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10 July 2014, Volume 28 Issue 4 Previous Issue    Next Issue
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Reviews and Special Topics
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Reviews and Special Topics

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Repartitioning of Nonstructural Carbohydrates in Rice Stems and Their Roles in Yield Stability and Stress Tolerance PAN Junfeng1,2, LI Guohui2, CUI Kehui2，* 2014, 28(4): 335-342.  DOI: 10.3969/j.issn.1001-7216.2014.04.001 Abstract ( )   PDF (458KB) ( )   High and stable grain yield of rice under changeable environments is significant for meeting the increasing food demand due to the rapid population growth. When assimilates are insufficient due to lower photosynthetic capability during the   grain filling stage  or under abiotic stresses, nonstructural carbohydrates (NSCs) stored in the rice stems (leaf sheath and culm) may be as a source of carbohydrates for grain filling and relief of grain yield reduction. Considering the importance of NSCs, traits related to NSCs accumulation and repartitioning are becoming a target for genetically improving grain yield and stress resistance in rice, and some attempts are made to regulate NSCs accumulation and repartitioning by integrated crop management. We review effects of several factors on NSCs accumulation and repartitioning, such as characteristics of sourceflowsink, nitrogen and water application, light density, ambient temperature, lodging resistance. On the other hand, we evaluate the regulation of NSCs accumulation and repartitioning by optimization of nitrogen fertilizer application, irrigation and transplanting density. Additionally, roles of stem NSCs in increasing grain yield stability and stress resistance are discussed.

Research Papers

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Cloning and Functional Characterization of talR26.5 Gene from Xanthomonas oryzae pv. oryzae OS198 Strain ZHU Yinyin, LIU Yongting, LI Shihe, SONG Congfeng* 2014, 28(4): 343-350.  DOI: 10.3969/j.issn.1001-7216.2014.04.002 Abstract ( )   PDF (3021KB) ( )   As the representative strain of Xanthomonas oryzae pv. oryzae (Xoo) China race 6, OS198 displayed low virulence in 26 rice varieties. talR26.5 is a transcription activatorlike (tal) gene cloned from the genomic DNA of OS198. TALR26.5 had 26.5 tandemrepeats of 34 amino acid residues and shared over 99% homology with the TAL effectors AvrXa73M of Philippines strain PXO357 and YP_451895 of Japanese strain MAFF 311018. The repeat domains were identical for the three proteins. The introduction of talR26.5 into PXO99A decreased  the virulence and suppressed the bacterial populations in three nearisogenic rice lines IRBB8,IRBB14 and IRBB214 compared with the wild type PXO99A. The transformant strains showed no difference of virulence with PXO99A in 22 other rice varieties including IRBB7. The induced resistance of IRBB8, IRBB14 and IRBB214 against the infection of PXO99A harboring talR26.5 was implemented by the suppression of disease susceptibility gene Os8N3. PXO99A/talR26.5 aroused enhanced hypersensitive response in tobacco leaves compared with PXO99A. The results indicated that the talR26.5 gene of OS198 might have dual functions of virulence and avirulence.

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Isolation and Characterization of a Novel Root Tipspecific Promoter in Rice ZHAO Hongyu1, 2, XU Lei2, WEI Xijuan1, DENG Minjuan2, WANG Fang2,*, YI Keke2 2014, 28(4): 351-357.  DOI: 10.3969/j.issn.1001-7216.2014.04.003 Abstract ( )   PDF (2187KB) ( )   To obtain the rootspecific promoters in rice, a rootspecific gene Os04g24469 was selected by analyzing the public microarray data and further confirmed by RTPCR. To determine the expression pattern of the novel promoter, the putative promoter was isolated and fused with the GUS reporter gene to transform into the  rice variety Nipponbare. Subsequent GUS staining of the transgenic plants showed that the Os04g24469 promoter was only activated in rice root tip. Using this root tipspecific promoter，we  characterized the function of a ubiquitously expressed gene OsSRG in root development. The absence of OsSRG led to a short root phenotype in the srg mutant, the root tipspecific expression of GUSOsSRG in srg plants significantly reversed the root growth defect, indicating that the expression of OsSRG in root tip, not in shoot, is important for root development in rice. The present study showed that Os04g24469 promoter is highly active in the root tip and can be useful for the root tipspecific expression of target genes and gene function analysis in rice root.

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Identification of QTLs for Salt Tolerance at the Germination and Early Seedling Stage Using Linkage and Association Analysis in japonica  Rice ZHENG Hongliang, LIU Bowen, ZHAO Hongwei, WANG Jingguo, LIU Hualong, SUN Jian, XING Jun, ZOU Detang* 2014, 28(4): 358-366.  DOI: 10.3969/j.issn.1001-7216.2014.04. 004 Abstract ( )   PDF (1398KB) ( )   QTL for salt tolerance at the germination and early seedling stage in rice were detected via linkage and association analyses. A BC2F2:3 population was constructed including 190 BC2F3 lines, derived from a cross between Dongnong 425 (highyielding rice variety with good grain quality, as the recurrent parent) and Changbai 10 (salt tolerant rice variety, as the donor parent). QTLs were detected for salt tolerance at the germination and early seedling stage including relative germination rate (RGR), relative seedling height (RSH), relative root number (RRN), relative root length (RRL) were detected by using ICIM with a genetic linkage map constructed with 137 SSR markers. A total of 11 QTLs were identified. A panel of 341 japonica rice accessions from different geographical origins were used for both wholegenome association and targeted regional association mapping. The accessions were genotyped with 160 selected SSR markers, and then association analysis between SSR markers and traits were performed using TASSEL 21 GLM and MLM programs. A total of 22 significant markertrait associations were identified within 18 markers, and 5 QTLs reported by linkage mapping were validated, and 9 novel alleles at these loci were mined from the set of  japonica  rice. By comparing the chromosomal positions of the 5 QTLs with those previously identified, four of them located in the same or near genome regions, qRRL7 was reported for the first time.

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Identification and Gene Mapping of a Lesion Mimic Mutant lmm4 in Rice QIU Jiehua1, MA Ning1, 2, JIANG Hanwei1, 2, SHENG Zhonghua1, SHAO Gaoneng1, TANG Shaoqing1, WEI Xiangjin1, *, HU Peisong1, * 2014, 28(4): 367-376.  DOI: 10.3969/j.issn.1001-7216.2014.04.005 Abstract ( )   PDF (7049KB) ( )   The lesion mimic mutant lmm4 was identified from an EMSinduced Nipponbare mutant library. Brown lesions were first observed on the tip of lmm4  leaves at the initial tillering stage, and spreaded gradually downward to the whole leaf blade and even the leaf sheath. Compared with the wild type, the chlorophyll and the net photosynthetic rate of lmm4  were significantly reduced. The plant height, panicle length, seed setting rate, grain weight were also decreased significantly. The shading assay showed that the lesions on lmm4  leaves were induced by natural light. The histological staining assay indicated that the lesions on lmm4  leaves were caused by programmed cell death and hydrogen peroxide accumulated in lmm4  leaves. The lmm4  displayed higher resistance to blast race C7 and G1 when compared with the wild type. In addition, pathogenesisrelated gene POC1, PAL,PBZ1, PR1 were found to be upregulated in lmm4. Genetic analysis suggested that the phenotype of lmm4  was controlled by a single recessive nuclear locus. Based a mapbased cloning strategy, the lmm4  was narrowed down to a 235 kb region between Ind4 and Ind6 near the centromere of chromosome 5.

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Identifying the Genetic Basis of Spikelet Fertility Differences Between BTtype ThreeLine japonica Hybrids ZHANG Honggen#, QIAN Kai#, SUN Yibiao, PEI Yan, FENG Zhiqiang, LIU Xiaoyu, TANG Shuzhu*, LIANG Guohua, GU Minghong 2014, 28(4): 377-383.  DOI: 10.3969/j.issn.1001-7216.2014.04.006 Abstract ( )   PDF (535KB) ( )   In order to understand the genetic basis of spikelet fertility differences between BTtype threeline japonica hybrids, the CMS lines Yujing 6A, 9201A and their  corresponding maintainer lines, and the restorer lines Min 120, TR2604 were used to develop the genetic populations for studying the genetic characteristics of BTtype CMS in different hybrid combinations. According to fertility segregation of the plants from the populations of 9201A//9201B/Min 120, Yujing 6A//Yujing 6B/Min 120 and 9201A//9201B/ TR2604, it was concluded that the fertility restoration of 9201A and Yujing 6A was controlled by one fertility restoration(Rf) gene. Then, the Rf genes in Min120, TR2604 were mapped between 18 772 374－18 967 996 bp with the physical distance of 195 kb and 18 817 631－18 967 996 bp with the physical distance of 150 kb on chromosome 10, respectively, indicating that the Rf genes in Min 120, TR2604 might be Rf1a according to the mapping results of Rf1 in former studies. The fertility restoration of Yujing 6A in the population derived from Yujing 6A and TR2604 was also controlled by Rf1a identified by the genotype and phenotype of plants in Yujing 6A/TR2604//TR2604 BC1F2 population, so the sterility of Yujing 6A/TR2604 was induced by hybrid incompatibility between the two parents.

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Effect of Alternate Wetting and Soil Drying Irrigation during Grain Filling on the Physiological Traits and Yield of Transgenic Rice  with Different  Protein Content in Grains LIU Lijun1，*, WANG Kangjun2, BIAN Jinlong1, XIONG Yiwei1, WANG Zhiqin1, YANG Jianchang1 2014, 28(4): 384-390.  DOI: 10.3969/j.issn.1001-7216.2014.04.007 Abstract ( )   PDF (1201KB) ( )   Little is known on the yield response to water management for those rice cultivars with different  protein content in grains (PCG). Effect of alternate wetting and soil drying irrigation during grain filling on grain yield and its physiological traits were investigated with Nipponbare and its two transgenic strains differing in PCG as materials. The results showed that the filled grain rate and grain yield were decreased with increasing PCG under the same water treatment. Alternate wetting and moderate soil drying irrigation (WMD) during grain filling significantly increased grain yield. Qenzyme activity in rice grains, root oxidation activity, membrane lipid peroxidation enzyme activities in the flag leaves and the translocation of nonstructural carbohydrate (NSC) in rice stem were also significantly increased under WMD. And the increasing extent of grain yield and the above physiological traits was higher in the rice  lines  with higher PCG than those with lower PCG. Alternate wetting and severe soil drying irrigation (WSD) during grain filling significantly decreased filled grain rate and yield, Qenzyme activity in rice grains, root oxidation activity, membrane lipid peroxidation enzyme activities in the flag leaves and the translocation of nonstructural carbohydrate (NSC) in rice stem, when compared with conventional irrigation. And the decreasing extent of grain yield and the above physiological traits was higher in the rice lines  with higher PCG than those with lower PCG. The changes of these physiological traits were probably  the main reasons for the yield variation of rice  lines  with different  PCG.

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Effect of Nitrogen Rates on Grain Yield and Some Physiological Traits of Super Rice FU Jing1,2, WANG Zhiqin1, YUAN Limin1, WANG Xueming1, YANG Jianchang1,* 2014, 28(4): 391-400.  DOI: 10.3969/j.issn.1001-7216.2014.04.008 Abstract ( )   PDF (3851KB) ( )   A field experiment was conducted to reveal the effects of nitrogen rate on super rice grain yield and its mechanism with two super rice cultivars, Liangyoupeijiu (twoline indica hybrid) and Huaidao 9 (japonica), and two highyielding elite check cultivars, Shanyou 63 (indica hybrid) and Yangfujing 8 (japonica)as material at four nitrogen (N) rates, no N application and N rates  of 120 kg/hm2, 240 kg/hm2, and 360 kg/hm2. The results showed that the grain yield of two super rice cultivars   increased with increasing N rates from 0 to 360 kg/hm2. Similarly, the physiological performance, such as net photosynthetic rate and nitrate reductase activity of the flag leaf, root oxidation activity and zeatin + zeatin riboside content, shoot dry weight, root dry weight and the root/shoot  ratio were  improved with increassing N rates for both super rice cultivars. The grain yield and the physiological performance of the two check cultivars were also improved with the increase of N rates from 0 to 240 kg/hm2. The abovementioned  indexes  were decreased at the N rate of 360kg/hm2 for the two check cultivars. At the same N rate the grain yield of the two super rice cultivars was higher than that of the two check cultivars, while the physiological performance of the super rice cultivars was just the opposite under N rates no more than 240kg/hm2. However, the physiological performance was better for super rice  at the N rate of 360 kg/hm2. The results suggested that super rice cultivars could obtain a higher grain yield than elite highyielding cultivars at either a low N rate or a high N rate, and a high N rate was favorable to realize highyielding potential of super rice.

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Interactive Effects of Ozone Concentration and Planting Density on Growth, Development and Yield Formation of Yangdao 6-A FACE Study PENG Bin1,2, LAI Shangkun1, LI Panlin1, WANG Yunxia 1, ZHU Jianguo3, YANG Lianxin1,*, 2014, 28(4): 401-410.  DOI: 10.3969/j.issn.1001-7216.2014.04. 009 Abstract ( )   PDF (1038KB) ( )   In order to investigate the effects of ozone stress on growth, development, yield formation of rice, we conducted a free air ozone concentration enrichment  (FACE) experiment. A conventional indica rice cultivar Yangdao 6 was grown in the field at ambient and elevated ozone concentrations (ambient×1.5) with 3 spacing levels: low planting density (LD, 16 hills/m2), medium (MD, 24 hills/m2) and high planting density (HD, 32 hills/m2) . The results were as follows: elevated ozone had no impact on heading stage, maturity stage and final plant height, but significantly reduced biological yield by 23%, 20% and 9% under LD, MD and HD, respectively. The ozoneinduced decrease in biological yield was mainly due to the decrease in dry matter production during jointingmaturity stage (-23%), while dry matter production before jointing stage was remained unaffected. The former was mainly due to the significant decrease in net assimilation rate (NAR), and partly due to the reduction in leaf area index (LAI) in the later growth stage. The biomass of plant tissues under elevated ozone was not affected at the vegetative stage, but significantly reduced at the reproductive stage, with larger decline in stem biomass than in leaf biomass. As a result, green leaf biomass ratio increased, while the faction of stem showed an opposite trend. Ozone stress had no effect on the panicle number per unit area and spikelet number per panicle, but significantly decreased filled grain percentage and filled grain weight, thus increased the blighted grain rate and empty grain rate. Across the three planting densities, grain yield reduced significantly by 16% due to ozone stress, with the average reduction of 24%, 14% and 10% under LD, MD, and HD, respectively. With rising planting density the negative effects of ozone stress showed decreasing trends on LAI, NAR and dry matter production in late season, as well as spikelet number per panicle, filled grain weight and grain yield. The above results indicated that appropriate increase in planting density could reduce ozone damage to  LAI, especially to NAR in the late growing stage, thus on the processes of spikelet formation and grain growth, and finally decreased ozoneinduced yield loss.

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Relationship Between the Conducting Tissue in the First Internode and the Grainfilling of Super Large Panicle Rice Restore  Line R1126 and Its Derived Combinations ZHOU Hongying, ZHANG Guilian, XIAO Yinghui, TANG Wenbang, CHEN Liyun* 2014, 28(4): 411-418.  DOI: 10.3969/j.issn.1001-7216.2014.04.010 Abstract ( )   PDF (759KB) ( )    The grain yield, the characteristics of conducting tissue in the first internode and their relations with the grainfilling were analyzed by using four hybrid rice combinations derived from R1126 as materials  and Shanyou 63 as a control. The results showed that the grain yield of the four hybrid rice combinations was 7.43% to 24.23% higher than that of Shanyou 63. Increased total grain number and filled grain number per panicle attributed to yield increase. Compared with Shangyou 63, hybrid rice combinations derived from R1126 had advantages in the neck diameter, area of stem wall, ration of stem wall to cross, No. of vascular bundles（VB）, total area of VB, total area of phloem,the ratio of VB area  to phloem  area as well as conducting tissue activity, while had  lower ratio of spikelet  number to area of VB, ratio of spikelet number to area of phloem,  ratio of total sink to area of VB， ratio of total  sink to area of phloem，ratio of full grain  weight to area  of VB, ratio of full grain  weight to area  of phloem,  and the organic material transfer to panicle was  fluency. The derived hybrid rice combinations were characterized by greater initial grainfilling potential (R0), maximum grainfilling rate (GRmax) and mean grainfilling rate（GRmean）, earlier maximum grainfilling rate (Tmax) , shorter active grainfilling period (D) and effective grainfilling time (T99), faster grain filling and reasonable filling dynamics, smaller dvalue of final weight of a kernel (A) between superior  and inferior grains, which contributed  to good grainfilling. The correlation analysis showed that the ration of spikelet number, grain weight, total sink capacity to area of phloem were  negatively correlated with  GRmax and GRmean of SG and IG, and grainfilling rate. And  D,T99 ,  Tmax were positively correlated with them as well as   conducting tissue activity.  Conducting tissue in the first internode had closed relationship with grainfilling, improving  its characteristics could be beneficial to  grain filling.

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Effects of Seed Soaking with Methyl Jasmonate on Resistance to Bacterial Leaf Blight and Antioxidant Enzyme Activities of Rice Seedlings XIANG Miaolian1 , FU Yongqi1 , HE Yongming1, HUANG Youming1, 2 , ZENG Xiaochun1, 2,* 2014, 28(4): 419-426.  DOI: 10.3969/j.issn.1001-7216.2014.04.011 Abstract ( )   PDF (1343KB) ( )   This experiment was carried out to study the effects of seed soaking with exogenous methyl jasmonate (MeJA) on resistance to bacterial leaf blight and antioxidant enzyme activities of rice seedlings with Wen 229 (susceptible to rice bacterial leaf blight ) and Jiazao 312 (resistant) as experimental materials. The results showed that MeJA soaking significantly decreased the disease indexes of bacterial leaf blight in rice seedlings, especially for the resistant cultivar. With rising MeJA solution concentration, the activities of superoxide dismutase, peroridase, catalase and ascorbate peroxidase in leaves of rice seedlings increased firstly and then decreased, while the malondialdehyde (MDA) content raised at first and dropped afterwards. At a concentration of  0.5 mmol/L, MeJA soaking caused damage to rice seedings. The responses of antioxidant enzyme activities and lipid peroxidation content to MeJA soaking varied with variety. The above results indicated that MeJA soaking could effectively relieve the bacterial leaf blight of rice seedlings. The increase of the antioxidant enzyme activities and the decrease of the MDA content are related to its resistant reactions to bacterial leaf blight.

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Analysis on the Immigration Process and Source Population of the Rice Leaf Roller (Cnaphalocrocis medinalis Guenee) at Funing  County in Southeast of Yunnan Province,China SHEN Huimei1, SHEN Aidong1,*, ZHAO Xueqing1 , YIN Yanqiong1, LI Xiangyong1， WEI Jiagui2 2014, 28(4): 427-434.  DOI: 10.3969/j.issn.1001-7216.2014.04.012 Abstract ( )   PDF (3197KB) ( )   The rice leaf roller (Cnaphalocrocis medinalis) is a serious migratory pest on rice in the southeast  of Yunnan,China. In order to illustrate the largescale landing mechanism of population of C. medinalis, two immigration processes in Funing County on 30 May 2007 and on 21 May 2009 and the atmospheric backgrounds during the peak days were analyzed based on the data from field survey and by using HYSPLIT, a trajectory analysis software, GrADS (Grid Analysis and Display System).We got the following results: 1) The early immigration of C. medinalis in 2007 directly come from the Red River Delta of Vietnam, and the continuous south airflow and precipitation were the key meteorological factors to the mass landing of the moths; 2) The main source areas of the early immigration of C. medinalis in 2009 were  the southwest  of Guangxi Province. The continuous rainfall and strong south airflow were the key factors which affected the immigration process of C. medinalis.

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Effects of Rice C2C2 Zinc Finger Protein Gene OsLSD2 on the Growth and Nitrogen Utilization of Nipponbare TONG Jun#， CHEN Jingguang#， ZHU Jingwen， FAN Xiaorong*， XU Guohua 2014, 28(4): 435-441.  DOI: 10.3969/j.issn.1001-7216.2014.04.013 Abstract ( )   PDF (1006KB) ( )   OsLSD2 is a member of LSD1  gene family， which encodes C2C2 zinc finger protein gene. As it is known that LSD1 family is involved in disease resistance. In order to create environmentfriendly rice plant, we investigated the effects of overexpression of this gene in Nipponbare (WT) on plant growth and nitrogen use efficiency. The T3 generation plants showed that the plant height was reduced significantly；tiller number was averagely decreased by two; seed setting rate was only 64%-72%; the grain yield was reduced by 33%-42% compared with WT; the growth duration was shortened by 15 days; and the absorption and utilization rate of nitrogen were reduced significantly as OsLSD2 overexpressed. The phenotype of transformed lines suggested the overexpression of OsLSD2 can significantly repress the growth and nitrogen translocation in rice.

Experimental Techniques

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Detection of Gene p/tms121  for Photoperiod and ThermoSensitive Genic Male Sterility by TetraPrimer Amplication Refractory Mutation System PCR in Rice LI Jun*, LI Bai, GAO Rongcun 2014, 28(4): 442-446.  DOI: 10.3969/j.issn.1001-7216.2014.04.014 Abstract ( )   PDF (748KB) ( )   Specific primers were designed for tetraprimer amplification refractory mutation system PCR (ARMSPCR) method according to the single nucleodide mutation in gene p/tms121.  Eleven twoline sterile lines and two normal varieties were analyzed by this method. The results could clearly distinguish the genotype of p/tms121,  which was completely consistent with the result of CAPs markerbased analysis. Therefore, as a lowcost, simple and reliable technique, this method could be widely used to the p/tms121  detection and molecular markerassisted breeding in rice.