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10 September 2008, Volume 22 Issue 5 Previous Issue    Next Issue
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研究报告
实验技术
综述与专论
研究简报


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研究报告

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Down-Regulated Expression of RACK1 Gene by RNA Interference Enhances drought Tolerance in Rice LI Da-hong ,LIU Hui,YANG Yan-li,ZHEN Ping-ping,LIANG Jian-sheng * 2008, 22(5): 447-453 .  Abstract ( )   PDF (1083KB) ( )   RACK1 is a scaffold protein with versatile functions,and plays important roles in the regulation of plant growth and development. Transgenic rice plants,of which the expression of RACK1 gene was inhibited using RNA interference (RNAi) approach,were used to study possible functions of RACK1 in the responses of rice to drought stress. Real-time PCR analysis showed that the expression of RACK1 in transgenic rice plants was inhibited more than 50%. The transgenic rice plants showed higher tolerance to drought stress as compared with the non-transgenic rice plants. The peroxidation of membrane and production of malondialchehyde were significantly lower,and the superoxide dismutase activity was significantly higher than those of the non-transgenic rice plants. It suggested that RACK1 negatively regulated rice tolerance to drought stress,which was related to redox system of rice plants.

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Cloning of the Promoter Sequence of Rice OsSABATH Gene Specifically Expressed by Chilo suppressalis Infestation and Construction of Its 5' Deletions LI Ran,Sumera AFSHEEN,ZHOU Guo-xin,REN Nan,LOU Yong-gen* 2008, 22(5): 454-458 .  Abstract ( )   PDF (3648KB) ( )   Northern blot analysis showed that the expression levels of the rice gene OsSABATH were up-regulated by infestation of rice striped stem borer,Chilo suppressalis,but not by mechanical wounding. A 2050-bp promoter sequence upstream of this gene was amplified using a pair of primers designed on the basis of the sequence of the OsSABATH and rice genome sequence database. With the aid of PLACE program,several cis-acting elements in the promoter sequence,including W-box,DOF binding motif,GT-1 element,and BIHD1 binding motif,were recognized. For analyzing the activity of the promoter sequence and the functions of the herbivore feeding responsive cis-acting elements,the promoter region sequence and its 5'deletion constructs were fused to the GUS reporter gene in pCAMBIA1391 vector.

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Expressing hrf1 Gene in Rice Exhibits Stable Nonspecific Resistance to Magnaporthe grisea SHAO Min*,XIAO Shan-shan,LI Lin,HUANG Wan-chun,WANG Jin-sheng 2008, 22(5): 459-464 .  Abstract ( )   PDF (5513KB) ( )   The harpin-encoding gene (hrf1),derived from Xanthomonas oryzae pv. oryzae,was transferred into a rice variety R109. Expressing hrf1 in rice enhanced the resistance to ZC3,ZD1 and ZG1 races of M. grisea,and only a few lesions developed on leaves of transgenic plants infested with ZB13 races,showing that the expression of hrf1 confers nonspecific resistance in rice to M. grisea. Transgenic plants and their T1,T3,T5 and T7 progenies were highly resistant to major M. grisea groups in rice-growing areas. The expression of several key plant defense genes (OsPR1a,OsPR1b,PAL,and Chia4a) and signal transduction gene NPR1 (non-expressor of PR genes) were enhanced in transgenic lines which were resistant to rice blast. Silicon content,which often correlates with resistance to M. grisea,was increased in transgenic lines. The results indicated that expressing harpin-encoding gene in rice exhibited stable nonspecific resistance,suggesting that the expression of harpin-encoding genes may provide effective controls on rice blast and offer new hope for generating broad spectrum resistance in other crops.

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Fine Mapping of Quantitative Trait Loci for Grain Length and Grain Width on the Short Arm of Rice Chromosome 1 Yu Shou-wu,FAN Ye-yang,YANG Chang-deng,LI Xi-ming* 2008, 22(5): 465-471 .  Abstract ( )   PDF (2024KB) ( )   Two residual heterozygous lines (RHLs),which contained a heterozygous region flanked by RM1-RM3746 and RM151-RM243 on the short arm of chromosome 1 were used to develop the F6 populations,respectively. By QTL analysis of two F6 populations and comparison of the common heterozygous segment presented in these RHLs,QTLs including qGL-1 and qGW-1 for grain length and grain width were identified in the same interval between RM3746 and RM243,respectively. Four RHLs carrying heterozygous segments in the intervals RM151-RM10404,RM10398-RM5359,RM10435-RM259 and RM10381-RM243 on the short arm of rice chromosome 1 were selected from one population by SSR marker survey,respectively. Ten maternal homozygotes and 10 paternal homozygotes were selected from each of the four F2 populations derived from the four RHLs. The four sets of near isogenic lines (NILs) were grown for phenotyping on grain length and grain width. With analysis on the phenotype differences among overlapping chromosome segment substitution lines,two QTLs of qGL-1 and qGW-1 for grain length and grain width were resolved,respectively. qGL-1 and qGW-1 were located in the intervals 437.5 kb and 392.9 kb flanked by RM10390-RM1344 and RM10376-RM10398,respectively. Alleles were all from maternal parent contributing to increase in grain length and grain width. The results clearly suggested that qGL-1 and qGW-1 were tightly linked. Genetic dissection of qGL-1 and qGW-1 has laid a foundation for cloning of the QTLs and molecular breeding of appearance quality in rice.

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QTL Analysis for Resistance to Rice False Smut by Using Recombinant Inbred Lines in Rice LI Yu-sheng,ZHANG Ya-dong,ZHU Zhen,ZHAO Ling,WANG Cai-lin* 2008, 22(5): 472-476 .  Abstract ( )   PDF (2470KB) ( )   A recombinant inbred line (RIL) population with 157 lines derived from an inter-subspecific cross of Daguandao/IR28 by the single seed descent method was used to detect quantitative trait loci (QTLs) conferring the resistance to rice false smut caused by Ustilaginoidea virens (Cooke) Takahashi. The disease index for the two parents and 157 RILs in response to rice false smut were scored and the QTLs responsible for rice false smut resistance were detected accordingly by QTL Cartographer software. Five QTLs controlling false smut resistance were detected on chromosomes 1,4,10,11 and 12,respectively,with the phenotypic variance explained from 9.8% to 22.5%. The directions of the additive effects at the four loci qFsr1,qFsr10,qFsr11 and qFsr12 coincided with those predicted according to phenotypes of the parents. At these four loci,the IR28 alleles had positive effects against rice false smut,while Daguandao alleles showed negative effects. The resistance was attributed to the alleles from Daguandao at the loci qFsr4.

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Correlation Analysis and QTL Mapping of Some Physiological Traits Related to Drought Resistance in Rice WANG Hui,CAO Li-yong,Guo Yu-hua,CHENG Shi-hua* 2008, 22(5): 477-484 .  Abstract ( )   PDF (1441KB) ( )   A doubled haploid population including 110 lines derived from the inter-subspecific cross between Azucena and IR64 were used to investigate six physiological traits of rice at the heading stage under drought stress and normal irrigation in 2004 and 2005. The changes in all the six traits were analyzed by t-test,as well as the correlations between the traits and drought resistance coefficient (DRC). Based on the genetic linkage map with 175 RFLP markers,QTLs associated with these traits were identified and analyzed. The results indicated that the proline content in rice leaves was significantly (P<0.01) increased,whereas,the relative water content,water potential,chlorophyll content and stomatal conductance of rice leaves significantly (P<0.01 or P<0.05) decreased under the drought stress compared with those under normal irrigation conditions. The relative water content and the water potential were significantly and positively correlated with DRC under the drought stress. Seven QTLs with additive effects and 31 pairs of QTLs with epistatic effects for the six physiological traits related to drought resistance were detected under the two water regimes. In the detected QTLs,two QTLs with additive effects and nine pairs of QTLs with epistatic effects showed QTL×environment interaction effects. There were obvious differences between QTLs under the two water regimes,which indicates that the drought stress has a remarkable effect on the expression of genes controlling the physiological traits related to drought resistance in rice. Among the physiological traits,more QTLs were detected for the stomatal conductance (three additive QTLs and eight pairs of epistatic QTLs),and for the water potential (eight pairs of epistatic QTLs). In addition,drought-resistant rice breeding through molecular marker assisted selection had also been discussed.

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Distribution Characterization of Leaf Pubescence and Hull Pubescence and Genetic Analyses of Their Numbers in japonica Rice(Oryza sativa) ZHU Xiao-biao,SUN Da-yun,CHENG Bao-shan,HONG De-lin* 2008, 22(5): 485-492 .  Abstract ( )   PDF (2936KB) ( )   Distribution characteristics of leaf pubescence on leaf blade and hull pubescence on hull were observed under an optical microscope. The numbers of leaf pubescences and hull pubescences in P1,P2,F1,B1(F1/P1),B2 (F1/P2) and F2 generations were investigated in three combinations of japonica rice,and genetic analyses for the two traits were conducted using the joint analysis method of P1,P2,F1,B1(F1/P1),B2(F1/P2) and F2 generations with mixed major gene plus polygene inheritance models. Leaf pubescence scattered regularly on the boundary line between sap green stripe and pea green stripe of leaf blade with intumescent fundus and exiguous top. Hull pubescence scattered irregularly on the whole hull with distinct length. The number of leaf pubescences was controlled by one pair of major genes with additive effect plus polygenes with additive-dominance effects in reciprocal combinations of Sidao 10A/Wuyujing 3R and Wuyujing 3A/Sidao 10R,and one pair of major genes with additive-dominance effect plus polygenes with additive-dominance effects in combination of Liuyan 189A/HR-122. Number of hull pubescences was controlled by one pair of major genes with additive effect plus polygenes with additive-dominance effects in all the three combinations. The numbers of leaf pubescences and hull pubescences were all mainly governed by major genes.

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Observation on the Double Fertilization and Early Stage Development of Embryo in Autotetraploid Polyembryonic Rice DAI Xi-mei,HUANG Qun-ce,LIANG Qiu-xia,QIN Guang-yong 2008, 22(5): 493-498 .  Abstract ( )   PDF (12120KB) ( )   By using autotetraploid polyembryonic mutant rice IR36-Shuang as material,the process and characters of its double fertilization,embryo and endosperm development were observed with a laser scanning confocal microscopy. Some abnormalities including degradated ovary,abortive embryo sac,single fertilization,double-ovule and double-embryo were found during the double fertilization and embryo development in IR36-Shuang. The rate of the abnormalities was 46.67%,significantly higher than that in the control IR36-4x(33.00%). Cytological and embryonic proofs were provided for seed setting decline and the initiation of additional embryo in the IR36-Shuang.

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Relationship between Decrease in Nitrogen Content and Activities of Key Enzymes Related to Nitrogen Metabolism in Rice Leaves under Elevated CO2 Concentration WANG Liang,ZHU Jian-guo*,ZHU Chun-wu,CAO Ji-ling,WANG Ming-na,ZENG Qing,XIE Zu-bin,LIU Gang 2008, 22(5): 499-506 .  Abstract ( )   PDF (3590KB) ( )   The activities of key enzymes related to nitrogen metabolism in functional leaves of rice at low nitrogen level (125 kg/hm2) and normal nitrogen level (250 kg/hm2) were studied under ambient air and elevated CO2 concentration(Ambient+200 μmol/mol) conditions at different developmental stages by Free Air Carbon-dioxide Enrichment (FACE) approach. Compared with the ambient conditions,the activities of nitrate reductase (NR) and protease increased under elevated CO2 concentration conditions at both the normal and the low nitrogen levels and the change extent of the activities of the two enzymes was larger at the normal nitrogen level than that at the low nitrogen level.NADH-glutamate dehydrogenase (NADH-GDH)and glutamine synthetase (GS) activities decreased at the low nitrogen level,whereas the decline trend was somewhat alleviated at the normal nitrogen level.Therefore,elevated CO2 concentration accelerated the transformation of NO3-to NH4+ but inhibited the assimilation of NH4+ to organic N and improved protein degradation after flowering,which might accelerate the decrease of nitrogen content in rice leaves and it was the inner factor that induced the decrease of nitrogen content in rice leaves.Nitrogen application increased the activities of enzymes related to nitrogen assimilation metabolism,decreased the activity of protease and so mitigated the decrease of nitrogen content in rice leaves.

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Effects of Transplanting Density and Nitrogen Fertilizer Rate on Yield Formation and Grain Quality of Super High Yielding Rice Zhongzao 22 Xu Chun-mei,WANG Dan-ying,SHAO Guo-sheng,ZHANG Xiu-fu 2008, 22(5): 507-512 .  Abstract ( )   PDF (924KB) ( )   A field experiment was conducted with different transplanting densities (24,30 and 36 hills/m2) and nitrogen fertilizer rates (0,105,150 and 195 kg/hm2 N) by using a super high yielding indica rice,Zhongzao 22 as material. The transplanting densities had less effect on the seed setting rate,1000-grain weight,number of productive panicles,grain number per panicle and grain yield. The effect of nitrogen fertilizer rate on grain number per panicle was lower than that on the number of productive panicles,seed-setting rate and 1000-grain weight. Seed-setting rate and 1000-grain weight were decreased significantly at 195 kg/hm2 of nitrogen applied rate. The transplanting density had no significant effect on rice quality. The protein content of rice increased with the increasing transplanting density. The increase in nitrogen fertilizer rate improved milling and appearance quality of rice,as well as protein content.

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Occurrence of the Third and Fourth Generations of Cnaphalocrocis medinalis in the Mixed Cropping Rice Region in Anqing,Anhui Province QI Guo-jun,QIN Ran-ran,XIAO Man-kai,ZHENG Zhao-yang,JIANG Chao,CHENG Xia-mian,HANG Xiao-xi,ZHAI Bao-ping* 2008, 22(5): 513-518 .  Abstract ( )   PDF (3128KB) ( )   The occurrence of the third and fourth generations of Cnaphalocrocis medinalis (Guenée) in Anqing City,Anhui Province,a mixed cropping rice region,were studied systematically. The results showed that the third and fourth generations of C. medinalis appeared two peaks in Anqing with the main infested period on early maturity type of middle-season rice in single-cropping paddy field from late July to early August,and on late rice in double-cropping paddy field from late August to early September. According to the data of female ovarian dissection and light-trap catches,the local generation was in the majority in the third generation but with a partial immigrants;however,the fourth generation was basically emigrants. Comparison on the ovarian dissection data for the field populations of C. medinalis revealed that the fourth generation on late rice in the double-cropping paddy field would be resident and no emigration,but the population on early maturity type of middle -season rice in the single-cropping paddy field would emigrate for a long distance,while some of them could disperse to the nearby double-cropping late rice fields,in which the moths settled down and bred. Because of calefacient autumn and changes in cultivated rice varieties and planting systems,the planting area and ratio of single-cropping rice increased rapidly in Anqing since 1995 and formed the mixed cropping rice region. Compared with the double-cropping areas,the incessancy rice growing in mixed cropping region could provide more favorable habitat and food resources for C. medinalis,causing the sustained infestation in autumn.

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Laboratory Screening and Cross-Resistance Analysis of Alternative Insecticides for Highly-Toxic Pesticides for Controlling Brown Planthopper,Nilaparvata lugens WANG Yan-hua ,CHEN Jin ,SHEN Jin-liang *,GAO Cong-fen ,HUANG Yue ,ZHANG Jiu-shuang ,LI Wen-hong ,ZHOU Wei-jun 2008, 22(5): 519-526 .  Abstract ( )   PDF (277KB) ( )   To screen alternative insecticides for highly-toxic pesticides,toxicities of more than twenty insecticides fallen in six groups to the 3rd instar nymphs of brown planthopper,Nilaparvata lugens populations collected from Nanning and Guilin Cities (Guangxi Zhuang Autonomous Region),Changde City (Hunan Province) and Nanjing City (Jiangsu Province),China were investigated by the rice stem-dipping method in laboratory from 2005 to 2006. Results showed that buprofezin,fipronil,thiamethoxam,nitenpyram,chlopyrifos,isoprocarb,promecarb and carbosulfan could be adopted as potential alternative insecticides for the highly-toxic pesticides. After selection with imidacloprid for 23 generations,the population developed extremely-high level resistance to imidacloprid (1298.5-fold),with a LC50 value of 103.88 mg/L,being 6.5-fold of the value of the original reference strain before the selection (16.01 mg/L). The selected strain of N. lugens showed obvious cross-resistance to imidaclothiz,thiacloprid and acetamiprid,whereas not to dinotefuran,thiamethoxam and nitenpyram. Management strategy of insecticide resistance of the insect was also discussed.

实验技术

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Application of Agarose Gel Electrophoresis in Rice EcoTILLING ZHANG Zhi-gang,XIE Yong,LI Cheng-yun,Lu Chun-ming,WANG Yun-yue,Zhu You-yong* 2008, 22(5): 527-532 .  Abstract ( )   PDF (1073KB) ( )   To establish a cheaper EcoTILLING system based on agarose-gel-electrophoresis for the detection of natural variation of rice or other plant species,a convenient EcoTILLING technique combined agarose gel electrophoresis with active rude CELⅠ nuclease extract from celery was constructed. By using the EcoTILLING technique,two SNPs were detected in a Yunnan conventional rice variety Dadiaonuo.

综述与专论

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Highlights in Identification and Application of Resistance Genes to Rice Blast E Zhi-guo ,ZHANG Li-jing ,JIAO Gui-ai ,CHEN Ben-yi ,WANG Lei* 2008, 22(5): 533-540 .  Abstract ( )   PDF (93KB) ( )   Studies on host resistance to blast in rice have been extensively conducted since 1960s. Following the initial work of Kiyosawa’s group in Japan for the identification of 14 resistance genes at eight loci and the development of Japanese differential cultivars (JDCs),the inheritance of rice blast resistance was comprehensively studied at the International Rice Research Institute and in rice-growing countries such as China. Up to December 2007,at least 67 resistance alleles at 58 loci had been identified. These genes are located in cluster and distributed on all the rice chromosomes except chromosome 3,of which 66 are dominant and the remaining one is recessive. Eight of the genes,namely,Pi-b,Pi-ta,Pi-z5,Pi-zt,Pi-9,Pi-d2,Pi-36 and Pi-37,have been cloned,among which Pi-z5,Pi-zt and Pi-9 are allelic. Application of resistance genes to rice blast was also discussed.

研究简报

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Cloning,Expression and Characterization of G Protein β-subunit Gene in Rhizoctonia solani from Rice XIAO Yong,LI Shuang-cheng,CHU Ming-guang,ZHOU Peng,GUAN Peng,LIU Li,WANG Ling-xia,ZHENG Ai-ping,LI Ping 2008, 22(5): 541-544 .  Abstract ( )   PDF (2272KB) ( )   A G protein β-subunit gene in Rhizoctonia solani AG-1IA of rice which causes rice sheath blight disease was isolated. A 1958-bp PCR fragment was obtained by using the specific primers designed from the conserved region in G protein β-subunit homologues from Thanatephorus cucumeris. Amino acid sequence analysis showed that the sequence involved 366 deduced amino acid,encoded a putative peptide which shared significant identity (57.34%-88.14%) with G protein β-subunit homologues from other species. The full-length of the PCR fragment was 1.9 kb with a 1.7-kb open reading frame of the G protein β-subunit gene in R.solani AG-1IA. The results of RT-PCR showed that the G protein β-subunit gene transcript was greatly expressed in all growth period especially at the exponential phase,which indicated that the expression of the G protein β-subunit gene in R.solani AG-1IA might be regulated temporally and spatially.

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Expression Analysis on OsAQP Gene in Rice Leaves LIU Yue-xia,LIANG Wei-hong*,ZHANG Li-juan 2008, 22(5): 545-547 .  Abstract ( )   PDF (595KB) ( )   Semi-quantitative RT-PCR was performed to examine the expression profile of an aquaporin gene,OsAQP gene,in rice leaves at different time after seed germination. By digoxigenin tagging in situ hybridization techniques,the transcripts of OsAQP gene were detected in rice leaf tissues. The results showed that the expression of OsAQP presented a descendent tendency in rice leaves within 15 days after germination. The transcripts in leaves were mainly in guard cells,weakly in mesophyll cells and seldomly in epidermal cells,which suggested that OsAQP may be involved in the functions of stoma by coupling the rapid transportation of water in guard cells.

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A Study on the Formation in the Character of Gelatinization Temperature of Rice Grains CHI Xiao-fei ,SHU Qing-yao* 2008, 22(5): 548-550 .  Abstract ( )   PDF (115KB) ( )   The gelatinization temperature (GT) character of rice grains was investigated during grain filling period starting from the 5th day after flowering (DAF) using a differential scanning calorimetry (DSC). The results indicated that the GT characteristics were gradually formed along with the maturing of rice grains with a trend of changing from high to low then being stabilized before maturing. The onset temperature (To) was almost stabilized on the 7th DAF for the low GT variety Huangyu B’ and on the 11th for the high GT variety Ⅱ32B (no significant decreases were observed later during grain filling). The peak temperature(Tp) and conclusion temperature (Tc) of 5-DAF rice grains were significantly higher than those of the samples at later stages for both varieties. From the 7th to 25th DAF,the To and Tp of Huangyu B presented a ’decrease-increase-decrease-increase’ process,but the To and Tp differed insignificantly between 7-DAF and 25-DAF rice grains;the Tc of Ⅱ32B appeared to be similar to that of Huangyu B,but the Tp of Ⅱ32B had only a ’decrease-increase’ process,with a significant higher Tp for 7-DAF rice grains than 25-DAF samples. These results suggest that high and low GT varieties might have a different formation process for the GT characteristic,and hence the GT should be regulated differently in rice production.

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Effects of Nitrogen and Potassium on Starch Content and Activities of Starch Synthase in Grains of Hybrid Rice B You 827 ZHANG Ling,XIE Chong-hua,LI Wei,YANG Guo-tao 2008, 22(5): 551-554 .  Abstract ( )   PDF (2264KB) ( )   To study the effects of nitrogen and potassium application on the amylose content,total starch content and the activities of starch synthase in rice grain during grain filling,a two-factor pot experiment was conducted using a hybrid rice combination B You 827 as material. In addition,the effects of nitrogen and potassium on the grain starch accumulation and the changes in starch synthase activities and their relationships during grain filling were further investigated. The amylose content of rice grain increased within 20 days after flowering,and then decreased. Both the changes in soluble starch synthase (SSS) and granule-bound starch synthase (GBSS) activities showed a single-peak curve. The activity of SSS reached the peak on the 12th day after flowering,and then drastically decreased. However,the activity of GBSS peaked on the 15th day after flowering,while the amylose content of rice grain was almost at the highest this time. Moreover,the activities of SSS,GBSS and amylose content...更多 were significantly positively correlated at middle and late grain-filling stages.Nitrogen fertilizer application enhanced SSS and GBSS activities. Potassium fertilizer application played the same role at the early growth stage,on the contrary,it reduced the activities of the two enzymes at the late growth stage. Nitrogen fertilizer and potassium fertilizer application both promoted the starch accumulation,but too much nitrogen fertilizer had a negative effect on the starch accumulation. The optimum application rates of nitrogen and potassium fertilizers were 90 kg/hm2 (N) and 180 kg/hm2(K2O) for B You 827,respectively.

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Measurement of Rice Leaf Chlorophyll and Seed Nitrogen Contents by Using Multi-Spectral Imagine ZHANG Hao,YAO Xu-guo,ZHANG Xiao-bin,ZHU Li-li,YE Shao-ting,ZHENG Ke-feng,HU Wei-qun 2008, 22(5): 555-558 .  Abstract ( )   PDF (2828KB) ( )   To determine rice leaf chlorophyll and seed nitrogen contents,a multi-spectral sensor which assesses the biochemical content of rice by means of gray values sensed using three channels (green,red,near-infrared) of the multi-spectral camera was used. The results showed that there were extremely significant correlations between the chlorophyll a content,chlorophyll b content in leaves and the gray values of green channel,near-infrared channel respectively and significant correlation between the chlorophyll (a+b) content in leaves and the gray values of green channel,near-infrared channel. Similarly,there was a significant correlation between the seed nitrogen content and the gray values of green channel,near-infrared channel and normalized difference vegetation index. Moreover,regression equations between gray values of multi-spectral imagine and leaf chlorophyll content or seed nitrogen content were verified with 21 samples and the relative error of 7 models ranged from 9.36% to 15.7%. ...更多Thus,the rapid,accurate and non-destructive estimations of leaf chlorophyll and seed nitrogen contents were realized.