28 September 2013, Volume 20 Issue 5 Previous Issue    Next Issue

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    Research Paper
    Genetic Analysis and QTL Mapping of Mature Seed Culturability in Indica Rice
    TIAN Fu-kuan1, 2, #, RUAN Ban-pu1, 3, #, YAN Mei-xian1, YE Shi-fang1, PENG You-lin1, DONG Guo-jun1, ZHU Li1, HU Jiang1, YAN Hong-lan1, GUO Long-biao1, QIAN Qian1, GAO Zhen-yu1
    2013, 20(5): 313-319.  DOI: 10.1016/S1672-6308(13)60152-3
    Abstract ( )   PDF (433KB) ( )  

    Genetic segregation analysis for mature seed culturability was conducted using recombinant inbred lines derived from a cross of indica rice, Yangdao 6 and Pei’ai 64s. Three indices of seed culturability, the frequency of callus induction, the frequency of brown callus and the increase of callus weight were investigated. A combined genetic map constructed with simple sequence repeat (SSR), sequence tag site (STS), cleaved amplified polymorphic sequences (CAPS) and single nucleotide polymorphism (SNP) markers covered a total distance of 1 732.5 cM, averaging approximately 12 cM between two neighboring loci. Three QTLs on chromosomes 7, 7 and 10 were detected for the frequency of callus induction; three QTLs on chromosomes 6, 7 and 9 were detected for the frequency of brown callus; and two QTLs on chromosomes 5 and 7 were detected for the increase of callus weight. Common QTLs mapped at the interval flanking RM5481 and RM6835 on chromosome 7 were identified to be involved in the frequency of callus induction and the frequency of brown callus, explaining 7.29% and 12.52% of phenotypic variation, respectively. A total of 14 epistatic effects were detected for the three indices of mature seed culturability.

    Cloning and Expression of Gene Responsible for High-Tillering Dwarf Phenotype in Indica Rice Mutant gsor23
    YUAN Shou-jiang, WANG Tao, YIN Liang, ZHAO Jin-feng, WAN Jian-min, LI Xue-yong
    2013, 20(5): 320-328.  DOI: 10.1016/S1672-6308(13)60134-1
    Abstract ( )   PDF (374KB) ( )  

    High-tillering dwarf mutant gsor23 was generated from an indica rice variety Indica9 radiatied by γ-ray. Genetic analysis showed that this phenotype was controlled by one single recessive gene, which was mapped within a physical distance of 386 kb between two insertion-deletion (InDel) markers C1-WT2 and C1-WT4 on the long arm of chromosome 1. There is a known gene D10 within this region, the mutation of which causes high-tillering in rice. Sequence analysis of the D10 allele in gsor23 revealed that the base cytosine (C) at the 404th position in the coding region was deleted, which would cause frameshift mutation after the 134th amino acids. The mutation site and indica background of gsor23 were different from the previously reported japonica mutants d10-1 and d10-2. Therefore, gsor23 is a novel allelic mutant of D10 which encodes the carotenoid-cleaving dioxygenase 8 (CCD8), a key enzyme involved in the biosynthesis of the new plant hormone strigolactones (SLs). After treatment with GR24, a synthetic analogue of SLs, the high-tillering phenotype of gsor23 was restored to normal. Real-time RT-PCR analysis showed that D10 expression was high in roots, but low in leaves. Compared with the wild type Indica9, the expression of the SL biosynthesis gene D10 was upregulated, while genes likely involved in the SL signal transduction pathway such as D3 and D14 were down-regulated in the gsor23 mutant.

    Fine Mapping and Cloning of Leafy Head Mutant Gene pla1-5 in Rice
    FENG Gong-Neng, ZHANG Chang-Quan, ZHAO Dong-Sheng, ZHU Kong-Zhi, TU Huai-Zhou, XU Chen-Wu, LIU Qiao-Quan
    2013, 20(5): 329-335.  DOI: 10.1016/S1672-6308(13)60140-7
    Abstract ( )   PDF (449KB) ( )  

    We identified a leafy head mutant pla1-5 (plastochron 1-5) from the progeny of japonica rice cultivar Taipei 309 treated with 60Co-γ ray irradiation. The pla1-5 mutant has a dwarf phenotype and small leaves. Compared with its wild type, pla1-5 has more leaves and fewer tillers, and it fails to produce normal panicles at the maturity stage. Genetic analysis showed that the pla1-5 phenotype is controlled by a single recessive nuclear gene. Using the map-based cloning strategy, we narrowed down the location of the target gene to a 58-kb region between simple sequence repeat markers CHR1027 and CHR1030 on the long arm of chromosome 10. The target gene cosegregated with molecular markers CHR1028 and CHR1029. There were five predicted genes in the mapped region. The results from sequencing analysis revealed that there was one base deletion in the first exon of LOC_Os10g26340 encoding cytochrome P450 CYP78A11 in the pla1-5 mutant, which might result in a downstream frame shift and premature termination. These results suggest that the P450 CYP78A11 gene is the candidate gene of PLA1-5.

    Genetic Analysis and Molecular Mapping of Novel White Striped Leaf Mutant Gene in Rice
    SHENG Zhong-hua, WEI Xiang-jin, SHAO Gao-neng, SONG Jian, LUO Ju, HU Pei-song, TANG Shao-qing2, CHEN Li-yun
    2013, 20(5): 336-342.  DOI: 10.1016/S1672-6308(13)60142-0
    Abstract ( )   PDF (515KB) ( )  

    A new white striped leaf mutant wsl1 was discovered from Nipponbare mutated by ethyl methanesulfonate. The mutant showed white striped leaves at the seedling stage and the leaves gradually turned green after the tillering stage. The chlorophyll content of wsl1 was significantly lower than that of wild-type during the fourth leaf stage, tillering stage and booting stage. The numbers of chloroplast, grana and grana lamella were reduced and the thylakoids were degenerated in wsl1 compared with wild type. Genetic analysis showed that the wsl1 was controlled by a single recessive gene. Molecular mapping of the wsl1 was performed using an F2 population derived from wsl1/Nanjing 11. The wsl1 was finally mapped on the telomere region of chromosome 9 and positioned between simple sequence repeat markers RM23742 and RM23759 which are separated by approximately 486.5 kb. The results may facilitate map-based cloning of wsl1 and understanding of the molecular mechanism of the regulation of leaf-color by WSL1 in rice.

    High Temperature During Rice Grain Filling Enhances Aspartate Metabolism in Grains and Results in Accumulation of Aspartate-Family Amino Acids and Protein Components
    LIANG Cheng-gang, ZHANG Qing, XU Guang-li, WANG Yan, OHSUGI Ryu, LI Tian
    2013, 20(5): 343-348.  DOI: 10.1016/S1672-6308(13)60146-8
    Abstract ( )   PDF (206KB) ( )  

    Global warming causes the exacerbation of rice growing environment, which seriously affects rice growth and reproduction, and finally results in the decrease of rice yield and quality. We investigated the activities of aspartate metabolism enzymes in grains, and the contents of Aspartate-family amino acids and protein components to further understand the effects of high temperature (HT) on rice nutritional quality during rice grain filling. Under HT, the average activities of aspartate aminotransferase (AAT) and aspartokinase (AK) in grains significantly increased, the amino acid contents of aspartate (Asp), lysine (Lys), threonine (Thr), methionine (Met) and isoleucine (Ile) and the protein contents of albumin, globulin, prolamin and glutelin also significantly increased. The results indicated that HT enhanced Asp metabolism during rice grain filling and the enhancement of Asp metabolism might play an important role in the increase of Asp-family amino acids and protein components in grains. In case of the partial appraisal of the change of Asp-family amino acids and protein components under HT, we introduced eight indicators (amino acid or protein content, ratio of amino acid or protein, amino acid or protein content per grain and amino acid or protein content per panicle) to estimate the effects of HT. It is suggested that HT during rice grain filling was benefit for the accumulation of Asp-family amino acids and protein components. Combined with the improvement of Asp-family amino acid ratio in grains under HT, it is suggested that HT during grain filling may improve the rice nutritional quality. However, the yields of parts of Asp-family amino acids and protein components were decreased under HT during rice grain filling.

    Foliar Application of Benzothiadiazole and Salicylic Acid to Combat Sheath Blight Disease of Rice
    Neerja SOOD, B. S. SOHAL, J. S. LORE
    2013, 20(5): 349-355.  DOI: 10.1016/S1672-6308(13)60155-9
    Abstract ( )   PDF (271KB) ( )  

    A field study was undertaken to ascertain the effects of elicitors viz. benzothiadiazole (BTH) and salicylic acid (SA) on defense related enzymes viz. peroxidase, phenylalanine ammonia lyase, superoxide dismutase, chitinase and β-1,3-glucanase, and phenols in rice (Pusa Basmati I) plants. First foliar spray of BTH (50 mg/kg) and SA (50 mg/kg) was done at the maximum tillering stage and inoculation with Rhizoctonia solani was carried 24 h after elicitor treatment. Elicitors were further sprayed at every growth stage. Time course analysis showed peak accumulation of defense related enzymes and phenols in the rice leaves treated with BTH and SA, and accumulation was the highest at the flowering stage. Higher enzymatic activity was observed in elicitor treated plants inoculated with R. solani. Compared to the untreated control plants, application of elicitors before R. solani inoculation significantly elicited the defense related enzymes and phenols. Moreover, application of elicitors had a positive effect on yield and disease reduction. It is suggested that pretreatment of rice leaves with BTH and SA could be used to enhance the level of protection against sheath blight and to improve rice yield in the fields.

    Rhizosphere Bacteria for Biocontrol of Bacterial Blight and Growth Promotion of Rice
    2013, 20(5): 356-362.  DOI: 10.1016/S1672-6308(13)60143-2
    Abstract ( )   PDF (338KB) ( )  

    Several bacterial strains were isolated from different rhizospheres. Among these, strain PDY7 exhibited strong antibacterial activity against the rice bacterial blight (BB) pathogen Xanthomonas oryzae pv. oryzae (Xoo) by the laboratory dual plate assays. The antibacterial property of the strain PDY7 was further investigated for the production of 2,4-diacetylphloroglucinol (DAPG), which amplified a characteristic of 629-bp DNA fragment by PCR-based screening method using phlD primers. The application of phlD positive strains was carefully evaluated for disease control and growth promotion of rice plants under field conditions. The selected strain PDY7 suppressed the rice BB by 58.83% and 51.88% under glass house and field conditions, respectively. In addition, the strain PDY7 showed significant two-fold increase in root length (18.08 cm), shoot length (29.81 cm), and grain yield (96.07 g). Strain PDY7 promoted the growth of rice plants by production of indole-3-acetic acid (IAA), which was determined by high performance liquid chromatography (HPLC) analysis. Our findings suggest that PDY7 belongs to the P. fluorescens group and can serve as potential biocontrol of BB as well as biofertilizer agent for growth promotion of rice.

    Defensive Responses of Rice Genotypes for Resistance Against Rice Leaffolder Cnaphalocrocis medinalis
    2013, 20(5): 363-370.  DOI: 10.1016/S1672-6308(13)60149-3
    Abstract ( )   PDF (265KB) ( )  

    The experiment was carried out to assess the reaction of different categories of rice genotypes viz., resistant, susceptible, hybrid, scented, popular and wild in response to the infestation by rice leaffolder (RLF), Cnaphalocrocis medinalis (Guenee) and to explore the possible use of these genotypes in developing RLF-resistant rice varieties. The changes of various biochemical constituents such as leaf soluble protein, phenol, ortho-dihydroxy phenol, tannin and enzymes viz., peroxidase, phenyl alanine ammonia lyase (PAL) were assessed spectrophotometrically in all the rice genotypes before and after RLF infestation. The protein profile was analyzed using sodium dodecyl sulphate-poly acrylamide gel electrophoresis (SDS-PAGE) method. A significant constituent of biochemical content such as tannin, phenol and ortho-dihydroxy phenol has been increased along with enzyme activities of peroxidase and PAL in the infested resistant (Ptb 33, TKM6 and LFR831311) and wild rice genotypes (Oryza minuta and O. rhizomatis). A decrease in leaf protein content was evident invariably in all the infested rice genotypes. It is also evident that the contents of biochemicals such as phenol, ortho-dihydroxy phenol and tannin were negatively correlated with leaffolder damage. However, leaf protein content was positively correlated with the damage by rice leaffolder. SDS-PAGE analysis for total protein profiling of healthy and C. medinalis-infested genotypes revealed the enhanced expression of a high molecular weight (> 97 kDa) protein in all the genotypes. Besides, there was also an increased induction of a 38 kDa protein in C. medinalis infested resistant genotypes, which was absent in uninfested plants. The present investigation proved that the elevated levels of biochemicals and enzymes may play a vital role in rice plants resistance to RLF.

    Susceptibility of Different Populations of Nilaparvata lugens from Major Rice Growing Areas of Karnataka, India to Different Groups of Insecticides
    2013, 20(5): 371-378.  DOI: 10.1016/S1672-6308(13)60147-X
    Abstract ( )   PDF (247KB) ( )  

    Susceptibility to insecticides was investigated by collecting field populations of brown planthopper from different locations of southern Karnataka, India (Gangavati, Kathalagere, Kollegala, Soraba and Mandya). All the field populations differed in their susceptibility to insecticides. In general, Soraba and Mandya populations were more susceptible to insecticides compared to Gangavati and Kathalagere populations. The resistance ratios varied greatly among the populations viz., chlorpyriphos (1.13- to 16.82-fold), imidacloprid (0.53- to 13.50-fold), acephate (1.34- to 5.32-fold), fipronil (1.13- to 4.06-fold), thiamethoxam (1.01- to 2.19-fold), clothianidin (1.92- to 4.86-fold), dinotefuran (0.82- to 2.22-fold), buprofezin (1.06- to 5.43-fold) and carbofuran (0.41- to 2.17-fold). The populations from Gangavati, Kathalagere and Kollegala exhibited higher resistance to some of the old insecticides and low resistance to new molecules.

    Short Communication
    Development of Novel Cytoplasmic Male Sterile Source from Dongxiang Wild Rice (Oryza rufipogon)
    SHEN Xian-hua, YAN Song, HUANG Ren-liang, ZHU Shan, XIONG Hong-liang, SHEN Lin-jun
    2013, 20(5): 379-382.  DOI: 10.1016/S1672-6308(13)60145-6
    Abstract ( )   PDF (254KB) ( )  

    This study was conducted to develop and characterize a novel cytoplasmic male sterile (CMS) source which was identified from Dongxiang wild rice (Oryza rufipogon) by crossing Dongxiang wild rice as female with Zhongzao 35, an indica inbred variety, as male and continuous backcrossing with Zhongzao 35. Observation under optical microscope manifested that this novel CMS belonged to typical abortion type with less pollen compared with wild abortive type cytoplasm (CMS-WA). Sequential planting showed that this novel CMS has complete and stable male sterility. Testcross experiment showed that all the 24 tested materials including maintainer and restorer lines of CMS-WA and Honglian type cytoplasm (CMS-HL) and other indica inbred varieties are the maintainers with complete maintaining ability, suggesting that this novel CMS has fertility restoration totally different from CMS-WA and CMS-HL and belongs to a novel type of CMS. So far, we only discovered a unique fertility restoration source for this novel CMS. Inheritance analysis showed that the fertility restoration of this CMS was governed by three pairs of independent dominant genes. Prospect for application of this novel CMS system in hybrid rice breeding was also discussed.