedling-tillering stage were studied. Under water stress, P content in the different parts of NH4+-N supplied rice plants was higher than that of the other two nitrogen forms supplied ones, meanwhile, P content in NO3--N supplied rice plants under non-water stress was higher than that under water stress, whereas water stress had no significant effect on P content in the rice plants supplied with NH4+-N and the mixture of NO3--N and NH4+-N. Regardless of water conditions, from the early tillering stage to the middle tillering stage, the ratio of P distributed to leaves and roots supplied with NH4+-N singly and the mixture of NO3--N and NH4+-N was reduced, while NO3-N nutrition only reduced the rate of P distributed to leaves at this stage. Furthermore, the increased rate of P accumulated in rice plants was higher under NH4+-N supplied plus water stress than other treatments in this period.

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Effects of Different Submergence Stresses on Agronomic Traits and Biochemical Characteristics in Hybrid and Traditional Rice CHEN Yong-hua ,ZHAO Sen ,YAN Qin-quan ,XIAO Guo-ying 2006, 20(5): 512-516 .  Abstract ( )   PDF (148KB) ( )   The agronomic traits and biochemical characteristic of 16 hybrid and traditional rice varieties popularized in Hunan Province of China, were investigated under different submergence stresses at the tillering stage. The submergence tolerance of hybrid rice, revealed by the relative injury rate of leaf, was significantly stronger than those of traditional rice. The plant height of hybrid and traditional rice increased firstly and then decreased with the increase of submergence day, and the highest plant height of hybrid rice appeared on the 4 th day after submergence and on the 2 nd day in the traditional rice. The delay of heading increased with the duration of submergence, but the delay scopes of hybrid rice were less than those of traditional rice. The effective panicle number per plant, grain number per panicle, 1000-grain weight and yield per plant decreased with the increasing days of submergence and the decreasing ranges in hybrid rice were less than those in traditional rice. When the submergence day increased, the increased range of relative conductivity of hybrid rice was less compared with traditional rice. The content of malondialdehyde increased stably in hybrid rice, but increased at first and then dropped dramatically in traditional rice. The increase of proline content in hybrid rice was more than that in traditional rice. All the results showed that the submergence tolerance ability of hybrid rice is superior to traditional rice.

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Effects of Integrated Fertilization with Commercial Organic Manure and Chemical Fertilizers on Heavy Metal Balance in Soil-Rice Cropping System KONG Wen-jie ,NI Wu-zhong 2006, 20(5): 517-523 .  Abstract ( )   PDF (56KB) ( )   A field experiment was conducted with rice plants to assess the effects of integrated fertilization on heavy metal balance in soil-rice cropping system and rice hygienic quality. Four treatments as chemical fertilizers, chemical fertilizers + lower rate of organic manure, chemical fertilizers + medium rate of organic manure, and chemical fertilizers + high rate of organic manure were designed with four replications for each treatment. The doses of N, P 2 O 5 , and K 2 O of all treatments were equal at 225, 112.5 and 150 kg/hm 2 , respectively. The differences of above-ground biomass and grain yield of rice plants among treatments were not significant (P>0.05). Cadmium concentration in brown rice increased with the increase in the ratio of organic manure applied. Health risk existed as Cd concentration in brown rice under the treatments with medium and high rate of organic manure were as high as the limit (0.2 mg/kg) in cereals. It was also found that zinc and copper deficits in the soil-rice system occurred under the treatments with no organic manure or lower rate of organic manure. Integrated fertilization with appropriate rate of organic manure and chemical fertilizers could not only contribute to maintaining the balance of zinc and copper as micronutrients, but also minimize the risk of heavy metal pollution in the cropping system, which can be regarded as an effective manner for the construction of sustainable agriculture.

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Effects of Proteins on RVA Viscosity Properties of Rice XIE Li-hong ,CHEN Neng ,DUAN Bin-wu ,ZHU Zhi-wei 2006, 20(5): 524-528 .  Abstract ( )   PDF (113KB) ( )   To understand the relationship between grain protein content and rice eating quality, changes on RVA viscosity properties of rice were analyzed through protein removal or disulphide bond disruption. Pre-incubation of flour with trypsin decreased viscosity and the slopes of the linear parts of the curves for each variety. Dithiothreitol(DTT) decreased the peak viscosities of flour at different degrees in various rice varieties, and increased the breakdown viscosities in five of the ten tested varieties. It was suggested that protein influenced viscosity curves through binding water, which increased the concentration of the dispersed and viscous phase of gelatinized starch, as well as the agency of a network linked by disulphide bonds. Protein may affect the amount of water absorption early in cooking, which will influence the eating quality of the cooked rice.

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Effects of Nitrogen Application on RVA Profile Characters under Different Soil Fertility Levels LIU Yan-yang ,ZHANG Hong-cheng ,DAI Qi-gen ,HUO Zhong-yang ,XU Ke 2006, 20(5): 529-534 .  Abstract ( )   PDF (117KB) ( )   By using rice varieties Wuxiangjing 14 and Wujing 15 as materials, the effects of nitrogen application on RVA profile characters under different soil fertility levels were studied. The curves of RVA profile decreased with the increased nitrogen rate. Soil fertility level and nitrogen rate had remarkable effects on the RVA profile characteristic value except one or two characteristic values. The interactive effect of soil fertility level and nitrogen was remarkable on hot viscosity, breakdown, cool viscosity, and consistence. With the increase of nitrogen rate, peak viscosity, hot viscosity, breakdown, cool viscosity, consistence and peak time decreased remarkably.The nitrogen rate of 225 kg/hm2 was the critical on the cooking and eating quality of rice.

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Some Canopy Indices Influencing Sheath Blight Development in Hybrid Rice ZHONG Xu-hua ,PENG Shao-bing ,Roland J. BURESH ,HUANG Nong-rong ,ZHENG Hai-bo 2006, 20(5): 535-542 .  Abstract ( )   PDF (115KB) ( )   The relationships between disease severity of sheath blight and several canopy indices of rice, i.e. stem number (TILPI) and chlorophyll content at panicle initiation (SPADPI), and stem number (TILHD), leaf area index (LAIHD) and chlorophyll content at heading (SPADHD) were investigated in the four-season field experiments conducted in Guangzhou, China during early and late seasons of 2004 and 2005. Yueza 122, a two-line hybrid rice, was arranged in a randomized complete block design with eight N-fertilizer treatments and four replications. There were two categories of factors, i.e. canopy conditions and climatic factors, which affected sheath blight development. Main canopy indices influencing disease severity were TILPI, SPADPI, TILHD, LAIHD, and SPADHD, which explained 44.8% of variation in disease severity among years, seasons and N treatments. Main climatic factors were daily mean temperature (Tav) and relative humidity (RH). The multiple regression equation with TILPI, SPADPI, LAIHD, SPADHD, Tav and RH as independent variables explained 82.7% of variation in disease severity. The disease severity decreased as light transmittance ratio of the canopy at heading (LTR) increased. The LTR, Tav and RH explained 80.2% of variation in disease severity. It is suggested that the reduced maximum tiller number, lower chlorophyll content of leaves, smaller LAI at heading and better ventilation of the rice canopy are the direction to establishing a healthy canopy with high grain yield potential and low sheath blight occurrence.

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Effects of Transgenic Rice Harboring cry1Ac and CpTI Genes on Survival of Chilo suppressalis and Sesamia inferens and Field Composition of Rice Stemborers GAO Yu-lin ,FU Qiang ,WANG Feng ,LAI Feng-xiang ,LUO Ju ,PENG Yu-fa ,ZHANG Zhi-tao 2006, 20(5): 543-548 .  Abstract ( )   PDF (123KB) ( )   The effects of transgenic rice containing both cry1Ac and CpTI genes on survival of the stripped stem borer (SSB), Chilo suppressalis, and the pink stem borer (PSB), Sesamia inferens, and the field composition of stem borers were studied in both laboratory and field tests. The laboratory bioassay results showed that the survival of SSB and PSB on transgenic rice was significantly lower than that on non-transgenic control. The toxicity of transgenic rice to SSB and PSB declined at the late growing stage of rice. The lethal effect of the transgenic rice to SSB was stronger than that to PSB. As for SSB, only a few larvae (0.5%-6.4%) could survive at the 4th day after infestation at the heading and maturity stage in transgenic rice, and the survival rate of PSB on transgenic rice was higher than that of SSB. Furthermore, there were a few larvae (<1.6%) could pupate and emerge although the pupation and emergence rates were substantially lower than those on non- transgenic control. The results of field tests in both early and late rice indicated that the number of SSB and PSB larvae on transgenic rice were significantly reduced compared with the control. Compared with non-transgenic check, the number of SSB in transgenic rice was reduced by over 99%, and the effect of transgenic rice on PSB was relatively low and varied with different cropping seasons. The number of PSB was decreased by over 93% in early rice and by 44%-64% in late rice. Among the surviving stem borers in transgenic rice field, the percentage of PSB increased significantly. It is inferred that the change is possibly caused by the different susceptibilities for the two stemborers to transgenic rice expressing Cry1Ac and CpTI toxins.

实验技术

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High-Resolution Two-Dimensional Electrophoresis for Total Proteins in Rice Roots, Leaves and Suspension Cells YU Chu-lang ,YAN Shun-ping ,SUN Wei-ning ,YANG Ling 2006, 20(5): 549-552 .  Abstract ( )   PDF (1KB) ( )   Total proteins from rice roots, leaves and suspension cells were extracted and separated by two-dimensional electrophoresis. At least 1190, 1320, 1080 protein spots were detected on the gels of root, leaf and suspension cell extracts, respectively. The gels were highly reproducible as determined by the correlation coefficient among replications, which varied from 0.87 to 0.94. The protein extraction procedure and the electrophoresis conditions were optimized, which may be helpful for proteomic analysis of other plant species by two-dimensional electrophoresis.

研究简报

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Identification of QTLs for Agronomic Traits Associated with Yield in a BC2F2 Population Between Oryza sativa and Oryza rufipogon CHENG Gui-ping ,FENG Jiu-huan ,LIANG Guo-hua ,LIU Xiang-dong ,LI Jin-quan 2006, 20(5): 553-556 .  Abstract ( )   PDF (79KB) ( )   A BC2F2 population was developed from an interspecific cross between a cultivated rice variety Guanglu′ai 4 (Oryza sativa ssp. indica) and a wild rice line from Oryza rufipogon by using Guanglu′ai 4 as the maternal parent as well as the recurrent parent. The substitution segments of wild rice in the genetic background of the cultivated variety were analyzed in BC2F1s using 241 polymorphic SSR markers and QTLs controlling agronomic traits associated with yield were identified in BC2F2 using 24 polymorphic SSR markers. Twenty substitution segments were identified on seven chromosomes, including chromosomes 1, 2, 3, 5, 8, 9 and 11. The total length of the substitution segments was 247.2 cM, and covered 16.21% of the rice haploid genome; the length of substitution segments ranged from 0.55 to 33.00 cM, with an average length 12.36 cM. Additionally, a total of 20 QTLs for eight traits associated with yield were identified in the population of 122 BC2F2s, and of which 55% had positive effect. Moreover, the QTLs controlling the traits associated with yield were found to be clustered, which agreed with the results from correlation analysis of the phenotypic traits

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Effect of Drought Stress Simulated by PEG on Malonaldehyde, Proline Contents and Superoxide Dismutase Activity in Low Potassium Tolerant Rice Seedlings DAI Gao-xing ,PENG Ke-qin ,XIAO Lang-tao ,DENG Guo-fu 2006, 20(5): 557-559 .  Abstract ( )   PDF (72KB) ( )   Malonaldehyde(MDA) content,proline content, superoxide dismutase(SOD) activity and relative permeability of plasma membrane were measured in seedlings of rice variety Guibao 8 and its low potassium tolerant mutant progeny under 20% PEG 6000-simulated drought stress. MDA content,proline content and relative permeability of plasma membrane in rice seedling increased rapidly after drough stress, and MDA,proline levels were much higher in Guibao 8 than those in its mutants.SOD activity in rice seedling firstly increased and then rapidly dropped after drough stress and it was always higher in the mutant progeny than that in Guibao 8. These results suggested that the drought resistance of the mutant progeny was stronger than that of Guibao 8.Correlation analysis showed that there were significantly positive correlations between proline content, and MDA content,and relative permeability of plasma membrane in rice, however,proline content was negatively related to SOD activity to a certain extent.

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On Carbon and Nitrogen Metabolism of Rice Plants under Elevated CO2 Conditions GUO Shi-wei ,RAN Wei ,ZHOU Yi ,SHEN Qi-rong 2006, 20(5): 560-566 .  Abstract ( )   PDF (135KB) ( )   The interaction between the nitrogen nutrition and the response of photosynthesis, carbon and nitrogen metabolism and growth under the elevated atmospheric CO2 was reviewed with rice served as an example plant, which is associated with nitrogen nutritional characters, the activity and amounts of photosynthetic enzymes, the regeneration of photosynthetic substrates and nitrogen nutrition. Nitrogen management in rice production system were suggested, and the further nitrogen nutrition of rice plants associated with yield and ecological aspect were discussed as well.