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10 May 2011, Volume 25 Issue 3 Previous Issue    Next Issue
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Reviews and Special Topics
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Reviews and Special Topics

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Highlights and Difficulties in Hybrid Rice Breeding in China LU Zuo-mei 2011, 25(3): 231-235 .  DOI: 10.3969/j.issn.1001-7216.2011.03.001 Abstract ( )   PDF (391KB) ( )   After forty years of development, China has made a series of achievements in hybrid rice breeding, such as threeline hybrid rice, twoline hybrid rice and seed production technology systems. Four highlights of hybrid rice breeding research were summarized, and four difficulties were analysed. The importance of strengthening basic theoretical research and training advanced breeding talents in hybrid rice breeding in China was described.

Research Letter

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Responses of Active Methyl Cycle and Transfer Genes to Drought Stress in Rice Leaves ZHANG Xiao-li,LIU Min,SHANG Qi,GE Cai-lin* 2011, 25(3): 236-242 .  DOI: 10.3969/j.issn.1001-7216.2011.03.002 Abstract ( )   PDF (746KB) ( )   The expressions of active methyl cycle and transfer genes in rice leaves of Zhonghan 3, Shanyou 63 and Aizaizhan were investigated by using genechip and mRNA differential display under 10% PEG6000 simulated drought stress. The results showed that the methyl cycle pathway was activated in leaves of Zhonghan 3 and Shanyou 63, but inhibited in leaves of Aizizhan under drought stress. The expression of methyltransferase genes was induced by drought stress in Zhonghan 3 leaves, especially for the transcription of methylation modification gene of Rubisco, which could reduce the degration of Rubisco protein. Drought stress inhibited the gene transcription of DNA methyltransferse and histone methyltransferse in Aizaizhan leaves. The results confirmed that the active methyl cycle and transfer genes were involved in rice drought resistance.

研究报告

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A Simple Selection Method for Effective Screening Concentration of NaCl for Generating Marker-Free Salt-Tolerant Transgenic Rice ZHAO Yan,LUO Yuan-yuan,ZHANG Xiao-li,GUO Long-biao,QIAN Qian,DONG Yu-ran 2011, 25(3): 243-248 .  DOI: 10.3969/j.issn.1001-7216.2011.03.003 Abstract ( )   PDF (538KB) ( )   The relevance between inhibition rates of rice seed germination and mature embryo callus growth by NaCl at different concentrations was studied by using four japonica rice cultivars (Nipponbare, Xiushui 11, Wuyunjing 7 and Zhonghua 11) as materials. Results showed that there was a significant positive correlation between the inhibition rates of rice seed germination and mature embryo callus growth under salt stress (on NB medium containting NaCl). The NaCl concentration at which the inhibition rate of rice seed germination reached about 50% was concordant with the concentration at which the inhibition rate of mature embryo callus growth reached about 80%. These could be used as important references to determine the effective concentrations of NaCl for screening of transformed cells in rice transformation with salttolerant gene. The effective NaCl concentrations were 200 mmol/L for Nipponbare, Wuyunjing 7 and Zhonghua 11 and 250 mmol/L for Xiushui 11. Transgenic rice plants were successfully obtained with the NaCl concentration as screening standard in the transformation of Nipponbare and Xiushui 11 with salttolerant gene BADH. The transformation frequency of Nipponbare and Xiushui 11 were 38.9% and 320%, respectively. The method that the suitable concentration of NaCl for screening in rice transformation was determined by testing the inhibition rate of rice seed germination, it is free of resistance marker genes and easy to operate with short experimental duration.

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Analysis of Special DNA Methylated Sites Between Haploid of TwinSeedling and Its Hybrids in Rice WU Shao-hua,XUE Jing-jing,ZHANG Hong-yu,XU Pei-zhou,WU Xian-jun* 2011, 25(3): 249-255 .  DOI: 10.3969/j.issn.1001-7216.2011.03.004 Abstract ( )   PDF (1231KB) ( )   The DNA cytosine methylation mutation at the 5′CpCpGpG sites of the haploid of SARII628, and its hybrids with Shuhui 527, Shuhui 363 were analyzed by employing the MSAP (methylation sensitive amplification polyphisim) method. A total of 765 DNA methylated sites were detected and the methylation level of hybrids was lower than that of the parents. Meanwhile, different bands between hybrids and parents were analyzed and two types of methylated sites were detected, of which one inherited from the haploid, and the other didn′t. The biological functions of genes related to methylated sites involved in cell structure, metabolize and stress reaction. Therefore, DNA methylated modifications may be involved in the regulation of related genes, playing an important role in plant growth, development and envolution.

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Identification and Fine Mapping of a Spotted and Yellow Leaf Mutant in Rice WU Chao,FU Ya-ping,HU Guo-cheng,SI Hua-min,LIU Xu-ri,SUN Zong-xiu,CHENG Shi-hua,LIU Wen-zhen 2011, 25(3): 256-260 .  DOI: 10.3969/j.issn.1001-7216.2011.03.005 Abstract ( )   PDF (790KB) ( )   A spotted and yellow leaf mutant was isolated from more than 15 000 transgenic rice lines. The mutant was featured by lesionmimic spots during the whole growth stage as well as leaf etiolation one by one from lower part to upper part. Genetic analysis revealed that the mutation was controlled by a single recessive gene, which was designated as syl1 (spotted and yellow leaves 1). PCR analysis and hygromycin resistance assay showed that the mutation was not caused by TDNA insertion. To isolate the syl1 gene, a positional cloning strategy was employed. The approximate map position of the syl1 gene was determined by SSR markers from published data, and then nine new InDel markers were developed. A highresolution physical map of the chromosomal region around the syl1 gene was made using F2 and F3 populations consisting of 1328 mutant individuals. Finally, the syl1 gene was located within 102 kb region between InDel markers WL32 and WL35 within the BAC clone OSJNBa0002O20 on chromosome 12.

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Genetic Analysis and Molecular Mapping of a Rice Rumpled and Twisted Leaf Mutant (rtl1) FANG Yun-xia,SONG Xiu-juan,PENG You-lin,DONG Guo-jun,GUO Long-biao,ZENG Da-li,ZHANG Guang-heng,YAN Hong-lan,QIAN Qian 2011, 25(3): 261-266 .  DOI: 10.3969/j.issn.1001-7216.2011.03.006 Abstract ( )   PDF (567KB) ( )   A rumpled and twisted leaf 1 (rtl1) mutant was derived from japonica cultivar Nipponbare by ethyl methane sulfonate (EMS) treatment, which was characterized by rumpled and twisted leaf at the seedling stage. The F2 population was constructed by crossing with indica cultivars TN1 and Zhefu 802, respectively. Genetic analysis confirmed that it was controlled by one recessive nuclear gene. The closely linked SSR marker RM1155 was obtained through bulked segregant analysis．Subsequently, new STS markers were developed using published rice genome sequence, and the gene was finally located between the STS marker T1591 and SSR marker RM1359 with the distances of 0.48 and 0.96 cM, respectively. This will contribute to cloning of the target gene in further studies.

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Genetic Analysis of Heading Date of Japonica Rice Cultivars in Southwest China ZHOU Zhen-ling,#,WEI Xiang-jin,JIANG Ling,LIU Kai,XU Da-yong,ZHAI Hu-qu,WAN Jian-min 2011, 25(3): 267-276 .  DOI: 10.3969/j.issn.1001-7216.2011.03.007 Abstract ( )   PDF (2559KB) ( )   Heading dates of 26 japonica rice cultivars native to Southwest China were investigated, and their basic vegetative growth(BVG), photoperiodsensitivities(PS) and temperaturesensitivities(TS) were analyzed under artificially shortday and natural longday conditions in Nanjing of Jiangsu Province, China, as well as artificially high temperature and natural low temperature conditions in winter in Hainan Province, China. The results showed that the PS and TS varied with different cultivars. The BVGs of all the japonica cultivars were well situated, but differed in cultivars. Regression analysis showed a significant correlation between heading date and PS, indicating that PS was the main factor affecting heading date of japonica cultivar in Southwest China. Genetic analyses were conducted on these 26 cultivars using a set of heading date near isogenic lines as tester lines. The results showed that all these japonica cultivars carried the dominant earlyheading gene Ef1 or Ef1t, and most of these cultivars carried the dominant photoperiod sensitivity allele E1 or E1t, the PS of which was slightly weaker than E1. For the Se1 locus, these japonica cultivars mainly carried recessive photoperiod insensitivity gene Se1e. In addition, the recessive allele hd2 could repress or weaken the PS of 22 japonica cultivars by inhibiting the expression of E1 and Se1. These results indicate that the heading date genotypes determined different PS and well situated BVG in japonica rice cultivars of Southwest China. The above results would be useful for breeding and expanding new japonica cultivars with well adaptability in Southwest China.

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Mining Applicable Elite Alleles of Growth Duration, Plant Height and Productive Panicle Number per Plant by Conditional QTL Mapping in Japonica Rice JIANG Jian-hua,ZHAO Qi-bing,LIU Qiang-ming,CHEN Lan,CHEN Fu-long,QIAO Bao-jian,HONG De-lin 2011, 25(3): 277-283 .  DOI: 0.3969/j.issn.1001-7216.2011.03.008 Abstract ( )   PDF (383KB) ( )   Unconditional QTL mapping and conditional QTL mapping were conducted for growth duration (GD), plant height (PH) and produtive panicle number per plant (PN) using a recombinant inbred line (RIL) population derived from a cross between japonica rice Xiushui 79 and C Bao. The 254line RIL population was planted in two environments, Nanjing and Sihong, Jiangsu Proivince. Results showed that with predominant additive effects in all QTLs for GD, PH and PN detected by the two methods, the epistatic effects explained a small percent of phenotypic variation. No interaction was detected between additive QTL and environment, or between epistatic QTL pairs and environment. After growth duration was adjusted to an identical level, RM80160bp was detected as an applicable elite allele for PN, with an additive effect of 0.71. After produtive panicle number per plant was adjusted to an identical level, RM448240bp was detected as an applicable elite allele for GD, with an additive effect of 464. After plant height was adjusted to an identical level, RM80160bp was detected as an applicable elite allele for PN, with an additive effect of 0.62, and RM448240bp was detected as an applicable elite allele for GD, with an additive effect of 3.89. These applicable elite alleles could be used to improve target traits without influencing the other two traits.

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Effects of Straw Mulching on Dry Matter Production and Grain Yield of Double Cropping LateSeason Rice (Oryza sativa) in South China ZHANG Shui-qing,ZHONG Xu-hua,HUANG Nong-rong,LU Guo-an 2011, 25(3): 284-290 .  DOI: 10.3969/j.issn.1001-7216.2011.03.009 Abstract ( )   PDF (957KB) ( )   Two field experiments were conducted during late seasons of 2006-2007 at Baiyun Experimental Station of Guangdong Academy of Agricultural Sciences, Guangzhou, China. Tianyou 998, a hybrid rice, was arranged in split plot design experiments with straw mulching as main factor and N treatment as split factor with four replications. There were two levels of straw management and four N treatments. Straw mulching resulted in significant increase in grain yield at all N treatments. No significant differences were found in grain yield between three N treatments with the same total N input but different distribution among key growth stages. Path analysis showed that panicle number per m2 had the biggest direct effect on grain yield. Both maximum tiller number per m2 and productive tiller percentage were greater in straw mulching treatment compared to those in zerostraw mulching treatment. Straw mulching significantly improved dry matter production of rice plants. Leaf area index, chlorophyll content (SPAD value), and dry matter accumulation were significantly higher in straw mulching treatments at key growth stages. Grain yield was positively and significantly related with tiller number per plant, chlorophyll content of leaves, and dry matter production. Applying more N at early stage had no significant effect on grain yield, indicating that additional N at early stage was not necessary under straw mulching.

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Uptake and Translocation of Cadmium and Its Physiological Effects in Two Rice Cultivars Differed in Grain Cadmium Concentration LI Peng,GE Ying,WU Long-hua,SHEN Li-bo,TAN Wei-na,LUO Yong-ming 2011, 25(3): 291-296 .  DOI: 10.3969/j.issn.1001-7216.2011.03.010 Abstract ( )   PDF (396KB) ( )   A hydroponic experiment and a pot experiment were conducted to investigate Cd uptake and translocation in rice and their physiological effects at several growth stages by using two rice cultivars with different grain Cd concentrations. In the pot experiment, the grain Cd contents of low Cd rice cultivar(A16) and high Cd cultivar(A54) were 0.31 mg/kg and 0.88 mg/kg, respectively at a total soil Cd concentration of 1.57 mg/kg. Both hydroponic and pot experiments showed that A16 absorbed and translocated more Cd than A54 at the seedling stage. However, after the seedling stage, the amounts of Cd uptake and translocation by A54 were higher than those of A16. By comparing Cd accumulation in two rice cultivars at various growth stages, the highest increase in Cd accumulation was observed at seedlingelongation stage. The amount of nonprotein thiol(NPT) was not only closely related to Cd stress, but also partly controlled Cd translocation from roots to shoots, thus affecting the Cd concentration in rice grain. According to Cd and NPT contents in shoots and roots of the two rice cultivars at each growth stage, it may be speculated that the variation of grain Cd concentration was largely controlled by root uptake and translocation to shoot. Root Cd sequestration and rhizosphere soil properties may result in the differences in rice Cd absorption and translocation between the seedling stage and other stages.

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Variation in Carbohydrate and Protein Accumulation Between Spikelets at Different Positions Within a Rice Panicle During Grain Filling DONG Ming-hui,XIE Yu-lin,QIAO Zhong-ying,LIU Xiao-bin,WU Xiang-zhou,ZHAO Bu-hong,YANG Jian-chang 2011, 25(3): 297-306 .  DOI: 10.3969/j.issn.1001-7216.2011.03.011 Abstract ( )   PDF (4476KB) ( )   he accumulation dynamic of filling matter for spikelets at different positions within a rice panicle was investigated during grain filling to understand the physiological reasons for the variations of grain quality. Two rice cultivars, Yangdao 6 (indica) and Yangjing 9538(japonica), were fieldgrown, and the grain filling character and the contents of starch, soluble sugar, and protein of the spikelets at different positions were studied. There were significant differences in matter accumulation between spikelets at different positions during grain filling. The earlierflowered spikelets presented dominance over the laterflowered spikelets in initial filling rate and filling intensity. The contents and rates of starch and amylose accumulation in spikelets were consistent with the flowering sequence at the initial and medium filling stages, i.e., the earlierflowered spikelets had greater contents and rates of starch and amylose accumulation than laterflowered spikelets, but the soluble sugar content (SSC) exhibited an opposite result. The difference in SSC between the spikelets of Yangjing 9538 was greater than that of Yangdao 6, but the amylase content in spikelets at maturity was not very identical with the flowering sequence of spikelets. The change in crude protein content (CPC) showed an Sshaped curve. The CPC of earlierflowered spikelets decreased more rapidly than that of those laterflowered ones at the initial filling stage, and CPC in the spikelets on the secondary rachis branch was more than that on the primary rachis branch, but CPC in laterflowered spikelets was higher than that in earlierflowered spikelets in the whole filling period. Grain water content (GWC) of earlierflowered spikelets decreased more rapidly than that of laterflowered spikelets in the same branch at the initial and medium filling stages, especially for the first grain among the spikelets on a primary rachis branch. The results suggested that the low biological activity of laterflowered inferior spikelets may be attributed to their poor grain filling rather than carbohydrate supply.

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Study on Dynamic Integrated Prediction of Early Rice Yield YI Xue,WANG Jian-lin,SONG Ying-bo,SHUAI Xi-qiang 2011, 25(3): 307-313 .  DOI: 10.3969/j.issn.1001-7216.2011.03.012 Abstract ( )   PDF (1409KB) ( )   应用作物产量历史丰歉气象影响指数、作物气候适宜指数、作物生长模拟模型分别建立早稻产量动态预报方法，利用这3种方法分别对1996―2005年湖南早稻产量进行动态模拟预报，在分析预报误差的基础上，确定每种方法的预报权重，建立动态集成预报方法。拟合检验结果表明, 集成预报方法的丰歉趋势预报正确率、产量预报准确率都较任意单一预报方法稳定，且有一定程度提高。利用上述方法分别对2006―2008年湖南早稻产量进行预报检验，结果表明,除2006年的丰歉趋势预报因早稻收获阶段遭遇台风出现错误外，集成预报法的丰歉趋势预报正确率、产量预报准确率都较高，且好于任意单一预报方法，能够满足业务服务的要求。

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Pathogenicity of Rice Blast Fungus Magnaporthe oryzae on Brachypodium distachyon WANG Xiao-yan,WANG Jiao-yu,JIANG Hua,WANG Yan-li,ZHANG Zhen,CHAI Rong-yao,MAO Xue-qin,QIU Hai-ping,DU Xin-fa,SUN Guo-chang 2011, 25(3): 314-320 .  DOI: 10.3969/j.issn.1001-7216.2011.03.013 Abstract ( )   PDF (1073KB) ( )   An inoculation method for rice blast fungus Magnaporthe oryzae to Brachypodium distachyon was developed to investigate the infection process and symptom development in comparison with those on rice (Oryza sativa) and barley (Hordeum Vulgare). M. oryzae could infect the leaves, sheathes, stems and panicles of B. distachyon and cause blast disease. Spraying conidium suspension on either whole seedlings or leaf segments led to typical symptoms on B. distachyon. During the whole seedling inoculation, the symptoms on B. distachyon leaves developed closely resemble with rice; but the lesions on B. distachyon had better uniformity in shapes and sizes than those on rice or barley. In the leaf segments inoculation, only initiate and lowdeveloped lesions could be found on rice, while normal symptoms on B. distachyon and barley. Inoculated with lowvirulent mutants of M. oryzae, B. distachyon produced lowlevel symptoms. And the symptom level of each mutant on B. distachyon corresponded well to that on rice. In addition, typical infection processes presented on B. distachyon leaves: forming melanized appressoria, penetrating into host epiderm and then forming hyphae in epidermal cells. According to these results, B. distachyon can be used as a candidate for studying fungusplant interactions and as a probable source of disease resistance.

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Growth and Reproduction of Cnaphalocrocis medialis Fed on Improved Artificial Diet LI Chuan-ming ,#,XU Jian,#,YANG Ya-jun,QI Jian-hang,ZHENG Xu-song ,WANG Yan,LIU Qin,LU Zhong-xian 2011, 25(3): 321-325 .  DOI: 10.3969/j.issn.1001-7216.2011.03.014 Abstract ( )   PDF (607KB) ( )   The growth and reproduction of rice leaffolder, Cnaphalocrocis medialis, fed on an artificial diet were studied. The results showed that larvae were able to grow and pupate fed on the artificial diet. Durations of larva and pupa were 28.1 d and 10.1 d, respectively, 6.1 d and 1.7 d longer compared with that reared on rice leaves. Number of ovipositions were 41.6 per female, 26.2 percent higher than that fed on rice leaves. the survival rate of larva followed a descent mortalityage function, and was not significantly different from that of larva fed on rice leaves. The net reproductive rate, intrinsic rate of increase and finite rate increase of population were 17.6928, 0.0884 and 1.0942. The mean generation time and population doubling time were prolonged for 4.9 d and 1.3 d in comparison with those of larvae fed on rice leaves. The population trend index was 3.26, indicating an ascent trend of the population of Cnaphalocrocis medialis fed on artificial diet.

研究简报

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Prokaryotic Expression, Purification and Activity Assay of Neomycin Phosphotransferase Ⅱ (nptⅡ) Gene WANG Ling,LIU Lian-meng,FU Qiang,HUANG Shi-wen* 2011, 25(3): 326-330 .  DOI: 10.3969/j.issn.1001-7216.2011.03.015 Abstract ( )   PDF (594KB) ( )   Neomycin phosphotransferaseⅡ (nptⅡ) gene, cloned from a pCAMBIA1305 vector by PCR method, was inserted into a pET30a (+) vector to construct the recombinant vector pET30anptⅡ. Then the recombinant vector was transformed into an Escherichia coli strain BL21 (DE3) and the expression of the NPTⅡ protein was successfully induced by adding isopropylβDthiogalactopyranoside (IPTG). The NPTⅡ fusion protein was produced in the form of the solubility or inclusion body with molecular weight around 35 kD, and a yield of approximately 45%. The inclusion bodies were solubilized and denatured by addition of 5 mmol/L dithiothreitol (DDT) and 1% sodium lauroyl sarcosine (SKL), then renatured by dialysis. The solubilized proteins were purified by Ni2+NTA affinity chromatography at approximately 95% purity. An in vitro assay revealed that, the NPTⅡ protein can inactivate the kanamycin at concentrations up to 30 μg/mL.

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Breeding of Rice Lines with Bacterial Blight Resistance Gene Xa23 by Using MarkerAssisted Selection FAN Hong-huan,WANG Lin-you,ZHANG Li-xia,YU Xin,WANG Xi,JIN Qing-sheng,WANG Jian-jun 2011, 25(3): 331-334 .  DOI: 10.3969/j.issn.1001-7216.2011.03.016 Abstract ( )   PDF (625KB) ( )   The rice bacterial blight resistance gene Xa23, which is carried by the donor parent 18113, was introduced into the intersubspecific restorer line H705 and good grain quality restorer line H706 by crossing and molecular markerassisted selection(MAS). Seventyone and 52 homozygous lines carrying Xa23 were obtained from the 18113/H705 F3 and 18113/H706 F3 lines, respectively by PCR with EST marker C189. The bacterial blight resistance of these lines was investigated with the pathotype Ⅳ representative strain Zhe 173 by clipping method. Sixtyone and 44 lines showed the bacterial blight resistance, with the MAS accuracies of 85.92% and 84.61%, respectively. The C189 was one of the effective MAS markers for testing Xa23 gene. In addition, further research is needed to elucidate the mechanisms of higher false positive rate than theoretical exchange rate.

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Effects of High Temperature Stress on Net Photosynthetic Rate and Chlorophyll Fluorescence Parameters of Flag Leaf in Rice ZHANG Shun-tang,ZHANG Gui-lian,CHEN Li-yun ,XIAO Ying-hui 2011, 25(3): 335-338 .  DOI: 10.3969/j.issn.1001-7216.2011.03.017 Abstract ( )   PDF (1468KB) ( )   The net photosynthetic rate and chlorophyll fluorescence parameters of flag leaves were measured under high temperature by using the hightemperature tolerant line 996 and hightemperature sensitive line 4628. Rice plants were subjected to high temperature（8:00-17:00,37℃; 17:00-8:00,30℃）treatment for seven days after heading. The net photosynthetic rates of flag leaves of the two rice lines decreased dramatically under the high temperature stress, with a greater decrease in the hightemperature sensitive line 4628 than in the hightemperature tolerant line 996; less accumulation of excess excitation energy in the reaction centers did less harm to the centers and the antenna systems in 996 under high temperature stress. Accordingly, higher qP and qN in 996 helped to dissipate the excess excitation energy and protect the reaction centers from heat injury. However, in 4628, qP declined rapidly, while Ex increased as the high temperature stress persisted. This indicates that the reaction centers and antenna systems in 4628 were damaged severely under high temperature stress, which led to the lower photosynthetic rate.

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Difenoconazole Residues in Rice and Paddy System ZHANG Zhi-yong,WANG Dong-lan,ZHANG Cun-zheng,WU Chang-fu,LIU Xian-jin* 2011, 25(3): 339-342 .  DOI: 10.3969/j.issn.1001-7216.2011.03.018 Abstract ( )   PDF (682KB) ( )   To determine the safety of difenoconazole in rice and paddy system, residual dynamics in rice plant, paddy water and soil, final residual levels in brown rice, rice husk, rice stem, and paddy soil were investigated in three typical rice planting areas Changsha, Changchun and Hangzhou in China. The halflives of difenoconazole at higher dosage (1125 g/hm2, spraying for one time) in rice plant, paddy water, and paddy soil were 6.1-8.9 d, 5.3-6.2 d and 3.8-4.1 d, respectively in different rice planting area. Residual levels of difenoconazole in brown rice were below the limit of detection 28 d after treatment (<0.01 mg/kg) in all treatments. However, the residual levels of difenoconazole in rice culm were higher than those in brown rice and rice husk, and the final residual levels of difenoconazole in paddy soil were below the limit of detection (<0.01 mg/kg) in all treatments. Based on the actual production, difenoconazole residues in brown rice, rice culm and rice husk were safe according to the recommended dosage, times and interval. In spite of that, the use of difenoconazole should be avoided in ricefish culture model, so as to prevent side effects on aquatic organisms such as fish.