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10 May 2013, Volume 27 Issue 3 Previous Issue    Next Issue
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Research Papers

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Suppressed Expression of OsAGO1a Leads to Adaxial Leaf Rolling in Rice LI Lei1,#, XUE Xiang1,#, ZUO Shimin1, CHEN Zongxiang1, ZHANG Yafang1, LI Qianqian1, ZHU Junkai2, MA Yuyin3, PAN Xuebiao1,*, PAN Cunhong2,* 2013, 27(3): 223-230.  DOI: 10.3969/j.issn.10017216.2013.03.001 Abstract ( )   PDF (2584KB) ( )   Argonaute (AGO) protein is the core effectors in RNAinduced silencing complexes (RISCs), playing an important role in plant development. The 2nd and the 11th-12th exon fragments of OsAGO1awere amplified independently to make two RNAi constructs: OsAGO1aI1E and OsAGO1aI2E. To clarify the function of OsAGO1a in rice development,  the expression of OsAGO1a has been suppressed by introducing RNAi constructs to Nipponbare through Agrobacteriummediated transformation. The result showed that the reduced expression of OsAGO1a lead to adaxial leaf rolling without affecting main agronomic traits.

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Mapbased Cloning of A ‘Zebra’ Leaf Mutant Gene zl2 in Rice LIU Sheng1, 2, #, WEI Xiangjin1, #, SHAO Gaoneng1, TANG Shaoqing1, *, HU Peisong1, * 2013, 27(3): 231-239.  DOI: 10.3969/j.issn.10017216.2013.03.002 Abstract ( )   PDF (2841KB) ( )   A yellow and green zebra leaf mutant zebraleaf 2 (zl2) displayed a distinctive zebra leaf at seedling stage, and the leaves of the mutant gradually turned yellow after heading. Compared with wild type, the chlorophyll and carotenoid contents of zl2 were significantly reduced at trileaf stage, tillering stage, heading stage and mature stage. The seed setting rate, grain weight and plant height of zl2 also decreased significantly. The ultrastructures of chloroplasts in the mesophyll cells of the yellow part of seedling of zl2 have obvious differences from that of wild type. Genetic analysis showed that the phenotype of zl2 was controlled by a single recessive nuclear gene. Total 1607 zebra leaf plants selected from the F2 population of  zl2 / Nanjing 11 were used to finemap the mutant gene. Finally, ZL2 gene was narrowed to the 164.3 kb region on chromosome 11. There are 13 ORFs in this region, and a single base mutation was found in the ORF12 which encode a carotenoid isomerase. And as a result, four bases were missed in cDNA of ORF12 of zl2, leading to frameshift and the amino acid premature termination at the 395th. Compared with the wild type, the expression level of  ZL2 and the genes involved in the control of leaf color and photosynthesis, such as PORA, RbcL, RbcS， Cab1， Cab2， psaA, psbA and OsDVR decreased significantly in the mutant, while those of HEMA1, YGL1, V1, V2, SPP and  OsPPR  increase significantly. The results suggested that ZL2 act a very important role in chlorophyll biosynthesis, chloroplast development and photosynthesis in rice.

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Genetic Analysis and Gene Mapping of an albino lethal Mutant in Rice CHENG Shichao1,2, LIU Heqin2, ZHAI Guowei2, FENG Shizuo1,2, ZHAO Hui1,2, WANG Dekai2,*, TAO Yuezhi2 2013, 27(3): 240-246.  DOI: 10.3969/j.issn.10017216.2013.03.003 Abstract ( )   PDF (1232KB) ( )   An albino lethal mutant, temporarily designated as albino lethal 4(abl4), was obtained from 60Co γray radiation mutant pool of  japonica rice Zhonghua 11. The seedling of abl4 showed albino phenotype from germination to 3leafstage, then died. The chlorophyll and carotenoid contents in  abl4 mutant were too low to be detected. Moreover, the electron transport rate and the effective quantum yield of photosystem Ⅱ in abl4  were about zero. On the other hand, the potential photochemical efficiency of PSⅡ in abl4 was also at an undetectably low level, indicating that the activity of photochemical reaction was lost in the leaves of abl4. The activities of antioxidant enzymes induding superoxide dismutase and peroxidase were significantly increased, while catalase was decreased significantly. As results, the content of malondialdehyde was also increased significantly in abl4 compared with the wild type, suggesting that abl4 was strongly subjected to high oxidant stress. Transmission electron microscopy examination showed that abl4 plastids contained some empty vesicles without thylakoids. It was revealed that the phenotype of abl4 was controlled by a single recessive nuclear gene. An F2 population generated by crossing the abl4 mutant with the indica rice cultivar Longtefu B was used for gene mapping,ABL4 was preliminarily located between RM3785 and RM303 on rice chromosome 4 and further mapped to a 201 kb region.

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QTL Mapping and Genetic Analysis of Eight Outcrossingrelated Traits and Its Midparental Heterosis in japonica Rice ZHANG Hong1, JIANG Jianhua1, 2, LIU Xiaoli1, JI Jiazeng1, NIU Fuan1, ZHANGYoufu1,3, HONG Delin1,* 2013, 27(3): 247-258.  DOI: 10.3969/j.issn.10017216.2013.03.004 Abstract ( )   PDF (1059KB) ( )   To understand the types of gene action controlling outcrossrelated traits and its midparental heterosis, QTL mapping of eight outcrossingrelated traits including panicle exsertion degree (PED), flag leaf length (FLL), flag leaf angle (FLA), vertical distance between panicle tip and flag leaf tip (DPFT), second leaf length (SLL), second leaf angle (SLA), vertical distance between panicle tip and second leaf tip (DPST) and length of the first internode (LFI) from the top was conducted using 254 Xiushui 79/C Bao recombinant inbred lines (RILs) and two backcross hybrid populations derived from these RILs. 45 maineffect QTLs (MQTL) were identified in the three populations. The percentage of phenotypic variance explained by each QTL ranged from 1.5% to 80.3%. Among them, 73.3% QTL showed an additive effect, 4.5% a partialtocomplete dominant effect, and 22.2% an overdominant effect. Eightytwo pairs of digenic epistatic QTL (EQTL) were detected in the 3 populations,of which 43 pairs were detected in RIL population, and the percentage of phenotypic variance explained by each pair of QTL ranged from 1.0% to 7.0%, with an average 2.7%. Sixteen pairs of EQTL were detected in XSBCF1 population. Among them, 11 pairs were detected by using XSBCF1 phenotypic value, and the percentage of phenotypic variance explained by each EQTL ranged from 11.2% to 36.8%, with an average 21.0%. Six pairs of EQTL were detected by using midparental heterosis value (HMP), and the percentage of phenotypic variance explained by each EQTL ranged from 33.1% to 76.8%, with an average 55.0%. Twentythree pairs of EQTL were detected in CBBCF1 population. Among them, 16 pairs of EQTL were detected by using BCF1 phenotypic value, and the percentage of phenotypic variance explained by each pair of EQTL ranged from 6.2% to 60.0%, with an average 24.0%. Seven pairs of EQTL were detected by using the midparental heterosis value, and the percentage of phenotypic variance explained by each pair of EQTL ranged from 21.3% to 44.4%, with an average 31.0%. These results showed that outcrossingrelated traits themselves were mainly controlled by multiple loci with additive effects, and the primary genetic basis of midparent heterosis for outcrossingrelated traits was overdominant and epistatic effect in  japonica  rice.

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Development and Application of a Functional Marker Associated with Fertilityrestoring   Gene for BTtype Cytoplasmic Male Sterility (CMS) in  japonica  Rice  CHEN Tao， LUO Mingrui， ZHANG Yadong， ZHU Zhen， ZHAO Ling， ZHAO Qingyong， ZHOU Lihui， YAO Shu， YU Xin， WANG Cailin* 2013, 27(3): 259-264.  DOI: 10.3969/j.issn.10017216.2013.03.005 Abstract ( )   PDF (1068KB) ( )   To improve the selection efficiency of restoring gene for BTtype cytoplasmic male sterility (CMS) in japonica  rice, we designed a functional marker InDelRf1a based on a 574 bp insertion/deletion (InDel) in Rf1a locus between  japonica  restorer line and CMS line reported by previous studies and used it to identify the genotypes of Rf1a locus in 72  indica  or  japonica  rice materials. The results showed that there was no 574 bp deletion in  indica  conventional rice varieties, restorer and maintain lines and they could restore the fertility of BTtype CMS in  japonica  rice, with genotypes of  Rf1aRf1a; However, the same deletion was detected in most of  japonica  conventional rice varieties, except in Aichi 106 and Yijing 12, and they had the ability to maintain sterility of BTtype CMS lines, with genotypes of Rf1aRf1a. For further verification of the detection effect with this marker for different genotypes in this locus, we used it to amplify the DNA of different  japonica  rice restorer lines, CMS lines, hybrid F1 and the F2 population derived from a cross between 863A and Ninghui 8, and three genotypes in Rf1a  locus could be distinguished distinctly by gel electrophoresis.

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Effect of Calcium Signaling Reagent on Negative Phototropism of Rice Seminal Roots CHEN Juan1, MO Yiwei2，3，*, XU Huawei4 2013, 27(3): 265-272.  DOI: 10.3969/j.issn.10017216.2013.03.006 Abstract ( )   PDF (1394KB) ( )   In order to investigate the relationship between calcium signaling and negative phototropism of rice roots, different concentration of calcium signaling reagent such as CaCl2, organic calcium channel blocker(verapamil), inorganic calcium channel blocker(LaCl3), calcineurin  inhibitor chloropromaize（CPZ), auxin polar transport inhibitor(NPA) were used to treat rice seminal roots which were unilaterally illuminated   at an intensity of 100-200 μmol/(m2·s)  for 24 h. Results showed that negative phototropism curvature and growth rate of rice roots were enhanced by a proper dose of CaCl2. Further experiments testified that it is because more IAA was transported from irradiated side to shaded side by exogenous Ca2+ that negative phototropism curvature was enhanced rather than increased growth rate. Simultaneously, negative phototropism curvature and growth rate of rice roots were inhibited by inhibitors above, and the inhibiting effects were enhanced as the rising concentration of inhibitors. Roots would stop growing and negative phototropism characteristic would disappear when the concentration reached a certain degree, such as 100 μmol/L verapamil, 12.5 μmol/L LaCl3, 60 μmol/L CPZ and 6 μmol/L NPA. 100 μmol/L CaCl2 relieved the inhibition degree of LaCl3, verapamil and NPA. The results indicated that calcium ion plays an important role as a second messenger in the process of light signaling regulating rice roots growth and negative phototropism.

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Effect of Different P Levels on the Growth, P and As Absorption of Different Pefficiency Rice Varieties under As Stress Conditions at Seedling Stage LIAN Juan, GUO Zaihua*, HE Liyuan 2013, 27(3): 273-279.  DOI: 10.3969/j.issn.10017216.2013.03.007 Abstract ( )   PDF (2123KB) ( )   A pot trial was conducted to clarify the effect of different phosphorus (P) levels on the growth, P and arsenic (As) absorption of Pefficient rice 99011 and Pinefficient rice 99056 under As stress conditions. P was applied at three rates (0, 30 and 150 mg/kg) and As at five rates (0, 25, 50, 100 and 200 mg/kg) in soil.  Results showed that application of As increased shoot and root As concentration and decreased plant height, tiller number, shoot and root dry weight of the two rice varieties.  Application of P increased the growth as well as the root As concentration of the two rice varieties.  At 25 mg/kg and 50 mg/kg of As in soil, application of 30 mg/kg P decreased the translocation of As from roots to shoots and application of 150 mg/kg P increased the translocation of As from roots to shoots of the two rice varieties.  Under the same treatment, shoot and root dry weight of Pefficient rice 99011 were significantly higher than those of Pinefficient rice 99056.  Under the As treatment, the translocation factor of As in Pinefficient rice 99056 minimized at 30 mg/kg P treatment.

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Effect of Salt Stress on Photosynthetic Characteristics and   Physiological and Biochemical  Traits of Different Rice Varieties XU Chen1， LING Fenglou2， XU Kezhang2， WU Zhihai2， LIU Xiaolong2， AN Jiuhai2， ZHAO Lanpo3,* 2013, 27(3): 280-286.  DOI: 10.3969/j.issn.10017216.2013.03.008 Abstract ( )   PDF (893KB) ( )   With two salttolerant rice varieties and two saltsensitive varieties as material, the influence of salt stress on plant biomass accumulation, photosynthetic characteristics and the other physiological characteristics was studied. The results showed that the dry weight and fresh weight of shoot and root of salttolerant rice varieties and saltsensitive varieties were declined under salt stress. The fresh weight of shoot and dry weight of roots were declined significantly. The net photosynthetic rate, stomatal conductance, transpiration and apparent mesophyll conductance were declined to different degrees under salt stress. The drop of Pn, Gs, Tr and Pn/Ci of salttolerant varieties was less than saltsensitive varieties. The water use efficiency(WUE) of salttolerant varieties was higher than that of saltsensitive ones at the same time. The intercellular CO2 concentration (Ci) of salttolerant varieties and saltsensitive ones was not changed obvirously under salt stress. The stomatal limitation percentage (Ls) under salt stress was low and the difference among the varieties was not significant. And apparent mesophyll conductance (Pn/Ci) was changed significantly. The decline of Pnresulted from the decline of RuBPCase rather than from stomatal limitation. The permeability regulation substance contents of leaf and root such as soluble sugar and proline, total amino acids were increasd under salt stress with significant increase in soluble sugar contents (P < 0.01). The protective enzyme SOD, POD and CAT activities were enhanced, as well as  the membrane permeability and the MDA content, the root vigor was declined under salt stress.

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Influence of Soil Type on Characteristics of Photosynthetic Production and Grain Quality of japonica Rice in Northeast China LI Hongliang1,*, SUN Yuyou1, QU Jinling1, WEI Caiqiang1, SUN Guohong1, ZHAO Yuntong1, ZHAO Lifei2, CHAI Yongshan1,* 2013, 27(3): 287-296.  DOI: 10.3969/j.issn.10017216.2013.03.009 Abstract ( )   PDF (1385KB) ( )   The influence of soil type（including the natural flagstone land of Xiangshui volcanic basalt, artificial flagstone land and nonflagstone land） on characteristics of photosynthesis, matter production and grain quality of japonica rice in Northeast China were researched. The results showed that there was significant difference in dry matter weight per stem between nonflagstone land and the two flagstone lands at each stage. Dry matter weight of population in nonflagstone land was significantly higher than that in natural and artificial flagstone lands from jointing to maturity, and there was no significant difference between the two flagstone lands. The leaf area index was generally no much difference in jointing stage among different soil types. After jointing, the leaf area index of nonflagstone land was significantly higher than that of natural flagstone land, and the leaf area index of natural flagstone land was significantly higher than that of artificial flagstone land. The leaf area rate of productive tillers at heading had no significant difference among different soil types, but the leaf area rate from flag leaf to 3rd leaf in nonflagstone land was significantly higher than that of natural flagstone land, and the minimum of leaf area rate from flag leaf to 3rd leaf was in artificial flagstone land. The total photosynthetic potential that from sowing to jointing, jointing to heading, heading to maturity and the whole growth duration was higher in nonflagstone land than that in natural flagstone land. The total photosynthetic potential was lowest in artificial flagstone land. And the difference among the three different environments was significant. In terms of the rice quality, the brown rice rate, head rice rate, chalky rice rate and chalkiness, gel consistency, protein content and sapor score in natural flagstone land were higher than those of artificial flagstone land and nonflagstone land, but the amylose content was lower than that in artificial flagstone and nonflagstone.

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Effects of Sowing Date and Site on Grain Quality of Rice Cultivars Planted in Different Ecological Types ZHAO Qingyong, ZHU Zhen, ZHANG Yadong, CHEN Tao, YAO Shu, ZHOU Lihui, YU Xin, ZHAO Ling, WANG Cailin* 2013, 27(3): 297-304.  DOI: 10.3969/j.issn.10017216.2013.03.010 Abstract ( )   PDF (488KB) ( )   In order to elucidate the basically variable rule of rice grain quality traits in Jiangsu Province, the effect of site and sowing date on grain milling quality, appearance quality, eating quality and nutrient quality was studied in five rice planting regions with five different dominantly cultivated japonica cultivars as material under seven sowing date treatments. The main results showed that the effects of site, sowing date and cultivars on the grain qualities were highly significant, the order of effect on most rice grain qualities was as follows: cultivar> site> sowing date. The change tendency of quality traits varied with site. Grain length, grain width and ratio of grain length and width changed slightly at different latitudes. Amylose content, gel consistency, gelatinization temperature and taste value were higher in the north than in the south while chalkiness rate, chalkiness degree and protein content were higher in the south than in the north. Eating quality showed an increasing trend with increasing latitude. Along with the delayed sowing date, milling quality, amylose content, gelatinization temperature and protein content showed an increasing trend. Grain length and ratio of grain length increased whereas grain width and gel consistency decreased with delaying sowing date. Chalkiness rate and chalkiness degree were significantly different among different sowing dates with little change. And earlier or delayed sowing would result in the degradation of taste value. The response of different traits to the site and sowing date was different. Brown rice rate, grain length, grain width, ratio of grain length and width and milled rice rate were rather stable, but chalkiness rate and chalkiness degree were relatively sensitive to environmental factors. Head milled rice rate, gel consistency, protein content, amylose content, gelatinization temperature and taste value were intermediate between the above two types. The stability of various quatity traits for different cultivars varied with the site and seeding time. Nanjing 46 with the best composited quality characters, was more sensitive to the site and sowing date.

Reviews and Special Topics

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Molecular Mechanisms of Rice Resistance Genes Recognized by Xanthomonas oryzae pv. oryzae ZHANG Fan, ZHOU Yongli* 2013, 27(3): 305-311.  DOI: 10.3969/j.issn.10017216.2013.03.011 Abstract ( )   PDF (681KB) ( )   Rice bacterial blight, caused by Xanthomonas oryzae  pv. oryzae（Xoo）, is a destructive disease in rice growing regions over the world. Xoorice pathosystem is considered as an ideal model to reveal how the pathogen surpasses  rice defense that leads to rice resistance or susceptibility. Rice immunity to Xoo  infection is thought to consist of two layers. One is taken as effectortrigged immunity (ETI) that is  formally defined as “geneforgene” resistance. The other is termed as pathogenassociated molecular patterns triggered immunity (PTI) that is referred to basic defense reaction. Recent evidences demonstrate that ETI is manipulated by TAL (transcriptional activatorlike) effectors and PTI is charged both by Xoo AX21 and rice Xa21. Here we reviewed recognition mechanisms of rice resistance (R) genes by TAL effector and by a PAMP AX21, and also discussed about possibilities in applications of these ETI and PTI in rice resistance breeding to bacterial blight.

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Research Progress on Populations and Physiological Race Distribution of Rice Blast  Pathogen (Magnaporthe grisea) in China XIAO Danfeng1 , ZHANG Peisheng2 , WANG Ling1 , HUANG Shiwen1，* 2013, 27(3): 312-320.  DOI: 10.3969/j.issn.10017216.2013.03.012 Abstract ( )   PDF (542KB) ( )   Magnaporthe grisea population distribution and the physiological race composition in major rice growing regions in China are summarized. Physiological races of M. grisea ZF, ZD, ZE and ZA were the dominant populations in Northeast China rice growing regions, with the occurring frequencies of 23.2%, 22.2%, 15.6% and 12.3%, respectively. High pathogenicity virulent populations of ZA and ZB are the major strains in Southwest China riceproducing regions, the occurrence frequency of ZB and ZA reached 53% and 22.3% in Sichuan Province. In Guizhou Province, the races of ZB, ZA and ZG were the dominant populations with occurrence frequency of 41.4%, 18.5% and 10.7%, respectively. ZB and ZC were the major populations in south China’s rice growing areas with the occurrence frequency 28.0% and 37.0%. Weak virulence races of ZE, ZF and ZG were the major populations in North China rice growing regions with the occurrence frequency of 21.5%, 22.1% and 44.3%. Races of ZB, ZG, ZC and ZA were the dominant populations in East China rice planting areas with the occurrence frequency of 43.3%, 25.0%, 13.9% and 12.3%, respectively. The major populations in central China were ZA, ZB, ZE and ZC，with the occurrence frequency of 34.9%, 288%, 21.4% and 14.1%, respectively. Few rice were planted in northwest China, however, the strong pathogenicity races of ZA and ZB were dominant populations.

Experimental Techniques

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Cloning Flanking Sequence of Bar gene by Singleprimer PCR in Transgenic Rice LI Daoheng1, MA Jian1, WANG Yunpeng1, MA Jingyong1,* 2013, 27(3): 321-324.  DOI: 10.3969/j.issn.10017216.2013.03.013 Abstract ( )   PDF (2259KB) ( )   The insertion position of exogenous genes in targeted plant genomes are usually identified by adapter ligationmediated polymerase chain reaction, thermal asymmetric interlaced PCR, and restriction site extension PCR in transgenic rice research. However, there are various limitations in these methods, such as complexity of designing primers, and use of timeconsuming and multiplestep procedures. The goal of the present study was to establish an easier, and a more rapid and accurate method for cloning flanking sequence using singleprimer PCR in transgenic rice. Unknown flanking genome sequences in transgenic rice were successfully cloned using the singleprimer PCR method established in this study, with the  gene as the anchor gene. Our data demonstrated that the singleprimer PCR is a more rapid and accurate method, justifying its application widely in cloning flanking sequences in transgenic rice.

Short Communications

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SNPbased Detecting Method of Rice Blast Resistance Gene Pita ZHANG Yu1， ZHANG Xiaojuan1， YANG Fengjiao2， FENG Zhifeng3 2013, 27(3): 325-328.  DOI: 10.3969/j.issn.10017216.2013.03.014 Abstract ( )   PDF (631KB) ( )   There is only one amino acid difference between rice blast resistance gene Pita and its susceptible allele. According to this, a SNPbased Pita diagnostic method has been estabished based on tetraprimer ARMS PCR technology.  The distribution of Pita gene among 62 rice germplasm from national rice regional test in the upper Yangtze River in 2012 and 97 rice germplasm from rice regional test in Shanxi Province in 2012 was analyzed by this method, and the result was consistent with  that with the other SNP marker previously reported.  It showed that the method can be effectively used in the detection of Pita gene in rice.

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Breeding of Rice Restore Lines with Whitebacked Planthopper Resistance by MarkerAssisted  Selection ZHANG Jianfu1 , ZENG Dali2 , ZHU Yongsheng1, XIE Hongguang1, CAI Qiuhua1, LIAN Ling1, WU Fangxi1, LUO Xi1, WANG Yingheng1, ZHENG Yi1, XIE Huaan1, * 2013, 27(3): 329-334.  DOI: 10.3969/j.issn.10017216.2013.03.015 Abstract ( )   PDF (3029KB) ( )   The whitebacked planthopper (WBPH, Sogatella furcifera) affects rice production and threatens food security in the world. It is very important to breed hybrid rice restorer lines with WPBH  resistance for rice production. The WBPH resistance locus  qSI4 from GL77 and GL84 were introduced into the susceptible restorer lines by molecular markerassisted selection (MAS), traditional breeding methods and WBPHresistance identification in multiple fields. Three improved lines of R38, R46 and R58, conferring WBPH resistance and with good agronomic characteristics were obtained by molecular marker test for the target genes and different parental genetic background analysis. The results indicated that the WBPH resistance of these new restorer lines with qSI4 was not significantly different to that   of Chunjiang 06. New hybrid rice combinations with WBPH resistance, high quality and high yield were bred.