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10 May 2006, Volume 20 Issue 3 Previous Issue    Next Issue
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研究报告
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研究报告

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Agrobacterium tumefaciens-Mediated Transformation of Magnaporthe grisea and Identification of Pathogenicity Defective Mutant LIU Peng-juan ,WANG Zheng-yi ,WANG Qiu-hua ,LI De-bao 2006, 20(3): 231-237 .  Abstract ( )   PDF (643KB) ( )   Based on the construction of two binary vectors containing hygromycin B, the use of Agrobacterium tumefaciens-mediated transformation as a successful method for insertional mutagenesis in rice blast fungus Magnaporthe grisea was reported. A library including more than 4000 transformants with a high transformation efficiency of over 300 hygromycin B resistant transformants per 1×106 conidia of M. grisea was generated. All of the hygromycin B resistant transformants tested were mitotically stable after several subcultures onto complete medium without hygromycin. Genomic Southern blot analysis showed that about two thirds of the transformants were single T-DNA insertional events. Through testing pathogenicity of mutational transformants by a rapid barley leaf assay method, an interesting mutant, A1-412, which was completely nonpathogenic to both barley and rice and also lost the ability to undergo infectious growth through abraded leaves was identified. Phenotypic analysis showed that the mutant A1-412 was significantly reduced in conidiation only accounting for 7% conidia of the wild type strain, and was unable to form appressorium on hydrophobic surfaces and its germination was slightly delayed. Southern blot analysis showed that T-DNA inserted into the A1-412 genome was single copy. These data suggest that an important biological process blocked in A1-412 was likely to be due to the insertion of T-DNA and the subsequent disruption of gene function.

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Cloning and Expression Analysis of a NADPH Oxidoreductase-Like Gene from Rice CHEN Jing ,JIANG Hua ,WAN Jia ,GAO Xiao-ling ,WANG Ping-rong ,XI Jiang ,XU Zheng-jun 2006, 20(3): 238-242 .  Abstract ( )   PDF (708KB) ( )   By using a fluorescent differential display method, the mRNA expression difference in rice leaves and roots under drought stress and normal conditions was compared. One positive fragment was isolated by combining the H. A. Yellow-PAGE (containing 0.1% H. A. Yellow) separation with macroarray screening methods. The gene has 96% identity to the Arabidopsis thaliana NADPH oxidoreductase gene. The cDNA was 1423 bp in size, including a complete open reading frame of 1048 bp encoding a protein with 345 amino acid residues. The gene expression level was higher under drought stress than that under normal conditions. The possible role of NADPH oxidoreductase-like gene under drought stress was discussed.

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Expression of Recombinant Phytase in Transgenic Rice LI Qian-feng ,LIU Qiao-quan ,ZHANG Da-jiang ,WANG Hong-mei ,YU Heng-xiu ,GU Ming-hong ,YAO Quan-hong 2006, 20(3): 243-247 .  Abstract ( )   PDF (243KB) ( )   For improving inorganic phosphorus use efficiency by expression of phytase in transgenic rice, a plant expression vector, containing the recombinant phytase gene driven by the maize ubiquitin (Ubi) promoter, was constructed, and was introduced into rice via Agrobacterium-mediated transformation, by using the rice immature embryo-derived callus as the explants. A total of 15 independent transgenic lines were regenerated, and the results of PCR and Southern blot analyses showed that the target gene had been integrated into the genome of transgenic rice. RT-PCR analysis of the total RNAs extracted from the immature seeds of several transgenic lines showed that the introduced phytase gene could be normally expressed. The result of measurement of the inorganic phosphorus level implied that the inorganic phosphorus content was significantly higher in the mature seeds of several primary transformants and the leaves of their progeny than that of the untransformed control.

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Identifying QTLs for Thermo-Tolerance of Amylose Content and Gel Consistency in Rice ZHU Chang-lan ,JIANG Ling ,ZHANG Wen-wei ,WANG Chun-ming ,ZHAI Hu-qu ,WAN Jian-min 2006, 20(3): 248-252 .  Abstract ( )   PDF (106KB) ( )   A mapping population of 98 backcross inbred lines (BILs) derived from a backcross, Nipponbare/Kasalath//Nipponbare, was used to identify the quantitative trait loci(QTL) conferring the thermo-tolerance of amylose content and gel consistency in rice by mixed linear model approaches. A total of nine QTLs including three QTLs for thermo-tolerance of amylose content and six QTLs for thermo-tolerance of gel consistency were detected in Nanchang and Nanjing, respectively. Three QTLs for these two traits were common in the two experimental locations. The same region as Wx locus on chromosome 6 and interval of G1073-R727 on chromosome 8 were important regions for the thermo-tolerance of amylose content and gel consistency respectively.

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Identification of QTL Associated with Pre-Harvest Sprouting Traits in Rice CHEN Hai-sheng ,TAO Long-xing ,WANG Xi ,HUANG Xiao-lin ,ZHUANG Jie-yun ,ZHENG Kang-le 2006, 20(3): 253-258 .  Abstract ( )   PDF (77KB) ( )   A recombinant inbred line(RIL) population including 305 lines, derived from a cross between indica rice(Oryza sativa L.) Zhong 156 and Gumei 2 was used to detect quantitative trait loci(QTLs) conferring pre-harvest sprouting. Three QTLs controlling panicle sprouting index (PSI) were detected on chromosomes 2, 9 and 11, three QTLs controlling pre- harvest sprouting speed (PDS) on chromosomes 1, 3 and 6, three QTLs for panicle sprouting rate by panicle (PSRp, percentage of panicles with 3 sprouting grains) on chromosomes 1, 9 and 10, and two QTLs conferring panicle sprouting rate by grain (PSRg, percentage of sprouting grains) on chromosomes 9 and 11, respectively. Meanwhile, nine pairs of epistatic loci affecting PSI, PDS, and PSRg were also detected (three pairs for each trait).

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QTL Analysis for Heading Date of Rice under Free Air CO2 Enrichment Conditions FAN Gui-zhi ,LI Jun-ying ,WANG Chun-ming ,XIE Hui ,XU Chang-liang ,ZHU Jian-guo ,WAN Jian-min ,CAI Qing-sheng 2006, 20(3): 259-264 .  Abstract ( )   PDF (99KB) ( )   A mapping population consisting of 65 chromosome segment substitution lines(CSSLs) was used to detect quantitative trait loci (QTL) for heading date of rice !(Oryza sativa L .) under the ambient atmosphere CO2 concentration (Ambient) and free air CO2 enrichment (FACE, ambient + 200 μmol/mol) conditions. Both positive and negative responses to elevated CO2 at heading date of CSSLs were found. Among them, two CSSLs, AI46 (advanced 11 days) and AI63 (delayed 6 days), were the most sensitive to elevated CO2 in different directions. A total of 9 QTLs for heading date were detected on chromosomes 3, 4, 6, 7, 8, 10 and 11 under the FACE and Ambient. Of them, qHD6-4 and qHD8-4 were simultaneously detected under both the FACE and Ambient, but the percentage of variation explained under the FACE was much higher than that under the Ambient, in addition, two QTLs, qHD3 A-3 and qHD11 A-7 were only detected under Ambient, and three QTLs, qHD4 F-4 , qHD10 F-4 and qHD11 F-4 only under FACE, suggesting that the genes affecting heading date were sensitive to atmosphere CO2 concentration.

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Ecological Difference and Correlation Among Cold Tolerance Traits at the Booting Stage for Core Collection of Rice Landrace in Yunnan, China ZENG Ya-wen ,LI Shen-chong ,PU Xiao-ying ,DU Juan ,YANG Shu-ming ,LIU Kun ,GUI Min ,ZHANG Hao 2006, 20(3): 265-271 .  Abstract ( )   PDF (137KB) ( )   Some cold tolerance traits at the booting stage were evaluated based on 548 accessions core collection of rice landrace in Yunnan under natural low temperature (18℃, cold damage) and greenhouse (23℃). All the morphological traits of core collection were closely related to cold tolerance traits at the booting stage under cold damage conditions, with higher significant correlation coefficients(≥0.549 ** ) between seed setting rate and eight cold tolerance index traits including filled grain number per panicle, peduncle length, unfilled grain number per panicle, length of the node under panicle, anther length, anther volume, and first to second node length. On the contrary, there were only significant correlation (r>0.6) between seed setting rate and filled grain number per panicle, unfilled grain number per panicle, and low correlation (≤0.292 ** ) between other traits and seed setting rate under greenhouse. There was a similar changing trend among five rice ecological regions based on five cold tolerance index traits, i.e. filled grain number per panicle, anther volume, length of the node under panicle, peduncle length and first to second node length. For 16 prefectures or cities in Yunnan, these differences were closely associated not only with plant height, length of the node under panicle, peduncle length and first to second node length, but also with the climate and ecological difference.On the contrary, there was no relationship in cold tolerance traits among rice ecological regions or prefectures under greenhouse conditions except for filled grain number per panicle and unfilled grain number per panicle.

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Genetic Analysis of Some Traits Related to Yield in japonica Rice Landrace from Taihu Lake Region LI Yu-sheng ,WANG Zhou-fei ,TANG Hai-juan ,GUAN Rong-zhan ,ZHANG Hong-sheng 2006, 20(3): 272-276 .  Abstract ( )   PDF (79KB) ( )   Three crosses derived from parents with distinctly different panicle traits, including Datoudao × Daichangqing(crossⅠ), Laolaihong × Yanjing 2(crossⅡ) and Daichangqing ×Shanghaiqing(cross Ⅲ), and their derived generations, were evaluated to analyze the genetics of yield-related traits of japonica rice landrace from Taihu Lake Region by the method of major gene plus polygene mixed inheritance model. The optimum model for total grain number per panicle in crossⅠ was one major gene plus additive-dominant polygene mixed inheritance model, while that for crossesⅡ and Ⅲ was one complete dominant major gene plus polygene mixed inheritance model. The optimum models for effective panicle number per plant in crossesⅡand Ⅲ were one major gene plus polygene, while that in cross I was two major genes. The genetic models for 1000-grain weight in crossesⅡandⅠ were two major genes plus polygene mixed inheritance model, and that in cross Ⅲ was one major gene plus polygene. The optimum model for filled grain number per panicle was two major genes model without polygene. It was suggested that segregation analysis of quantitative traits among multiple generations of P 1 , P 2 , F 1 , B 1 , B 2 and F 2 offered a higher accuracy and could identify polygene than that of single generation. Based on the genetic information provided by joint analysis of multiple generations, breeding strategies for different crosses and traits were discussed.

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Caryopsis Development and Substance Accumulation of Transgenic Rice with Antisense Wx Gene CHEN Gang ,WANG Zhong ,LIU Qiao-quan ,XIONG Fei ,GU Yun-jie ,GU Guo-jun 2006, 20(3): 277-282 .  Abstract ( )   PDF (182KB) ( )   The development and substance accumulation of rice caryopsis were studied by using the transgenic japonica and indica rice lines with antisense Wx gene. The weights of caryopses in the transgenic rice were lower than those of the non-transgenic ones, and the reduction of weight was significantly correlated with the degree of reduction in amylose content. In the caryopsis of the transgenic rice, the number of endosperm cells was less, but the proliferation speed was obviously higher compared with non-transgenic ones during the first six days after flowering (DAF). During the first nine DAF, the content of soluble sugar in the caryopsis of the transgenic rice was less than that in non-transgenic ones, but it was reversed after 9 DAF. With the decrease of amylose content in the caryopsis of the transgenic rice, the total starch content also declined while the amylopectin content increased accordingly, so the composition of starch in caryopsis was changed, but it did not affect the accumulation of protein in the caryopsis of the transgenic rice.

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Structure of Mature Embryo Sac and Its Abnormal Phenomena in Autotetraploid Rice GUO Hai-bin ,LIU Xiang-dong ,LU Yong-gen ,FENG Jiu-huan 2006, 20(3): 283-289 .  Abstract ( )   PDF (1518KB) ( )   The structure of mature embryo sacs of 13 pieces of autotetraploid rice, including indica, japonica and javanica, was studied by using the techniques of whole-mount stain-clearing laser scanning confocal microscopy(WCLSM). The majority of ovaries with normal polygonum embryo sac were found in each autotetraploid rice. Some ovaries in each were charactered by abnormal embryo sac. Six types of abnormal embryo sacs were observed, which included: (1) the embryo sac with no female germ unit; (2) the embryo sac with polar nuclei in abnormal position or number; (3) embryo sac degeneration; (4) the embryo sac without egg apparatus; (5) small embryo sac in size; (6) double set of embryo sac. The percentage of abnormal embryo sac in japonica, being 25.66% in average, was higher than that in indica, 19.34% in average. The percentage of each kind of abnormal embryo sac was significantly different in each variety, suggesting that the abnormal phenomena were related possibly to the genotype of variety.

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Formula about Basic Population under Scattered-Planting with Dry-Raised Seedling in Plastic Trays for Double-Season Rice PAN Xiao-hua,CHEN Xiao-rong ,YANG Fu-sun 2006, 20(3): 290-294 .  Abstract ( )   PDF (37KB) ( )   The emergence of the tillers and the formation of the panicles during the seedling and field periods under scattered-planting with seedling dry-raised in plastic trays (DPT) in double-season rice were investigated. It was found that there was not only asynchronous tillers, but also great difference in the percentage of the available synchronously tillers with that of the seedlings raised in nursery beds under moist conditions (WB). Hereby, the traditional formula about basic population of rice planting was improved and a formula for basic population under scattered-planting with DPT in double-season rice was drawn up. For early rice, it was X=Y/{(1+t 1 r 1 ) +(N-n-SN)Rr 2 +(SN-3-t 1 )R 2 r 5 }; for late rice, X=Y/{(1+t 1 r 1 ) +(N-n-SN)Rr 2 +(N-n-SN-3)Rr 2 R 1 r 3 +(SN-3-t 1 )R 2 r 5 }. Where, X represents reasonable basic population; Y, no. of fitting panicles per unit area; t 1 , number of total tillers per plant; r 1 , percentage of the available total tillers; N, total number of leaves of the main culm; n, total number of stretched-out nodes of the main culm; SN, seedling leaf ages at scattering; R, percentage of the emerged primary tillers in available node-position; r 2 , percentage of the available primary tillers; R 1 , percentage of the emerged secondary tillers(except the secondary tillers of the seedlings); r 3 , percentage of the available secondary tillers; R 2 , percentage of the asynchronous emerged tillers after scattering; r 5 , percentage of the available asychronous tillers after scattering.

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Effects of 1,2,4-Trichlorobenzene and Naphthalene on Grain Yield and Quality of Rice WANG Ze-gang ,WAN Ding-zhen ,YANG Ya-chun ,GE Cai-lin ,MA Fei ,YANG Jian-chang 2006, 20(3): 295-300 .  Abstract ( )   PDF (104KB) ( )   With rice varieties Shanyou 63 (indica hybrid) and Wuyujing 7 (japonica) as materials, the effects of 1,2,4-trichlorobenzene (TCB) and naphthalene (NAP) on grain yield, yield components, and grain quality were studied and regulation strategies to reduce the residue in rice grain were proposed. The survival percentage of rice seedlings was significantly reduced by TCB, which was the main reason for the decrease of the grain yield, while NAP had little effect. Both TCB and NAP delayed the heading date of rice. Among the yield components, decreases in number of panicles per pot and seed setting rate were two main reasons for the yield reduction. Both of the organic pollutants affected the grain quality, and their effects on chalkiness were the greatest, the next was on milled rice rate, head rice rate, protein content and amylose content in order, and the both pollutants had little effect on brown rice rate of the two tested varieties. The NAP content was as ten times as TCB content in grains, indicating that the bioavailability of NAP was higher than that of TCB. Shanyou 63 accumulated more organic pollutants than Wuyunjing 7. Application of organic and inorganic fertilizer could reduce the harm of TCB and NAP, and increase grain yield. The results suggested that in sewage water irrigation practice, the supply of irrigation water in good quality is necessary for higher survival percentage of seedlings after transplanting, and controlling TCB, especially NAP content, and adoption of reasonable cultivation strategies are very important for high grain yield and food safety.

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Source-Sink Characteristics of Intersubspecific F1 in Rice LI Ji-hang ,XIANG Xun-chao ,HE Li-bin ,LI Ping 2006, 20(3): 301-305 .  Abstract ( )   PDF (89KB) ( )   Three indica restorer lines Mianhui 725, Shuhui 527, Shuhui 881 and an American rice variety Lemont and a javanica rice Xiangdali were crossed with a Japanese japonica rice Kitaake, and five intersubspecific hybrids derived from the parents with different genetic background were made. The net photosynthetic rate (Pn) in leaves of the five combinations were significantly higher than that of their parents or one of them under high photo flux density; the performance of the combinations was better than their corresponding parents on the apparent quantum yield, carboxylation efficiency and CO 2 compensation point. Photosynthetic ability of the five F 1 performed differently with their genetic differences and the typical intersubspecific hybrids Mianhui 725/Kitaake, Shuhui 527/Kitaake were better than the others on the aspect. The five F1 exhibited different heterosis on agronomic traits and Shuhui 881/Kitaake showed the largest sink size, followed by Mianhui 725/Kitaake, Shuhui 527/Kitaake, Lemont/Kitaake and Xiangdali/Kitaake in order.The potential yield of indica/japonica hybrids was consistent with the performance of Pn in leaves. But the superiority of indica /japonica on sink size had not turned into the superiority of yield because of poor grain filling. So the coordination of their genomes and appropriate genetic distance should be paid attention to for achieving super high yield.

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Concentrations and Accumulation of Cadmium in Different Organs of Hybrid Rice ZHAO Bu-hong ,ZHANG Hong-xi ,XI Ling-lin ,ZHU Qing-sen ,YANG Jian-chang 2006, 20(3): 306-312 .  Abstract ( )   PDF (50KB) ( )   Six hybrid rice combinations including Liangyoupeijiu, Yangliangyou 6, 103S/Zhengjing 2, Fengyouxiangzhan, Kyou 818 and Shanyou 63 were used in the pot experiments. Cadmium(Cd)was added into pots before rice transplanting and the concentration of Cd in pot soil was 100 mg/kg. The concentration and accumulation of Cd in different plant organs were measured. Compared with the control (no Cd was added), Cd addition significantly reduced the grain yield of Liangyoupeijiu and 103S/Zhengjing 2 mainly due to the reduction of spikelet number per panicle. There was no significant difference in the grain yield between the control and the Cd treatment for the other hybrid combinations. Significant differences in uptake and distribution of Cd were observed among the six combinations, with Shanyou 63 having the highest and Kyou 818 the lowest Cd accumulation in plants. Concentration or accumulation of Cd in various plant organs was in the order of root>culm and sheath >leaf, and Cd concentration in a grain was in the order of bran >hull>milled rice. Cd in milled rice was about 30% of total amount of Cd accumulated in grain. The concentration and accumulation of Cd in the same organ at the heading and maturity stages were positively and significantly correlated, but the correlation was not significant between different organs. Among the six tested hybrids, Yangliangyou 6 contained the highest, and Kyou 818 the lowest Cd concentration in milled rice. The reasons for variations of Cd concentration and accumulation in plants among the hybrids were also discussed.

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Effects of Nitrogen Form and Water Stress Interaction on Photosynthesis,Utilization of Water and Nitrogen of Rice Plants at the Tillering Stage ZHOU Yi ,GUO Shi-wei ,SONG Na ,ZHANG Lei ,SHEN Qi-rong 2006, 20(3): 313-318 .  Abstract ( )   PDF (89KB) ( )   By using the method of nutrient solution culture and simulated water stress (by adding PEG6000), the effects of different nitrogen forms (NO3-, NH4+, and the ratio of NO3- to NH4+ is 50∶50) and water stress interaction on nitrogen use efficiency and the characteristics of nitrogen consumption of rice plants at the tillering stage were studied. Under non-water stress, the increased biomass of rice plants under the mixed supply of nitrate and ammonium was higher than that under the other two sole nitrogen supply. However, under water stress, the increased biomass of rice plants under sole ammonium supply was the highest. The photosynthetic rate, nitrogen use efficiency and water use efficiency of rice plants supplied with sole ammonium were higher than those of the other two treatments under the two water regimes. Furthermore, under the mixture supply of nitrate and ammonium, nitrate consumption was higher than ammonium consumption of rice plants at the tillering stage regardless of water regimes.

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Simulation and Validation of Rice Potential Growth Process in Zhejiang by Utilizing WOFOST Model XIE Wen-xia ,YAN Li-jiao ,WANG Guang-huo 2006, 20(3): 319-323 .  Abstract ( )   PDF (115KB) ( )   A crop growth model of WOFOST was calibrated and validated through rice field experiments conducted from 2001 to 2004 in Jinhua and Hangzhou, Zhejiang Province. For the late rice variety Xiushui 11 and hybrid rice Xieyou 46, the model was calibrated to obtain parameter values using the experimental data of years 2001 and 2002, then the parameters were validated by the data of 2003. For single cropping hybrid rice Liangyoupeijiu, data of 2004 and 2003 were used for calibration and validation, respectively. WOFOST model was good in simulating rice potential growth process in Zhejiang. It can be used to analyze the process of rice growth and yield potential. The potential yield obtained from WOFOST was about 8100 kg/hm2 for late rice and 9300 kg/hm 2 for single cropping rice. The current average yield is only about 78% (late rice) and 70% (single cropping rice) of their potential yields. The results also showed that the current practice of management at the middle and late growth stages of rice should be reexamined and improved to reach optimal rice growth.

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Identification and Detection of Two Types of Opportunistic Human Bacterial Pathogens from Rice HAO Xiao-juan ,XIE Guan-lin ,LU Yi-lin ,LUO Yuan-chan ,ZHANG Li-xin ,LUO Jin-yan ,ZHAO Li-han ,LIU Shao-ying 2006, 20(3): 324-328 .  Abstract ( )   PDF (81KB) ( )   Burkholderia cepacia (Bc) and Pseudomonas aeruginosa (Pa) are both biocontrol agents in agriculture and opportunistic human pathogens in hospitals. It’s the key point to understand their characteristics and distribution in rice so as to effectively manage and utilize them. In the past nine years, the two opportunistic human pathogens were identified and detected from 631 rice seed samples and 117 rice plant samples from plain, highland and mountain of rice growing areas in China. Bc and Pa could be primarily differentiated by common bacteriological characteristics and pathogenicity tests and identified into species level by Biolog and FAME. However, the genotypes of Bc still could not be distinguished. Bc and Pa mainly existed in rice roots. The distribution of Bc and Pa in the rice growing areas was the highest in the plain, being 6.1% and 16.1%, and the lowest in the mountain, being 1.0% and 7.8%, respectively.

实验技术

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A Rapid DNA Miniprep Extraction Method for Large-Scale Rice Mutant Screening QIU Fu-lin ,WANG He-he ,CHEN Jie ,ZHUANG Jie-yun ,Hei LEUNG ,CHENG Shi-hua ,WU Jian-li 2006, 20(3): 329-332 .  Abstract ( )   PDF (388KB) ( )   A high throughput rice DNA mini-preparation method was developed. The method is suitable for large-scale mutant bank screening as well as large mapping populations with characteristics of maintaining relatively high level of DNA purity and concentration. The extracted DNA was tested and suitable for regular PCR amplification (SSR) and TILLING(targeting induced local lesion in genome) analysis.

研究简报

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Ecological Difference in Ability for Activating Unavailable Soil Phosphorus in Core Collection of Yunnan Rice ZHANG Hao ,ZENG Ya-wen ,DU Juan ,PU Xiao-ying ,YANG Shu-ming ,GUI Min 2006, 20(3): 333-336 .  Abstract ( )   PDF (35KB) ( )   A 608-accession core collection (including 548 landrace accessions and 60 improved varieties) from 5 rice cropping regions and 16 prefectures in Yunnan Province was evaluated in P-deficient (available P: 0.02 mg/kg) and P-sufficient (available P: 80 mg/kg) acid red soil. Rice landraces from Northwest Yunnan cold highland japonica rice region and Northeast Yunnan highland japonica rice region had a stronger ability of activating unavailable soil phosphorus, and those from South Yunnan single/double season rice region and South marginal paddy-upland rice region were strong and greatly different with the diversiform distribution; those from Central Yunnan single season japonica-indica region were relatively weak in the ability. As for prefecture, rice landraces from Wenshan, Dehong, Lincang, Lijiang and Zhaotong had the strongest ability of activating unavailable soil phosphorus, and those from Xishuangbanna, Nujiang, Chuxiong, Yuxi and Qujing were next, but those from Kunming, Dali, Honghe, Baoshan and Diqing were the weakest. The ability of activating unavailable soil phosphorus of rice landraces was stronger than that of the improved varieties.

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Biocontrol of Rice Sheath Blight by Helminthosporium gramineum Rabenh f. sp. echinochloae and Its Metabolite Ophiobolin A DUAN Gui-fang ,ZHANG Jian-ping ,ZHOU Yong-jun ,YU Liu-qing ,YUAN Qin-sheng 2006, 20(3): 337-339 .  Abstract ( )   PDF (78KB) ( )   Helminthosporium gramineum Rabenh f. sp.echinochloae (HGE), a promising fungus for controlling barnyardgrass, was evaluated for biocontrol of sheath blight in rice caused by Rhizoctonia solani Kuhn. On a PDA plate, the antagonistic result showed that the inhibitory activity of HGE strain against the mycelial growth of R. solani was 83.5%. Culture filtrate of HGE strain showed strong inhibitory activity against R. solani with a relative inhibitory rate of 84.1% at the 5-fold diluted filtrate. On PDA plate, mycelial growth of R. solani was completely inhibited by crude toxins (ethyl acetate extract of culture filtrate and mycelia of HGE) produced by HGE strain at 200 μg/mL. One compound with high inhibitory activity against the growth of R. solani was isolated from the extracts of culture filtrate and mycelia of HGE. The bioactive compound was identified as Ophiobolin A through detailed analysis of NMR and MS data of the compound and the comparison with the reported spectra data. The relative inhibitory rate of Ophiobolin A against R. solani was 100% and 70.2% at 25 μg/mL and 1 μg/mL, respectively. These results indicated that HGE strain and its metabolite Ophiobolin A could be potentially developed as a natural fungicide for the control of rice sheath blight.

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Deterrent Activity of Extracts from Several Species of Wild Rice to Panonychus citri and Aphis citricola in Associated with Esterase Isoenzyme in Pests WAN Shu-qing ,LIU Xiang-fa ,FENG Guo-zhong ,PAN Da-jian 2006, 20(3): 340-342 .  Abstract ( )   PDF (113KB) ( )   Six species of wild rice and their different ecotypes including Oryza grandiglumis (E6-1, E6-3/6-4), O.minuta (E13-9, E13-13), O. officinalis (E15-8, E15-13), O.punctata(E16-1, E16-3, E16-13), O.granulata(E7-4), O.latifolia(101392, E9-1, E9-10) were extracted with methanol. Deterrent activity of the extracts to Aphis citricola and Panonychus citri was tested. The extract from the wild rice O.officinalis E15-8 was better than the others in the deterrent activity to the two pests. The deterrent rates of E15-8 to Panonychus citri and Aphis citricola were 83.26% and 87.86% in 24 h and 87.95% and 82.43% in 48 h at 5×10 4 μg/mL concentration, respectively. The methanol extracts from O. officinalis E15-8 had the effect of inhibition to the esterase of the two pests.