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28 December 2012, Volume 19 Issue 4 Previous Issue    Next Issue
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Research Paper

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Expression Patterns of OsPIL11, a Phytochrome-Interacting Factor in Rice, and Preliminary Analysis of Its Roles in Light Signal Transduction LI Li, PENG Wei-feng, LIU Qian-qian, ZHOU Jin-jun, LIANG Wei-hong, XIE Xian-zhi 2012, 19(4): 263-268.  Abstract ( )   PDF (243KB) ( )   The expression patterns of OsPIL11, one of six putative phytochrome-interacting factors, were analyzed in different organs of transgenic tobacco. The expression of OsPIL11 was organ-specific and was regulated by leaf development, abscisic acid (ABA), jasmonic acid (JA) and salicylic acid (SA). To further explore the role of OsPIL11 in plant light signal transduction, a plant expression vector of OsPIL11 was constructed and introduced into tobacco (Nicotiana tabacum). When grown under continuous red light, OsPIL11-overexpressed transgenic tobacco exhibited shorter hypocotyls and larger cotyledons and leaves compared to wild-type seedlings. When grown under continuous far-red light, however, transgenic and wild-type seedlings showed similar phenotypes. These results indicate that OsPIL11 is involved in red light induced de-etiolation, but not in far-red light induced de-etiolation in transgenic tobacco, which lays the foundation for dissecting the function of OsPIL11 in phytochrome-mediated light signal transduction in rice.

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Identification and Fine Mapping of Heading Date Related Mutant in Rice SHANG Hai-xuan1, 2, #, YE Sheng-hai2, #, DENG Xiao-mei2, 3, ZHOU Ya1, 2, XIU Fen-lian1, 2, JI Xian-jun2, 3, LIU Ji-yun1, 2, CHEN Ping-ping1, 2, JIN Qing-sheng2, ZHANG Xiao-ming2 2012, 19(4): 269-276.  Abstract ( )   PDF (1257KB) ( )   A rice heading-date-related mutant was isolated from a 60Co-γ-ray-induced mutation pool of Zhejing 22, a conventional japonica cultivar in Zhejiang Province, China. The mutant was characterized by a delayed heading date of almost 20 d longer than the wild type plant. Genetic analysis revealed that the mutation was controlled by a single nuclear-encoded recessive gene that was designed as HD(t) (heading date tentatively). To isolate the HD(t) gene, a map-based cloning approach was employed using 479 F2 mutant individual plants derived from the cross between the hd(t) mutant (japonica) × Zhenshan 97 (indica). Finally, the HD(t) gene was mapped to an approximate 53 kb region between the InDel markers of 10-61W and 10-66W on chromosome 10. According to the genome sequence of Nipponbare, the target region contains 11 annotated genes. It is helpful for future cloning of HD(t) gene based on this fine mapping results.

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Genetic Analysis and QTL Mapping of Large Flag Leaf Angle Trait in Japonica Rice HU Wen-de, ZHANG Hong, JIANG Jian-hua, WANG Ying-ying, SUN Da-yun, WANG Xiao-shuai, LIANG Kui, HONG De-lin 2012, 19(4): 277-285.  Abstract ( )   PDF (368KB) ( )   Genetic segregation analysis for flag leaf angle was conducted using six generations of P1, P2, F1, B1, B2 and F2 derived from a cross of 863B (a maintainer line of japonica rice) and A7444 (a germplasm with large flag leaf angle). Genotypes and phenotypes of flag leaf angle were investigated in 863B (P1), A7444 (P2) and 141 plants in BC1F1 (863B/A7444//863B) population. An SSR genetic linkage map was constructed and QTLs for flag leaf angle were detected. The genetic map containing 79 information loci was constructed, which covers a total distance of 441.6 cM, averaging 5.6 cM between two neighboring loci. Results showed that the trait was controlled by two major genes plus polygene and the major genes were more important. Fifteen markers showed highly significant correlations with flag leaf angle based on single marker regression analysis. Two QTLs (qFLA2 and qFLA8) for flag leaf angle were detected by both composite interval method in software WinQTLCart 2.5 and composite interval method based on mixed linear model in QTL Network 2.0. The qFLA2 explained 10.50% and 13.28% of phenotypic variation and was located at the interval of RM300 and RM145 on the short arm of chromosome 2. The qFLA8 explained 9.59% and 7.64% of phenotypic variation and was located at the interval flanking RM6215 and RM8265 on the long arm of chromosome 8. The positive alleles at the two QTLs were both contributed from A7444.

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Seed Priming Improves Agronomic Trait Performance under Flooding and Non-flooding Conditions in Rice with QTL SUB1 Ramni Kumar SARKAR 2012, 19(4): 286-294.  Abstract ( )   PDF (332KB) ( )   Farmers in South East Asia are adopting rice crop establishment methods from transplanting to direct wet or dry seeding as it requires less labour and time and comparatively less energy than transplanting. In contrast to irrigated condition, in rainfed lowland, direct seeding is a common practice. Early flooding controls weeds but decreases seedling establishment in direct seeded rice. Anaerobic germination is an important trait to counteract damages caused by early flooding. Management options which can help in crop establishment and improve crop growth under flooding might remove the constraints related to direct seeding. The investigation was carried out with two near isogenic lines Swarna and Swarna-Sub1. Swarna-Sub1 is tolerant to submergence whereas Swarna is susceptible. Seed priming was done with water and 2% Jamun (Syzygium cumini) leaf extract, and it improved seedling establishment under flooding. Acceleration of growth occurred due to seed pretreatment, which resulted longer seedling and greater accumulation of biomass. Seed priming greatly hastened the activities of total amylase and alcohol dehydrogenase in Swarna-Sub1 than in Swarna. Swarna-Sub1 outperformed Swarna when the plants were cultivated under flooding. Weed biomass decreased significantly under flooding compared to non-flooding conditions. Seed priming had positive effects on yield and yield attributing parameters both under non-flooding and early flooding conditions.

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Evaluation of Rice Seedling Tolerance to Constant and Intermittent Low Temperature Stress Sang-Ic KIM1, Dong-min KIM2, Thomas H. TAI1 2012, 19(4): 295-308.  Abstract ( )   PDF (492KB) ( )   M202, IR50 and advanced backcross (BC4F6) lines carrying the cold tolerance QTLs qCTS4 and qCTS12 were evaluated using three low temperature stress assays (constant, intermittent, and constant with recovery period). Under constant stress, two BC4F6 lines (MIb 4853-9 and MIb 6885-2) exhibited differences in seedling growth and accumulation of stress-related compounds although both carry the two QTLs in the IR50 background. Differences between these lines were also observed in the constant with recovery period assay, although both of them performed comparably under intermittent stress. MIb 6885-2 performed more similarly to M202 in the constant and constant with recovery period assays, suggesting that this line contains an introgressed region(s) not present in MIb 4853-9. The three assays were also applied to assess variation in cold tolerance in a set of diverse germplasms. Performance metrics and visual ratings were comparable for evaluating tolerance to constant stress. However, differences in response to intermittent stress were more evident from growth and total chlorophyll measurements than from visual ratings. With regard to the constant with recovery period assay, about 15% of the germplasm accessions did not recover. However, some lines which exhibited chilling injuries of comparable severity were able to overcome them. This recovery phenotype may improve rice performance in the field and warrant further investigation.

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Thermal Resistance of Common Rice Maintainer and Restorer Lines to High Temperature during Flowering and Early Grain Filling Stages FU Guan-fu, SONG Jian, XIONG Jie, LIAO Xi-yuan, ZHANG Xiu-fu, WANG Xi, LE Ming-kai,TAO Long-xing 2012, 19(4): 309-314.  Abstract ( )   PDF (242KB) ( )   Fifteen common rice maintainer lines and 26 high-yielding restorer lines were used to evaluate their thermal resistance and fertility during flowering and early grain filling stages. The rice plants were subjected to high temperature stress (39–43 oC) for 1–15 d from main stem flowering. Based on the heat stress index, they were divided into thermal resistant lines, semi-thermal resistant lines, semi-thermal sensitive lines and thermal sensitive lines. Therefore, the maintainer lines K22B, Bobai B and V20B belonged to thermal resistant lines, whereas II-32B, Zhongzhe B and Zhong 9B belonged to thermal sensitive lines. For rice restorer lines, Minghui 63 had the highest thermal resistance, followed by R207, P32, P929, and the lowest thermal resistant lines P62-2-2, R8006 and P51. The correlation analysis indicated that the heat stress index was significantly correlated with seed-setting rate and abortive grain rate under heat stress, but not under natural conditions. This indicated that heat stress occurred during flowering and early grain filling stages mainly decreased the seed- setting rate and significantly increased the abortive grain rate in both rice maintainer and restorer lines.

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Effects of Lodging at Different Filling Stages on Rice Yield and Grain Quality LANG You-zhong, YANG Xiao-dong, WANG Mei-e, ZHU Qing-sen 2012, 19(4): 315-319.  Abstract ( )   PDF (183KB) ( )   The effects of lodging of rice plants from 20 d after full heading to maturity on yield and grain quality were investigated with a hybrid rice combination Liangyoupeijiu and a japonica rice cultivar CY-6. The results showed that, except for brown rice rate, almost all parameters for yield and grain quality including ratio of grain length to grain width, gelatinization temperature and gel consistency, were significantly influenced by lodging and thus deteriorated. Regression analysis suggested that, lodging one day earlier at the grain-filling stage could cause 2.66% to 2.71% of yield loss, 1.8 to 2.6 percentage points decrease of seed-setting rate, 0.26 to 0.32 g reduction of 1000-grain weight, 0.097 to 0.155 percentage point decline of milled rice rate, as well as 0.13 to 0.27 percentage point increase of chalky grain rate, and 0.021 to 0.024 percentage point rise of protein content, and subsequently lower the eating quality.

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Virulence Types of Magnaporthe oryzae to Hybrid Rice in Sichuan, China BAI Yu-lian1,2, ZHANG Xue-mei1,3, FENG Hui1,3, JI Hong-li1, HUANG Yun2, PENG Yun-liang1,3 2012, 19(4): 320-326.  Abstract ( )   PDF (214KB) ( )   A total of 638 isolates of rice blast (Magnaporthe oryzae) were isolated in 2002–2009 from different rice varieties in different regions of Sichuan, China and inoculated onto seven rice varieties (Lijiangxintuanheigu, IR24, Minghui 63, Duohui 1, Chenghui 448, Neihui 99-14 and RHR-1) to differentiate the virulence types of the fungus and trace the changes. The virulence to the seven varieties was respectively scored at 1, 2, 4, 8, 16, 32 and 64. The total scores of individual M. grisea isolates which were the sum of scores infecting differential varieties could, in turn, be used for the nomenclature of the virulence types due to their accordance to the special virulence patterns. The 638 tested isolates were then differentiated into 56 different virulence types. Type 15 virulent to Lijiangxintuanheigu, IR24 and Minghui 63, and Type 127 virulent to all of the seven varieties were the most dominant virulence types respectively with the occurrence frequencies of 15.99% and 15.83%. Type 19 and other seven virulence types were not monitored during 2002–2009. Type 15 was the predominant virulence type in 2002, 2003, 2004 and 2007, whereas Type 127 had been the most dominant virulence type after 2005 except for the year 2007 when the province underwent severe drought. Five hundred and seven out of the 638 tested isolates were virulent to Minghui 63, and 89.58% of the 384 isolates virulent to either Duohui 1, Chenghui 448 or Neihui 99-14 were virulent to Minghui 63, which indicated the impact of the extensive plantation of hybrid rice Minghui 63 as the restorer line on the virulence evolution of M. oryzae in Sichuan. The virulence pattern of the dominant virulence types suggested that the acquiring of virulence to all the major resistant restorer lines was the main routes of the evolution in virulence of M. oryzae to hybrid rice in Sichuan. The virulence frequencies of the 638 tested isolates to IR24, Minghui 63, Duohui 1, Chenghui 448, Neihui 99-14 and RHR-1 were respectively 74.6%, 79.5%, 73.8%, 37.0%, 39.0% and 40.4%. The analysis for the sources of the different virulence type isolates indicated the pathogen on the newly released resistant varieties were stronger than conventional rice varieties which had become susceptible in the field since 1980s.

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Global Information Resources on Rice for Research and Development Shri RAM1, N. LAXMAN RAO2 2012, 19(4): 327-334.  Abstract ( )   PDF (286KB) ( )   Various issues concerning the progress of rice research are related to ambiguous germplasm identification, difficulty in tracing pedigree information, and lack of integration between genetic resources, characterization, breeding, evaluation and utilization data. These issues are the constraints in developing knowledge-intensive crop improvement programs. The rapid growth, development and the global spread of modern information and communication technology allow quick adoption in fundamental research. Thus, there is a need to provide an opportunity for the establishment of services which describe the rice information for better accessibility to information resources used by researchers to enhance the competitiveness. This work reviews some of available resources on rice bioinformatics and their roles in elucidating and propagating biological and genomic information in rice research. These reviews will also enable stakeholders to understand and adopt the change in research and development and share knowledge with the global community of agricultural scientists. The establishment like International Rice Information System, Rice Genome Research Project and Integrated Rice Genome Explorer are major initiatives for the improvement of rice. Creation of databases for comparative studies of rice and other cereals are major steps in further improvement of genetic compositions. This paper will also highlight some of the initiatives and organizations working in the field of rice improvement and explore the availability of the various web resources for the purpose of research and development of rice. We are developing a meta web server for integration of online resources such as databases, web servers and journals in the area of bioinformatics. This integrated platform, with acronym iBIRA, is available online at http://ibiranet.in. The resources reviewed here are the excerpts from the resources integrated in iBIRA.

Short Communication

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Ecological Fitness of Non-vector Planthopper Sogatella furcifera on Rice Plants Infected with Rice Black Streaked Dwarf Virus HE Xiao-chan1, 2, XU Hong-xing1, ZHENG Xu-song1, YANG Ya-jun1, GAO Guang-chun1,PAN Jian-hong1, LU Zhong-xian1 2012, 19(4): 335-338.  Abstract ( )   PDF (160KB) ( )   We evaluated the effects of rice black streak dwarf virus (RBSDV)-infested rice plants on the ecological parameters and its relevant defensive and detoxification enzymes of White-backed planthopper (WBPH) in laboratory for exploring the relationship between RBSDV and the non-vector planthopper. The results showed that nymph survival rate, female adult weight and fecundity, and egg hatchability of WBPH fed on RBSDV-infested rice plants did not markedly differ from those on healthy plants, while the female adult longevity and egg duration significantly shortened on diseased plants. Furthermore, significantly higher activities of defensive enzymes (dismutase, catalase and peroxidase) and detoxification enzymes (acetylcholinesterase, carboxylesterase and glutathione S-transferase) were found in WBPH adults fed on infected plants. Results implied that infestation by RBSDV increased the ecological fitness of non-vector planthopper population.